Hip Arthroplasty

Number: 0287

Table Of Contents

Applicable CPT / HCPCS / ICD-10 Codes


Scope of Policy

This Clinical Policy Bulletin addresses hip arthroplasty.

  1. Medical Necessity

    1. 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:

      1. Member has advanced joint disease demonstrated by:

        1. 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
        2. Limited range of motion (ROM), antalgic gait, and pain in hip joint with passive ROM on physical examination: and
        3. Radiographic evidence of either of the following:

          1. Avascular necrosis (osteonecrosis) with stage III collapse of the femoral head; or
          2. Moderate/severe osteoarthritis or rheumatoid arthritis of the hip joint (Tonnis grade 2 or 3; see Appendix for Tonnis grading scale); and
        4. History of 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 as opposed to home or virtual physical therapy)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

      2. Fracture of the femoral neck by imaging; or
      3. Malunion of acetabular, femoral head or proximal femur fracture with pain interfering with ADLs; or
      4. Nonunion by imaging or failure of previous hip fracture surgery; or
      5. 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:

        1. Anti-inflammatory medications or analgesics; and
        2. Flexibility and muscle strengthening exercises, and
        3. Activity modification; and
        4. Supervised physical therapy (in-person 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
        5. Assistive device use (required for persons with relative contraindicationsFootnote2** to joint replacement, optional for others); and
        6. 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.

      6. Total joint replacement is considered not medically necessary in persons with any of the following absolute contraindications:

        1. Active infection of the joint or active systemic bacteremia that has not been totally eradicated; or
        2. Active skin infection (exception recurrent cutaneous staph infections) or open wound within the planned surgical site of the hip; or
        3. Allergy to components of the implant (e.g., cobalt, chromium or alumina); or
        4. Paraplegia or quadriplegia; or
        5. Permanent or irreversible muscle weakness in the absence of pain that prevents ambulation; or
        6. Rapidly progressive neurological disease except in the clinical situation of a concomitant displaced femoral neck fracture; or
        7. Skeletal immaturity; or
      7. 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 and investigational for all other indications because of insufficient evidence of effectiveness.

    2. Revision or replacement of a THA or hip resurfacing arthroplasty is considered medically necessary for the following indications when accompanied by pain and functional disability (interference with ADLs):

      1. Aseptic loosening of one or more prosthetic components confirmed by imaging, or
      2. Fracture or mechanical failure of 1 or more components of the prosthesis confirmed by imaging, or
      3. Confirmed periprosthetic infection confirmed by gram stain and culture, or
      4. Displaced periprosthetic fracture confirmed by imaging, or
      5. Progressive or substantial periprosthetic bone loss confirmed by imaging, or
      6. Bearing surface wear leading to symptomatic synovitis or local bone or soft tissue reactionFootnote3***, or
      7. Recurrent (2 or more) dislocations confirmed by imaging not responsive to a reasonable course of conservative management or irreducible dislocation confirmed by imaging; or
      8. Clinically significant leg length discrepancy; or
      9. Upon individual case review, persistent hip pain of unknown etiology not responsive to a period of non-surgical care for six (6) months, and the member does not have any of the following contraindications to total hip revision or replacement:

        1. Loss of musculature (in particular hip abductor musculature), neuromuscular compromise or vascular deficiency in the affected limb, rendering the procedure unjustifiable; or 
        2. Osteoporosis or other osseous abnormalities which would make the likelihood of a poor outcome more probable; or
        3. Poor skin coverage; or
        4. 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 and investigational when criteria are not met.

    3. Aetna considers the following medically necessary:

      1. Minimal incision or minimally invasive THA an acceptable alternative to conventional THA;
      2. 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;
      3. Prophylactic use of tranexamic acid in total hip arthroplasty to decrease blood loss.
  2. Experimental and Investigational

    The following are considered experimental and investigational because the effectiveness of the approach has not been established:

    1. Measurement of synovial C-reactive protein, and the alpha-defensin test (Synovasure) as a marker for peri-prosthetic infection in THA;
    2. Obturator nerve blocks for management of post-operative pain following THA
    3. Computer-assisted surgical navigation (e.g., MAKOplasty/MAKO Tactile Guidance System) for total hip replacement because there is a lack of reliable evidence that it improves clinical outcomes of total hip arthroplasty. Note: Robotic assistance is considered integral to the procedure and not separately reimbursed.
    4. The use of a portable accelerometer-based navigation system because its clinical value has not been established. See also CPB 0710 - Actigraphy and Accelerometry.
    5. Footnote3*** Aetna considers removal and revision surgery due to post total hip replacement (THR) metallosis alone, without evidence of loosening or malposition, experimental and investigational because there is insufficient clinical evidence in the published peer-reviewed medical literature.
  3. Related Policies


Applicable CPT / HCPCS / ICD-10 Codes

Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

Total hip replacement (THA):

CPT codes covered if selection criteria are met:

27130 Arthroplasty, acetabular and proximal femoral prosthetic replacement (total hip arthroplasty), with or without autograft or allograft [minimally invasive or conventional approach]
27132 Conversion of previous hip surgery to total hip arthroplasty, with or without autograft or allograft [minimally invasive or conventional approach]

CPT codes not covered for indications listed in the CPB:

0054T Computer-assisted musculoskeletal surgical navigation orthopedic procedure, with image-guidance based on fluoroscopic images
0055T Computer-assisted musculoskeletal surgical navigational orthopedic procedure, with image-guidance based on CT/MRI images (List separately in addition to code for primary procedure) [MAKOplasty/MAKO Tactile Guidance System]
20985 Computer-assisted surgical navigation procedure for musculoskeletal procedures, image-less
64450 Injection, anesthetic agent; other peripheral nerve or branch [obturator nerve blocks]
86140 - 86141 C-reactive protein [as a marker for peri-prosthetic infection]

HCPCS codes covered if selection criteria are met:

C1776 Joint device (implantable)

ICD-10 codes covered if selection criteria are met:

C40.20 - C40.22 Malignant neoplasm of long bones of lower limb [proximal femur]
C79.51 Secondary malignant neoplasm of bone [proximal femur]
M05.00 - M14.89 Rheumatoid arthritis
M12.551 - M12.559 Traumatic arthropathy, hip
M16.0 - M16.9 Osteoarthritis of hip
Other specific joint derangements of hip, not elsewhere classified [Paprosky type III acetabular defects]
M80.051+ - M80.059+, M80.851+ - M80.859+, M84.451+ - M84.453+, M84.459+, M84.551+ - M84.559+, M84.651+ - M84.659+ Pathologic fracture of neck of femur (hip)
M84.750+ - M84.759+ Atypical femoral fracture
M85.651- M85.659 Other cyst of bone, thigh [cyst femoral head]
M87.00, M87.10, M87.20, M87.30, M87.80, M87.9, M90.50 Osteonecrosis of bone, site unspecified
M87.051 - M87.059, M87.151 - M87.159, M87.251 - M87.255, M87.351 - M87.353, M87.851 - M87.859, M90.551 - M90.559 Osteonecrosis of femur
M97.01x+ - M97.02x+ Periprosthetic fracture around internal prosthetic hip joint
S32.411+ - S32.9xx+ Fracture of acetabulum, closed and open
S72.001+ - S72.26x+ Fracture of head and neck of femur
T84.010 - T84.011, T84.020 - T84.021, T84.030 - T84.031, T84.050 - T84.051, T84.060 - T84.061, T84.090 - T84.091 Mechanical complication of internal orthopedic device, implant, and graft
Z96.641 - Z96.649 Presence of artificial hip joint

ICD-10 codes contraindicated for this CPB :

A00.0 - B99 Infectious and parasitic diseases [active infection of the joint, active systemic bacteremia or active skin infection]
G82.20 - G82.54 Paraplegia (paraparesis) and quadriplegia (quadriparesis)
M00.051 - M00.059, M00.151 - M00.159, M00.251 - M00.259, M00.851 - M00.859, M00.9 Pyogenic arthritis involving pelvic region and thigh
M01.X51 - M01.X59 Direct infection of hip in infection and parasitic diseases classified elsewhere
M62.81 Muscle weakness (generalized) [permanent or irreversible muscle weakness preventing ambulation in the absence of pain
R62.50, R62.59 Lack of expected normal physiological development in childhood [skeletal immaturity]
S71.001+ - S71.159 Open wound of hip and thigh
T56.2x1+ - T56.2x4+ Toxic effect of chromium and its compounds [not covered for metallosis alone without evidence of loosening or malposition]
T56.811+ - T56.894 Toxic effect of other metals [not covered for metallosis alone without evidence of loosening or malposition]
T78.40x+ Allergy, unspecified

Revision, replacement of total hip arthroplasty, or revision hip resurfacing arthroplasty:

CPT codes covered if selection criteria are met:

27125 Hemiarthroplasty, hip, partial (eg, femoral stem prosthesis, bipolar arthroplasty) [Revision of resurfacing arthroplasty]
27130 Arthroplasty, acetabular and proximal femoral prosthetic replacement (total hip arthroplasty), with or without autograft or allograft [revision of resurfacing arthroplasty]
27134 - 27138 Revision of total hip arthroplasty; with or without autograft or allograft

CPT codes not covered for indications listed in the CPB:

0054T Computer-assisted musculoskeletal surgical navigation orthopedic procedure, with image-guidance based on fluoroscopic images
0055T Computer-assisted musculoskeletal surgical navigational orthopedic procedure, with image-guidance based on CT/MRI images (List separately in addition to code for primary procedure) [MAKOplasty/MAKO Tactile Guidance System]
20985 Computer-assisted surgical navigation procedure for musculoskeletal procedures, image-less
64450 Injection, anesthetic agent; other peripheral nerve or branch [obturator nerve blocks]

HCPCS codes covered if selection criteria are met:

C1776 Joint device (implantable)
S2118 Metal-on-metal total hip resurfacing, including acetabular and femoral components

ICD-10 codes covered if selection criteria are met:

T84.010+ - T84.099 Mechanical complication of internal joint prosthesis
T84.50x+ - T84.59x+ Infection and inflammatory reaction due to internal joint prosthesis


CPT codes not covered for indications listed in the CPB:

Alpha-defensin test (Synovasure) - no specific code:

ICD-10 codes not covered for indications listed in the CPB:

T84.51xA - T84.52xS Infection and inflammatory reaction due to internal hip prosthesis

Portable Accelerometer-Based Navigation System:

CPT codes not covered for indications listed in the CPB:

Portable Accelerometer-Based Navigation System- no specific code

ICD-10 codes not covered for indications listed in the CPB:

Z96.641 - Z96.649 Presence of artificial hip joint


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:

  1. Active infection (local or systemic)
  2. Preexisting significant medical problems (e.g., recent myocardial infarction, unstable angina, heart failure, or severe anemia)
  3. Skeletal immaturity
  4. Paraplegia or quadriplegia
  5. 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

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.

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 Techologies 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.

Glossary of Terms

Table: Glossary of Terms
Term Definition
Conservative therapy Non-surgical medical management
Functional disability Interference with activities of daily living (ADLs)


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:

  1. Slight narrowing of joint space; and
  2. Slight lipping at joint margin; and
  3. Slight sclerosis of the femoral head or acetabulum

Grade 2:

  1. Small cysts in the femoral head or acetabulum; and
  2. Increased narrowing of joint space; and
  3. Moderate loss of sphericity of femoral head

Grade 3:

  1. Large cysts; and
  2. Severe narrowing or obliteration of joint space; and
  3. Severe deformity of femoral head; and
  4. Avascular necrosis

Source: Kovalenko, et al., 2018.


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