Hip Arthroplasty
Number: 0287
Table Of Contents
PolicyApplicable CPT / HCPCS / ICD-10 Codes
Background
References
Policy
Scope of Policy
This Clinical Policy Bulletin addresses hip arthroplasty.
Note: Precertification may be required for select procedures and interventions. Use the CPT code search tool to see if precertification is required.
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Medical Necessity
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Aetna considers an Food and Drug Administration (FDA)-approved metal-on-metal, metal-on-plastic, ceramic-on-plastic, or ceramic-on-ceramic total hip arthroplasty (THA) prosthesis medically necessary for adult members when the following criteria are met:
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Member has advanced joint disease demonstrated by:
- Pain and functional disability that interferes with activities of daily living (ADLs) from injury due to osteoarthritis, rheumatoid arthritis, avascular necrosis, or post-traumatic arthritis of the hip joint; and
- Limited range of motion (ROM), antalgic gait, and pain in hip joint with passive ROM on physical examination: and
- Radiographic evidence of either of the following:
- Avascular necrosis (osteonecrosis) with stage II or III disease; or
- Moderate/severe osteoarthritis or rheumatoid arthritis of the hip joint (Tonnis grade 2 or 3; see Appendix for Tonnis grading scale); and
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History of unsuccessful conservative therapy (non-surgical medical management; 12 or 24 weeks depending on age/BMI) that is clearly addressed in the medical record with at least half of the necessary conservative therapy consisting of formal physical therapy (in-person with a licensed physical therapist as opposed to home or virtual physical therapy) in the past year Footnote1*. Physical therapy needs to be confirmed either by the actual PT notes, or by documentation in the member claims history. If conservative therapy is not appropriate (such as for progressive flexion contracture, avascular necrosis with collapse of the femoral head, or bone on bone arthritis in the weight-bearing portion of the joint for example), the medical record must clearly document why such approach is not reasonable; or
- Fracture of the femoral neck by imaging; or
- Malunion of acetabular, femoral head or proximal femur fracture with pain interfering with ADLs; or
- Nonunion by imaging or failure of previous hip fracture surgery; or
- Malignancy of the joint involving the bones or soft tissues of the pelvis or proximal femur by imaging;
Footnote1*Note: Members with osteoarthritis, traumatic arthritis, rheumatoid arthritis, or avascular necrosis should have at least 12 weeks of non-surgical treatment documented in the medical record (at least 24 weeks for persons with a relative contraindicationFootnote2**), including all of the following, unless contraindicated:
- Anti-inflammatory medications or analgesics; and
- Flexibility and muscle strengthening exercises, and
- Activity modification; and
- Supervised physical therapy (in-person with a licensed physical therapist as opposed to home or virtual physical therapy; ADLs diminished despite completing a plan of care). Physical therapy needs to be confirmed either by the actual PT notes, or by documentation in the member claims history; and
- Assistive device use (required for persons with relative contraindicationsFootnote2** to joint replacement, optional for others); and
- Therapeutic injections into the hip (required for persons with relative contraindications Footnote2** to joint replacement, optional for others); or
Footnote2** Relative contraindications to joint replacement include the following: morbid obesity (body mass index (BMI) greater than 40), age less than 50 years). Persons with relative contraindications should exhaust all non-surgical treatment options.
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Total joint replacement is considered not medically necessary in persons with any of the following absolute contraindications:
- Active infection of the joint or active systemic bacteremia that has not been totally eradicated; or
- Active skin infection (exception recurrent cutaneous staph infections) or open wound within the planned surgical site of the hip; or
- Allergy to components of the implant (e.g., cobalt, chromium or alumina); or
- Corticosteroid injection into the joint within 12 weeks of the planned arthroplasty; or
- Paraplegia or quadriplegia; or
- Permanent or irreversible muscle weakness in the absence of pain that prevents ambulation; or
- Rapidly progressive neurological disease except in the clinical situation of a concomitant displaced femoral neck fracture; or
- Skeletal immaturity; or
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For persons with significant conditions or co-morbidities, the risk/benefit of THA should be appropriately addressed in the medical record.
Aetna considers THA experimental, investigational, or unproven for all other indications because of insufficient evidence of effectiveness.
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Revision or replacement of a THA or hip resurfacing arthroplasty is considered medically necessary when accompanied by pain and functional disability (interference with ADLs) when the following criteria are met:
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Member has one or more of the following indications for revision or replacement:
- Aseptic loosening of one or more prosthetic components confirmed by imaging, or
- Fracture or mechanical failure of 1 or more components of the prosthesis confirmed by imaging, or
- Confirmed periprosthetic infection confirmed by gram stain and culture (Note: A single stage revision is considered medically necessary for this indication, unless there has been a prior infection in the same joint, in which case a multi-stage revision may be considered medically necessary), or
- Displaced periprosthetic fracture confirmed by imaging, or
- Progressive or substantial periprosthetic bone loss confirmed by imaging, or
- Bearing surface wear leading to symptomatic synovitis or local bone or soft tissue reactionFootnote3***, or
- Recurrent (2 or more) dislocations confirmed by imaging not responsive to a reasonable course of conservative management or irreducible dislocation confirmed by imaging; or
- Clinically significant leg length discrepancy; and
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The member does not have any of the following contraindications to total hip revision or replacement:
- Loss of musculature (in particular hip abductor musculature), neuromuscular compromise or vascular deficiency in the affected limb, rendering the procedure unjustifiable; or
- Osteoporosis or other osseous abnormalities which would make the likelihood of a poor outcome more probable; or
- Poor skin coverage; or
- Severe instability due to anatomic causes that would make the likelihood of a poor surgical outcome more probable.
Aetna considers a revision or replacement of a THA or hip resurfacing experimental, investigational, or unproven when criteria are not met.
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Aetna considers the following medically necessary:
- FDA-approved custom-made implant for Paprosky type III acetabular defects where the feature of the defect cannot be handled with standard implants, and member meets criteria for revision total hip arthroplasty listed above;
- Iliopsoas tenotomy (or lengthening) by any surgical approach for iliopsoas tendinopathy following total hip arthroplasty with the failure of at least 6 weeks of formal in-person physical therapy in the past year, and at least 1 therapeutic injection (steroid with or without local anesthetic) with significant but temporary benefit in the past 6 months;
- Minimal incision or minimally invasive THA an acceptable alternative to conventional THA;
- Prophylactic use of tranexamic acid in total hip arthroplasty to decrease blood loss.
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Experimental, Investigational, or Unproven
The following are considered experimental, investigational, or unproven because the effectiveness of the approach has not been established:
- Augmented or virtual reality (AR/VR) assistance for hip arthroplasty
- Computer-assisted surgical navigation (e.g., MAKOplasty/MAKO Tactile Guidance System) for total hip replacement (THR) because there is a lack of reliable evidence that it improves clinical outcomes of THA Note: Robotic assistance is considered integral to the procedure and not separately reimbursed
- Custom joint implants and/or instrumentation
- Measurement of synovial C-reactive protein, and the alpha-defensin test (Synovasure) as a marker for peri-prosthetic infection in THA
- Obturator nerve blocks for management of post-operative pain following THA
- Pre-operative advanced imaging that is required for any experimental, investigational, or unproven procedure (e.g., where required for computer-assisted surgical navigation, robotic-assisted surgical navigation, or for customized patient implants and/or instrumentation)
- The use of a portable accelerometer-based navigation system because its clinical value has not been established. See also CPB 0710 - Actigraphy and Accelerometry.
Footnote3*** Aetna considers removal and revision surgery due to post-THR metallosis alone, without evidence of loosening or malposition, experimental, investigational, or unproven because there is insufficient clinical evidence in the published peer-reviewed medical literature.
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Related CMS Coverage Guidance
This Clinical Policy Bulletin (CPB) supplements but does not replace, modify, or supersede existing Medicare Regulations or applicable National Coverage Determinations (NCDs) or Local Coverage Determinations (LCDs). The supplemental medical necessity criteria in this CPB further define those indications for services that are proven safe and effective where those indications are not fully established in applicable NCDs and LCDs. These supplemental medical necessity criteria are based upon evidence-based guidelines and clinical studies in the peer-reviewed published medical literature. The background section of this CPB includes an explanation of the rationale that supports adoption of the medical necessity criteria and a summary of evidence that was considered during the development of the CPB; the reference section includes a list of the sources of such evidence. While there is a possible risk of reduced or delayed care with any coverage criteria, Aetna believes that the benefits of these criteria – ensuring patients receive services that are appropriate, safe, and effective – substantially outweigh any clinical harms.
This CPB is being used to supplement Medicare LCDs on hip arthroplasty (Total Joint (Hip/Knee) – LCD L33456, LCD L33618, LCD L36007, LCD L36039; Total Hip – LCD L34163, LCD L36573). This CPB is used to define appropriate conservative therapy (non-surgical medical management), as some patients may respond to conservative therapy (see, e.g., Conley, et al., 2023; Fernandes, et al., 2013; Fransen, et al., 2014; Goh, et al., 2019; Sampath, et al., 2016; Sasaki, et al., 2022), avoiding the need for surgery and its inherent risks (see, e.g., Agodi, et al., 2017; Dale, et al., 2011; Davidson, et al., 2008; DeHart, et al., 1999; Desai, et al., 2013; Gundtoft, et al., 2015; Januel, et al., 2002; Lieberman, et al., 2017; Lindeque, et al., 2014; Morrey, et al., 1997; Pinson, et al., 2014; Saleh, et al., 2002; Schmalzried, et al., 1997; Sharma, et al., 2003). We believe the clinical benefits of avoiding unnecessary and potentially harmful care outweighs any potential risks in delayed or reduced access to care.
Code of Federal Regulations (CFR):
42 CFR 417; 42 CFR 422; 42 CFR 423.
Internet-Only Manual (IOM) Citations:
CMS IOM Publication 100-02, Medicare Benefit Policy Manual; CMS IOM Publication 100-03 Medicare National Coverage Determination Manual.
Medicare Coverage Determinations:
Centers for Medicare & Medicaid Services (CMS), Medicare Coverage Database [Internet]. Baltimore, MD: CMS; updated periodically. Available at: Medicare Coverage Center. Accessed November 7, 2023.
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Related Policies
Background
Previously, most total hip prostheses utilize an acetabular cup either lined with polyethylene or composed entirely of polyethylene articulating against a cobalt-chromium-molybdenum (CoCr) or ceramic femoral head. Serious problems affecting the outcome of total joint replacement with these types of prostheses have been extensive and progressive peri-prosthetic osteolysis and aseptic loosening, which may result in revision, even though the components are still well fixed and functioning. Polyethylene particulate debris generated from metal-on-polyethylene bearing surfaces and the resulting biologic response to this debris are thought to be largely responsible.
In recent years, there has been renewed interest in metal-on-metal bearing surfaces for total joint arthroplasty. This is especially true in younger and more active patients who face the possibility of multiple revision procedures during their lifetime. In the long-term, the second-generation all-metal prostheses have demonstrated lower friction and wear rates than metal-on-polyethylene bearing surfaces. Recent studies reported that the second-generation metal-on-metal hip replacement prostheses exhibit a lower rate of acetabular revision and loosening than did those with previous metal-on-metal designs and that they had no more acetabular loosening or osteolysis than did those with metal-on-polyethylene articulations for follow-up periods of 5 to 10 years.
Another alternative to standard polyethylene is alumina-on-alumina ceramic. When comparing hard-on-hard bearings, the ceramic-on-ceramic coupling has several theoretical advantages over metal-on-metal. Because of the ceramic's extremely low coefficient of friction and its potential for superior wear resistance, these couples promise both wear rates that are appreciably less than polyethylene-on-metal and metal-on-metal couples.
Available literature indicates that alumina-on-alumina ceramic couplings are a viable alternative to metal-on-polyethylene designs. The combination of new high quality ceramic acetabular and femoral bearing heads with hip systems that have achieved long-term stable fixation can result in a substantial increase in the longevity of fixation for implants especially in the younger and more active patients.
Available studies of metal-on-metal and ceramic-on-ceramic total hip implants primarily involve cohorts of younger, more active patients. The chief advantage of these hip implants over standard metal-on-polyethylene hip implants is their greater longevity. There is no adequate evidence that metal-on-metal or ceramic-on-ceramic total hip implants offer clinically significant benefits over standard metal-on-polyethylene hip implants for older patients.
Bhandari et al (2005) reported a meta-analysis of 6 randomized controlled studies suggested that bisphosphonates have a beneficial effect with regard to maintaining more peri-prosthetic bone mineral density than that in controls. However, the limitations of the available studies and the lack of analyses of clinically relevant outcomes (e.g., functional outcomes, revision rates, and quality of life) necessitate the planning and conduct of a sufficiently sized, methodologically sound trial with clinically relevant end points. Until this has been done, the current evidence regarding the beneficial effects of bisphosphonates on peri-prosthetic bone following total joint (e.g., knee and hip) arthroplasty should be interpreted with caution.
A technology assessment of hip implants by the Institute for Clinical Effectiveness and Health Policy (Augustovsky et al, 2006) found that the clinical trials comparing ceramic against conventional prostheses found no significant differences in the revision rate among the different types of prostheses. In case series of patients with the ceramic prosthesis, reported revision rates at 10 years were less than 10 %, which is considered within acceptable limits and comparable to those reported for conventional prostheses. Similar results have been reported for metal-on-metal hip prostheses, where randomized controlled trials with follow-up up to 5 years found no differences between metal-on-metal and conventional prostheses in effectiveness and complication rates (Augustovsky et al, 2006). The assessment noted that, although there are some reports of an increase in cancer in persons with metal-on-metal hip prostheses, there are other reports evaluating metal-on-metal prostheses with follow-up up to 28 years that have found no increase in the incidence of any cancer. The assessment stated that no study comparing ceramic prosthesis with metal-on metal prosthesis was found. The assessment concluded that, although interim results with both the ceramic and metal-on-metal prostheses are promising, available studies have found no significant differences in revision rates during follow-up periods of 10 to 15 years. The assessment stated that, because the advantages of these materials may be observed at longer terms, their potential benefits would be greatest for younger patients (under 50 years of age) (Augustovsky et al, 2006).
In a meta-analysis, Smith and colleagues (2010) compared the clinical and radiological outcomes and complication rates of hip resurfacing (HRS) and total hip arthroplasty (THA). A systematic review was undertaken of all published (Medline, CINAHL, AMED, EMBASE) and unpublished or gray literature research databases up to January 2010. Clinical and radiological outcomes as well as complications of HRS were compared to those of THA using risk ratio, mean difference, and standardized mean difference statistics. Studies were critically appraised using the CASP appraisal tool. A total of 46 studies were identified from 1,124 citations. These included 3,799 HRSs and 3,282 THAs. On meta-analysis, functional outcomes for subjects following HRS were better than or the same as for subjects with a THA, but there were statistically significantly greater incidences of heterotopic ossification, aseptic loosening, and revision surgery with HRS compared to THA. The evidence base showed a number of methodological inadequacies such as the limited use of power calculations and poor or absent blinding of both patients and assessors, possibly giving rise to assessor bias. The authors concluded that on the basis of the current evidence base, HRS may have better functional outcomes than THA, but the increased risks of heterotopic ossification, aseptic loosening, and revision surgery following HRS indicate that THA is superior in terms of implant survival.
Garbuz and associates (2010) conducted a prospective randomized clinical trial to compare clinical outcomes of resurfacing versus large-head metal-on-metal THA. These researchers randomized 107 patients deemed eligible for resurfacing arthroplasty to have either resurfacing or standard THA. Patients were assessed for quality-of-life outcomes using the PAT-5D index, WOMAC, SF-36, and UCLA activity score. The minimum follow-up was 0.8 years (mean of 1.1 years; range of 0.8 to 2.2 years). Of the 73 patients followed at least 1 year, both groups reported improvement in quality of life on all outcome measures. There was no difference in quality of life between the 2 arms in the study. Serum levels of cobalt and chromium were measured in a subset of 30 patients. In both groups cobalt and chromium was elevated compared to baseline. Patients receiving a large-head metal-on-metal total hip had elevated ion levels compared to the resurfacing arm of the study. At 1 year, the median serum cobalt increased 46-fold from baseline in patients in the large-head total hip group, while the median serum chromium increased 10-fold. At 1 year, serum cobalt was 10-fold higher and serum chromium 2.6-fold higher than in the resurfacing arm. Due to these excessively high metal ion levels, the authors recommended against further use of this particular large-head THA.
Kim and colleagues (2013) stated that the timing of total hip replacement (THR) in patients with active tuberculosis (TB) of the hip is controversial, because of the potential risk of re-activation of infection. There is little information about the outcome of THR in these patients. These investigators performed a systematic review of published studies that evaluated the outcome of THR in patients with active TB of the hip. A review of multiple databases referenced articles published between 1950 and 2012 was carried out. A total of 6 articles were identified, comprising 65 patients. Tuberculosis was confirmed histologically in all patients. The mean follow-up was 53.2 months (range of 24 to 108). Anti-TB treatment continued post-operatively for between 6 and 15 months, after debridement and THR. One non-compliant patient had re-activation of infection. At the final follow-up the mean Harris hip score was 91.7 (range of 56 to 98). The authors concluded that THR in patients with active TB of the hip is a safe procedure, providing symptomatic relief and functional improvement if undertaken in association with extensive debridement and appropriate anti-TB treatment.
In a multi-center randomized, controlled trial with a non-inferiority design based on a minimal clinically important difference of 2.0 %, Anderson et al (2013) compared extended prophylaxis with aspirin and dalteparin for prevention of symptomatic venous thrombo-embolism (VTE) after THA. Randomization was electronically generated; patients were assigned to a treatment group through a Web-based program. Patients, physicians, study coordinators, health care team members, outcome adjudicators, and data analysts were blinded to interventions. The setting of this study was 12 tertiary care orthopedic referral centers in Canada; and a total of 778 patients who had elective unilateral THA between 2007 and 2010 were enrolled. After an initial 10 days of dalteparin prophylaxis after elective THA, patients were randomly assigned to 28 days of dalteparin (n = 400) or aspirin (n = 386). Main outcome measures were symptomatic VTE confirmed by objective testing (primary efficacy outcome) and bleeding. Five of 398 patients (1.3 %) randomly assigned to dalteparin and 1 of 380 (0.3 %) randomly assigned to aspirin had VTE (absolute difference, 1.0 percentage point [95 % confidence interval [CI]: -0.5 to 2.5 percentage points]). Aspirin was non-inferior (p < 0.001) but not superior (p = 0.22) to dalteparin. Clinically significant bleeding occurred in 5 patients (1.3 %) receiving dalteparin and 2 (0.5 %) receiving aspirin. The absolute between-group difference in a composite of all VTE and clinically significant bleeding events was 1.7 percentage points (CI: -0.3 to 3.8 percentage points; p = 0.091) in favor of aspirin. The authors concluded that extended prophylaxis for 28 days with aspirin was non-inferior to and as safe as dalteparin for the prevention of VTE after THA in patients who initially received dalteparin for 10 days. Given its low cost and greater convenience, aspirin may be considered a reasonable alternative for extended thrombo-prophylaxis following THA.
An UpToDate review on "Total hip arthroplasty" (Erens et al, 2014) states that: "Contraindications -- Total hip arthroplasty (THA) should not be undertaken in a number of clinical settings, including:
- Active infection (local or systemic)
- Preexisting significant medical problems (e.g., recent myocardial infarction, unstable angina, heart failure, or severe anemia)
- Skeletal immaturity
- Paraplegia or quadriplegia
- Permanent or irreversible muscle weakness in the absence of pain.
Relative contraindications include a neuropathic (Charcot) joint, inability to ambulate that is not related to the hip disorder per se, absence of hip abductor muscle mass, progressive neurologic loss, and morbid obesity. However, the effects of obesity on outcome remain uncertain. Most studies do show an increased risk of infection, particularly in the highly obese. This must be weighed against the fact that some morbidly obese patients can have significant improvement postoperatively. A 2011 study from Canada noted that patients with morbid obesity can experience substantial benefit, despite a very small but statistically significant increase in the need for revision due to septic complications. Other studies have emphasized the increased risk of both superficial and deep infections and have described an increased risk of dislocation in such patients."
Omar et al (2015) examined the role of synovial C-reactive protein (CRP) in the diagnosis of chronic peri-prosthetic hip infection. These researchers prospectively collected synovial fluid from 89 patients undergoing revision hip arthroplasty and measured synovial CRP, serum CRP, erythrocyte sedimentation rate (ESR), synovial white blood cell (WBC) count and synovial percentages of polymorphonuclear neutrophils (PMN). Patients were classified as septic or aseptic by means of clinical, microbiological, serum and synovial fluid findings. The high viscosity of the synovial fluid precluded the analyses in 9 patients permitting the results in 80 patients to be studied. There was a significant difference in synovial CRP levels between the septic (n = 21) and the aseptic (n = 59) cohort. According to the receiver operating characteristic curve, a synovial CRP threshold of 2.5 mg/L had a sensitivity of 95.5 % and specificity of 93.3 %. The area under the curve was 0.96. Compared with serum CRP and ESR, synovial CRP showed a high diagnostic value. The authors concluded that according to these preliminary results, synovial CRP may be a useful parameter in diagnosing chronic peri-prosthetic hip infection.
Furthermore, an UpToDate review on "Total hip arthroplasty" (Erens et al, 2014) does not mention the use of synovial CRP as a post-operative management tool.
MAKOplasty/MAKO Tactile Guidance System
Lewinnek et al (1978) noted that in a series of 300 total hip replacements, 9 (3 %) dislocated. Precise measurements of the orientation of the acetabular cup were made and it was found that anterior dislocations were associated with increased acetabular-component anteversion. There was no significant correlation between cup-orientation angle and posterior dislocation. The dislocation rate for cup orientation with anteversion of 15 +/- 10 degrees and lateral opening of 40 +/- 10 degrees was 1.5 %, while outside this "safe" range the dislocation rate was 6.1 %. Other factors that were documented include time after surgery (with the greatest risk in the first 30 days) and surgical history (with a greater risk in hips that have had prior surgery). This study provided no clinical data on the MAKO total hip arthroplasty (THA) System.
Werner and colleagues (2014) stated that in comparison with standard surgical techniques robotic-assisted surgery has the advantages of increased surgical accuracy, reproducibility, optimization of component position, and improved patient outcomes in unicompartmental knee arthroplasty (UKA) and THA procedures. The MAKO Tactile Guidance System (TGS; MAKO Surgical Corp, Fort Lauderdale, FL) facilitates robotic-assisted arthroplasty procedures currently implemented in many operating rooms. The benefits of this technology are evident, but have not been shown to improve patient outcomes and justify the added financial burden imposed. The authors concluded that further research is needed to determine if this technological advancement will translate into improvements in longevity and clinical outcomes.
Domb et al (2014) compared THA with a robotic-assisted posterior approach with manual alignment techniques through a posterior approach, using a matched-pair controlled study design, to assess whether the use of the robot made it more likely for the acetabular cup to be positioned in the safe zones described by Lewinnek et al and Callanan et al. Between September 2008 and September 2012, a total of 160 THAs were performed by the senior surgeon; 62 patients (38.8 %) underwent THA using a conventional posterior approach, 69 (43.1 %) underwent robotic-assisted THA using the posterior approach, and 29 (18.1 %) underwent radiographic-guided anterior-approach THAs. From September 2008 to June 2011, all patients were offered anterior or posterior approaches regardless of bone mass index (BMI) and anatomy. Since introduction of the robot in June 2011, all THAs were performed using the robotic technique through the posterior approach, unless a patient specifically requested otherwise. The radiographic cup positioning of the robotic-assisted THAs was compared with a matched-pair control group of conventional THAs performed by the same surgeon through the same posterior approach. The safe zone (inclination, 30° to 50°; ante-version, 5° to 25°) described by Lewinnek et al and the modified safe zone (inclination, 30° to 45°; ante-version, 5° to 25°) of Callanan et al were used for cup placement assessment. Matching criteria were gender, age ± 5 years, and (BMI) ± 7 units. After exclusions, a total of 50 THAs were included in each group. Strong inter-observer and intra-observer correlations were found for all radiographic measurements (r > 0.82; p < 0.001). One hundred percent (50/50) of the robotic-assisted THAs were within the safe zone described by Lewinnek et al compared with 80 % (40/50) of the conventional THAs (p = 0.001); 92 % (46/50) of robotic-assisted THAs were within the modified safe zone described by Callanan et al compared with 62 % (31/50) of conventional THAs (p = 0.001). The odds ratios for an implanted cup out of the safe zones of Lewinnek et al and Callanan et al were zero and 0.142, respectively (95 % CI: 0.044 to 0.457). The authors concluded that use of the robot allowed for improvement in placement of the cup in both safe zones, an important parameter that plays a significant role in long-term success of THA. However, whether the radiographic improvements that were observed would translate into clinical benefits for patients (e.g., acetabular wear, prosthetic dislocations, reductions in component impingement, and improved longevity) remains unproven.
Elmallah and associates (2015) stated that complications following THA (e.g., dislocation, component loosening and wear) continue to be common indications for revision surgery. Multiple studies have attributed some of these problems to poor acetabular cup alignment and placement outside of the purported radiographic safe zone. In addition, it has been shown that conventional manually performed acetabular cup placement may not lead to optimal alignment, regardless of surgical experience. Additionally, incorrect leg length and offset can lead to dissatisfaction and instability. Therefore, robotic-arm assisted surgery has been introduced to improve accuracy of cup placement and leg length, and to offset with the aim of reducing the risk of hip instability and improving satisfaction after primary THA. These investigators reviewed the use of robotic-arm assisted surgery in 224 patients and examined if pre-operatively determined radiographic targets were achieved post-operatively and the proportion of acetabular cups outside of the safe zone. Pre-determined ante-version and inclination were 15 and 40 degrees, respectively. Results have shown that the use of robotic-arm assisted surgery resulted in a post-operative mean inclination of 40 degrees (range of 34 to 51 degrees) and a mean ante-version of 16 degrees (range of 9 to 25 degrees); 99 % of the patients remained within the pre-designated safe zone. Evidence has shown that robotic-arm assisted surgery may have improved accuracy in cup placement when compared to conventional surgery and possibly to computer-assisted surgery. The authors concluded that when compared to the literature on robotic-arm assisted surgery, thee findings were comparable. They believed that this surgical technique may aid in reducing post-operative THA complications (e.g., aseptic loosening and dislocations); but further prospective studies are needed to evaluate clinical outcomes and long-term results.
Banerjee et al (2016) stated that precise and accurate biomechanical reconstruction during THA is essential for durable long-term survivorship. Accurate fit of cementless hip implants is also crucial to reduce micro-motion between the bone-implant interfaces to allow for stable osseointegration. Robotic technology aims to minimize potential human errors and improve implant alignment and fit, and address persisting concerns with modern-day cementless THA. Although robotic THA dated back to the early 1990s, concerns with increased operating times, costs, and complications led to its withdrawal. However, semi-active systems have renewed interest in robot-assisted joint arthroplasty. These researchers reviewed the current technology, its potential benefits, and the reported clinical and radiographic outcomes. Early evidence suggested that robotic use may lead to more accurate reconstruction of radiographic parameters (e.g., implant positioning, fit, center-of-rotation, and leg-length discrepancy). The authors concluded that further research is needed to determine if these will translate into better outcomes and improved implant longevity to justify increased costs. (Keywords of this article included MAKO).
Furthermore, an UpToDate review on “Total hip arthroplasty” (Erens et al, 2016) does not mention “robotic-assisted arthroplasty/MAKOplasty” as a therapeutic option.
In a prospective, cohort study, Kayani et al (2018) compared macroscopic bone and soft tissue injury between robotic-arm assisted total knee arthroplasty (RA-TKA) and conventional jig-based TKA (CJ-TKA) and created a validated classification system for reporting iatrogenic bone and peri-articular soft tissue injury following TKA. This study included 30 consecutive CJ-TKAs followed by 30 consecutive RA-TKAs carried out by a single surgeon. Intra-operative photographs of the femur, tibia, and peri-articular soft tissues were taken before implantation of prostheses. Using these outcomes, the macroscopic soft tissue injury (MASTI) classification system was developed to grade iatrogenic bone and soft tissue injuries. Inter-observer and Intra-observer validity of the proposed classification system was evaluated. Patients undergoing RA-TKA had reduced medial soft tissue injury in both passively correctible (p < 0.05) and non-correctible varus deformities (p < 0.05); more pristine femoral (p < 0.05) and tibial (p < 0.05) bone resection cuts; and improved MASTI scores compared to CJ-TKA (p < 0.05). There was high inter-observer (intra-class correlation coefficient [ICC] 0.92; 95 % CI: 0.88 to 0.96, p < 0.05) and intra-observer agreement (ICC 0.94; 95 % CI: 0.92 to 0.97, p < 0.05) of the proposed MASTI classification system. The authors concluded that there was reduced bone and peri-articular soft tissue injury in patients undergoing RA-TKA compared to CJ-TKA. The proposed MASTI classification system is a reproducible grading scheme for describing iatrogenic bone and soft tissue injury in TKA. Moreover, these researchers stated that the proposed MASTI classification may facilitate further research correlating macroscopic soft tissue injury during TKA may facilitate further research comparing and correlating the invasiveness of different surgical techniques to long-term clinical outcomes and implant survivorship.
The authors stated that there were several limitations to this study that needed to be addressed when interpreting the findings. First, the MASTI score provided a general grade for bone and soft tissue injury during TKA with limited information on the state of the individual compartments of the knee joint. Second, the classification system was constructed using cruciate-sacrificing implants and further modifications may subsequently be needed with cruciate-retaining implant designs. Third, clinical photographs were used for evaluation and determination of the grade of soft tissue injury as opposed to determining injury at the time of the surgical procedure. Fourth, the impact of this peri-articular injury on the systemic inflammatory response, which could affect post-operative pain, and early functional recovery was not examined in this study. Fifth, the majority of arthroplasty surgeons currently use CJ-TKA; thus, any potential benefits of this RA-TKA on bone and soft tissue injury may be purely academic until further studies correlating these benefits to long-term clinical outcomes are published.
Tezuka et al (2019) stated that the Lewinnek "safe zone" is not always predictive of stability following THA. Recent studies have focused on functional hip motion as observed on lateral spine-pelvis-hip X-rays. These researchers examined the correlation between the Lewinnek safe zone and the functional safe zone based on hip and pelvic motion in the sagittal plane. A total of 320 hips (291 patients) underwent primary THA using computer navigation; 296 of these hips (92.5 %) were within the Lewinnek safe zone as determined by inclination of 40° ± 10° and anteversion of 15° ± 10°. All patients had pre-operative and post-operative standing and sitting lateral spinopelvic x-rays. The combined sagittal index (CSI), a combination of sagittal acetabular and femoral position, was measured for each patient and used to evaluate the functional safe zone. Data analysis was carried out to identify hips in the Lewinnek safe zone inside and outside the sagittal functional safe zone. Predictive factors for hips outside the functional safe zone were identified. Of the 296 hips within the Lewinnek safe zone, 254 (85.8 %) were also in the functional safe zone; 42 patients were outside the functional safe zone based on CSI; 19 had an increased standing CSI and 23 had a decreased sitting CSI, all were considered at risk for dislocation. Predictive factors for falling outside the functional safe zone were increased femoral mobility (p < 0.001, r = 0.632), decreased spinopelvic mobility (p < 0.001, r = 0.455), and pelvic incidence (p < 0.001, r = 0.400). The authors concluded that in this study, 14.2 % of hips within the Lewinnek safe zone were outside the functional safe zone, identifying a potential reason hips dislocate despite having "normal" cup angles. The best predictor for falling outside the functional safe zone, both pre-operatively and post-operatively, was femoral mobility, not the sagittal cup position (i.e., cup ante-inclination). Level of Evidence = III. Again, this study provided no clinical data on the MAKO THA System.
Golladay et al (2019) stated patient-reported outcome measures (PROMs) are increasingly recognized as an important tool in quantifying the clinical success of arthroplasty surgery. In a multi-center study, these researchers measured post-operative joint awareness and satisfaction in patients with and without a quantitatively balanced knee following primary total knee arthroplasty (TKA). A total of 318 eligible patients were assigned to 1 of the 2 patient groups: sensor-guided TKA or surgeon-guided TKA. In the sensor-guided group, quantitative balancing was carried out according to inter-compartmental tibio-femoral load measurements measured by an instrumented tibial trial component. In contrast, for the surgeon-guided group, the knees were balanced according to the surgeons' standard manual techniques while blinding the surgeon to the sensor measurements. Patients were blinded to their allocation and filled out the validated Forgotten Joint Score and 2011 Knee Society Satisfaction (KSS) questionnaires at 6 weeks and 6 months. For the purposes of this study, the subjects were pooled and stratified by their state of soft tissue balance, based on the mediolateral load differential through the range of motion (ROM). In the surgeon-guided group, approximately 50 % of the cases yielded a quantitatively balanced knee. Significantly more balanced knees were observed in the sensor-guided group (84.0 %). More importantly, for both outcome measures, the balanced group of patients reported significantly better outcomes scores. The authors concluded that the findings of this study showed that using sensor feedback during knee arthroplasty resulted in a more reproducible procedure, resulting in a higher percentage of balanced patients who in turn showed superior clinical outcomes compared to unbalanced patients.
The authors stated that this study had several drawbacks. First, while the surgical protocol was defined at the outset of the study, individual differences in surgical technique among the participating surgeons, especially in the blinded cohort, may have affected the results. In an attempt to minimize this effect, the surgeon as an independent predictor was included in the backward multi-variate analyses. Second, while the definition used to designate a balanced knee was determined at the outset of the study, there are currently no data to categorically establish an objective target range for absolute load values. Third, despite having load data available in the sensor-guided arm, only 84.0 % of the knees in that group were quantitatively balanced. These investigators were unable to determine the reason the surgeons knowingly left some knees in an unbalanced state. It was hypothesized that the surgeons’ experience with sensor feedback partially explained this observation as observed from the differences between experienced and inexperienced users, although even experienced surgeons left some knees unbalanced. A recent study found that the learning curve for use of this device was 41 cases. Furthermore, it was hypothesized that addressing an isolated imbalance in mid-flexion could be challenging and could explain some of the unbalanced cases in the study. These researchers stated that further analysis is needed to examine this question. Fourth, while early clinical results were often predictive of long-term outcomes, these investigators acknowledged that longer term data are needed to confirm whether the differences found between balanced and unbalanced patients at 6 weeks and 6 months would be maintained at later time intervals. They stated that follow-up is currently ongoing to capture data at the 1-year and 2-year post-operative time-points.
Bhimani et al (2020) stated that robotic-assisted TKA (RA-TKA) has been introduced to provide accurate bone cuts and help achieve the target knee alignment, along with symmetric gap balancing. These investigators examined if any early clinical benefits could be realized following TKA using robotic-assisted technology. A total of 140 consecutive patients undergoing RA-TKA and 127 consecutive patients undergoing conventional TKA with minimum 6-week follow-up were reviewed. Differences in visual analog scores (VAS) for pain at rest and with activity, post-operative opiate usage, and length of stay (LOS) between the RA-TKA and conventional TKA groups were compared. Patients undergoing RA-TKA had lower average VAS pain scores at rest (p = 0.001) and with activity (p = 0.03) at 2 weeks following the index procedure. At the 6-week interval, the RA-TKA group had lower VAS pain scores with rest (p = 0.03) and with activity (p = 0.02), and required 3.2 mg less morphine equivalents per day relative to the conventional group (p < 0.001). At 6 weeks, a significantly greater number of patients in the RA-TKA group were free of opioid use compared to the conventional TKA group; 70.7 % versus 57.0 % (p = 0.02). Patients in the RA-TKA group had a shorter LOS (1.9 days versus 2.3 days, p < 0.001), and also had a greater percentage of patient discharged on post-operative day 1 (41.3 % versus 20.5 %, p < 0.001). The authors concluded that patients undergoing RA-TKA had lower pain levels at both rest and with activity, required less opioid medication, and had a shorter LOS. Moreover, these researchers stated that the short-term results of robotic-assisted surgery compared to the use of manual jig-based instruments in patients undergoing primary TKA appeared promising; however, longer follow-up is needed to determine the true effectiveness of this innovative technology.
The authors stated that this study had several drawbacks that must be considered when interpreting these findings. First, this was a retrospective review and not a prospective randomized study. However, this was a consecutive series with patients allocated to the robotic or conventional TKA groups in order of appearance, and based on the availability of robotic instrumentation. Second, this study design may allow for the inadvertent introduction of selection bias; however, there were no differences between the 2 groups with respect to age, sex, and ASA scores. Third, the results of this study were only short-term, evaluating pain scores, opioid consumption, and LOS; there was no long-term follow-up to determine if the benefits of RA-TKA would continue to surpass those carried out using manual jig-based instruments. Fourth, this study also did not include any radiological findings given the short-term focus of this study.
St Mart et al (2020) noted that there has been a significant reduction in unicompartmental knee arthroplasty (UKA) procedures recorded in Australia. This followed several national joint registry studies documenting high UKA revision rates when compared to TKA. With the recent introduction of robotically assisted UKA procedures, it was hoped that outcomes improve. These researchers examined the cumulative revision rate of UKA procedures implanted with a newly introduced robotic system and compared the results to one of the best performing non-robotically assisted UKA prostheses, as well as all other non-robotically assisted UKA procedures. Data from the Australian Orthopedic Association National Joint Arthroplasty Registry (AOANJRR) for all UKA procedures carried out for osteoarthritis (OA) between 2015 and 2018 were analyzed. Procedures using the Restoris MCK UKA prosthesis implanted using the Mako Robotic-Arm Assisted System were compared to non-robotically assisted Zimmer Unicompartmental High Flex Knee System (ZUK) UKA, a commonly used UKA with previously reported good outcomes and to all other non-robotically assisted UKA procedures using Cox proportional hazard ratios (HRs) and Kaplan-Meier estimates of survivorship. There was no difference in the rate of revision when the Mako-assisted Restoris UKA was compared to the ZUK UKA (0 to 9 months: HR 1.14 (95 % CI: 0.71 to 1.83; p = 0.596) versus 9 months and over: HR 0.66 (95 % CI: 0.42 to 1.02; p = 0.058)). The Mako-assisted Restoris had a significantly lower overall revision rate compared to the other types of non-robotically assisted procedures (HR 0.58 (95 % CI: 0.42 to 0.79); p < 0.001) at 3 years. Revision for aseptic loosening was lower for the Mako-assisted Restoris compared to all other non-robotically assisted UKA (entire period: HR 0.34 (95 % CI: 0.17 to 0.65); p = 0.001), but not the ZUK prosthesis. However, revision for infection was significantly higher for the Mako-assisted Restoris compared to the 2 comparator groups (ZUK: entire period: HR 2.91 (95 % CI: 1.22 to 6.98; p = 0.016); other non-robotically assisted UKA: 0 to t3 months: HR 5.57 (95 % CI: 2.17 to 14.31; p < 0.001)). The authors concluded that the findings of this study reported comparable short-term survivorship for the Mako robotically assisted UKA compared to the ZUK UKA and improved survivorship compared to all other non-robotic UKA. These researchers stated that these findings justified the continued use and investigation of this procedure. Moreover, they stated that the higher rate of early revision for infection for robotically assisted UKA requires further investigation.
The authors stated that there were limitations to this study using registry data. The outcome measure was time to 1st revision (i.e., change or addition of 1 or more component). This did not include other complications such as superficial wound infection of pin sites, which may have required surgery or medical treatment. Follow-up was short and long-term follow-up is needed. There were several studies reporting higher revision rates for UKA in low-experience surgeons or low-volume hospitals; thus, adoption of this new robotic technology may potentially have been biased towards more experienced surgeons performing higher numbers of UKA procedures. Another limitation may be selection bias of surgeons potentially using easier cases to familiarize themselves with this new technique. Conversely however, there was potentially a reduction in the learning curve with robotic assistance because component alignment was already pre-planned; therefore, possible mal-alignment may be avoided while surgical experience was being acquired, compared to conventionally instrumented UKAs. This may explain the increase of UKA procedures being performed over the last few years since the introduction of robotic assistance.
In a systematic review and meta-analysis, Agarwal et al (2020) examined if rTKA resulted in improved clinical and radiological outcomes; and assessed the breadth and depth of studies conducted on this topic. These researchers carried out a Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review using 4 databases (Medline, Embase, Cochrane, and Web of Science) to identify all clinical studies that examined clinical or radiological outcomes using rTKA. The Critical Appraisal Skills Program checklist for cohort studies was used for critical appraisal and evaluation of all 22 studies that met the inclusion criteria. All studies reviewed determined that knee arthroplasty improved clinical outcomes; 12 studies found statistically better clinical outcomes with rTKA compared with conventional mTKA, whereas 9 studies found no difference; 1 study did not examine clinical outcomes. When assessing radiological outcomes, 14 studies reported that rTKA resulted in more consistent and accurate post-operative mechanical alignment, whereas 2 studies reported no difference; 6 studies did not examine radiological outcomes. The authors concluded that although knee arthroplasty is one of the most commonly performed orthopedic operations, the level of patient satisfaction varies. The meta-analyses conducted in this systematic review showed that rTKA resulted in greater improvements in post-operative Hospital for Special Surgery score and Western Ontario and McMaster Universities scores compared to conventional mTKA. Furthermore, it showed that rTKA resulted in more accurate post-operative alignment of prostheses. These together can explain the improved post-operative outcomes. Moreover, these researchers stated that more randomized controlled trials must be conducted before this technique is integrated into routine clinical practice.
In a systematic review, Batailler et al (2021) examined the clinical and radiological results of the MAKO CT-based robotic-assisted system for TKA. These investigators carried out a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement-based systematic review using 4 databases (Medline, Embase, PubMed, Google Scholar) to identify all clinical and radiological studies reporting information regarding the use and results of the CT-based robotic-assisted system to perform TKA between 2016 and 2020. The main investigated outcome criteria were post-operative pain, analgesia requirements, clinical scores, knee ROM, implant positioning, as well as the revision rate. The ROBINS-I tool (Risk Of Bias In Non-randomized Studies of Interventions) was employed to evaluate the quality of included studies and the risk of bias. A total of 36 studies were identified, of which 26 met inclusion criteria. Of these 26 studies, 14 were comparative. The follow-up varied from 30 days to 17 months. This CT-based, saw-cutting robotic TKA was associated with a significantly lower post-operative pain score (2.6 versus 4.5) and with significantly reduced time to hospital discharge (77 versus 105 hours), compared with conventional TKA. The 2 comparative studies examining functional outcomes at 1 year reported significantly better functional scores with CT-based robotic TKA compared with conventional TKA (WOMAC score: 6 ± 6 versus 9 ± 8 (p < 0.05); KSS function score: 80 versus 73 (p = 0.005)). Only 3 comparative studies assessed implant positioning, and these reported better implant positioning with CT-based robotic-assisted TKA. The authors concluded that the CT-based robotic-assisted system for TKA reduced post-operative pain and improved implant positioning with equal or slightly superior improvement of the functional outcomes at 1 year, compared to conventional TKA. Moreover, these researchers stated that powerful studies at longer term follow-up are needed to examine the long-term advantages of this robotic system, particularly for TKA survivorship or potential benefits of alternate alignment philosophies. Level of Evidence = IV.
The authors stated that this study had several drawbacks. First, the inclusion criteria, such as English language or the requirement of full text access, may have excluded relevant studies. Second, the methodology score has known limitations with regard to the type of studies included (cohort and cadaveric studies) and the difficulties in assessing the validity of the analyses conducted without having access to the raw data. Third, there was an important variability between the studies with respect to the type of outcome measurement parameters used, the follow-up period, the patient population and cohorts evaluated, and the analyses performed. This heterogeneity limited the possibility of performing a true meta-analysis of the results. Moreover, there are not yet any published randomized controlled trials (RCTs); these randomized studies are currently in progress. The studies on robotic arm-assisted TKA with the MAKO image-based robotic-assisted system were few in number and mainly have short-term follow-up (less than 2 years). In addition, the follow-up period for these studies remained short, mainly because this system is so new. These investigators stated that future studies with longer term follow-up will be more conclusive in assessing the outcomes and benefits. Furthermore, this systematic review was only about one robotic-assisted system. There are a lot of studies reporting the results of TKA using various robotic-assisted systems with interesting results. Nevertheless, the objective of this systematic review was to target this particular robotic-assisted system. Indeed, all robotic-assisted systems are not equivalent and use different planning data (CT-based, image-free). It is important to assess each specific system.
Maldonado et al (2021) noted that THA is the benchmark surgical treatment of advanced and symptomatic hip osteoarthritis (OA). Preliminary evidence suggested that the robotic arm-assisted (RAA) technology yielded more accurate and reproducible acetabular cup placement, which may improve survival rate and clinical results; however, economic considerations are less well-defined. These researchers compared the cost-effectiveness of the RAA THA with manual THA (mTHA) modalities, considering direct medical costs and utilities from a payer's perspective. They constructed a Markov model to analyze 2 potential interventions for hip OA and degenerative joint disorder: RAA THA and mTHA. Potential outcomes of THA were categorized into the transition states: infection, dislocation, no major complications, or revision. Cumulative costs and utilities were examined using a cycle length of 1 year over a time horizon of 5 years. RAA THA cohort was cost-effective relative to mTHA cohort for cumulative Medicare and cumulative private payer insurance costs over the 5-year period. RAA THA cost-saving had an average differential of $945 for Medicare, and $1,810 for private insurance relative to mTHA while generating slightly more utility (0.04 quality-adjusted life year [QALY]). The preferred treatment was sensitive to the utilities generated by successful RAA THA and mTHA. Micro-simulations indicated that RAA THA was cost-effective in 99.4 % of cases. The authors concluded that in the Medicare and private payer scenarios, RAA THA was more cost-effective than conventional mTHA when considering direct medical costs from a payer's perspective. Level of Evidence = III.
The authors stated that this analysis had several drawbacks. First, as a note of caution, this empiric investigation provided quantitative data, which should be accepted as a theoretical approximation of complex reality and not held as a fact. Robotic system costs or benefits to a hospital were not included because it could be influenced by factors such as surgical volume, efficiency gains, reductions in the length of stay (LOS), and re-admissions. Furthermore, patient payers are not responsible for the upfront costs associated with acquiring the technology. Outcomes were derived from the literature and from the authors’ high-volume institution, which may have limited its generalizability. However, sensitivity analysis conducted and showed that model conclusions could tolerate notable variation of variables; therefore, these researchers believed that the objective findings were relevant to the payer when considering a primary THA patient cohort treated at a high-volume surgical center. These investigators stated that mid-term follow-up trends must be assessed for persistence over time, including longer duration of follow-up. However, previous economic analyses have indicated that 91 % of re-interventions occurred within the 1st year, and longer follow-up may not alter conclusions of this study. Furthermore, short-term complications were found to have more effect on the cost-effectiveness of THA relative to implant longevity. Lastly, this study examined direct costs only. Indirect costs and their subsequent societal implications are salient points to consider. This review did not consider surgical time, cost of the robotic arm, or hospital LOS. Indirect costs could not be inferred because of the paucity of literature, considering their estimates and impact.
Banger et al (2021) noted that UKA is a bone-preserving therapeutic option for OA localized to a single compartment in the knee. The success of the procedure was sensitive to patient selection and alignment errors. Robotic arm-assisted UKA provides technological assistance to intra-operative bony resection accuracy, which is thought to improve ligament balancing. In a prospective, randomized, parallel, single-center study, these researchers presented the 5-year outcomes of a comparison between manual and robotically assisted UKAs. They compared surgical alignment in patients undergoing UKA for the treatment of medial compartment OA. Subjects underwent surgery using either robotic arm-assisted surgery or conventional manual instrumentation. The primary outcome measure (surgical accuracy) has previously been reported, and, along with secondary outcomes, were collected at 1-, 2-, and 5-year time-points. Analysis of 5-year results and longitudinal analysis for all time-points was carried out to compare the 2 groups. A total of 104 (80 %) patients of the original 130 who received surgery were available at 5 years (55 robotic, 49 manual). Both procedures reported successful results over all outcomes. At 5 years, there were no statistical differences between the groups in any of the PROMs or clinical outcomes. There was a lower re-intervention rate in the robotic arm-assisted group with 0 % requiring further surgery compared with 6 (9 %) of the manual group requiring additional surgical intervention (p < 0.001). The authors concluded that the findings of this study has shown excellent clinical outcomes in both groups with no statistical or clinical differences in the PROMs. The notable difference was the lower re-intervention rate at 5 years for robotic arm-assisted UKA when compared with a manual approach.
The authors stated that this was a small, single-center study powered to examine post-operative alignment and Oxford Knee Score (OKS) at 5 years. These researchers stated that larger multi-center studies, combined with registry data, in the future should provide sufficient data on large enough numbers of patients to allow robust sub-group analyses to determine which patients benefit most from the technology.
Sugano et al (2024) noted that femoral component anteversion is an important factor in the success of THA. In a retrospective study, these investigators examined the accuracy of femoral component anteversion with the Mako THA system and software using the Exeter cemented femoral component, compared to the Accolade II cementless femoral component. They reviewed the data of 30 hips from 24 patients who underwent THA using the posterior approach with Exeter femoral components, and 30 hips from 24 patients with Accolade II components. Both groups did not differ significantly in age, sex, BMI, bone quality, or disease. Two weeks post-operatively, CT images were obtained to measure acetabular and femoral component anteversion. The mean difference (MD) in femoral component anteversion between intra-operative and post-operative CT measurements (system accuracy of component anteversion) was 0.8° (SD 1.8°) in the Exeter group, and 2.1° (SD 2.3°) in the Accolade II group, respectively (p = 0.020). The MD in anteversion between the plan and the post-operative CT measurements (clinical accuracy of femoral component anteversion) was 1.2° (SD 3.6°) in the Exeter group, and 4.2° (SD 3.9°) in the Accolade II group (p = 0.003). No significant differences were found in acetabular component inclination and anteversion; however, the clinical accuracy of combined anteversion was significantly better in the Exeter group (0.6° (SD 3.9°)) than the Accolade II group (3.6° (SD 4.1°)). The authors concluded that the Mako THA system and software helped surgeons control the femoral component anteversion to achieve the target angle of insertion. The Exeter femoral component, inserted using Mako THA system, showed greater precision for femoral component and combined component anteversion than the Accolade II component.
The authors stated that this study had several drawbacks. First, all procedures were carried out by 1 experienced surgeon; thus, the accuracy range in this study could not be generalized. However, using the same surgeon allowed these researchers to compare the accuracy of cementless and cemented femoral component anteversion independent of surgical skill and experience using the Mako THA system. Second, although no significant differences were found in the native femoral anteversion between the groups, or relative differences between the planned femoral component anteversion and native femoral anteversion, the absolute difference between planned anteversion and native femoral anteversion was less in the Accolade II group than in the Exeter group; cementless cases should have been easier to target for anteversion because the target stem anteversion was closer to the native femoral anteversion than that in cement cases. However, the clinical accuracy of femoral component anteversion was better in the Exeter group, suggesting that it facilitated achieving component anteversion as planned with the Mako THA system. Third, the sample size was small, causing a risk of β error in the parameters without significant differences. However, statistical analysis showed significant differences in the clinical accuracy of femoral component anteversion and combined anteversion between the 2 groups which were worthy of attention. Fourth, the results were not compared directly with dislocation rate or functional scores, as this was beyond the scope of this trial. Whether the greater accuracy of this system is associated with better long-term clinical outcomes remains unclear. These investigators stated that further studies involving longer follow-up, with larger study groups and involving multiple surgeons, are needed to examine the clinical outcomes in the future. However, evaluation of the method to precisely execute planned femoral component anteversion is important, and the findings of this study were encouraging and support the use of the Mako THA system.
The Alpha-Defensin Test (Synovasure)
Patel and colleagues 92016) noted that synovial fluid biomarkers can be considerably helpful in the diagnosis of peri-prosthetic joint infection (PJI) and improve the accuracy of other tests such as serum biomarkers. Synovial fluid white blood cell (WBC) count and differential are currently minor criteria in the definition of PJI as proposed by the International Consensus Group. In recent years, however, numerous biomarkers have been investigated for patients with PJI, including inflammatory cytokines (e.g., interleukins 1, 6, 8,10, and 17, tumor necrosis factor-alpha [TNF-α], interferon-γ, resistin, and thrombospondin), inflammatory reactive proteins (such as CRP), bactericidal leukocyte enzymes (e.g., esterase, elastase, and bactericidal/permeability-increasing protein, gelatinase-associated lipocalin, and lactoferrin, all of which are present in polymorphonuclear leukocytes), markers of angiogenesis (e.g., vascular endothelial growth factor) and anti-microbial proteins (e.g., as alpha- defensing [α-defensin], β-defensin, and cathelicidin LL-37). Many of these synovial fluid biomarkers did not have any correlation with synovial WBC count, so these synovial fluid markers are not simply surrogate markers for an increase in local inflammation in the joint as a result of a PJI. Additionally, it was found that the markers that had the highest specificity and sensitivity were proteins that have anti-microbial properties, which is likely the reason for their increased concentration in synovial fluid during PJI. Since the mechanism of action for these biomarkers is different than that of currently used tests, these biomarkers hold great promise for a novel approach in diagnosing PJI. The authors stated that the main disadvantage of synovial biomarkers is that these tests depend on the availability of synovial fluid, and synovial fluid cannot be aspirated from a joint in all PJI cases. Moreover, some of the inflammatory biomarkers may represent any type of inflammatory process in the prosthetic joint (e.g., an adverse reaction to foreign material); thus, these tests may not be specific enough for PJI.
Kasparek and co-workers (2016) investigated the novel Synovasure PJI lateral flow test device for detection of alpha-defensin and determined its diagnostic accuracy for the intra-operative diagnosis of PJI and compared it to frozen section. A total of 40 consecutive patients, who underwent revision surgery, between September 2014 and September 2015 were included. Patients underwent 29 revision total knee arthroplasties (TKAs) and 11 revision THAs; 12 patients had a confirmed PJI based on Musculo-Skeletal Infection Society (MSIS) criteria, and 28 patients were considered aseptic. The overall accuracy to detect PJI using the lateral flow assay was 85 % (95 % CI: 70 % to 93 %). The device has a positive predictive value (PPV) of 80 % (95 % CI: 44 % to 96 %) and a negative predictive value (NPV) of 87 % (95 % CI: 68 % to 96 %) and showed a sensitivity of 67 % (95 % CI: 35 % to 89 %) and specificity of 93 % (95 % CI: 75 % to 99 %). Frozen section had a lower sensitivity (58 % [95 % CI: 29 % to 84 %]) but a higher specificity (96 % [95 % CI: 80 % to 100 %]). Receiver operator curve analysis demonstrated an area under the curve of the Synovasure PJI Lateral Flow Test Kit and frozen section of 0.80 and 0.77, respectively. The authors concluded that the findings of the present study suggested that the intra-operative lateral flow test was at least equivalent to intra-operative frozen section and was a useful tool to confirm the absence of PJI. Moreover, they stated that although the clinical results are promising, they are not as good as previous studies using alpha-defensin levels measured in a laboratory.
Pupaibool and colleagues (2016) reviewed the current evidence on the utility of serum and synovial fluid biomarkers to help aid in the diagnosis of PJI with focusing on synovial fluid alpha-defensin. Articles and data for this review were identified by searches of PubMed and Ovid Medline up to June 1, 2016. In addition, these investigators manually reviewed the bibliographies of the retrieved articles for additional citations for references from relevant articles on the diagnosis of PJI. Serum biomarkers can be elevated in various inflammatory conditions. Synovial fluid biomarkers are more accurate for the diagnosis of PJI compared to serum biomarkers. Based on current available data, alpha-defensin is the most promising synovial fluid biomarker for the diagnosis of PJI and is commercially available. The authors concluded that synovial fluid alpha-defensin could enhance the ability to identify PJI and incorporate into the diagnostic algorithm in the future. Moreover, they stated that large-scale studies are needed to provide more data for its significance for the diagnosis of PJI.
Sigmund and associates (2017) stated that the diagnosis of PJI remains demanding due to limitations of all the available diagnostic tests. The synovial fluid marker, α-defensin, is a promising adjunct for the assessment of potential PJI. These investigators examined the qualitative assessment of α-defensin, using Synovasure to detect or exclude peri-prosthetic infection in total joint arthroplasty. In a prospective diagnostic study, these researchers studied 50 patients (28 women, 22 men, mean age of 65 years; range of 20 to 89) with a clinical indication for revision arthroplasty who met the inclusion criteria. The presence of α-defensin was determined using the qualitative Synovasure test and compared with standard diagnostic methods for PJI. Based on modified MSIS criteria, 13 cases were categorized as septic and 36 as aseptic revisions; 1 test was inconclusive. The Synovasure test achieved a sensitivity of 69 % and a specificity of 94 %. The positive and negative likelihood ratios were 12.46 and 0.33, respectively. A good diagnostic accuracy for PJI, with an area under the curve of 0.82, was demonstrated. Adjusted p-values using the method of Hochberg showed that Synovasure was as good at diagnosing PJI as histology (p = 0.0042) and bacteriology with 1 positive culture (p = 0.0327). The authors concluded that with its ease of use and rapid results after approximately 10 minutes, Synovasure may be a useful adjunct in the diagnosis of PJI.
Suda and colleagues (2017) noted that diagnosing peri-prosthetic infection remains a challenge. Multiplex-PCR and biomarkers such as alpha-defensin are potentially useful and fast methods for detecting peri-prosthetic infection. These researchers compared these new methods with clinical assessment, conventional microbiological methods and histo-pathological examination. A total of 28 consecutive patients with 30 joints and a mean age of 67.7 years (range of 39 to 88) with removal of THA or TKA were included in this study. Patients were classified according to the modified MSIS for infected joints. Punction fluid and tissue specimens were taken for conventional microbiological examination, the alpha defensin test was performed, a synovial membrane specimen was used for multiplex-PCR and histopathological examination was carried out. The alpha-defensin test and multiplex-PCR showed a sensitivity of 76.9 versus 30.8 % and a specificity of 82.4 versus 100 %, respectively. These investigators found a significant difference between the positive and negative results (p = 0.0023). The conventional microbiological methods were not significantly different from the alpha-defensin test (p = 0.244) with a sensitivity of 84.6 % and a specificity of 100 % but did differ significantly from the multiplex PCR (p = 0.0030). There was a significant difference between modified MSIS classification and multiplex PCR (p = 0.0007). The authors concluded that neither the alpha-defensin test nor multiplex-PCR could detect peri-prosthetic infection immediately and reliably. They stated that the multiplex-PCR was suitable for detecting the non-infected but not the truly infected; and the alpha-defensin test was helpful but showed no satisfactory results. These researchers stated that the conventional microbiological methods remain the most reliable for peri-prosthetic infection diagnosis.
Tranexamic Acid in Total Hip Replacement
Zhang and colleagues (2016) stated that as the prevalence of THA is increasing, it is usually associated with considerable blood loss. Tranexamic acid (TXA) has been reported to reduce peri-operative blood loss in hip joint arthroplasty. However, the best route of TXA administration continues to be controversial. Ina meta-analysis, these investigators integrated all data from the 7 included trials to compare the safety and effectiveness of topical and intravenous TXA administration in primary THA. The end-points assessed in this meta-analysis included the comparisons of total blood loss, post-operative hemoglobin (Hb) decline, transfusion rates, the incidence rate of deep vein thrombosis (DVT), pulmonary embolisms (PE), and wound infection. Literature searches of PubMed, Embase, the Cochrane Library, the Chinese Biomedical Literature database, the CNKI database, and Wan Fang Data were performed up to August 30, 2016. Randomized controlled trials (RCTs) were included in this meta-analysis if they compared the safety and effectiveness of intravenous versus topical administration of TXA in patients who underwent primary THA. The meta-analysis was performed following the guidelines of the Cochrane Reviewer's Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The pooling of data was carried out by using RevMan 5.3, Denmark. A total of 7 RCTs involving 964 patients met the inclusion criteria. the meta-analysis indicated that there were no significant differences in the 2 groups in terms of total blood loss ([mean difference (MD) = -14.74, 95 % CI: -89.21 to 59.74, p = 0.7], transfusion rates [RD = -0.02, 95 % CI: -0.05 to 0.02, p = 0.39]; no significant differences were found regarding the incidence of adverse effects (AEs) such as DVT [RD = 0.00, 95 % CI: -0.01 to 0.01, p = 1.00], PE [RD = 0.00, 95 % CI: -0.01 to 0.01, p = 0.71], or wound infection [RD = -0.01, 95 % CI: -0.06 to 0.04, p = 0.66]). The pooled results showed that the intravenous groups had a lower post-operative Hb decline (MD = -0.47, 95 % CI: -0.74 to -0.20, p = 0.0006). It was probably due to insufficient data and the varied reporting of outcomes. There was some inherent heterogeneity due to the small sample size of each primary study. The authors concluded that topical and intravenous administrations of TXA had a similar effect on the decrease of blood loss without an increased risk of complications (e.g., DVT, PE, and wound infection). They noted that intravenous TXA administration may have a maximum efficacy; while topical TXA administration may be preferred in patients who with high risk of thrombo-embolic events. However, they stated that larger, high-quality RCTs are needed to examine the optimal regimen, dosage, timing before recommending the widespread use of TXA in total joint arthroplasty.
Moskal and Capps (2016) stated that previous meta-analyses established that TXA confers benefits when used during THA. However, 2 of these meta-analyses included a variety of routes of administration of TXA in THA (topical, intravenous, oral, and intra-articular), another meta-analysis included a variety of anti-fibrinolytic drugs (not restricted to a single drug), and the final meta-analysis included non-RCTs. This meta-analysis focused on a single medication, TXA, administered in a specific way, intravenously in patients undergoing primary THA, using data reported only in RCTs. Outcomes were restricted to blood loss, allogeneic transfusion rates, and complications. Other outcomes, such as return to function or clinical scores, could not be evaluated because of lack of consistent reporting. The authors stated that to better understand the effects of intravenous TXA in THA on clinical outcomes, such as recovery, return to function, and patient-reported outcome measures, it would be helpful to have more RCTs examining these measures in a standardized manner. They noted that intravenous TXA was beneficial for blood loss intra-operatively, blood loss through drains, and total blood loss during hospitalization, in addition to reducing allogeneic transfusion rates. However, no difference between intravenous TXA and placebo was found for most complications, except DVT, which showed favorable results with placebo.
In a meta-analysis, Shang and colleagues (2016) compared the safety and effectiveness of combined intravenous and topical TXA versus intravenous use alone in primary TKA and THA. PubMed, Embase, Cochrane library and OVID were searched. Eligible RCTs evaluating combined intravenous and topical TXA versus intravenous alone in primary TKA and THA were included. The relative risk (RR) or the mean difference (MD) for dichotomous or continuous data was calculated respectively, and heterogeneity was analyzed by Chi-square and I2 tests. A total of 5 RCTs met the inclusion criteria and were included in the study. The meta-analysis indicated that there was statistically significant difference favoring the combined group in total blood loss(MD = -160.90, 95 % CI: -201.26 to -120.54, p < 0.00001), Hb drop (MD = -0.41, 95 % CI:-0.73 to 0.08], p = 0.01), transfusion requirements(RR = 0.29, 95 % CI: 0.12 to 0.70], p = 0.006) and length of hospital stays (MD = -0.21, 95 %CI: -0.40 to -0.02], p = 0.03). Both groups showed similar outcomes regarding thrombo-embolic complications(RR = 0.84, 95 % CI: 0.26 to 2.70], p = 0.76). The authors concluded that based on the findings of this study, combined use of intravenous and topical TXA was more effective than intravenous TXA alone in primary TKA or THA without increasing the risk of thrombo-embolic complications. Moreover, they stated that further high quality studies with more patients are needed in future studies.
In a meta-analysis, Li and associates (2017) evaluated the safety and effectiveness of combined intravenous and topical methods of application versus single intravenous of TXA in primary TKA and THA. These researchers performed a systematic search in Medline(from 1966 to September 25, 2016), PubMed (from 1966 to September 25, 2016), Embase (from 1980 to September 25, 2016), ScienceDirect (from 1985 to September 25, 2016) and the Cochrane Library. Only high-quality RCT were identified; 2 authors independently performed data extraction and quality assessment of included studies. Meta-analysis was conducted using Review Manager 5.1 software. A total of 6 RCTs that included 687 patients met the inclusion criteria. The present meta-analysis indicated that there were significant differences in terms of total blood loss (MD = -193.59, 95 % CI -338.06 to -49.13, p = 0.009), transfusion rate (RD = -0.07, 95 % CI -0.12 to -0.03, p = 0.001), Hb decline (MD = -0.51, 95 % CI -0.83 to -0.18, p = 0.01) and length of stay (MD = -0.20, 95 % CI -0.38 to -0.02, p = 0.03) between groups. The authors concluded that combined administration of TXA in patients with TKA and THA was associated with significantly reduced total blood loss, transfusion requirements, post-operative Hb decline and length of stay compared to single application alone, but was not associated with prolonged operation time. Moreover, no AEs, such as superficial infection, DVT or PE, were associated with TXA. These researchers suggested that combined administration of TXA demonstrated excellent clinical safety and effectiveness in patients with TKA and THA. Moreover, they stated that well-designed studies with larger sample size are needed to provide further reliable evidence for the combined use of TXA.
A Veteran's Health Administration assessment (VHA, 2014) found evidence for use of TXA in patients undergoing total knee arthroplasty and total hip arthroplasty. They found, however, that "[e]vidence is lacking for the safe and effective use of TXA in joint revision surgery or use in hip fracture surgery, therefore the risk/benefit of TXA in these settings is unknown."
An assessment by the Canadian Agency for Drugs and Technologies in Health (CADTH, 2015) found that, overall, the conclusions of published reviews supported the use of TXA to decrease intraoperative and postoperative blood loss in primary hip and knee arthroplasty. An evidence-based guideline from Health Quality Ontario (2014) recommends the use of TXA for knee and hip replacement.
Guidelines on perioperative blood loss from the American Society of Anesthesiologists (2015) found: "Meta-analysis of placebo-controlled RCTs indicate that tranexamic acid for prophylaxis of excessive bleeding administered before and/or during a procedure is effective in reducing perioperative blood loss, the number of patients transfused, and the volume of blood products transfused (Category A1-B evidence). Randomized trials comparing tranexamic acid with placebo or no tranexamic acid controls report no differences for stroke, myocardial infarction, renal failure, reoperation for bleeding, or mortality (Category A2-B evidence). Meta-analysis of placebo-controlled RCTs indicate that tranexamic acid for prophylaxis of excessive bleeding initiated after a knee and hip arthroplasty and before tourniquet deflation compared with placebo also reported lower blood loss volumes (Category A1-B evidence). . . . The literature is insufficient to evaluate the postoperative administration of tranexamic acid for treatment of excessive blood loss."
Preoperative Intravenous Glucocorticoids for Reduction of Acute Pain and Post-Operative Nausea and Vomiting Following Total Hip Arthroplasty
Yang and colleagues (2017) performed a systematic review and meta-analysis of published RCTs to evaluate the safety and efficacy of pre-operative intravenous glucocorticoids versus controls for the prevention of post-operative acute pain and post-operative nausea and vomiting (PONV) after primary THA. A computer literature search of electronic databases, including PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, China National Knowledge Infrastructure (CNKI), and China Wanfang database, was conducted to identify the relevant RCTs comparing pre-operative intravenous glucocorticoids versus placebos for reducing acute pain and PONV in THA patients. The primary outcomes included the use of the visual analog scale (VAS) with rest or mobilization at 6, 24, 48, and 72 hours and the occurrence of PONV. The secondary outcome was total morphine consumption. These researchers calculated the RR with a 95 % CI for dichotomous outcomes, and the weighted mean difference (WMD) with a 95 % CI for continuous outcomes. Pooled data from 7 RCTs (411 THAs) favored pre-operative intravenous glucocorticoids against acute pain intensity at 4, 24, and 48 hours (p < 0.05). There was no significant difference between the VAS with rest or mobilization at 72 hours (p > 0.05). Subsequently, pre-operative intravenous glucocorticoids provided a total morphine-sparing effect of 9.36 mg (WMD = -9.36, 95 % CI: -12.33 to -6.38, p = 0.000). In addition, pre-operative intravenous glucocorticoids were associated with a significant reduction of the occurrence of PONV (RR = 0.41, 95 % CI: 0.30 to 0.57, p = 0.000). The authors concluded that intravenous glucocorticoids could decrease early pain intensity and PONV following THA. However, they stated that the low number of studies and variation in dosing regimens limited the evidence for its use. Thus, more high-quality RCTs are needed to identify the optimal drug and the safety of intravenous glucocorticoids.
These investigators stated that this meta-analysis had several potential limitations. Their analysis comprised only 7 RCTs, and the sample size of the included studies was limited. The potential risk of publication bias may exist due to the limited number of included studies; and the follow-up in the included studies ranged from 24 hours to 1 year after THA. Thus, AEs may have been under-estimated. Finally, the different dose and type of glucocorticoids also influenced the final conclusion.
Intra-Wound Vancomycin for Reduction of Peri-Prosthetic Joint Infection Following Total Hip Arthroplasty
Patel and colleagues (2018) noted that peri-prosthetic joint infection (PJI) is a devastating complication after hip and knee arthroplasty. Intra-wound vancomycin has been described extensively in the spine literature; however, information regarding use in arthroplasty is limited. These investigators examined the safety and efficacy of intra-wound vancomycin in arthroplasty surgery. All primary THA and total knee arthroplasty (TKA) cases (n = 460) performed by a single surgeon from April 2016 to October 2017 were reviewed. Starting in October 2016, intra-wound vancomycin was used in all total joints. Baseline characteristics, infection rates, 90-day re-admission, and other complications were compared between untreated subjects and those who received intra-wound vancomycin. In addition, cost data were considered. Mean follow-up durations for the control and vancomycin groups were 11.3 and 7.7 months, respectively. Baseline characteristics and co-morbidities were similar for the control (n = 112) and vancomycin groups (n = 348). The vancomycin cohort demonstrated decreased both overall infection rate (0.57 % versus 2.7 %; p = 0.031) and PJI rate (0.29 % versus 2.7 %; p = 0.009) compared with the untreated group. There was no statistical difference in incidence of ototoxicity or acute kidney injury (AKI). Although there was no difference in overall 90-day re-admission rate, the vancomycin subset demonstrated lower re-admission rate due to infection (0.57 % versus 2.7 %; p = 0.031). Based on the cost of vancomycin powder and calculated number needed to treat (NNT = 47.5), the cost to prevent 1 infection with the addition of intra-wound vancomycin was $816. The authors concluded that these findings suggested that intra-wound vancomycin may be a safe, cost-effective approach that showed promise in reducing PJI in early follow-up. They stated that future prospective and randomized research is needed before any formal recommendations for its routine use in total joint arthroplasty can be made.
The authors stated that the non-randomized and retrospective nature of the study was a drawback. The relatively short-term and variable follow-up observed in the control and treatment groups was another drawback. Although these investigators strived to capture all infections, there was the possibility that more indolent infections may have presented past the recorded follow-up period. Similarly, these researchers acknowledged that the difference in post-operative follow-up between the control and vancomycin groups may introduce confounding variables. Other limitations included the low effect size with regard to number of surgical site infections. A sample size of 3,416 patients would be needed to adequately detect a 50 % reduction in infection rate from 2.7 % to 1.35 % with power of 0.80 and alpha of 0.05. To obtain this number of control-group patients, a historical control infection rate would have to be used, or information from more than 1 surgeon should be used, which would introduce other confounding variables and protocol changes. Furthermore, several consecutive years of clinical practice would be needed to identify enough vancomycin-group patients to gain appropriate power which would delay the reporting of a potentially safe and beneficial strategy in decreasing overall infection rate. Consideration was given to including data from other surgeons and institutions, but the authors believed this would have introduced numerous confounding variables in an effort to increase sample size. Future research on increasing the sample size to allow for appropriate power without introducing confounders is a worthy endeavor. The allotted sample size of 460 was, however, sufficient in detecting the significantly decreased early infection rate noted in this investigation. In addition, future higher powered investigations may consider potential variable effects on infection rate associated with THA versus TKA.
Dial and associates (2018) examined the safety profile of using vancomycin powder (VP) to reduce infection rates by reviewing acute post-operative complications. These researchers carried out a retrospective review of 265 consecutive patients undergoing THA. The first 128 patients, the control group, did not receive VP, and the subsequent 137 patients, the VP group, received VP at the time of wound closure. Patient demographic data, medical co-morbidities, and peri-operative information were compared. The primary outcome was a post-operative surgical complication within 90 days from surgery. The control and VP group's demographic, medical co-morbidities and peri-operative information data were statistically similar. Deep infection rate in the control group was 5.5 %, whereas the deep infection rate in the VP group was 0.7 % (p = 0.031). Sterile wound complication rate was 4.4 % in the VP group, and 0 % in the control group (p = 0.030). Remaining complications were not statistically different between the groups. The authors concluded that VP was associated with an increase rate of sterile wound complications compared to the control group; however, the rate of PJI was decreased with the use of VP. These investigators stated that they do not recommend for or against the use of VP at time of wound closure to prevent PJI, and higher powered studies are needed to demonstrate the efficacy of VP.
The authors stated that while the statistically significant decreased rate of PJI in the VP group may be explained by VP use, it is unclear why the control group PJI rate of 5.4 % was much higher than the 1 % to 2 % PJI rate reported in the literature, and this was a major limitation of this study. While the cause was unclear, during this period the hospital had an increase in infection rates and a thorough evaluation by infectious disease experts was performed with no clear cause identified. One consideration was that 6 of the 7 patients with PJI had a BMI greater than 30 kg/m2, which has been shown to be a risk factor for PJI in patients having THA through an anterior approach. As mentioned, the higher rate of chronic obstructive pulmonary disease (COPD) in the control group could also have contributed to a higher infection rate. Lastly, one of the PJI in the control group received clindamycin for pre-operative prophylaxis, a bacteriostatic antibiotic, which could be associated with higher rates of PJI.
Obturator Nerve Blocks for management of Post-Operative Pain Following Total Hip Arthroplasty
Nielsen and colleagues (2019) noted that a substantial group of patients suffer from moderate-to-severe pain following elective total hip arthroplasty THA. Due to the complex innervation of the hip, peripheral nerve block techniques can be challenging and are not widely used. Since the obturator nerve innervates both the antero-medial part of the joint capsule as well as intra-articular nociceptors, these researchers hypothesized that an obturator nerve block (ONB) would decrease the opioid consumption following THA. Sixty-two patients were randomized to receive ONB or placebo (PCB) after primary THA in spinal anesthesia. Primary outcome measure was opioid consumption during the first 12 postoperative hours. Secondary outcome measures included postoperative pain score, nausea score and ability to ambulate. In a randomized clinical trial, a total of 60 patients were included in the analysis. Mean (SD) opioid consumption during the first 12 post-operative hours was 39.9 (22.3) mg peroral morphine equivalents (PME) in the ONB group and 40.5 (30.5) mg PME in the PCB group (p = 0.93). No difference in level of pain or nausea was found between the groups. Paralysis of the hip adductor muscles in the ONB group reduced the control of the operated lower extremity compared with the PCB group (p = 0.026); however, his did not affect the subjects' ability to ambulate. The authors concluded that a significant reduction in post-operative opioid consumption was not observed for active versus placebo ONB following THA.
Custom-Made Acetabular Implants for Revision Total Hip Arthroplasty
Gladnick and colleagues (2018) stated that custom triflange acetabular components (CTACs) are being increasingly used for the reconstruction of Paprosky type IIIB acetabular defects. However, mid-term survivorship data are lacking. These investigators examined the prospective registries at 2 high-volume revision centers for patients who had undergone revision THA (rTHA) using a custom triflange component between 2000 and 2011. They identified 73 patients with minimum 5-year follow-up. These patients' records were reviewed to determine incidence of revision or re-operation, clinical performance, and radiographic stability. The mean follow-up was 7.5 years (range of 5 to 12 years); 15 of 73 triflange components (20.5 %) were indicated for revision during the follow-up period, including 6 for instability (8 %) and 8 for infection (11 %); 12 of 73 patients (16 %) underwent re-operation for reasons other than failure of the triflange component. The median hip disability and osteoarthritis (OA) outcome score for joint replacement score at mid-term follow-up was 85 (interquartile range [IQR] 73 to 100). Only 1 of 73 implants was determined to be radiographically loose at mid-term follow-up. The authors concluded that custom triflange reconstruction for severe acetabular deficiency is a viable option; however, complications were common and significant challenges remained for those that failed.
Aprato and associates (2019) examined the recently introduced Lima Promade custom-made acetabular device for the treatment of complex acetabular Paprosky 3B defects. Between 2016 and 2018, a total of 8 patients with major acetabular osteolysis and multiple revisions history were treated with a custom-made implant in a single center and by a single surgeon. These researchers evaluated patients' demographics, peri-operative data, and complications and a specific questionnaire was submitted to the surgeon after each procedure. All the devices were correctly positioned. In 2 cases, a post-operative dislocation occurred, where extensive soft tissue impairment was present. The questionnaire showed a good pre-operative and intra-operative experience of the surgeon. The authors concluded that the Promade custom-made acetabular system showed encouraging results for complex defects and the entire procedure was positively rated. These investigators stated that further analysis with a higher number of cases and a longer follow-up should be performed for a complete clinical and cost-effective evaluation.
De Martino and co-workers (2019) noted that several studies have evaluated the survivorship and clinical outcomes of CTAC usage in complex acetabular revision; however, there remains no consensus on the overall performance of this custom implant design. These researchers conducted a systematic review of the literature to examine survivorship and complication rate of CTAC usage. They carried out a systematic review of the literature according to the PRISMA guidelines. A comprehensive search of PubMed, Medline, Embase, and the Cochrane Database of Systematic Reviews was conducted for English articles using various combinations of the keywords "custom triflange", "custom-made triflange", "acetabular triflange", "THA", "THR", "revision", "bone loss", "bone defect", and "pelvic discontinuity". A total of 17 articles met inclusion criteria; 579 CTACs were implanted. The all-cause revision-free survivorship was 82.7 %. The overall complication rate was 29 %. Dislocation and infection were the most common complications observed with an incidence of 11 % and 6.2 %, respectively. Nerve injuries following CTAC placement had an incidence of 3.8 %. The incidence of CTAC aseptic loosening (AL) was 1.7 %. Overall, patients had improved outcomes as documented by post-operative hip scores. The authors concluded that based on the current data, CTACs had a high complication rate but remain an effective therapeutic option in complex acetabular reconstructions. When dealing with patients with significant acetabular bone loss for rTHA, surgeons should continue to consider CTACs as a viable option but educate patients as to the increased risk of post-operative complications and re-operations.
Weber and associates (2019) stated that in rTHA, custom-made implants are an option in patients with acetabular Paprosky III defects. In a retrospective analysis, these researchers identified 11 patients undergoing cup revision using a custom-made implant. The accuracy of the intended position of the implant was examined on post-operative 3D computed tomography (CT) and compared to the pre-operative 3D planning in terms of inclination, anteversion, and center of rotation. In addition, the accuracy of post-operative plain radiographs for measuring implant position was evaluated in relation to the 3D CT standard. These investigators found a mean deviation between the planned and the final position of the custom-made acetabular implant on 3D CT of 3.6° ± 2.8° for inclination and of - 1.2° ± 7.0° for anteversion, respectively. Restoration of center of rotation succeeded with an accuracy of 0.3 mm ± 3.9 mm in the medio-lateral (x) direction, - 1.1 mm ± 3.8 mm in the antero-posterior (y) direction, and 0.4 mm ± 3.2 mm in the cranio-caudal (z) direction. The accuracy of the post-operative plain radiographs in measuring the position of the custom-made implant in relation to 3D CT was 1.1° ± 1.7° for implant inclination, - 2.6° ± 1.3° for anteversion and 1.3 mm ± 3.5 mm in the x-direction, and - 0.9 mm ± 3.8 mm in the z-direction for center of rotation. The authors concluded that custom-made acetabular implants could be positioned with good accuracy in Paprosky III defects according to the pre-operative planning. Plain radiographs were adequate for evaluating implant position in routine follow-up.
Froschen and colleagues (2020) noted that severe acetabular bone loss, both with or without pelvic discontinuity, remains a challenge in rTHA. These researchers examined the mid-term results for consecutive patients with Paprosky III acetabular bone loss with or without pelvic discontinuity who needed rTHA with custom-made acetabular implants and compared the results to those of other studies. A total of 68 patients with severe acetabular bone loss (Paprosky Type IIIa and IIIb), who required rTHA, were included in this trial. All prostheses were constructed on the basis of thin-layer CT scans of the pelvis. The VAS, Harrison hip score (HHS), and clinical and radiographic follow-up assessments were used to evaluate the outcome. The average follow-up time was 43 months (range of 1 to 120 months). Implant survival at last follow-up was 75 % (51 of 68). Kaplan-Meier survival analysis, with explantation as the end-point, revealed survival rates of 82.7 % (3 years) and 77 % (5 years). Patients with revision of the acetabular component only had a significant higher survival rate (p < 0.012). Overall revision rate was 36.7 %; re-infection rate was 34.4 %. Complications included 15 (22 %) peri-prosthetic joint infections (PJI), 7 dislocations (10.2 %), and 2 AL (2.9 %). Mean VAS at last follow-up was 1.45 compared to 3.2 pre-operatively, while mean HHS improved from 21.1 points pre-operatively to 61 at last follow-up. The change in both scores was thus significant (p < 0.001). The authors concluded that defect reconstruction with custom-made modular acetabular implants could be a good, nevertheless expensive, therapeutic option with clinically and radiologically satisfying results in comparison to recent studies in the literature. Nevertheless, high post-operative complication rates, especially in terms of PJI, remain a challenge.
Chiarlone and associates (2020) stated that the management of acetabular bone loss is a challenging problem in rTHA. In a systematic review, these investigators analyzed indications, complications, clinical and radiological outcomes of custom-made acetabular components in rTHA. They carried out a systematic review of English literature on Medline. Retrospective or prospective studies with minimum 2 years of follow-up (FU) were included. The PRISMA 2009 flowchart and checklist were considered to edit the review. Rates of intra- or post-operative complications, AL, PJI, re-operations and re-revisions rates were extrapolated. A total of 18 articles with a level of evidence of IV were included. A total of 634 acetabular custom components (627 patients) with a mean FU of 58.6 ± 29.8 months were analyzed. The studies showed good clinical and functional outcomes. Custom-made acetabular components allowed a stable fixation with 94.0 ± 5.0 % survival rate. The estimated rate of re-operations and re-revisions were 19.3 ± 17.3 % and 5.2 ± 4.7 %, respectively. The incidence of PJI was 4.0 ± 3.9 %. The authors concluded that the acetabular custom-made implants represented a reliable solution for pelvic discontinuity and particular cases of bone loss classified as Paprosky Type IIIa and IIIb or type III-IV according to American Academy of Orthopedic Surgeons system where the feature of the defect cannot be handled with standard implants. This strategy allowed to fit the implant to the residual host bone, bypassing the bony deficiency and restoring hip biomechanics. Satisfactory clinical and radiological outcomes at mid-term follow-up were reported in literature.
Portable Accelerometer-Based Navigation System in Total Hip Arthroplasty
Kamenaga and colleagues (2019) examined the accuracy of cup orientation and learning curve of the disposable accelerometer-based portable navigation system for THA in the supine position. A total of 75 patients who underwent THA through the anterolateral supine approach (ALS) with an accelerometer-based portable navigation system for the supine position (HipAlign) between July 2017 and October 2018 were analyzed in this study. These researchers compared the intra-operative cup angles using navigation records with the post-operative angles using post-operative CT data. All participants were categorized into the following groups according to the course of 3 discrete, sequential operative time periods: 1 to 25 (initial group), 26 to 50 (intermediate group), and 51 to 75 (recent group). These investigators compared the accuracy of cup inclination and anteversion among the 3 groups. The time required for navigation and the operative time of all patients were measured. The average absolute error in measurement (post-operative CT-navigation record) was 2.6° ± 2.7° (inclination) and 2.8° ± 2.7° (anteversion). There were no significant differences among the 3 groups. The average time needed for navigation and the operative time were 365.1 ± 90.3 seconds and 76.1 ± 1.6 minutes, respectively. The required time for HipAlign navigation and operative time were constant in most patients, except for those of the initial 5 cases. The authors concluded that the accelerometer-based portable navigation system provided good accuracy of cup orientation, had a short learning curve, and required a minimal surgical time for THA in supine position. These researchers stated that the main drawback of this study was the absence of a control group that used other navigation systems; thus, they should compare the accuracy of cup orientation and learning curve of single surgeon between the accelerometer-based portable navigation and other navigation in the future trials.
Hayashi and associates (2020) stated that accurate orientation of acetabular and femoral components is important during THA. In recent years, several navigation systems have been developed. In a prospective, cohort study, these researchers examined the orientation accuracy of cups inserted using a disposable accelerometer-based portable navigation system for THAs. They analyzed 63 hips with navigation prospectively and 30 hips without navigation retrospectively as historical control. Subjects underwent THA via the mini anterolateral approach in the supine position using an accelerometer-based portable navigation system. These investigators compared the pre-operative target angles, intra-operative cup angles using navigation records, post-operative angles using post-operative CT data, measurement errors of cup angles, and clinical parameters such as sex, treated side, age at surgery, and BMI. The average absolute error (post-operative CT-navigation record) was 2.7 ± 2.1° (inclination) and 2.7 ± 1.8° (anteversion), and the absolute error (post-operative CT-pre-operative target angle) was 2.6 ± 1.9° (inclination) and 2.7 ± 2.2° (anteversion). The absolute error between post-operative CT and target angle with navigation was significantly lower than the error without navigation (inclination; p = 0.025, anteversion; p = 0.005). Cup malalignment (absolute difference of inclination or anteversion between post-operative CT and pre-operative target angle of over 5°) was significantly associated with BMI value (odds ratio [OR]: 1.3, 95 % CI: 1.1 to 1.7). The absolute measurement error of cup inclination and anteversion was significantly correlated with patients' BMI (inclination error: correlation coefficient = 0.53, p < 0.001, anteversion error: correlation coefficient = 0.58, p < 0.001). The authors concluded that the clinical accuracy of accelerometer-based portable navigation was precise for the orientation of cup placement, although accurate cup placement was affected by high BMI. This was the first study to report the accuracy of accelerometer-based portable navigation for THA in the supine position.
Shigemura and co-workers (2021) noted that precise implant alignment is a crucial prognostic factor for successful outcomes following THA. A portable accelerometer-based navigation (PN) device may achieve the same accuracy as that achieved by the computer-assisted navigation surgery technique, with the convenience of a conventional technique. Although the usefulness of PN in THA (PN-THA) has been reported, whether it is more accurate than performing THA with a conventional technique (CON-THA) remains controversial. The difference in surgical time between PN-THA and CON-THA is also unclear. These researchers carried out a systematic review and meta-analysis of studies comparing results of PN-THA with those of CON-THA. They focused on the following question: is PN-THA superior to CON-THA in terms of radiological parameters and surgical time? These investigators performed literature searches in PubMed, Web of Science, and Cochrane Library to identify studies that met the following inclusion criteria: RCTs or non-RCTs, studies involving patients who underwent PN-THA and patients who underwent CON-THA, studies including data on radiological parameters and surgical outcomes. Author names, publication year, country, study design, surgical approach, demographic characteristics of the participants (diagnosis, gender, age, and BMI), and surgical outcomes (the radiological parameters and the surgical time) were extracted. These researchers calculated the MDs for continuous data with 95 % CIs for each outcome; p < 0.05 was considered significant. A total of 3 studies were included in this meta-analysis. The meta-analysis showed that absolute deviation of the post-operative measured angles from the target position for the cup anteversion was significantly smaller in PN-THA than in CON-THA (MD = -1.70, 95 % CI: -2.91 to -0.50, p = 0.005). There was no significant difference in the absolute deviation of the post-operative measured angles from the target position for cup abduction between the groups (MD = -1.82, 95 % CI: -4.32 to 0.67, p = 0.15). The surgical time was significantly longer in PN-THA than in CON-THA (MD = 8.58, 95 % CI: 4.05 to 13.10, p = 0.0002). The authors concluded that this systematic review and meta-analysis of studies comparing the results of PN-THA with those of CON-THA showed that the PN-THA was advantageous for precise cup implantation compared to CON-THA, although PN-THA has a longer surgical time compared to CON-THA. Level of Evidence = III. It should also be noted that all 3 studies discussed post-operative cup position but not clinical outcomes.
Asai and colleagues (2021) noted that a portable navigation system (PNS) was recently introduced. The PNS enables surgeons to place the acetabular component accurately. While the margin of error for the cup abduction and anteversion was larger than the values obtained from a CT-based navigation system, these researchers hypothesized that the accuracy of the PNS might be affected by pelvic tilt. A bone substitute model of the pelvis was used in this in-vitro study. These investigators set the acetabular component using PNS. They set the acetabular component angle after changing the sagittal, coronal, and axial pelvic tilt. These researchers calculated the difference between the angle displayed on the PNS display and the actual angle of the acetabular component. The difference in inclination angle was defined as ΔRI, and the difference in the anteversion angle was defined as ΔRA. They examined the trends in this ΔRI and ΔRA due to the pelvic tilt. In this in-vitro study, the placement of the acetabular component was accurate in the neutral position; ΔRI was 0.5 ± 0.7° and ΔRA was 1.0 ± 0.7°. Sagittal pelvic tilt and axial pelvic tilt increased both the ΔRA and ΔRI (p = 0.017). Coronal tilt increased ΔRI; but did not change ΔRA. The authors concluded that while the PNS may enable surgeons to place accurate component placement in the neutral position, its accuracy decreased by pelvic tilt. The surgeons should use a solid pelvic lateral positioner for reducing discrepancies in pelvic tilt when using the PNS in the lateral decubitus position.
The authors stated that this study had several drawbacks. First, they did not examine factors that affect the placement of the acetabular component, e.g., soft tissue, because they used a pelvic model. Second, the impaction energy needed to fit the acetabular component could deform the pelvic model and wooden board, which may have resulted in the variations. Third, these researchers only examined a single direction of pelvic tilt and did not evaluate the combination of axial, sagittal, and coronal pelvic tilt that could occur intra-operatively. Fourth, these investigators set the acetabular component in the left acetabulum only, which might have affected the results because both operators were right-handed. However, the result would be reversed regarding left and right tilt and rotation if these investigators set it in the right acetabulum. Finally, these researchers only examined combinations with the pelvis, and any correlation with spinal alignment was unknown.
Comparison of Aspirin and Enoxaparin on Symptomatic Venous Thromboembolism After Hip Arthroplasty
On behalf of the CRISTAL Study Group, Sidhu et al (2022) examined if aspirin was non-inferior to enoxaparin in preventing symptomatic VTE after THA or total knee arthroplasty (TKA). The CRISTAL Trial was a cluster-randomized, cross-over, registry-nested study across 31 hospitals in Australia. Clusters were hospitals performing greater than 250 THA or TKA procedures annually. Patients (aged 18 years or older) undergoing hip or knee arthroplasty procedures were enrolled at each hospital. Patients receiving pre-operative anti-coagulation or who had a medical contraindication to either study drug were excluded. A total of 9,711 eligible patients were enrolled (5,675 in the aspirin group and 4,036 in the enoxaparin group) between April 20, 2019, and December 18, 2020. Final follow-up occurred on August 14, 2021. Hospitals were randomized to administer aspirin (100 mg/day) or enoxaparin (40 mg/day) for 35 days after THA and for 14 days after TKA. Cross-over occurred after the patient enrollment target had been met for the first group. All 31 hospitals were initially randomized and 16 cross-ed over before trial cessation. The primary outcome was symptomatic VTE within 90 days, including PE and DVT (above or below the knee). The non-inferiority margin was 1 %; and a total of 6 secondary outcomes were reported, including death and major bleeding within 90 days. Analyses were performed by randomization group. Enrollment was stopped after an interim analysis determined the stopping rule was met, with 9,711 patients (median age of 68 years; 56.8 % female) of the pre-specified 15,562 enrolled (62 %). Of these, 9,203 (95 %) completed the trial. Within 90 days of surgery, symptomatic VTE occurred in 256 patients, including PE (79 cases), above-knee DVT (18 cases), and below-knee DVT (174 cases). The symptomatic VTE rate in the aspirin group was 3.45 %; and in the enoxaparin group was 1.82 % (estimated difference, 1.97 %; 95 % CI: 0.54 % to 3.41 %). This failed to meet the criterion for non-inferiority for aspirin and was significantly superior for enoxaparin (p = 0.007). Of 6 secondary outcomes, none was significantly better in the enoxaparin group compared with the aspirin group. The authors concluded that among patients undergoing hip or knee arthroplasty for OA, aspirin compared with enoxaparin resulted in a significantly higher rate of symptomatic VTE within 90 days, defined as below- or above-knee DVT or PE.
Comparison of Rivaroxaban and Enoxaparin for Thromboprophylaxis After Total Hip Arthroplasty
Wang et al (2024) stated that VTE is one of the major and potentially life-threatening complications following major orthopedic surgeries. Evidence comparing the effectiveness of rivaroxaban and enoxaparin for thromboprophylaxis specific to THA has been limited. In a systematic review and meta-analysis, these investigators compared the safety and effectiveness of rivaroxaban against enoxaparin for thromboprophylaxis following THA. They carried out a search in databases including Medline, Embase, ScienceDirect, Google Scholar, and Cochrane Library from inception until May 2021; RCTs directly comparing the effectiveness of rivaroxaban and enoxaparin for thromboprophylaxis among patients undergoing THA were eligible for inclusion. Outcome parameters evaluated were effectiveness in terms of total VTE and all-cause mortality, major VTE, DVT, symptomatic VTE, and safety in terms of major bleeding events, clinically relevant non-major bleeding events, minor bleeding events, total bleeding events, drug-related AEs, and wound infection. These researchers conducted a meta-analysis with a random effects model and reported a pooled RR with a 95 % CI. A total of 11 studies, including 9,057 subjects, were analyzed. Among effectiveness outcomes, VTE and all-cause mortality pooled an RR of 0.58 (95 % CI: 0.34 to 0.99), major VTE pooled an RR of 0.37 (95 % CI: 0.15 to 0.90), DVT pooled an RR of 0.57 (95 % CI: 0.32 to 1.02), and symptomatic VTE pooled an RR of 0.51 (95 % CI: 0.30 to 0.87). Among safety outcomes, major bleeding events pooled an RR of 1.18 (95 % CI: 0.77 to 1.80), total bleeding events pooled an RR of 1.12 (95 % CI: 0.93 to 1.34), drug-related AE pooled an RR of 0.99 (95 % CI: 0.87 to 1.12), and wound infection pooled an RR of 1.11 (95 % CI: 0.58 to 2.14). The authors concluded that rivaroxaban was a more effective drug in terms of VTE and all-cause mortality compared to enoxaparin following THA, and rivaroxaban was non-inferior in terms of safety profiles such as wound infection, bleeding, and drug-related AEs.
Total Hip Arthroplasty in the Setting of Post-Traumatic Arthritis Following Acetabular Fracture
O’Driscoll et al (2023) noted that acetabular fractures are frequently associated with post-traumatic arthritis (PTA), for which THA has emerged as the established procedure. In a systematic review, these investigators reported the patient outcomes, complications, and implant survival of delayed THA for patients with PTA following acetabular fracture. They carried out a systematic review in December 2021 using the PRISMA statement to identify all studies reporting outcomes of delayed THA performed for PTA with a history of acetabular fracture. From an initial screen of 893 studies, 29 studies that met defined inclusion criteria including minimum 12 months of follow-up and minimum 10 THA were included in the final review. A total of 1,220 THAs were reported across 29 studies, with 1,174 THA completing a minimum of 1-year follow-up at a mean of 86 months. All 29 studies reported upon complications, with a control included in 6 for comparison. Higher complication rates were observed both in patients who had prior open reduction internal fixation (ORIF) and conservative treatment, most notably infection that was observed following 3.6 % THA. The total joint revision rate was 9.7 %. An improvement was noted in all 25 studies that recorded patient-reported outcomes, with a mean rise in the Harris hip score from 45 to 86 across 18 studies. The authors concluded that THA may reduce reported pain levels and improve functional outcomes in selected patients experiencing PTA following acetabular fractures. There was an increased risk of complications, necessitating careful consideration when planning the operation and open discussion with prospective patients and caregivers.
The authors stated that this review had several drawbacks. First, bias may have been introduced in the reporting of complications by virtue of the retrospective nature of included studies that were heterogenic by nature. Second, over the studied time frame, there may have been variation in diagnostic criteria and tools that may have affected reporting of results. Third, the initial search found a number of studies from the same institution with overlapping patient groups, whereby the series of the largest cohort was selected for inclusion. Fourth, statistical analysis for subgroups was limited due to discrepancies in reporting of results among included studies.
Iliopsoas Tenotomy (or Lengthening) for the Treatment of Iliopsoas Tendinopathy Following Total Hip Arthroplasty
Gedouin and Huten (2012) noted that there have been numerous recommendations for management of iliopsoas tendinopathy secondary to hip replacement: medical treatment, cup replacement, and open or arthroscopic tenotomy. In a retrospective, case-series study, these investigators reported on a series of 10 endoscopic iliopsoas tenotomies. Arthroplasty comprised 5 primary conventional total prostheses, 2 large head diameter metal-metal models, 1 resurfacing and 1 revision arthroplasty. All patients underwent clinical (Postel-Merle d'Aubigne (PMA), WOMAC), imaging (X-ray, CT, scintigraphy) and biological assessment. A total of 7 cases showed mechanical impingement (6 involving the anterior edge of the cup, and 1 a cement fragment); the other 3 involved large femoral components (2 large head diameter models, 1 resurfacing). Infiltration test was positive in 8 cases out of 9. Endoscopic iliopsoas tenotomy for recurrence was performed in dorsal decubitus on an ordinary table, under fluoroscopy, using 2 approaches (inferior for the endoscope, superior for the instruments) converging on the lesser trochanter. There were no complications. At a mean 20 months' follow-up (range of 12 to 60 months), mean pain grade was 5.5 (4 to 6); 8 patients showed complete relief, and 2 partial relief (2 atypical cases). Mean PMA score was 16.9 (15 to 18) and mean WOMAC score 84 (60 to 95). Muscle force was recovered at a mean 3.25 months (0.5 to 6); 8 patients were very satisfied, 1 satisfied and 1 moderately satisfied. The authors concluded that this technique was much less heavy than implant replacement; post-operative course was shorter than for open tenotomy and the technique was simpler than arthroscopic tenotomy, with lower risk. Subsequent cup change, where necessary, was not compromised. Level of Evidence = IV.
Filanti et al (2016) presented their arthroscopic surgical technique and the results in patient with pain after a hip replacement. Between November 2009 and September 2011, a total of 35 patients with groin pain after total hip arthroplasty (THA) were treated arthroscopically. The patients underwent a pre-operative examination consisting of careful history, physical examination, laboratory evaluation, diagnostic evaluation using X-rays and pelvis computed tomography (CT) scans. In patients for whom the clinical picture suggested iliopsoas tendonitis, these researchers also carried out injection of local anesthetic on the iliopsoas tendon sheath. All the patients were positioned in the supine decubitus position with traction applied, using 2 arthroscopic portals (AL, MID-A). An extensive debridement of adhesions, peri-prosthetic tissue and neocapsula were performed; when there were signs of iliopsoas impingement, a trans-capsular tenotomy was carried out according to Wettstein technique. The average age was 57 (29 to77) years old. The average time to onset of symptoms was 10.8 (5 to 15) months after THA. The average pre-operative Harris Hip Score (HHS) was 44.1 (range of 32 to 56). The average pre-operative Medical Research Council (MRC) scale for muscle strength was 3.27 (range of 3 to 4). After 24 months of follow-up patients showed an average HHS of 75.73 (range of 50 to 91). Patients who underwent iliopsoas release showed a post-operative HHS of 83.28 (range of 61 to 91). The average post-operative MRC scale was 4.45. The authors concluded that groin pain still remains a difficult challenge for surgeons to diagnose and treat because of the heterogeneity of symptoms and etiology. Hip arthroscopy as a therapeutic approach to groin pain following THA revealed itself to be an important instrument. Hip arthroscopy in treatment of reactive synovitis and adhesions showed good results according to literature. Hip arthroscopy in treatment of anterior iliopsoas impingement was the most useful instrument, being less invasive than classic open technique. Surgical intra-articular approach gave the surgeon the possibility to make easier massive debridement and trans-capsular tenotomy, reducing the chance of complications and functional post-operative loss. This procedure requires a long learning curve; thus, results were strictly related to the surgeon’s expertise. Currently, studies in the reviewed literature showed small groups of patients only. For this reason, it is not yet possible to provide an accurate statistical evaluation.
The authors stated that the main drawback of the present study was its multi-center design, introducing treatment bias (e.g., injection tests were not systematic). It also led to inter-observer variation, which might undermine correlation with such-and-such a pre-operative parameter. There was also a significant difference between radiologists and surgeons in interpreting CT images in terms of anterior cup projection; reliable anatomic landmarks need to be defined. Surgeons may have been alerted by prior clinical findings, and radiologists may have lacked information as to what anatomic abnormality to look for.
Guicherd et al (2017) stated that impingement between the acetabular component and the iliopsoas tendon is a cause of anterior pain following total hip replacement (THR). Treatment can be non-operative, endoscopic or arthroscopic, or by open revision of the acetabular component. Few studies have assessed these options. In a prospective, multi-center study, these researchers hypothesized that endoscopic/arthroscopic treatment would provide rapid pain relief with a low rate of complications. This trial included 64 endoscopic or arthroscopic tenotomies for impingement between the acetabular component and the iliopsoas tendon, performed in 8 centers. Mean follow-up was 8 months, with a minimum of 6 months and no loss to follow-up. Oxford score, patient satisfaction, anterior pain and iliopsoas strength were assessed at last follow-up. Complications and revision procedures were collated; 44 % of patients underwent rehabilitation. At last follow-up, 92 % of patients reported pain alleviation. Oxford score, muscle strength and pain in hip-flexion showed significant improvement. The complications rate was 3.2 %, with complete resolution. Mean hospital length of stay (LOS) was 0.8 nights. In 2 cases, arthroscopy revealed metallosis, indicating revision of the acetabular component. The only predictive factor was acetabular projection on oblique view. Rehabilitation significantly improved muscle strength. The authors concluded that endoscopic or arthroscopic tenotomy for impingement between the acetabular component and the iliopsoas tendon following THR significantly alleviated anterior pain in more than 92 % of cases. The low complications rate made this the treatment of choice in case of failure of non-operative management. Arthroscopy also re-oriented diagnosis in case of associated joint pathology. Projection of the acetabular component on pre-operative oblique view was the most predictive criterion, guiding treatment.
In a systematic review, O'Connell et al (2018) compared patient outcomes following arthroscopic and open operative management of iliopsoas tendonitis (IPT) following total hip replacement (THR). This review study was carried out in accordance with the Preferred Reporting Items for Systematic review and Meta-Analysis (PRISMA) statement. Inclusion criteria were as follows: outcome studies following open or arthroscopic iliopsoas tendon release after THR with at least 6 months of follow-up, English language, and human studies. The exclusion criteria included case reports, studies examining non-surgical management or cup revision, and studies without a specific diagnosis of IPT or in which results between open and arthroscopic treatment were reported in conjunction. A total of 131 studies were initially retrieved, with 7 satisfying all inclusion criteria (4 studies on arthroscopic tenotomy and 3 studies on open tenotomy). The review included a total of 88 patients with IPT-61 patients treated arthroscopically and 27 patients treated with open tenotomy. A total of 77 of the 88 patients demonstrated successful outcomes following surgery. In the group treated with arthroscopy, 91.8 % (56/61) of patients had successful outcomes, whereas in those treated with open tenotomy, 77.8 % (21/27) of patients had successful outcomes. Of patients with signs of mechanical impingement from acetabular component overhang, those who underwent open tenotomy had complete pain relief in 6/8 patients (75 %) compared to arthroscopic tenotomy in which there was relief in 40/43 patients (93 %). The authors concluded that arthroscopic iliopsoas release for management of IPT was suggested to be an effective minimally invasive operative technique that may also yield a lower complication rate in comparison to open tenotomy. These researchers stated that tenotomy, both arthroscopic and open, were successful therapeutic options for IPT, including those with signs of mechanical impingement, and were recommended prior to cup revision. Level of Evidence = IV.
The authors stated that the key drawback of this study was the level of evidence of the included studies. All studies were Level IV evidence, consisting of retrospective reviews of unmatched or controlled cohorts. The majority of studies on treating IPT included small sample sizes with limited follow-up and heterogeneous outcome measures. Subsequently, it was difficult to attain statistically significant conclusions and carry out meta-analysis; thus, this review was only a descriptive systematic review, and no definitive conclusions could be made. Furthermore, only 1 study examining open tenotomy reported on complications. Although the lack of data for complications in the remaining open studies definitely introduced bias, it only under-estimated the potential upside of arthroscopic treatment, as complications in the open group might be under-represented. However, based on the available literature, these researchers felt they were able to provide some analysis of the current treatment modalities that could provide guidance for treatment of patients with IPT following THR. Another drawback was that there were no studies that directly compared open versus arthroscopic techniques. Finally, as with any systematic review there was the possibility of non-inclusion of relevant articles. However, these investigators felt that their search strategy combined with searching all relevant articles’ reference lists should have minimized this type of bias. However, there could always be unpublished data that these researchers did not have access to that could have increased their patient numbers.
Shapira et al (2019) stated that non-operative and operative management of iliopsoas impingement (IPI) is commonly performed following THA. In a systematic review, these investigators compared patient-reported outcomes (PROs) following conservative treatment, IP tenotomy, and revision arthroplasty in patients presenting with IPI following THA. PubMed and Embase databases were searched for studies regarding IPI following THA. Studies were included if IPI following THA was treated with conservative management, an IP tenotomy, or acetabular component revision and included PROs. A total of 11 studies were selected for review and there were 280 hips treated for IPI following THA. Harris hip scores reported for the conservative group, the IP tenotomy group, and the cup revision group were 59.0 pre-operatively to 77.8, 58.0 pre-operatively to 85.4, and 58.1 pre-operatively to 82.4 at latest follow-up, respectively. The IP tenotomy cohort also demonstrated superior post-operative functional outcomes using the WOMAC, MRC score, Oxford Hip Score, and PMA pain score. Patients who had a revision exhibited higher Oxford Hip Scores, higher MRC scores, and lower visual analog scale (VAS) pain scores post-operatively. The authors concluded that management of IPI following THA included non-operative measures, IP tenotomy, or acetabular component revision. Patients have been shown to experience favorable PROs at latest follow-up, with an apparent advantage for surgical treatment. Compared to revision arthroplasty, IP tenotomy resulted in a lower overall rate of complications with less severe complication types; thus, IP tenotomy should be considered as a 2nd line of treatment for patients who failed conservative measures. Revision arthroplasty should be reserved for recalcitrant cases. Level of Evidence = IV.
The authors stated that this systematic review had several drawbacks. First, there was heterogeneity in the selected studies with respect to the dispersion of the reported PROs. Second, none of the articles reported on a control group who did not experience IPI following THA, limiting the level of evidence of the selected studies. Third, these researchers acknowledged there was a selection bias inherent in some of the reviewed studies, as the surgeon’s decision-making process in performing a tenotomy versus revision was only elucidated in 3 studies. Fourth, although these investigators included 3 studies regarding outcomes on patients who underwent conservative management, it was likely that outcomes following conservative management were under-reported in the literature.
Bell et al (2019) noted that iliopsoas impingement following total hip arthroplasty (THA) occurs in up to 4.3 % of patients resulting in functional groin pain. Operative treatment historically has included open iliopsoas tenotomy or acetabulum revision. These researchers described a large, retrospective, single-surgeon series of patients treated with endoscopic iliopsoas tenotomy for iliopsoas impingement following THA to examine the effectiveness and risks. This trial included a consecutive series of 60 patients with iliopsoas impingement following THA treated with endoscopic iliopsoas tenotomy. Outcomes assessed were resolution of pain, change in Hip Outcome Score (HOS), and complications. Radiographs were reviewed by a musculoskeletal radiologist to evaluate component positioning and to compare with a control cohort. At last follow-up (mean of 5.5 months), 93.3 % of patients had resolution of pain. The HOS ADL subscale mean was 57.5 (range of 10.9 to 89.3, SD of 18.8) pre-operatively and 71.6 (range of 14.1 to 100, SD of 26.1) post-operatively (p = 0.005). The HOS sports subscale mean was 37.3 (range of 0 to 83.3, SD of 24.0) pre-operatively and 58.1 (range of 0 to 100, SD of 33.2) post-operatively (p = 0.002). One complication was reported, a post-operative hematoma managed conservatively. BMI and increased offset were associated with iliopsoas symptoms following THA in this series. The authors concluded that endoscopic iliopsoas tenotomy following THA had a 93.3 % resolution of pain, clinically important improvements in HOS, and low rate of complications.
The authors stated that the limitations of this retrospective study included a small sample size (n = 60) and the lack of cross table lateral to evaluate acetabular prominence. Objective hip-flexion strength data were not recorded before or after tenotomy in a systematic manner, so this could not be evaluated. These researchers stated that further research regarding change in hip-flexion strength after tenotomy would be beneficial as this was some concern patients had prior to surgery. Selection bias was also a limitation of this study, which these researchers attempted to limit by including all patients who underwent psoas tenotomy. These investigators stated that a larger control group sample size, would likely have increased the study power. There were 5 patients who did not have a pre-operative iliopsoas injection to confirm diagnosis; however, similar results were observed when those 5 patients were excluded from analysis.
Moreta et al (2021) noted that one of the causes of groin pain following THA is impingement of the iliopsoas tendon. In a retrospective study, these researchers presented their findings with outside-in arthroscopic tenotomy for iliopsoas impingement following THA. They reviewed the findings of 12 patients who were treated between 2009 and 2016 with a minimum follow-up of 2 years. Anterior acetabular component prominence was measured on a true lateral hip radiograph. A transcapsular tenotomy was carried out near the edge of the acetabular component via an outside-in arthroscopic approach. The primary clinical outcomes evaluated were groin pain, assessed with a VAS, and the HHS. Secondary outcomes included strength of hip-flexion, measured with the Medical Research Council (MRC) scale. All patients had groin pain improvement, although 1 patient continued to have moderate pain. The mean VAS score was significantly lower post-operatively (1.08) than pre-operatively (6.2) (p < 0.001). The mean HHS improved from 58.8 (range of 37 to 76) to 86.1 (range of 59 to 98) (p = 0.001). The average post-operative MRC scale was 4.58. The mean anterior prominence was 7.25 mm (range of 3 to 12 mm). In patients with less than 10 mm of component prominence, tenotomy provided groin pain resolution in all cases (n = 8). In patients with 10 mm or larger of prominence, symptoms resolved in 3 out of 4 cases. The authors concluded that outside-in arthroscopic iliopsoas release provided a high rate of success with no complications in this study, even in patients with moderate acetabular component prominence. Moreover, these investigators stated that further studies are needed to examine the use of MRI in iliopsoas impingement following THA.
The authors stated that although to their knowledge this was the largest series of patients with a transcapsular tenotomy, they recognized that this study had several drawbacks. In particular, the small sample size (n = 12) and the mixed population (hemispherical cups or threaded cups) were likely responsible for some differences not reaching statistical significance. Another drawback was that the mean follow-up was relatively short.
Tassinari et al (2021) described the clinical outcomes of 16 patients with iliopsoas impingement following primary THA, treated with an arthroscopic tendon release. A total of 16 patients (11 females, 5 males), with a mean age of 57.8 ± 11.1 years (age at THA: 54.4 ± 11 years) and a diagnosis of iliopsoas impingement following primary THA, were treated with the Wettstein tenotomy. Pre-operatively, every patient underwent a diagnostic ultrasonography (US)-guided peritendinous injection and a CT scan. Every patient was clinically evaluated using WOMAC score. Subjective pain relief and active hip-flexion strength were measured. No complications related to arthroscopy were detected. Every cup was prominent with a mean axial overhang of 13 ± 4.8 mm (range of 5 to 20 mm). At a mean follow-up of 27 ± 20.1 months (range of 6 to 48 months), the WOMAC score was 83.7 ± 10.1 points. A total of 13 patients out of 16 (81.3 %) had a complete pain relief; 14 patients out of 16 (88 %) regained full active hip-flexion strength at the final follow-up; 1 patient was scheduled for cup revision after 6 months, due to persistent symptomatology. No demographic data or CT measurements regarding cup position statistically influenced the outcome. The authors concluded that when preceded by an appropriate diagnosis, arthroscopic tenotomy proved safe and effective for iliopsoas impingement, regardless the magnitude of cup protrusion. Moreover, these researchers stated that this retrospective, limited case series did not allow definitive conclusions. They stated that prospective, matched studies are needed to point out the advantages and indications of this procedure, in particular in comparison with the endoscopic technique.
The authors stated that the present cohort study shared the same limits as the previously published literature: retrospective design, small numbers and the lack of direct comparison between different techniques. Furthermore, quantitative evaluation of the hip strength was also not performed.
In a retrospective, cohort study, Viamont-Guerra et al (2021) reported outcomes of endoscopic iliopsoas tenotomy (EIT) in patients with iliopsoas tendinopathy following THA and examined if improvements in clinical scores were associated with acetabular cup anteversion measured on plain radiographs or overhang measured using established and alternative CT-based methods. These investigators examined patients who underwent EIT for iliopsoas tendinopathy following THA (2014 to 2017), performed between the lesser trochanter and psoas valley. Indications were groin pain during active hip-flexion, exclusion of other complications, and no pain relief after 6 months of conservative treatment. Pre-tenotomy inclination and anteversion were measured on radiographs; sagittal and axial overhang were measured on CT scans on slices passing through: (Method 1) prosthetic head center and (Method 2) anterior margin of acetabular cup. Modified HHS (mHHS), Oxford Hip Score (OHS), and level of groin pain were recorded at 12 or more months. Wilcoxon signed-rank tests were used to compare pre- and post-tenotomy scores, and intra-class correlation coefficients (ICCs) to evaluate inter-method agreement. Participants comprised 16 men (17 hips) and 32 women (33 hips), aged 60.8 ± 10.5 years at EIT. For the 30 (60 %) hips that had pre-tenotomy CT scans, axial and sagittal overhang were, respectively, 3.4 ± 3.7 mm and 4.6 ± 4.6 mm, using Method 1, compared with 3.9 ± 3.9 mm and 6.9 ± 5.0 mm using Method 2. Inter-method agreement was good for axial (ICC, 0.67; p < 0.001) and sagittal (ICC, 0.68; p < 0.001) overhang. At a minimum 1 year after EIT, 3 hips had cup and stem revision and 1 hip had isolated cup revision, leaving 46 hips for clinical assessment. No complications were noted. mHHS improved by 26 ± 19 (p < 0.001) and OHS improved by 20 ± 11 (p < 0.001). A total of 26 hips (57 %) achieved the patient acceptable symptom state for mHHS, whereas 42 hips (91 %) achieved the patient acceptable symptom state for OHS. Post-tenotomy groin pain was slight in 15 %, mild in 17 %, and moderate in 11 %. Regression analyses revealed no associations between clinical scores and overhang/anteversion. The authors concluded that for patients with iliopsoas tendinopathy following THA, endoscopic iliopsoas tenotomy granted clinically important improvements of mHHS in 76 % and OHS in 89 %, despite moderate residual groin pain in 11 %. Improvements in clinical scores did not appear to be associated with the extent of cup overhang or anteversion in the cases for which adequate pre-operative imaging was available. Level of Evidence = IV.
Valenzuela and O'Donnell (2021) noted that iliopsoas impingement is an under-diagnosed cause of groin pain following THA, being responsible for 4.4 % of cases. Non-surgical treatment may be effective in approximately 50 % of cases. Endoscopic surgery has gained popularity as an option for non-responsive patients because of its non-invasive characteristics, faster recovery and encouraging results. In a retrospective review, these researchers compared 2 different sites of endoscopic psoas tenotomy performed following THA: at the edge of the acetabulum (AR) versus at the lesser trochanter (LT). They examined prospectively collected data from a single-surgeon case series. A total of 35 iliopsoas tenotomy cases that had 24-month or longer follow-up were identified. There were 21 tenotomies at the lesser trochanter. Demographic data, pre-operative as well as post-operative pain, mHHS and NAHS scores, strength and patient satisfaction data were collected and analyzed. Average age at the time of surgery was 62 years. Mean follow-up for the LT group was 49.11 months and 42.42 months for the AR group. Pain decreased significantly for both groups (p < 0.001). Both mHHS and NAHS showed superiority in the LT group; however, this difference did not reach significance (p = 0.06). LT patients showed better strength with 71.42 % of them having normal strength at latest follow-up, compared with 41.6 % in the AR group. There were no complications in either group. The authors concluded that the findings of this study supported arthroscopic/endoscopic surgical management for patients with iliopsoas impingement following THA, which was not responsive to non-surgical treatment. Both tenotomy techniques led to improved symptoms in a high percentage of patients and had no early, or late, complications. However, tenotomy at the LT consistently showed less post-operative pain, better strength and higher functional scores in comparison with the AR group, although these results did not reach statistical significance. Moreover, these researchers stated that although these results suggested that both approaches were reliable surgical options, with a trend for better outcomes for the LT group, a larger, prospective study is needed to definitively determine which technique is superior.
The authors stated that this study had several drawbacks. First, data were collected retrospectively; thus, some data points were missing. Second, many mHHS and NAHS pre-operative values were not collected; however, patients consistently had scores above the PASS, with better results reported for the LT group. Third, specific radiographical assessment of the degree of acetabular prominence was not carried out.
In a systematic review, Coulomb et al (2022) examined the technique, results and complications of arthroscopic iliopsoas tenotomies either on native hips or THA. This systematic review was carried out using 3 databases: PubMed, Embase and the Cochrane library from January 2000 to December 2018 in accordance with the PRISMA procedure. The literature search, data extraction and quality assessment were performed by 2 independent reviewers. Surgical technique, clinical outcomes, recurrences and complication rates were evaluated. Out of 115 studies reviewed, 20 concerned native hips and 8 articles THA; and 3 levels of release were described. For native hips, the recurrence rate was higher for central compartment than peripheral or lesser trochanter releases. Complication rates were similar for hip arthroscopy but remained low in all series. Loss of strength was examined mainly using the MRC muscle scale. Most studies noted strength recovery. MRI analysis of muscle atrophy was greater for lesser trochanter than for central compartment release but unrelated to loss of strength. The complication rate was low for tenotomy following THA, heterotopic ossification being the most common complication. The authors concluded that central compartment releases resulted in the highest rate of recurrence due to incomplete release. Peripheral releases had a potential risk of vascular injury. The lesser trochanteric approach had the disadvantage of not having direct access to the joint. The main difficulty with THA lied in the diagnosis of cup/iliopsoas impingement. Diagnostic tests with infiltration should be made before iliopsoas release to prevent its failure. Cup protrusion of over 8 mm was a potential indication for acetabular revision. This review identified 8 studies of iliopsoas tenotomy following THA. These researchers noted that the studies analyzed had low statistical power as most of them were grade-4 and a few of them were grade-3. This was explained by the low frequency of pathologies related to the iliopsoas tendon that did not allow for larger series. Given the low level of scientific proof (grade-3 or grade-4), the validity of the conclusions was questionable.
The authors stated that this analysis had several drawbacks. First, the heterogeneity of the evaluation scales in the articles (HHS, OHS, WOMAC) raised the problem of measurement bias. Second, the populations in the series under study were not comparable (e.g., different countries, age, gender, athletic), which may have led to a selection bias. Third, due to its methodology, a literature review may be the cause of non-communication of certain results. This “file drawer” effect may be responsible for a publication bias.
In a retrospective study, Nikou et al (2023) examined the outcome of arthroscopic treatment for iliopsoas impingement following THA 2 years after surgery using PROs. A total of 12 patients (13 hips) were included from a local hip arthroscopy registry. Patients completed web-based PROs pre-operatively and at a minimum of 2 years post-operatively. The PROs included the International Hip Outcome Tool short version (iHOT-12), the Copenhagen Hip and Groin Outcome Score (HAGOS), the European QOL-5 Dimensions Questionnaire (EQ-5D), the Hip Sports Activity Scale (HSAS) for physical activity level, the VAS for overall hip function and a single question regarding overall satisfaction with the surgery. The mean age was 64.4 years (± 15.1 SD), mean BMI was 26.6 (± 4.3 SD), mean follow-up time was 49.8 months (± 25 SD). Comparing PROs pre-operatively with 2-year follow up showed an improvement for many of the PROs used. The PROs scores were iHOT-12 (24.9 versus 34.5, p = 0.13), HAGOS subscales (symptoms 38.2 versus 54.5, p = 0.05; pain 36 versus 53, p = 0.04; sport 14.1 versus 35.1, p = 0.03; daily activity 31 versus 47.5, p = 0.04; physical activity 21.8 versus 24, p = 0.76; QOL 24 versus 35, p = 0.03), EQ-VAS (57.9 versus 58, p = 0.08), EQ-5D (0.34 versus 0.13, p = 0.07) and VAS for overall hip function (43.1 versus 46.2, p = 0.14). A total of 10 out of the 12 patients (83 %) were satisfied with the intervention. The authors concluded that patients undergoing surgery for iliopsoas impingement following previous THA showed improved self-reported hip function where most patients were satisfied with treatment.
The authors stated that this study had several drawbacks. It was a retrospective analysis of prospectively collected data. The small patient sample (n = 12) imposed certain limitations regarding the conclusions that could be drawn from this study. A power analysis was not conducted before analysis as this was a retrospective study, which meant that there was a significant possibility of type-II error. However, to the knowledge of the authors, this was one of the few current studies examining results after arthroscopic psoas tenotomy following THA using recommended PROs for hip arthroscopy patients. Although a thorough search was executed with both the local registry data as well as a search in the hospital registers, there was still a risk that not all patients were found. However, the risk was deemed to be small. Another drawback of this study was the short follow-up of 2 years. A longer follow-up could be warranted to strengthen conclusions regarding the long-term effects of this method. Another aspect was that the radiological analysis was performed by only 1 surgeon without any inter- or intra-observer agreement analysis of the radiological findings, potentially limiting the accuracy of the radiological values registered. Furthermore, the hip-flexion muscle strength pre- and post-operatively was not measured; thus, not being able to examine the effect of iliopsoas tenotomy on the hip-flexion muscle strength.
Furthermore, an UpToDate review on “Complications of total hip arthroplasty” (Erens, 2023) does not mention iliopsoas tendon lengthening as a management / therapeutic option.
Augmented or Virtual Reality (AR/VR) Assistance for Hip Arthroplasty
Tsukada et al (2022) stated that there have been no studies regarding the effectiveness of augmented reality (AR)-based portable navigation systems compared with accelerometer-based portable navigation systems in total hip arthroplasty (THA). In a retrospective, non-randomized study, these researchers compared THAs performed using an AR-based portable navigation system (n = 45) with those performed using an accelerometer-based portable navigation system (n = 42). All THAs were carried out with the patient in the lateral decubitus position. The primary outcome was the absolute difference between cup placement angles displayed on the navigation screen and those measured on post-operative X-ray. The mean absolute differences were significantly smaller in the AR-based portable navigation system group than the accelerometer-based portable navigation system group in radiographic inclination (2.5° ± 1.7° versus 4.6° ± 3.1°; 95 % CI: 1.1° to 3.2°, p < 0.0001). Similarly, the mean absolute differences were significantly better in the AR-based portable navigation system group in radiographic anteversion (2.1° ± 1.8° versus 6.4° ± 4.2°; 95 % CI: 3.0° to 5.7°, p < 0.0001). Neither hip dislocation, surgical site infection (SSI), nor other complications associated with use of the navigation system occurred in either group. The authors concluded that the AR-based portable navigation system may provide more precise acetabular cup placement compared with the accelerometer-based portable navigation system in THA.
The authors stated that this study had several drawbacks. First, although the results of this study showed that the accuracy of the AR-Hip system was significantly better than HipAlign system in THA with patients in the lateral decubitus position, the study design could not determine the specific factors responsible for the differences. These investigators deduced that the difference in registration between HipAlign and AR-Hip systems would be one factor associated with the significant difference in accuracy of acetabular cup placement. The HipAlign system creates a 3-dimensional (3D) coordinate system to define the positional information of the acetabular cup based on the surgical table during THA with the patient in the lateral decubitus position. The HipAlign system calculates inclination and anteversion angles of the acetabular cup under the assumption that the pelvis is accurately positioned during registration; therefore, the surgeon must align the pelvis vertical to the upper surface of the surgical table. However, several studies showed that the initial position of the patients’ pelvis had large variation and changed easily during the THA procedure. To resolve the issue of the instability of the pelvis, several investigators took an intra-operative pelvic X-ray immediately before registration and adjusted the tilt of the surgical table to align the pelvis vertical to the surgical table. Inaccurate pelvic alignment in the lateral decubitus position may have decreased the accuracy of the HipAlign system in this study. In contrast, even when THA is performed with the patient in the lateral decubitus position, the AR-Hip system allows the surgeon to create a 3D coordinate system for the positional information of the acetabular cup with the patient in the supine position. Registration in the supine position may enable the surgeon to achieve more precise placement of the acetabular cup during THA with the patient in the lateral decubitus position. It should be noted that the pelvic tilt before THA is different from that after THA. Thus, although both registration and X-ray were performed in the supine position when using the AR-Hip system, the change in pelvic tilt influences the reference plane and can decrease the accuracy.
Second, this was a retrospective, comparative study in which the allocation of 2 groups was not randomized. Although there were no significant differences in the demographic data between the HipAlign and AR-Hip groups, randomly assigning the intervention could avoid the influence of confounding variables. Selection bias can produce unreliable results in non-randomized studies. Third, these researchers routinely inserted 2 screws to reinforce the initial stability of the acetabular cup. This study could not eliminate the effect of screw fixation on the acetabular cup placement angles. Screw fixation could change both the inclination and anteversion angles by approximately 2°. Fourth, the authors evaluated the cup placement angle using plain X-ray. Although plain X-ray has been the most important diagnostic measure of inclination and anteversion after THA, measurements using CT may be more suitable for comparison of the accuracy between navigation systems, especially in terms of anteversion. Fifth, all THAs were performed using the modified Watson-Jones approach. It would require careful consideration to apply these findings to patients undergoing THA using other surgical approaches. Sixth, although the sample size of this study fulfilled the primary outcome of this study, the accuracy of acetabular cup placement angle during THA with the patient in the lateral decubitus position, it was still under-powered to determine whether the difference in navigation system could be attributed to the revision rate after THA. These researchers stated that further studies including random allocation and larger sample size are needed to demonstrate the superiority of the AR-Hip system compared with HipAlign system.
Sun et al (2023) noted that virtual and augmented reality (VAR) represents a combination of current state-of-the-art computer and imaging technologies and has the potential to be a revolutionary technology in many surgical fields. An increasing number of investigators have developed and applied VAR in hip-related surgery with the objective of using this technology to reduce hip surgery-related complications, improve surgical success rates, and reduce surgical risks. These technologies are beginning to be widely used in hip-related pre-operative operation simulation and training, intra-operative navigation tools in the operating room, as well as post-operative rehabilitation. With the objective of reviewing the current status of virtual reality (VR) and augmented reality (AR) in hip-related surgery and summarizing its benefits, these researchers described the applicability, advantages, limitations, and future perspectives of VR and AR techniques in hip-related surgery, such as pre-operative operation simulation and training; examined the possible future applications of AR in the operating room; and discussed the bright prospects of VR and AR technologies in post-operative rehabilitation following hip surgery. They searched the PubMed and Web of Science databases using the following key search terms: ("virtual reality" OR "augmented reality") AND ("pelvis" OR "hip"). The literature on basic and clinical research related to the afore-mentioned key search terms, i.e., studies examining the key factors, challenges, or problems of using of VAR technology in hip-related surgery, was collected. A total of 40 studies and reports were included and classified into the following categories: THA, hip resurfacing, femoral neck fracture, pelvic fracture, acetabular fracture, tumor, arthroscopy, and post-operative rehabilitation. Quality assessment could be carried out in 30 studies. Among the clinical studies, there were 16 case series with an average score of 89 out of 100 points (89 %) and 1 case report that scored 81 (SD 10.11) out of 100 points (81 %) according to the Joanna Briggs Institute Critical Appraisal Checklist. Two cadaveric studies scored 85 of 100 points (85 %) and 92 of 100 points (92 %) according to the Quality Appraisal for Cadaveric Studies scale. The authors concluded that VR and AR technologies hold great promise for hip-related surgeries, especially for pre-operative operation simulation and training, feasibility applications in the operating room, and post-operative rehabilitation, and have the potential to assist orthopedic surgeons in operating more accurately and safely. These researchers stated that this systematic review suggested that VAR technologies have the potential to aid surgeons in performing surgeries faster and more accurately. Although VAR are promising modern technologies, more comparative studies on technical accuracy, operative time, clinical outcomes, and cost-effectiveness are needed. Furthermore, these investigators expect future studies to demonstrate whether augmented technology is beneficial in the field of post-operative rehabilitation.
Su et al (2023) stated that extended reality (XR), including VR, AR, as well as mixed reality, has been employed to aid surgeons in attaining accurate acetabular cup placement in THA. In a systematic review and meta-analysis, these investigators compared the differences between XR-assisted and conventional THA. They searched electronic databases including PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), and clinicaltrials.gov for studies from inception to September 10, 2023. The outcomes were accuracy of inclination and anteversion, duration of surgery, and intra-operative blood loss. Meta-analysis was performed using Review Manager 5.4 software. A total of 5 studies with 396 patients were included in this study. The pooled results indicated AR-assisted THA exhibited better accuracy of inclination and anteversion than conventional THA (SMD = - 0.51, 95 % CI: - 0.96 to - 0.07, p = 0.02; SMD = - 0.96, 95 % CI: - 1.19 to - 0.72, p < 0.00001), but duration of surgery and intra-operative blood loss were similar in the 2 groups. The authors concluded that this systematic review and meta-analysis found that AR-assisted THA had better accuracy of inclination and anteversion than conventional THA; however, the duration of surgery and intra-operative blood loss were similar in the 2 groups. Based on the pooled results, these investigators suggested that AR can provide more precise acetabular cup placement than conventional methods in THA. Moreover, these investigators stated that further research is needed to minimize heterogeneity and improve statistical power.
The authors stated that this study had several drawbacks. First, the sample size of this study was small (n = 396 patients in 5 studies), and both RCTs and non-RCTs were included due to a lack of data, which added to potential bias to this study. Second, because all the included studies were published in English, the language bias was difficult to avoid. Third, although these researchers have carried out sensitivity and subgroup analyses, significant heterogeneity remained between studies.
Corticosteroid Injection Prior to Hip Arthroplasty and Periprosthetic Joint Infection
Avila, et al. (2023) conducted a systematic review and meta-analysis exploring the relationship between intraarticular injections (IAIs) and periprosthetic joint infection (PJI) following THA reported in the current literature. Five online databases were queried for analyses published from January 1st, 2000-May 1st, 2021 reporting on PJI rates between patients undergoing primary THA who did and did not preoperatively receive an IAI. The overall pooled effect of injection status on PJI incidence was determined using Mantel-Haenszel (M-H) models. This was similarly conducted for segregated preoperative intervals: 0-3 months, > 3-6 months, > 6 + months. A total of 11 articles were included in the analysis reporting on 278,782 THAs (IAI: n = 41,138; no IAI: n = 237,644). Patients receiving pre-operative injections had a significantly higher risk of PJI (OR: 1.31, 95% CI 1.07-1.62; p = 0.009). However, this finding was not robust. IAI receipt within 3-months of THA was associated with significantly higher PJI rates (OR: 1.68, 95% CI 1.48-1.90; p < 0.001). However, no significant difference was demonstrated in the > 3-6 month (OR: 1.19, 95% CI 0.94-1.52; p = 0.16) and > 6 + month sub-analyses (OR: 1.20, 95% CI 0.96-1.50; p = 0.11). The results of all sub-analyses remained were robust. The authors concluded that their findings suggest that patients requiring THA should wait at least 3-months following IAI to reduce post-operative infection risk.
Saracco, et al. (2023) conducted a literature review and meta-analysis to evaluate the effect of prior intra-articular injections on the risk of periprosthetic joint infection (PJI) in patients undergoing total hip arthroplasty (THA) and to identify which is the minimum waiting time between hip injection and replacement in order to reduce the risk of infection. The database of PubMed, Embase, Google Scholar and Cochrane Library was systematically and independently searched, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. To assess the potential risk of bias and the applicability of the evidence found in the primary studies to the review, the Newcastle-Ottawa scale (NOS) was used. The statistical analysis was performed by using the software 'R' version 4.2.2. The pooling of data revealed an increased risk of PJI in the injection group that was statistically significative (P = 0.0427). In the attempt to identify a 'safe time interval' between the injection and the elective surgery, investigators conducted a further subgroup analysis: in the subgroup 0-3 months, they noted an increased risk of PJI after injection. The authors concluded that intra-articular injection is a procedure that may increase the risk of developing periprosthetic infection. This risk is higher if the injection is performed less than 3 months before hip replacement.
Glossary of Terms
| Term | Definition |
|---|---|
| Conservative therapy | Non-surgical medical management |
| Functional disability | Interference with activities of daily living (ADLs) |
Appendix
Paprosky Classification of Acetabular Deficiencies for Revision Total Hip Arthroplasty
Type I: Defect with undistorted rim
Type II: Defect with distorted rim but adequate to support a hemispherical cup
- II A: Superior and medial with intact superior rim.
- II B: Superior with less than 1/3 superior rim deficient.
- II C: Medial wall defect.
Type III: Defect with non-supportive rim
- III A: Superior and lateral with 40 to 60 % of the host bone intact and partial inherent mechanical stability.
- III B: Superior and medial with host bone less than 40 % and possibility of occult discontinuity.
Source: Classifications Used in Total Hip Arthroplasty. Ashraf M. November 2018.
Tonnis Grading Scale of Hip Osteoarthritis
Grade 0:
No signs of osteoarthritis
Grade 1:
- Slight narrowing of joint space; and
- Slight lipping at joint margin; and
- Slight sclerosis of the femoral head or acetabulum
Grade 2:
- Small cysts in the femoral head or acetabulum; and
- Increased narrowing of joint space; and
- Moderate loss of sphericity of femoral head
Grade 3:
- Large cysts; and
- Severe narrowing or obliteration of joint space; and
- Severe deformity of femoral head; and
- Avascular necrosis
Source: Kovalenko, et al., 2018.
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The above policy is based on the following references:
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