Osteochondral Autografts (Mosaicplasty, OATS)

Number: 0637

Table Of Contents

Applicable CPT / HCPCS / ICD-10 Codes


Scope of Policy

This Clinical Policy Bulletin addresses osteochondral autografts (mosaicplasty, OATS).

  1. Medical Necessity

    Aetna considers osteochondral autografts (OATS or mosaicplasty) medically necessary for symptomatic focal full-thickness articular cartilage defects of the knee when all of the following criteria are met:

    1. The member is skeletally mature with documented closure of growth plates (e.g., 15 years or older); and
    2. The member is not considered a candidate for total knee replacement (i.e., member is under 55 years of age); and
    3. The member has disabling symptoms limiting ambulation that have not been relieved by appropriate non-surgical therapies (e.g., medication, physical therapy); and
    4. The member has focal, full thickness (grade III or IV) unipolar lesions on the weight bearing surface of the femoral condyles or trochlea; and
    5. The member has minimal to absent degenerative changes in the surrounding articular cartilage (Outerbridge grade II or less) and normal appearing hyaline cartilage surrounding the border of the defect; and
    6. Stable and aligned knee with intact meniscus and normal joint space on X-ray (a corrective procedure in combination with, or prior to, chondrocyte implantation may be necessary to ensure stability, alignment and normal weight distribution within the joint); and
    7. The opposing articular surface should be generally free of disease or injury.
  2. Experimental and Investigational

    Aetna considers all of the following procedures experimental and investigational because their effectiveness has not been established:

    1. Agili-C for the treatment of osteoarthritis
    2. Autologous cartilage chip transplantation for osteochondral repair
    3. Biologic augmentation (e.g., use of bone marrow concentrate or platelet-rich plasma) for the operative treatment of osteochondral defects of the knee
    4. Combination of adipose-derived stem cells and mosaicplasty for repair of osteochondral defects
    5. Combination of autologous chondrocyte implantation and osteochondral autograft transfer for repair of knee osteochondral lesions
    6. Hybrid autologous chondrocyte implantation performed with osteochondral autograft transfer system (Hybrid ACI/OATS) technique for the treatment of osteochondral defects
    7. Minced articular cartilage (whether synthetic, allograft or autograft) to repair osteochondral defects of the ankle or knee
    8. Non-autologous mosaicplasty using resorbable synthetic bone filler materials (including but not limited to plugs and granules) to repair osteochondral defects of the ankle
    9. Osteochondral autografts/allografts for the treatment of osteochondral lesions of the tibial plafond (distal end of tibia)
    10. Osteochondral autografts (OATS, mosaicplasty) of other joints (ankle, elbow, hip, patella, shoulder)
    11. Osteochondral autograft transplantation for the treatment of Freiberg disease or repair chondral defects of the elbow, patella, shoulder, or joints other than the knee
    12. Synthetic resorbable polymers (e.g., PolyGraft BGS, TruFit [cylindrical plug], TruGraft [granules]) to repair osteochondral articular cartilage defects.
  3. 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.

    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.

  4. Related Policies

    1. CPB 0247 - Autologous Chondrocyte Implantation
    2. CPB 0364 - Allograft Transplants of the Extremities
    3. CPB 0411 - Bone and Tendon Graft Substitutes and Adjuncts


CPT Codes / HCPCS Codes / ICD-10 Codes

Code Code Description

CPT codes covered if selection criteria are met:

27416 Osteochondral autograft(s), knee, open (eg, mosaicplasty) (includes harvesting of autograft[s]) [except to repair chondral defects of the patella] [excludes synthetic resorbable polymers]
29866 Arthroscopy, knee, surgical; implantation of osteochondral autograft(s) (e.g., mosaicplasty) (includes harvesting of autografts) [except to repair chondral defects of the patella] [excludes synthetic resorbable polymers]

CPT codes not covered for indications listed in the CPB:

Autologous cartilage chip transplantation, Osteochondral autografts/allografts for the treatment of osteochondral lesions of the tibial plafond - no specific code:

27412 Autologous chondrocyte implantation, knee
28446 Open osteochondral autograft, talus (includes obtaining graft(s)) [excludes synthetic resorbable polymers]

Other CPT codes related to the CPB:

0232T Injection(s), platelet rich plasma, any site, including image guidance, harvesting and preparation when performed
27447 Arthroplasty, knee, condyle and plateau; medial AND lateral compartments with or without patella resurfacing (total knee arthroplasty)
29871 Arthroscopy, knee, surgical; for infection, lavage and drainage
29874     for removal of loose body or foreign body (e.g., osteochondritis dissecans fragmentation, chondral fragmentation)
29877     debridement/shaving of articular cartilage (chondroplasty)
29879     abrasion arthroplasty (includes chondroplasty where necessary) or multiple drilling or microfracture
29885     drilling for osteochondritis dissecans with bone grafting, with or without internal fixation (including debridement of base of lesion)
29886     drilling for intact osteochondritis dissecans lesion
29887     drilling for intact osteochondritis dissecans lesion with internal fixation

HCPCS codes covered if selection criteria are met:

J7330 Autologous cultured chondrocytes, implant [except minced articular cartilage (whether synthetic, allograft or autograft)]
S2112 Arthroscopy, knee, surgical, for harvesting of cartilage (chondrocyte cells)

HCPCS codes not covered for indications listed in the CPB (not all inclusive):

Minced articular cartilage, synthetic, allograft or autograft, Agili-C -no specific code:

Other HCPCS codes related to the CPB:

P9020 Platelet rich plasma, each unit

ICD-10 codes covered if selection criteria are met:

M23.000 - M23.92 Internal derangement of knee [articular cartilage defect]
M25.161 - M25.169 Fistula, knee [articular cartilage of knee]
M25.861 - M25.869 Other specified joint disorders, knee [articular cartilage of knee]
M92.40 - M92.52 Juvenile osteochondrosis of lower extremity [excluding foot]
M92.8 Other specified juvenile osteochondrosis [leg] [articular cartilage of knee]
M93.261 - M93.269 Osteochondritis dissecans knee

ICD-10 codes not covered for indications listed in the CPB (not all-inclusive):

M17.0 - M17.9 Osteoarthritis of knee
M21.861 - M21.869 Other specified acquired deformities of lower leg [non-correctable varus or valgus deformities]
M24.111 - M24.129 Other articular cartilage disorders, shoulder and elbow
M24.151 - M24.176 Other articular cartilage disorders, hip, ankle & foot
M25.151 - M25.159
M25.171 - M25.176
Fistula of hip and ankle & foot
M25.251 - M25.259
M25.271 - M25.279
Flail joint, hip and ankle & foot
M25.351 - M25.359
M25.371 - M25.376
Other instability, hip and ankle & foot
M25.851 - M25.859
M25.871 - M25.879
Other specified joint disorders, hip and ankle & foot
M91.0 - M91.92 Juvenile osteochondrosis of hip and pelvis
M92.00 - M92.32 Juvenile osteochondrosis of upper extremity
M92.60 - M92.72 Juvenile osteochondrosis of foot


Articular cartilage damaged through acute or chronic trauma or osteochondritis dissecans has limited ability to regenerate, resulting in persistent joint line pain, recurrent synovitis and altered joint mechanics most commonly in weight-bearing joints. Loose bodies may develop, which may then cause joint destruction, restricted mobility and/or locking. Long standing severe damage to the articular cartilage can lead to debilitating osteoarthritis, which ultimately may require a total knee arthroplasty. Current therapeutic options include lavage and debridement, which may offer pain relief for up to several years, but offer no prospect of long-term cure. Similarly, marrow-stimulation techniques such as drilling or microfracture of the subchondral bone of cartilage lesions and abrasion arthroplasty may fail to provide long-term solutions because these procedures usually promote the development of fibrocartilage, which may be less durable than the hyaline cartilage that normally covers articular surfaces.

Osteochondral autografts have been examined as an alternative to allografts for the treatment of osteochondral defects. An osteochondral defect is any type of damage to articular cartilage and underlying (subchondral) bone. Osteochondral autograft transplant (OAT) involves the transplantation of small plugs of healthy bone and hyaline cartilage from joint areas with less weight bearing. The most common donor sites are the areas of the knee or ankle (on the same side). Small holes are drilled through the lesion and the newly harvested plugs are inserted into the holes. Two related procedures have been investigated:
  1. mosaicplasty, and
  2. the osteochondral autograft transfer system (OATS).

Mosaicplasty is a reconstructive bone grafting procedure for the treatment of articular defects of the knee. Mosaicplasty consists of removing small osteochondral cylinders from low weight bearing surfaces of the affected joint or another joint in the same individual and transplanting them in a mosaic-like formation into focal chondral or osteochondral defects in the knee. It is usually utilized to treat larger defects. In general, treatment of articular defect of the knee by mosaicplasty entails transplantation of small cylindrical osteochondral grafts (4 to 10 mm in diameter, 15 to 20 mm deep) from the less weight-bearing periphery of the femoral condyles at the level of the patello-femoral joint, and transplanting them in a mosaic-like fashion into a prepared defect site on the weight-bearing surfaces of the same knee. Its goal is to produce a smooth gliding articular surface of hyaline or hyaline-like cartilage in weight-bearing surfaces of the knee. Mosaicplasty is carried out either by an open approach or arthroscopically if the defect/lesion is small and not more than 4 to 6 grafts are needed. Both open and arthroscopic mosaicplasty require a relatively short rehabilitation period – normal daily activity can be allowed after 5 to 8 weeks.

Animal studies and subsequent clinical trials have demonstrated the survival of transplanted hyaline cartilage. In addition, there are limited studies comparing the results of mosaicplasty with other established procedures. However, long-term data are limited and it is unclear whether mosaicplasty can prevent further deterioration in the affected articular cartilage.

In a review on treatment osteochondral injuries of the knee, Cain and Clancy (2001) stated that the treatment of osteochondral fractures and osteochondral lesions in the knee is controversial. Although the results of many reconstructive procedures (e.g., autologous osteochondral mosaicplasty and osteochondral allograft transplantation) are quite encouraging with early follow-up, the ultimate goal is to prevent long-term degenerative arthritis. Only well-designed prospective studies with long-term follow-up will determine the effectiveness of these procedures in reaching the ultimate goal.

In a review on management of osteochondral injuries of the knee, Alleyne and Galloway (2001) stated that the management of articular cartilage lesions has yet to reveal a "right answer", and that long-term follow-up studies of all of the techniques reviewed are needed to give definitive answers about the durability of the repaired and transplanted tissues.

In a review on mosaicplasty for the treatment of osteochondral defects of the ankle joint, Mendicino and associates (2001) stated that this procedure shows excellent promise for use in the ankle and warrants larger investigational studies to assess outcomes. In a randomized, clinical trial (n = 100),

Guidelines from the American College of Rheumatology on management of osteoarthritis (OA) of the hip and knee state that autologous osteochondral plugs (mosaicplasty) is being investigated for repair of focal chondral defects, but that this procedure is "not currently indicated in the treatment of patients with OA" (Altman et al, 2000).

An assessment of mosaicplasty for knee cartilage defects from the National Institute for Health and Clinical Excellence (NICE, 2006) concluded: "Current evidence suggests that there are no major safety concerns associated with mosaicplasty for knee cartilage defects. There is some evidence of short-term efficacy, but data on long-term efficacy are inadequate. In view of the uncertainties about the efficacy of the procedure, it should not be used without special arrangements for consent and audit or research."

More recently, an assessment of mosaicplasty for knee cartilage defects by the Institute for Clinical Effectiveness and Health Policy (Pichon-Riviere, et al., 2009) concluded: "At present, there is not good quality evidence that would allow the assessment of mosaicplasty versus other techniques. There are few clinical trials, with different surgical techniques; different rehabilitation protocols and outcomes evaluated using different scales. Additionally, these studies presented different follow-up periods which does not allow result comparison with others where surgical follow-up was not performed; it does not it allow long-term morbidity assessment of the graft donation site either. Because of the poor methodological quality of the studies, it is not possible to make specific recommendations on its use, considering it as experimental."

The osteochondral autograft transfer system (OATS) is a procedure employed for medium sized areas of discrete damage (mosaicplasty is employed for even larger but discrete areas of damage). This procedure is similar to mosaicplasty; however, it involves the use of a larger, single plug that usually fills an entire defect (eg, those associated with anterior cruciate ligament [ACL] tears).

The OATS procedure focuses on chondral defects that are associated with chronic tears of the anterior cruciate ligament (ACL), using an arthroscopic approach that can provide access to both the ACL for reconstruction and performance of the autograft. The orthopedic surgeon uses an apple-corer like instrument to core out a circle of damaged cartilage and replaces it with a piece of normal cartilage from a less important part of the same knee. The underlying principal is that the transferred cartilage will grow to cover the edges of the core with proper cartilage cells and not the weaker fibrocartilage cells.

Bobic (1996) reported the results of a case-series study (n = 12) regarding the use of OATS in patients with ACL-deficient knees. The series examined arthroscopic osteochondral autograft transplantation in conjunction with ACL reconstruction using bone-patellar tendon-bone autograft. Eight procedures were primary, and 4 were revisions of failed synthetic grafts. Chondral lesions in this series ranged from 10 to 22 mm in diameter. Donor site was selected prior to notchplasty, and 3 to 5 osteochondral cylinders, 5 to10 mm in diameter, 10 to15 mm long, were harvested. The author stated that improved surgical technique, tubular cutting instruments enabling minimal damage to harvested articular cartilage, and press-fit insertion yielded promising uniform results in 10 of 12 cases with 2 years' follow-up.

Wang (2002) reported a retrospective study of 15 patients with 16 knees who underwent osteochondral autografts for focal full thickness articular cartilage defects of the knee. Two to 4 years follow-up of these patients showed 80 % good or excellent clinical results. There was no correlation of the clinical results with the underlying diagnoses, including osteonecrosis, osteochondritis dissecans and traumatic cartilage defect, or a size of the lesion smaller than 600 mm2. However, cartilage lesions larger than 600 mm2 were associated with increasing fibrous tissue formation and fissuring between the grafts and the host tissues and poor results. The improvement in symptoms appeared time-dependent, ranging from 6 to 16 weeks, suggesting that post-operative protection of the graft is warranted. There was no radiographical progression of degenerative changes of the knee on the medium-term follow-up.

The BlueCross BlueShield Association Technology Evaluation Center (2003) stated that autogenous osteochondral transplantation (OATS or mosaicplasty) are not established treatments for chondral defects. "Although preliminary reports" of autogenous osteochondral transplantation (OATS or mosaicplasty) "appear favorable, only limited outcome data are available on this technology."

Sharpe et al (2005) reported their 3-year post-operative findings on the use of a combination of autologous chondrocyte implantation (ACI) and the OATS procedure as a treatment option for the repair of large areas of degenerative articular cartilage. Osteochondral cores were used to restore the contour of articular cartilage in 13 patients with large lesions of the lateral femoral condyle (n = 5), medial femoral condyle (n = 7) and patella (n = 1). Autologous cultured chondrocytes were injected underneath a periosteal patch covering the cores. After 1 year, patients had a significant improvement in their symptoms and after 3 years this level of improvement was maintained in 10 of the 13 patients. Arthroscopic examination revealed that the osteochondral cores became well integrated with the surrounding cartilage. These investigators concluded that the hybrid ACI/OATS technique provides a promising surgical approach for the treatment of patients with large degenerative osteochondral defects.

Scheibel and colleagues (2004) performed 8 osteochondral autologous transplantations from the knee joint to the shoulder. All patients (2 women and 6 men; mean age of 43.1 years) were documented prospectively. In each patient the stage of the osteochondral lesion was Outerbridge grade IV with a mean size of the affected area of 150 mm2. All patients were assessed by using the Constant score for the shoulder and the Lysholm score for the knee. Standard radiographs, magnetic resonance imaging and second-look arthroscopy were used to evaluate the presence of glenohumeral osteoarthritis and the integrity of the grafts. After a mean of 32.6 months (8 to 47), the mean Constant score increased significantly. Magnetic resonance imaging revealed good osseo-integration of the osteochondral plugs and congruent articular cartilage at the transplantation site in all but 1 patient. Second-look arthroscopy performed in 2 cases revealed a macroscopically good integration of the autograft with an intact articular surface. The authors noted that osteochondral autologous transplantation in the shoulder appears to offer good clinical results for treating full-thickness osteochondral lesions of the glenohumeral joint. However, they also noted that the findings of their study suggest that the development of osteoarthritis and the progression of pre-existing osteoarthritic changes cannot be altered by this technique.

The Institute for Clinical Effectiveness and Health Policy (Pichon-Riviere et al, 2006) evaluated the literature on the effectiveness of OATS and mosaicplasty on ankle bone cartilage lesions. The assessment concluded: "There is still not enough evidence available on the efficacy of mosaicplasty or the OATS procedure for the treatment of talus cartilage joint lesions. There is very little published about the assessment of the osteochondral grafting viability. There is not enough evidence determining whether the tissues coming from places that do not carry weight could absorb the stress of weight bearing areas, neither the degree of donor site morbidity. Patient inclusion criteria are not well settled in the literature, and there is no uniform consensus on the procedure's indication. ...Only well designed prospective clinical trials with long follow-ups could determine the efficacy of these procedures to relieve the symptoms caused by osteochondral lesions, improve joint function and achieve the final objective, which is the prevention of secondary arthrosis."

Zengerink and colleagues (2010) compared the effectiveness of treatment strategies for osteochondral defects (OCD) of the talus. Electronic databases from January 1966 to December 2006 were systematically screened. The proportion of the patient population treated successfully was noted, and percentages were calculated. For each treatment strategy, study size weighted success rates were calculated. A total of 52 studies described the results of 65 treatment groups of treatment strategies for OCD of the talus: 1 randomized clinical trial was identified; 7 studies described the results of non-operative treatment, 4 of excision, 13 of excision and curettage, 18 of excision, curettage and bone marrow stimulation (BMS), 4 of an autogenous bone graft, 2 of trans-malleolar drilling (TMD), 9 of OATS, 4 of ACI, 3 of retrograde drilling, and 1 of fixation. OATS, BMS and ACI scored success rates of 87 %, 85 %, and 76 %, respectively. Retrograde drilling and fixation scored 88 % and 89 %, respectively. Together with the newer techniques OATS and ACI, BMS was identified as an effective treatment strategy for OCD of the talus. Because of the relatively high cost of ACI and the knee morbidity seen in OATS, the authors concluded that BMS is the treatment of choice for primary osteochondral talar lesions. However, due to great diversity in the articles and variability in treatment results, no definitive conclusions can be drawn. They stated that further sufficiently powered, randomized clinical trials with uniform methodology and validated outcome measures should be initiated to compare the outcome of surgical strategies for OCD of the talus.

Lu and Hame (2005) noted that treatment options for chondral and osteochondral defects of the patella have been few and results have been inconsistent at best. Autologous osteochondral transplantation presents a new way to revisit these patellar defects. These researchers reported the case of a young female softball player with a simple cyst in the patella and an osteochondral defect that serves as the indication for autograft osteochondral transplantation.

Nho et al (2008) stated that autologous osteochondral transplantation (AOT) has been successfully used in the femoral condyle and trochlea and is an attractive treatment option for full-thickness patellar cartilage lesions. These investigators hypothesized that patients treated with AOT for the repair of symptomatic, isolated patellar cartilage lesions will demonstrate improvement in functional outcomes and post-operative MRI appearance. In a case-series study, patients with focal patellar cartilage lesions treated with AOT were prospectively followed. The mean age at the time of surgery was 30 years. Clinical assessment was performed with the International Knee Documentation Committee (IKDC), activities of daily living of the Knee Outcome Survey (ADL), and Short Form-36 (SF-36) at baseline and most recent follow-up. Magnetic resonance imaging was used to evaluate the cartilage repair morphologic characteristics in 14 cases. Twenty-two patients met the study criteria with a mean follow-up of 28.7 months (range of 17.7 to 57.8 months). The mean patellar lesion size was 165.6 +/- 127.8 mm(2), and the mean size of the donor plug was 9.7 +/- 1.1 mm in diameter with 1.8 +/- 1.4 plugs/defect. The mean pre-operative IKDC score was 47.2 +/- 14.0 and improved to 74.4 +/- 12.3 (p = 0.028). The mean pre-operative ADL score was 60.1 +/- 16.9 and increased to 84.7 +/- 8.3 (p = 0.022). The mean SF-36 also demonstrated an improvement, from 64.0 +/- 14.8 at baseline to 79.4 +/- 15.4 (p = 0.059). Nine patients underwent concomitant distal re-alignment and demonstrated improvement between pre-operative and post-operative outcomes scores, but these differences were not statistically significant. Magnetic resonance imaging appearance demonstrated that all plugs demonstrated good (67 % to 100 %) cartilage fill, 64 % with fissures greater than 2 mm at the articular cartilage interface, 71 % with complete trabecular incorporation, and 71 % with flush plug appearance. The authors concluded that patellar AOT is an effective treatment for focal patellar chondral lesions, with significant improvement in clinical follow-up. This study suggested that patients with patellar mal-alignment may represent a subset of patients who have a poor prognostic outlook compared with patients with normal alignment. This was a small case-series study; its findings need to be validated by well-designed studies.

Colvin and West (2008) stated that recurrent patellar instability can result from osseous abnormalities, such as patella alta, a distance of greater than 20 mm between the tibial tubercle and the trochlear groove, and trochlear dysplasia, or it can result from soft-tissue abnormalities, such as a torn medial patellofemoral ligament or a weakened vastus medialis obliquus. Non-operative treatment includes physical therapy, focusing on strengthening of the gluteal muscles and the vastus medialis obliquus, and patellar taping or bracing. Acute medial-sided repair may be indicated when there is an osteochondral fracture fragment or a retinacular injury. The recent literature does not support the use of an isolated lateral release for the treatment of patellar instability. A patient with recurrent instability, with or without trochlear dysplasia, who has a normal tibial tubercle-trochlear groove distance and a normal patellar height may be a candidate for a reconstruction of the medial patello-femoral ligament with autograft or allograft. Distal re-alignment procedures are used in patients who have an increased tibial tubercle-trochlear groove distance or patella alta. The degree of anteriorization, distalization, and/or medialization depends on associated arthrosis of the lateral patellar facet and the presence of patella alta. Associated medial or proximal patellar chondrosis is a contraindication to distal realignment because of the potential to overload tissues that have already undergone degeneration.

Matricali et al (2010) stated that in order to perform an osteochondral autologous transplantation (OAT) or an autologous chondrocyte implantation (ACI), the integrity of healthy intact articular cartilage at a second location needs to be violated. This creates the possibility for donor site morbidity. Only recently have any publications addressed this issue. These researchers reviewed the current knowledge on donor site morbidity after an OAT or an ACI. Reports were identified by searching Medline and PubMed up to March 2010. Donor site morbidity was described mostly considering a clinical outcome, both in a qualitative (parameters in history or physical examination) and/or quantitative way (knee status reported by means of a numerical score). An increasing rate of problems is noted when using quantitative instead of qualitative parameters, and when donor site morbidity is the focus of attention, affecting up to more than 50 % of the patients, especially for an OAT procedure. The decision to harvest an osteochondral or cartilage biopsy to perform a repair procedure should therefore be taken with caution. This also underscores the need for further research to identify safe donor sites or to develop techniques that eliminate the need for a formal biopsy completely.

The Washington State Health Care Authority Technology Assessment Program (2011) commissioned a technology assessment of Osteochondral Allograft Transplantation and Autograft Transfer System (OATS/mosaicplasty). In commissioning the assessment, the Program stated: "Significant questions remain about the safety, efficacy and effectiveness, and cost effectiveness of OATS/mosaicplasty cartilage surgery. The  choice of suitable patients for OATS/mosaicplasty surgery is controversial because the size and number of damage sites for which it is functional are not well defined, because the harvesting of cartilage from another site or cadaver tissue adds risk and healing issues, and because other, less invasive procedures may be equally effective in the short term (autologous chondrocyte injection). Effectiveness questions particularly center on whether the potential beneficial outcomes of long term pain and functional improvement, prevention of osteoarthritis or further joint deterioration occur with this surgical intervention."

The systematic evidence review prepared for the Washington State Health Care Authority (Skelly et al, 2011) reported that two small randomized controlled trials (RCTs) (level of evidence IIb) in younger populations compared OAT with microfracture and three RCTs (or quasi RCTs, level of evidence IIb) compared OAT/mosaicplasty with ACI in general (older)populations. The review found substantial differences in patient populations, lesion sizes, comparators and outcomes measures used across studies, making it difficult to draw overall conclusions. Compared with microfracture (MF), OAT was associated with better patient-reported (based on International Cartilage Repair Society (ICRS) cartilage repair assessment), and clinician-reported (based on the Hospital for Special Surgery (HSS) Score) functional outcomes in young athletes and children based on two small RCTs (total n = 104) (citing Gudas, et al., 2005; Gudas, et al., 2009). For comparisons with ACI, three poor quality RCTs in general (older) populations reported functional outcomes. Two small, poor quality RCTs suggest that function based on patient-reported outcomes (Lysholm Knee Scoring Scale and a modification of it) was better for OAT compared with ACI; however statistical significance was reached in only one of the RCTs (n = 40) (citing Horas, et al., 2003) and in the other RCT (citing Dozin, et al., 2005), conclusions are difficult given the significant loss to follow-up (50%). The largest RCT (n = 100) (citing Bentley, et al., 2003) reported that a significantly smaller proportion of participants receiving mosaicplasty had excellent or good results based on the author’s modification of the Cincinnati Rating Scale. One of the smaller RCTs reported no significant differences in the Meyer score. Both these studies included substantial proportions of participants who had prior surgeries (94% and 45% respectively).

The assessment (2011) found that there were substantial differences across studies with respect to populations, lesion sizes, comparators and outcomes measures making it difficult to draw overall conclusions. The indications for OAT versus mosaicplasty, autograft versus allograft appear to be based on case series primarily. The majority of studies are in populations less than 50 years of age. The overall quality of the literature is poor, particularly with respect to evaluation of autograft.

The Washington State Health Care Authority Agency Medical Directors (2011) concluded that there is some evidence of benefit of osteochondral transplantation procedures in cases failing conservative management. The agency noted that the evidence of effectiveness and efficacy of osteochondral transplantation procedures is of low quality and shows variable outcomes. The agency found that the case selection criteria for osteochondral transplantation procedures is uncertain and that there are no long-term outcomes data. They stated that osteochondral transplantation is an evolving technology with a weak evidence base, and that the long-term safety and effectiveness are uncertain. They noted the potential for overuse and misuse given the lack of patient and technique selection criteria. The agency recommended coverage of osteochondral transplantation procedures only for the knee (and possibly talus) in person less than 50 years of age who have failed conservative management and who do not have arthritis. 

The Washington State Health Care Authority Health Technology Clinical Committee (2012) has concluded that osteochondral allograft/autograft transplantation for the knee is a covered benefit when the following conditions are met:
  1. age less than 50 years, older at the discretion of the agency;
  2. excluding malignancy, degenerative and inflammatory arthritis in the joint; and
  3. single focal full-thickness articular cartilage defect.

The Committee stated that osteochondral allograft/autograft transplantation is not covered for joints other than the knee.

Non-autologous mosaicplasty has been proposed as an alternative to conventional mosaicplasty.  Non-autologous mosaicplasty entails a series of small holes drilled into the area of the osteochondral defect.   The holes are then packed with a synthetic polymer (as a bone void filler); providing a scaffold for the growth of new bone.   The synthetic graft is gradually resorbed by the body and replaced with bone.   The proposed advantage of this procedure over conventional osteochondral autograft transplantation is the elimination of the need for harvesting bone and cartilage from a donor graft site.  However, there is currently insufficient evidence to support the use of non-autologous mosaicplasty for repair of osteochondral defects.

Lu and colleagues (2006) stated that traumatic articular cartilage injuries heal poorly and may predispose patients to the early onset of osteoarthritis.  One current treatment relies on surgical delivery of autologous chondrocytes that are prepared, prior to implantation, through ex-vivo cell expansion of cartilage biopsy cells.  The requirement for cell expansion, however, is both complex and expensive and has proven to be a major hurdle in achieving a widespread adoption of the treatment.  These researchers presented evidence that autologous chondrocyte implantation can be delivered without requiring ex-vivo cell expansion.  The proposed improvement relies on mechanical fragmentation of cartilage tissue sufficient to mobilize embedded chondrocytes via increased tissue surface area.  The authors’ outgrowth study, which was used to demonstrate chondrocyte migration and growth, indicated that fragmented cartilage tissue is a rich source for chondrocyte re-distribution.  The chondrocytes outgrown into 3-D scaffolds also formed cartilage-like tissue when implanted in mice homozygous for the scid mutation (SCID mice).  Direct treatment of full-thickness chondral defects in goats using cartilage fragments on a resorbable scaffold produced hyaline-like repair tissue at 6 months.  Thus, delivery of chondrocytes in the form of cartilage tissue fragments in conjunction with appropriate polymeric scaffolds provides a novel intra-operative approach for cell-based cartilage repair

An alternative to allografting that has been proposed by some researchers is the synthetic graft.  Synthetic bone void fillers can be categorized into 3 groups:
  1. ceramics,
  2. composites, and
  3. polymers.

Ceramics are osteo-conductive and are composed of calcium; total degradation time depends on the composition.  Composite grafts combine osteo-conductive matrix with bioactive agents that provide osteo-inductive and osteogenic properties.  Polymers are osteo-conductive and when used with marrow could provide a biodegradable osteo-inductive implant for repairing large defects.

Baker and colleagues (2011) noted that the development of synthetic bone graft substitutes is an intense area of research due to the complications associated with the harvest of autogenous bone and concerns about the supply of allogeneic bone.  Porous resorbable polymers have been used extensively in hard tissue engineering applications, but currently lack load-bearing capacity.

Vundelinckx et al (2012) reported that under arthroscopic control and guided by fluoroscopy, a TruFit Plug was successfully implanted to repair an osteochondral lesion of the head of the femur.  The procedure was evaluated clinically using the HOOS score and MRI of the hip.  The short-term (6 months) clinical results were encouraging: the HOOS score improved clearly and the patient was satisfied.  Interpretation of MRI images in the early post-operative period was very difficult: in the early months history and clinical examination prevail in the evaluation.

Joshi et al (2012) evaluated prospectively short- and medium-term results in patients with osteochondral patellar defects treated with synthetic re-absorbable scaffolds.  Patient outcome scores (Short Form 36 [SF-36] and Knee injury and Osteoarthritis Outcome Score [KOOS]), demographics, prior surgeries, and data from a physical examination were collected at baseline (before implantation) and at 6, 12, and 24 months after surgery.  Defect characteristics were collected during implantation.  Diagnosis and monitoring were performed by MRI.  A total of 10 patients with a mean age of 33.3 years (range of 16 to 49 years) were evaluated prospectively at 24 months' follow-up.  The number of plugs used for each patient ranged from 1 to 4.  At 1-year follow-up, the results were satisfactory in 8 of 10 patients, and poor in 2, according to clinical assessment (KOOS, visual analog scale, and SF-36).  At 18 months of follow-up, all patients except 1 complained of pain and knee swelling.  Re-operation rate for implant failure at final follow-up was 70 %.  Magnetic resonance imaging at final follow-up showed a cylindrical cavity of fibrous tissue instead of subchondral bone restoration.  The authors concluded that a synthetic implant can improve symptoms and joint function, especially for small lesions, only for a short period of time.  However, 2 years of monitoring has shown its failure in restoring the subchondral bone despite the formation of predominant hyaline cartilage from synthetic resorbable scaffolds.  Under current conditions and according to the authors’ experience, they do not recommend TruFit synthetic implants for osteochondral patellar defects in active patients.

Hindle et al (2014) evaluated functional outcome of patients using the EQ-5D, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Modified Cincinnati scores at follow-up of 1 to 5 years.  There were 66 patients in the study (35 TruFit and 31 mosaicplasty): 44 males and 22 females with a mean age of 37.3 years (SD of 12.6).  The mean body mass index (BMI) was 26.8; 36 articular cartilage lesions were due to trauma, 26 due to osteochondritis dissecans and 3 due to non-specific degenerative change or unknown.  There were no significant differences between the 2 groups in terms of age, sex, BMI, defect location, or etiology.  The median follow-up was 22 months for the TruFit cohort and 30 months for the mosaicplasty group.  There was no significant difference in the requirement for re-operation.  Patients undergoing autologous mosaicplasty had a higher rate of returning to sport (p = 0.006), lower EQ-5D pain scores (p = 0.048) and higher KOOS activities of daily living (p = 0.029) scores.  Sub-group analysis showed no difference related to the number of cases the surgeon performed.  Patients requiring re-operation had lower outcome scores regardless of their initial procedure.  The authors concluded that the findings of this study demonstrated significantly better outcomes using 2 validated outcome scores (KOOS, EQ-5D), and an ability to return to sport in those undergoing autologous mosaicplasty compared to those receiving TruFit plugs.

Quarch et al (2014) examined if the potential donor site morbidity for large defects could be reduced by means of TruFit plugs.  An autologous OCT was performed in 37 patients and the cylinders were received from the dorsal medial femoral condyle.  The donor site defects of 21 patients (average defect size 5.5 cm(2)) were filled with artificial TruFit cylinders (study group); the donor site defects (average defect size 4.6 cm(2)) were left untreated for 16 patients.  In the study group, the Tegner, Western Ontario and McMaster Universities (WOMAC), knee society score, and visual analog scale pain scores improved from pre-operatively 3.2 (± 0.8), 60.9 (± 41.6), 133.6 (± 27.1), and 4.8 (± 2.3) points, respectively, to 3.9 (± 0.6), 35.5 (± 27.1), 177.8 (± 16.6), and 3.3 (± 2.9) points, respectively, at the time of the second follow-up; the control group's pre-operative score values came to 2.8 (± 0.9), 73.3 (± 50.2), 123.8 (± 41.5), and 5.3 (± 2.7) points, respectively, and changed to 3.6 (± 0.8), 41.4 (± 28.8), 179.3 (± 17.5), and 3.1 (± 2.0) points, respectively, at the time of the second follow-up.  The smaller the initial chondral defect was in the study group, the better the WOMAC score values became (p < 0.05).  The modified Henderson score at the study group's donor sites improved from 19.2 (± 3.3) to 13.7 (± 2.1) points (p < 0.001); the control group's score values for the donor sites were 18.3 (± 3.4) and 15.4 (± 4.4) points (p = 0.0015).  The authors concluded that OCT is an effective therapy even for large chondral defects greater than 3 cm(2).  By filling the defects with TruFit implants, no clinical improvements could be found since the donor site morbidity was already low anyway.  However, the regeneration of defects filled with TruFit implants took more than 2 years.

Gelber et al (2014) evaluated the relationship between MRI findings and functional scores of patients with osteochondral lesions of the knee treated with TruFit.  Patients were evaluated with Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score for MRI assessment of the repair tissue.  Knee injury and Osteoarthritis Outcome Score, SF-36 and visual analog scale (VAS) were used for clinical evaluation.  Correlation between size of the treated chondral defect and functional scores was also analyzed.  A total of 57 patients with median follow-up of 44.8 months (range of 24 to 73) were included.  KOOS, SF-36 and VAS improved from a mean 58.5, 53.9 and 8.5 points to a mean 87.4, 86.6 and 1.2 at last follow-up (p < 0.001).  Larger lesions showed less improvement in KOOS (p = 0.04) and SF-36 (p = 0.029).  Median Tegner values were restored to pre-injury situation (5, range of 2 to 10).  Mean MOCART score was 43.2 ± 16.1.  Although the cartilage layer had good integration, it showed high heterogeneity and no filling of the subchondral bone layer.  The authors concluded that TruFit failed to restore the normal MRI aspect of the subchondral bone and lamina in most cases.  The appearance of the chondral layer in MRI was partially re-established.  This unfavorable MRI appearance did not adversely influence the patient's outcome in the short-term and they restored their previous level of activity.  There was an inverse linear relationship between the size of the lesion and the functional scores.

There is currently insufficient evidence to support the safety and effectiveness of synthetic resorbable polymers as an alternative to allograft or autograft for the repair of osteochondral defects.

Vannini and colleagues (2014) stated that juvenile osteochondritis dissecans of the talus (JODT) affects the subchondral bone primarily and, in a skeletally immature population, articular cartilage secondarily.  It probably consists of aseptic bone necrosis whose spontaneous healing is impaired by micro-traumas, resulting in an osteochondral injury and, in some cases, in osteoarthritis.  In many cases the clinical presentation is asymptomatic.  Mild chronic pain is frequent, sometimes accompanied by swelling, stiffness or locking.  Few data are currently available on this topic and, moreover, most existing data were obtained from mixed groups and populations; it is therefore difficult to outline a scheme for the treatment of JODT.  However, the most suitable treatment in the first stages of the disease is conservative.  The presence of a loose body is an indication for surgical fixation, drilling or regenerative procedures, depending on the presence/extent of subchondral bone sclerosis and the surgeon's experience.  Drilling has been shown to promote the healing of lesions with minimal surgical trauma.  Micro-fractures, since they induce fibrocartilage repair, are to be considered only for small injuries.  The authors noted that mosaicplasty and osteochondral autograft transplantation may cause donor site morbidity and are techniques little reported in JODT.  Moreover, they stated that degenerative techniques and fresh allografts gave good results in osteochondral lesions, but further studies are needed to describe the results that can be obtained in JODT alone.

Hindle et al (2014) stated that autologous osteochondral mosaicplasty and TruFit bone graft substitute plugs are methods used to repair symptomatic articular cartilage defects in the adult knee.  There have been no comparative studies of the 2 techniques.  In a retrospective study, these researchers evaluated functional outcome of patients using the EQ-5D, KOOS and Modified Cincinnati scores at follow-up of 1 to 5 years.  There were 66 patients in the study (35 TruFit and 31 mosaicplasty): 44 males and 22 females with a mean age of 37.3 years (SD 12.6).  The mean BMI was 26.8; 36 articular cartilage lesions were due to trauma, 26 due to osteochondritis dissecans and 3 due to non-specific degenerative change or unknown.  There was no difference between the 2 groups in age (n.s.), sex (n.s.), BMI (n.s.), defect location (n.s.) or etiology (n.s.).  The median follow-up was 22 months for the TruFit cohort and 30 months for the mosaicplasty group.  There was no significant difference in the requirement for re-operation (n.s).  Patients undergoing autologous mosaicplasty had a higher rate of returning to sport (p = 0.006), lower EQ-5D pain scores (p = 0.048) and higher KOOS activities of daily living (p = 0.029) scores.  Sub-group analysis showed no difference related to the number of cases the surgeon performed.  Patients requiring re-operation had lower outcome scores regardless of their initial procedure.  The authors concluded that the findings of this study demonstrated significantly better outcomes using 2 validated outcome scores (KOOS, EQ-5D), and an ability to return to sport in those undergoing autologous mosaicplasty compared to those receiving TruFit plugs. This was a small study (n = 35 for TruFit) with short-term follow-up (median of 22 months for TruFit).  Well-designed studies with larger sample size and longer follow-up are needed to ascertain the clinical value of TruFit.

Guney and co-workers (2016) compared medium-term functional effects of 3 different treatment modalities in patients with osteochondral lesions of the talus (OLT). A total of 54 patients undergoing arthroscopic surgery for OLT were included in this study. Patients were assigned to 1 of the 3 treatment groups:
  1. MF surgery (n = 19),
  2. MF surgery plus platelet-rich plasma (PRP) (n = 22), and
  3. mosaicplasty (n = 13).

Function was assessed using the American Orthopedic Foot and Ankle Society (AOFAS) scoring system and VAS scores for pain, before and after surgery.  In addition, the Foot and Ankle Ability Measure (FAAM) tests for pain and 15-min walking were done at follow-up visits.  The median duration of follow-up was 42 months (range of 12 to 84).  All groups showed significant improvements in AOFAS and VAS pain scores at the last follow-up visit, when compared to baseline.  The groups did not differ with regard to change in baseline AOFAS score; however, improvement in VAS pain scores was significantly better in the mosaicplasty group when compared to the MF group (change from baseline, -5.8 ± 1.0 versus -3.2 ± 2.9, p = 0.018).  The authors concluded that all the 3 treatment modalities resulted in good medium-term functional results.  However, they stated that mosaicplasty appeared to be a promising option and it might be preferred particularly in patients where pain control is important.

Richter and colleagues (2016) stated that isolated chondral and osteochondral defects of the knee are a difficult clinical challenge, particularly in younger patients for whom alternatives such as partial or total knee arthroplasty are rarely advised. Numerous surgical techniques have been developed to address focal cartilage defects.  Cartilage treatment strategies are characterized as palliation (e.g., chondroplasty and debridement), repair (e.g., drilling and MF), or restoration (e.g., ACI, OAT, and osteochondral allograft [OCA]).  PubMed was searched for treatment articles using the keywords knee, articular cartilage, and osteochondral defect, with a focus on articles published in the past 5 years.  In general, smaller lesions (less than 2 cm(2)) are best treated with MF or OAT. Furthermore, OAT shows trends toward greater longevity and durability as well as improved outcomes in high-demand patients.  Intermediate-size lesions (2 to 4 cm(2)) have shown fairly equivalent treatment results using either OAT or ACI options.  For larger lesions (greater than 4 cm(2)), ACI or OCA have shown the best results, with OCA being an option for large osteochondritis dissecans lesions and post-traumatic defects.  The authors concluded that these techniques may improve patient outcomes, though no single technique can reproduce normal hyaline cartilage.

Hybrid Autologous Chondrocyte Implantation (ACI) and Osteochondral Autograft Transfer System (OATS)

Duif and colleagues (2015) stated that modern orthopedic surgery provides a variety of techniques for cartilage repair.  Despite comprehensive scientific data about the single procedures, there is little experience with the combination of these methods.  These investigators performed a PubMed-based literature search about the combination of cartilage restoration principles.  The literature search was performed using the terms: "mosaicplasty'' or "osteochondral transplantation'' or "OATS'' and "autologous chondrocyte implantation'' or "autologous chondrocyte transplantation'' or "ACI'' or "matrix-associated autologous chondrocyte implantation'' or "MACI'' and "combination''.  Additionally, the authors presented a case report of the combinatory use of 3 established techniques.  Two relevant publications, both reporting satisfying results concerning post-operative functional outcome, were found.  The results confirmed this first encouraging assessment, although statistically valid data and prospective studies are still missing.  The authors concluded that the simultaneous use of different techniques for cartilage repair may provide alternative operative solutions for single complex cases, although further studies are needed for a general recommendation.

The TruFit Plug

Synthetic resorbable polymers (eg, PolyGraft, TruGraft granules, and TruFit plugs) are polymer scaffolds that are being proposed for the repair of osteochondral articular cartilage defects. The implant functions as a scaffold for chondral and osteogenic cells with the synthetic polymer being resorbed as the cells produce their normal matrices.

Verhaegen and associates (2015) stated that treatment of osteochondral defects remains a challenge in orthopedic surgery. The TruFit plug has been examined as a potential therapy for osteochondral defects.  The TruFit plug is a bi-phasic scaffold designed to stimulate cartilage and subchondral bone formation.  The authors examined clinical, radiological, and histological effectiveness of the TruFit plug in restoring osteochondral defects in the joint.  They performed a systematic search in 5 data-bases for clinical trials in which patients were treated with a TruFit plug for osteochondral defects.  Studies had to report clinical, radiological, or histological outcome data; and quality of the included studies was also assessed.  A total of 5 studies described clinical results, all indicating improvement at follow-up of 12 months compared to pre-operative status.  However, 2 studies reporting longer follow-up showed deterioration of early improvement.  Radiological evaluation indicated favorable MRI findings regarding filling of the defect and incorporation with adjacent cartilage at 24 months follow-up, but conflicting evidence existed on the properties of the newly formed overlying cartilage surface.  None of the included studies showed evidence for bone ingrowth.  The few histological data available confirmed these results.  The authors concluded that there are no data available that support superiority or equality of TruFit compared to conservative treatment or mosaicplasty / micro-fracture (MF).  They stated that further investigation is needed to improve synthetic bi-phasic implants as therapy for osteochondral lesions; RCTs comparing TruFit plugs with an established treatment method are needed before further clinical use can be supported.

Di Cave and associates (2017) noted that the TruFit plug has been investigated as a potential treatment method for osteochondral defects.  This is a bi-phasic scaffold designed to stimulate cartilage and subchondral bone formation.  In a retrospective study, these investigators examined the long-term functional and MRI outcomes of the TruFit Plug for the treatment of osteochondral lesions of the talus (OLT).  A total of 12 consecutive patients treated from March 2007 to April 2009 for OLT were evaluated.  Clinical examination included the AOFAS ankle score and the VAS for pain; MRI scans were obtained pre-treatment and at last follow-up; the MOCART score was used to assess cartilage incorporation.  Mean follow-up was 7.5 years (range of 6.5 to 8.7 years).  The average age was of 38.6 years (range of 22 to 57 years).  The sex ratio between males and females was 3:1 (9 men, 3 women).  The mean AOFAS score improved from a pre-operative score of 47.2 ± 10.7 to 84.4 ± 8 (p < 0.05).  According to the post-operative AOFAS scores, 1 case obtained excellent results, 9 were classified as good, and 2 were fair; VAS score improved from a pre-operative value of 6.9 ± 1.4 points to 1.2 ± 1.1 points at last follow-up (p < 0.05).  The MOCART score for cartilage repair tissue on post-operative MRI averaged 61.1 points (range of 25 to 85 points).  The authors concluded that the long-term results suggested that the technique of Trufit Plug for OLT was safe and demonstrated good post-operative scores including improvement of pain and function, with discordant MRI results.  Moreover, they stated that RCTs comparing TruFit Plug with an established treatment method are needed to improve synthetic bi-phasic implants as therapy for osteochondral lesions.

Bugelli and co-workers (2018) followed morphological imaging characteristics and osteo-integration of TruFit bone graft substitute (BGS) plugs in cases of chondral and osteochondral defects of the articular surface of the knee joint, using high-quality cartilage-sensitive 3-T MRI, linked to clinical outcomes.  The MRI was used to assess osteo-integration and biological evolution of the TruFit BGS plugs in cases with minimum 5-year follow-up: The TruFit plug was used in 46 patients for a total of 47 cases with mean age of 57.89 (range of 32 to 80).  In this study, these investigators reviewed only the cases with minimum follow-up of 5 years: 5 patients with mean age 64.4 years (minimum 38, maximum 80).  The mean follow-up was 71 months (range of 63 to 77).  Patients were evaluated clinically, with Lysholm Knee Scoring Scale and MOCART Scale; 3-T MRI, which was preferable to 1.5 T for the better signal-to-noise ratio, contrast and the ability to acquire morphological images at higher spatial resolution, showed a satisfactory integration of bone scaffolds in studied cases for more than 5 years and a satisfactory restoration of the articular cartilage, with the exception of a case of which these researchers still have to consider the factors of age, type of lesion and the relationship between the plugs implanted.  The authors concluded that clinical and radiological results significantly improved in a longer follow-up time.

Azam and colleagues (2018) evaluated the functional and radiological outcome of TruFit plugs; they retrospectively reviewed 10 patients who underwent treatment for a symptomatic chondral/osteochondral lesion using 1 or more Trufit Plugs.  Full incorporation of the bony portion of the plug occurred in only 3 and partial incorporation in 7 lesions.  The remaining portion of these 7 lesions looked cystic on MRI.  The significance of this cystic change was unclear.  The authors concluded that although all 10 patients showed some improvement on the IKDC scoring system, the amount of the improvement was small.

Freiberg Disease

Miyamoto and associates (2016) evaluated the mid-term clinical results of OAT for the treatment of advanced stage Freiberg disease (also known as a Freiberg infraction), which is a form of avascular necrosis in the metatarsal. This study included consecutive patients who underwent OAT for advanced stage Freiberg disease and were followed post-operatively for more than 5 years.  In all cases, the autograft was harvested from the ipsilateral knee joint.  Clinical evaluation was performed based on the AOFAS score and VAS score, which were done pre-operatively and at the most recent follow-up.  Radiological evaluation was performed at 2 years after the operation.  Furthermore, the most recent 6 patients underwent MRI 5 years after the operation to assess the configuration of the articular surface.  A total of 13 patients (all females; mean age of 16.7 years; range of 10 to 38) were included and followed-up for a mean duration of 67.2 months (range of 60 to 100). The mean AOFAS significantly improved from a score of 66.9 ± 5.3 (range of 59 to 77) to 93.0 ± 7.6 (range of 82 to 100) (p < 0.0001).  Likewise, the mean VAS significantly improved from a score of 72.7 ± 10.3 (range of 60 to 90) to 7.8 ± 7.2 (range of 0 to 20) (p < 0.0001).  Radiographs at 2 years after the operation revealed no osteoarthritic change in all cases; MRI at 5 years after the operation showed consolidation of the transplanted autograft and smooth configuration of the articular surface in the 6 cases.  The authors concluded that OAT may be effective for advanced stage Freiberg disease.  Moreover , they stated that further studies are needed before this technique can become the standard operative treatment.

Osteochondral Autograft Transfer Technique for Glenoid Osteochondral Defect

Wyland and Beicker (2016) stated that glenoid osteochondral defects can be a significant source of pain and disability in an active population.  Many treatments are available, but most joint-preserving procedures are limited to debridement, abrasion chondroplasty, or marrow-stimulation techniques, all of which depend on healthy underlying bone, and none of which addresses underlying bony pathology.  These researchers described an arthroscopic method of treating glenoid osteochondral lesions with an OAT using a graft from the patient's ipsilateral knee.  This technique addresses both cartilage and osseous pathology with minimal morbidity and provides a good biological restorative option for patients with isolated glenoid osteochondral defects.  The authors concluded that as with other glenoid cartilage restoration or preservation techniques, larger studies with longer-term follow-up are needed to evaluate this technique fully.

Minced Articular Cartilage Repair Technique

Minced cartilage repair is considered a second generation technique that does not require in-vitro cell expansion and is described as a single-staged minimally invasive procedure.  The procedure uses minced pieces of cartilage seeded over a scaffold that allows for even distribution of the chondrocytes to expand within the defect providing structural as well as mechanical protection.   The first clinical application of the minced cartilage technique was the cartilage autograft implantation system (CAIS) developed by DePuy Mitek.  A second technology, DeNOVO NT Graft ("Natural Tissue Graft"; Zimmer Inc., Warsaw, IN/ISTO Technologies Inc.) is another application for cartilage regeneration using minced donated juvenile (less than 12 years of age) fresh allograft cartilage tissue obtained from human cadavers.  Randomized trials that compare the outcomes of minced articular cartilage repair with standard methods have not been published.  Well-designed studies are needed to establish the safety and effectiveness of this approach over standard methods of cartilage repair.

Salzmann and associates (2016) stated that articular cartilage defects at the knee joint are being identified and treated with increasing frequency.  Autologous chondrocytes may have strongest potential to generate high-quality repair tissue within the defective region, in particular when large diameter defects are present.  Autologous chondrocyte implantation is not available in every country.  These researchers presented a case where they spontaneously covered an acute cartilage defect, which was significantly larger than expected and loose during initial arthroscopic inspection after reading pre-operative MRI, by mincing the separated fragment and directly implanting the autologous cartilage chips into the defective region.  The authors considered the described case as an example on how to potentially treat unexpected (and also planned), large, fresh, chondral lesions.  Moreover, they stated that high-quality, long-term studies with large patient cohorts are needed to provide better evidence.

Salzmann and colleagues (2017) presented a surgical technique where the surgeon can apply autologous chondrocytes in a 1-step procedure to treat articular cartilage defects at the knee joint.  These authors concluded that this technique can be considered as rather novel besides previous publication effort and thus several pearls/advantages as well as pitfalls/disadvantages have to be considered.  They stated that prospective and comparative long-term clinical trials with large patient cohorts (including the use of MRI) have to be performed to fully support the use of this technique.

Autologous Cartilage Chip Transplantation for Osteochondral Repair

In laboratory study using a mini-pig model, Christensen and colleagues (2017) examined in-vivo cartilage repair outcome of autologous cartilage chips (ACC) compared with marrow stimulation in full-thickness cartilage defects.  A total of 6 Gottingen mini-pigs received two 6-mm chondral defects in the medial and lateral trochlea of each knee.  The 2 treatment groups were
  1. ACC embedded in fibrin glue (n = 12), and
  2. marrow stimulation (MST) (n = 12).

The animals were euthanized after 6 months, and the composition of repair tissue was quantitatively determined using histomorphometry.  Semi-quantitative evaluation was performed by means of the International Cartilage Repair Society (ICRS) II score.  Collagen type II staining was used to further evaluate the repair tissue composition.  Significantly more hyaline cartilage was found in the ACC (17.1 %) compared with MST (2.9 %) group (p < 0.01).  Furthermore, the ACC group had significantly less fibrous tissue (23.8 %) compared with the MST group (41.1 %) (p < 0.01).  No significant difference in fibro-cartilage content was found (54.7 % for ACC versus 50.8 % for MST).  The ACC group had significantly higher ICRS II scores for tissue morphological characteristics, matrix staining, cell morphological characteristics, surface assessment, mid/deep assessment, and overall assessment (p < 0.05).  The ACC-treated defects had significantly more collagen type II staining (54.5 %) compared with the MST-treated defects (28.1 %) (p < 0.05).  The authors concluded that ACC transplant resulted in improved quality of cartilage repair tissue compared with MST at 6 months post-operatively.  Moreover, they stated that further studies are needed to investigate ACC as a possible alternative first-line treatment for focal cartilage injuries in the knee.

Microfracture versus Mosaicplasty / Osteochondral Autograft Transplantation (OAT) in the Treatment of Knee Articular Cartilage Defects

In a RCT, Solheim and colleagues (2018) compared the clinical outcome of microfracture versus mosaicplasty/OAT in symptomatic cartilage lesions.  The null hypothesis was that the outcome was not statistically different at any time-point.  A total of 40 patients with articular cartilage defects were randomized to undergo cartilage repair by either microfracture (n = 20) or mosaicplasty (n = 20).  Inclusion criteria were as follows: age of 18 to 50 years at the time of surgery, 1 or 2 symptomatic focal full-thickness articular chondral defects on the femoral condyles or trochlea, and size 2 to 6 cm2.  The main outcome variable was the Lysholm knee score recorded before the surgery and at 12 months, median 5 years, median 10 years, and minimum 15 years after the surgery.  Subjects included 28 men and 12 women; median age of 32 years; range of 18 to 48 years.  Defects with a median size of 3.5 cm2 (range of 2 to 5 cm2) were treated.  A significant increase in the Lysholm score was seen for all subjects – from a mean of 53 (SD, 16) at baseline to 69 (SD, 21) at the minimum 15-year follow-up (p = 0.001).  The mean Lysholm score was significantly higher in the mosaicplasty group than the microfracture group at 12 months, median 5 years, median 10 years, and minimum 15 years: 77 (SD, 17) versus 61 (SD, 22), respectively (p = 0.01), at the last follow-up.  At all follow-up time-points, the difference in mean Lysholm score was clinically significant (greater than 10 points).  The authors concluded that at short-, medium-, and long-term (minimum 15 years), mosaicplasty resulted in a better, clinically relevant outcome than microfracture in articular cartilage defects (2 to 5 cm2) of the distal femur of the knee in patients aged 18 to 50 years.  Level of Evidence = I.

In a comparative study, Solheim and colleagues (2020) examined survival of cartilage repair in the knee by microfracture (MFX; n = 119) or mosaicplasty osteochondral autograft transfer (OAT; n = 84).  For survival analyses, "failure" was defined as the event of a patient reporting a Lysholm score  of less than 65 or undergoing an ipsilateral knee replacement.  The Kaplan-Meier method was used for construction of a survival functions plot for the event "failure".  Log rank (Mantel-Cox) test was used for comparison of survival distributions in the 2 groups.  The long-term failure rate (62 % overall) was significantly higher in the MFX group (66 %) compared with the OAT group (51 %, p = 0.01).  Furthermore, the mean time to failure was significantly shorter (p < 0.001) in the MFX group, 4.0 years (SD 4.1) compared with the OAT group, 8.4 years (SD 4.8).  In the OAT group, the survival rate stayed higher than 80 % for the first 7 years, and higher than 60 % for 15 years, while the survival rate dropped to less than 80 % within 12 months, and to less than 60 % within 3 years in the MFX group, log rank (Mantel-Cox) 20.295 (p < 0.001).  The same pattern was found in a subgroup of patients (n = 134) of same age (less than 51 years) and size of treated lesion (less than 500 mm2), log rank (Mantel-Cox) 10.738 (p = 0.001).  The non-failures (48 %) were followed for a median of 15 yeas (1 to 18).  The authors concluded that MFX articular cartilage repairs failed more often and earlier than the OAT repairs, both in the whole cohort and in a subgroup of patients matched for age and size of treated lesion, indicating that the OAT repair is the more durable.  Level of evidence = III.

In a large-scale, systematic review and network meta-analysis, Zamborsky and Danisovic (2020) examined the most appropriate surgical interventions for patients with knee articular cartilage defects from the level I randomized clinical trials.  These investigators searched five databases for level I randomized clinical trials.  Treatments were compared if reported in more than 1 study using network meta-analysis to boost the number of included studies per comparison.  They studied 21 articles that included 891 patients.  Traumatic lesion was the most common cause in the included patients.  There were significantly higher failure rates in the MF group compared to ACI group at 10-year follow-up.  Moreover, OAT showed significantly more excellent or good results at greater than 3-year follow-up compared to MF, whereas MF showed significantly more poor results versus ACI and MACI.  Furthermore, OAT showed significantly more poor results than MACI at 1-year follow-up.  Similarly, patients who underwent OAT had higher return-to-activity rates than those with MF.  It should be noted that the KOOS was higher in patients who underwent characterized chondrocyte implantation or MACI compared to MF.  Finally, there were no significant differences among the various interventions regarding re-intervention, biopsy types or adverse events (AEs).  According to the p scores for interventions ranking, there was a disagreement concerning the best intervention; however, MF was always ranked as the last.  The authors concluded that cartilage repair techniques, rather than MF, provided higher quality repair of tissue and had lower failure and higher return-to-activity rates.  Moreover, OAT had significantly more excellent or good results compared to MF, whereas MF had significantly more poor results than ACI and MACI.  Moreover, these researchers stated that future studies need to have longer follow-up periods and more representative populations to examine the safety and efficacy of these interventions.

Surgical Treatment for Secondary Osteochondral Defects of the Talus

In a systematic review, Lambers and colleagues (2018) identified the most effective surgical treatment for talar osteochondral defects after failed primary surgery.  These investigators carried out a literature search to find studies published from January 1996 till July 2016 using PubMed (Medline), Embase, CDSR, DARE and CENTRAL.  Two authors screened the search results separately and conducted quality assessment independently using the Newcastle-Ottawa scale. Weighted success rates were calculated; studies eligible for pooling were combined.  A total of 21 studies (299 patients with 301 talar OCDs that failed primary surgery) were examined; 8 studies were retrospective case series, 12 were prospective case series and there was 1 RCT.  Calculated success percentages varied widely and ranged from 17 % to 100 %.  Because of the low level of evidence and the scarce number of patients, no methodologically proper meta-analysis could be performed.  A simplified pooling method resulted in a calculated mean success rate of 90 % confidence interval [CI]: 82 % to 95 %] for the osteochondral autograft transfer procedure, 65 % [CI: 46 % to 81 %] for mosaicplasty and 55 % [CI: 40 % to 70 %] for the osteochondral allograft transfer procedure.  There was no significant difference between classic autologous chondrocyte implantation (success rate of 59 % [CI: 39 % to 77 %]) and matrix-associated chondrocyte implantation (success rate of 73 % [CI: 56 % to 85 %]).  The authors concluded that multiple surgical treatments were used for talar OCDs after primary surgical failure.  More invasive methods were administered in comparison with primary treatment.  No methodologically proper meta-analysis could be performed because of the low level of evidence and the limited number of patients.  Thus, it was inappropriate to draw firm conclusions from the collected results.  Besides an expected difference in outcome between the autograft transfer procedure and the more extensive procedures of mosaicplasty and the use of an allograft, neither a clear nor a significant difference between therapeutic options could be demonstrated.  These researchers stated that the need for sufficiently powered prospective studies in a randomized comparative clinical setting remains high.  The findings of this systematic review could be used in order to inform patients regarding expected outcome of the various therapeutic options used after failed primary surgery.  Level of Evidence = IV.

Dahmen et al (2022) noted that skeletally immature OLTs are under-reported; and little is known regarding the effectiveness of various therapeutic options.  These investigators examined the effectiveness of different conservative and surgical therapeutic options.  In addition, these investigators examined RTS and radiologic outcomes for the various therapeutic options.  They performed an electronic literature search in the databases PubMed, Embase, Cochrane, CDSR, CENTRAL, and DARE from January 1996 to September 2021 to identify suitable studies for this review.  The authors separately screened the articles for eligibility and conducted the quality assessment using the MINORS.  Clinical success rates were calculated per separate study and pooled per treatment strategy.  Radiologic outcomes and sports outcomes for the different treatment strategies were assessed.  A total of 20 studies with a total of 381 lesions were included.  The mean MINORS score of the included study was 7.6 (range of 5 to 9).  The pooled success rate was 44 % [95 % CI: 37 % to 51 %] in the conservative group (n = 192), 77 % (95 % CI: 68 % to 85 %) in the bone marrow stimulation (BMS) group (n = 97), 95 % (95 % CI: 78 % to 99 %) in the retrograde drilling (RD) group (n = 22), 79 % (95 % CI: 61 % to 91 %) in the fixation group (n = 33) and 67 % (95 % CI: 35 % to 88 %) in the osteo(chondral) autograft group (n = 9).  RTS rates were reported in 2 treatment groups: BMS showed an RTS rate of 86 % (95 % CI: 42 % to 100 %) without specified levels and an RTS rate to pre-injury level of 43 % (95 % CI: 10 % to 82%).  RD showed an RTS rate of 100 % (95 % CI: 63 % to 100 %) without specified levels, an RTS rate to pre-injury level was not given.  RTS times were not given for any therapeutic option.  The radiologic success according to MRI were 29 % (95 % CI: 16 % to 47 %) (n = 31) in the conservative group, 81 % (95 % CI: 65 % to 92 %) (n=37) in the BMS group, 41 % (95 % CI: 18 % to 67 %) (n = 19) in the RD group, 87 % (95 % CI: 65 % to 97 %) (n = 19) in the fixation group; and were not reported in the osteo(chondral) transplantation group.  Radiologic success rates based on computed tomography (CT) scans were 62 % (95 % CI: 32 % to 86 %) (n = 13) in the conservative group, 30 % (95 % CI: 7 % to 65 %) (n = 10) in the BMS group, 57 % (95 % CI: 25 % to 84 %) (n = 7) in the RD group, and were not reported for the fixation and the osteo(chondral) transplantation groups.  The authors concluded that this study showed that for skeletally immature patients presenting with symptomatic OLTs, conservative treatment was clinically successful in 4 out of 10 children, whereas the various surgical therapeutic options were found to be successful in 7 to 10 out of 10 children.  Specifically, fixation was clinically successful in 8 out of 10 patients and showed radiologically successful outcomes in 9 out of 10 patients; thus, would be the primary preferred surgical treatment modality.  The treatment provided should be tailor-made, considering lesion characteristics and patient and parent preferences.  Moreover, these researchers stated that the findings of this study including the summative analysis on the clinical, radiologic as well as return to sport outcomes should be interpreted with caution.  Level of Evidence = IV.

The authors stated that this review had several drawbacks.  First, the mean MINORS score of 7.6 revealed that the included studies were of limited quality.  All included studies were retrospective case series with a wide range in follow-up time, mostly including short- to mid-term follow-ups; thus, resulting in a considerable risk of bias.  Second, for studies not reporting on physeal status, a cut-off age of 15 years for girls and 16 years for boys was used, this introduced a risk of bias, as for some patients physeal arrest may have already occurred at these ages and potentially, some skeletally mature patients may have been included.  Third, it must be noted that due to the low number of included patients per study, a well-powered novel prospective study could potentially adjust the findings of this review; however, this review provided clinicians the best current evidence.  Fourth, the most reported clinical outcome in the included studies was the AOFAS.  This score appeared to be inappropriate for this population as it has never been validated in the skeletally immature population; thus, there is a significant chance on bias as over-estimation or under-estimation of the results were likely to occur.

Combination of Adipose-Derived Stem Cells and Mosaicplasty for Repair of Large Osteochondral Defects

Chen and colleagues (2019) stated that cartilage repair presents a challenge to clinicians and researchers.  A more effective procedure that can produce hyaline-like cartilage is needed for articular cartilage repair.  Mosaic osteochondral grafts for large osteochondral defects often show poor integration between the grafts and the surrounding normal cartilage, leading to defective cracks filled with fibrous tissue instead of hyaline-like cartilage.  In the present study, these researchers aimed to repair the defective cracks with a calcium alginate (CaAlg) hydrogel containing bone morphogenetic protein 4 (BMP4)-enhanced adipose-derived stem cells (ADSCs).  ADSCs were transduced with BMP4 (B-ADSCs).  The expression of BMP4 and type II collagen was confirmed using an enzyme-linked immunosorbent assay (ELISA).  Swine models of large cartilage defects of the knee were constructed and received 1 of the 4 treatments: mosaicplasty only, mosaicplasty with the CaAlg hydrogel, mosaicplasty with the CaAlg hydrogel containing ADSCs, or mosaicplasty with the CaAlg hydrogel containing B-ADSCs injected into the defective cracks.  Outcomes were evaluated at 12 and 24 weeks following surgery.  The in-vitro study showed that the osteogenic and chondrogenic activities of the B-ADSCs were enhanced compared with those of the control.  In-vivo, in the group that received mosaicplasty-containing B-ADSCs, osteochondral tissue was completely integrated with an intact surface.  Additionally, the histological scores of the mosaicplasty-containing B-ADSCs group were significantly higher than those of the other groups.  Biomechanical examination confirmed that the neocartilage possessed properties similar to those of normal cartilage.  The authors concluded that mosaicplasty and hydrogel containing B-ADSCs promoted the repair of large cartilage defects by regenerating hyaline cartilage and repairing dead spaces between osteochondral grafts and donor-site defects, thus improving the feasibility and success rate of 1-stage complete repair surgery for large osteochondral defects.  This proposed method provides a novel and effective means for the repair of large articular osteochondral defects.

Combination of Autologous Chondrocyte Implantation and Osteochondral Autograft Transfer for Repair of Large Knee Osteochondral Lesion

Kato and colleagues (2018) noted that full-thickness knee cartilage defects greater than 4 cm2 are best treated with ACI.  Since the articular cartilage surrounding the site of implantation does not always have the normal thickness desirable for successful engraftment, there may be benefit in combining ACI with OAT, which provides immediate restoration of condylar contour and mechanical function.  These researchers presented the findings of a 19-year old man who sustained a traumatic antero-lateral femoral condyle osteochondral fracture and underwent arthroscopic knee surgery 3 months after injury to harvest healthy cartilage to be sent to the Japan Tissue Engineering Co., Ltd. (J-TEC) for cartilage culture.  The patient was re-admitted after 4 weeks to undergo a procedure using the Osteochondral Autograft Transfer System (OATS) and the J-TEC autologous cultured cartilage (JACC) system.  Three 4.75-mm osteochondral cylindrical cores were harvested from non-weight-bearing areas of the knee and were transplanted to the lateral periphery of the lateral femoral condyle defect.  The cultured cartilage was implanted to the remaining defect with a periosteal cover harvested from the antero-lateral ridge of the lateral femoral condyle.  Continuous passive range of motion (ROM) exercises and gait re-training were immediately initiated, with strict no weight-bearing precaution on the operated limb.  Partial weight-bearing was allowed 4 weeks following surgery, which was progressed to full weight-bearing after another 2 weeks.  The authors concluded that ACI must be viewed as a complementary procedure to osteochondral transplantation; and this hybrid technique appeared to be a promising surgical approach and therapeutic option for large cartilage lesions, especially in the younger population.  These preliminary findings from a single-case study need to be validated by well-designed studies with larger sample size and longer follow-up (this patient was followed-up for just 1 year).

Osteochondral Autograft in the Treatment of Capitellar Osteochondritis Dissecans Lesions of the Elbow

Tsuda and co-workers (2005) reported the use of osteochondral autograft transplantation in 3 cases of non-throwing athletes with osteochondritis dissecans of the capitellum. Pre-operatively, these patients complained of elbow pain during sports activities (rhythmic gymnastics, table tennis, and basketball, respectively). Magnetic resonance imaging (MRI) showed a completely separated osteochondral fragment or a full-thickness cartilage defect. All 3 patients were treated with transplantation of an osteochondral autograft harvested from the lateral femoral condyle. They returned fully to their sports activities within 6 months of surgery. The continuity of the cartilage layer between the osteochondral graft and the capitellum was shown on MRI taken at 12 months post-operatively. The authors believed that osteochondral autograft transplantation provides successful results for non-throwing athletes with end-stage osteochondritis dissecans of the capitellum.

Shimada and associates (2005) stated that the treatment of large, advanced osteochondritis dissecans of the elbow is controversial. To determine if better results could be obtained using osteochondral autografts, these researchers retrospectively reviewed the results in 10 young athletes (mean age of 14.3 years with a range of 12 to 17 years) who were followed-up for a mean of 25.5 months (range of 18 to 45 months). After abrasion of the fragments, cylindrical osteochondral bone plugs were transferred from a lateral femoral condyle. They were evaluated clinically by the Japanese Orthopedic Association (JOA) elbow score and radiologically by radio-capitellar congruity. All patients achieved bony union in 3 months. The average JOA elbow score was 80.6 points before surgery and improved to 93.8 points at follow-up. The average percentage of radio-capitellar congruity was 35.7 % before surgery and improved to 64.2 % at follow-up. Clinical and radiological results were excellent in 8 patients and poor in 2. Poor results may be dependent on pre-existing osteoarthritis and technical difficulty related to the location of the lesion. In 8 patients, a durable load-bearing elbow was obtained with this procedure, which made hyaline-like cartilage resurfacing with healthy subchondral bony support possible. The authors concluded that osteochondral autograft is a reasonable surgical option for an advanced lesion of osteochondritis dissecans of the elbow, although long-term follow-up is needed to ascertain if the early results persist. The scientific evidence supporting the use of osteochondral autografts to repair the elbow and shoulder consists mainly of single case reports. The authors stated that currently available published studies are small, non-randomized, and lack long-term follow-up. Thus, further investigation is needed to ascertain the clinical value of osteochondral autografts for repairing  the elbow and shoulder.

Lyons et al (2015) noted that OCD of the elbow is a condition most commonly observed in adolescents involved in repetitive overhead sports and can profoundly affect ability to return to play and long-term elbow function.  Treatment of large, unstable defects in the elbow with osteochondral autograft plug transfer has not been adequately studied.  In a retrospective, case-series study, these investigators identified 11 teenaged patients with large (greater than 1 cm(2)) capitellar OCD treated with osteochondral autograft plug transfer.  Average age at the time of surgery was 14.5 years (range of 13 to 17 years).  Outcome measures obtained included return-to-play, pre-operative and post-operative elbow ROM, Disabilities of Arm, Shoulder and Hand (DASH; Institute for Work and Health, Toronto, ON, Canada) by telephone interview, and osseous integration on radiographs.  All 11 patients were available for evaluation at an average of 22.7 months (range of 6 to 49 months) post-operatively.  All patients were involved in competitive high school athletics and returned to at least their pre-injury level of play.  Average return-to-play was 4.4 months (range of 3 to 7 months).  The average final DASH was 1.4 (95 % CI: 0.6 to 2.1), and the average final sport-specific DASH was 1.7 (95 % CI: -1.8 to 5.2).  Elbow ROM significantly improved, including improvement in flexion from a pre-operative average of 126° to a post-operative average of 141° (p = 0.009) and improvement in extension from a pre-operative average of 21° to a post-operative average of 5° (p = 0.006).  The authors concluded that treatment of large, unstable OCD lesions of the capitellum in adolescent athletes allowed reliable return-to-play, was safe, and has good clinical outcomes at short-term follow-up.  Level of Evidence = IV.  These researchers stated that the main drawbacks of this trial were its retrospective design, small sample size (n = 11) and short-term follow-up (mean of 22.7 months).

Kirsch et al (2016) stated that OCD of the capitellum is a painful condition, which often affects young throwing athletes.  The current understanding regarding the etiology, risks factors, diagnosis, and effectiveness of the available therapeutic options has expanded over recent years; however, remains suboptimal.  Recent data on patient-reported outcomes following OAT for the treatment of large osteochondral lesions of the capitellum have been promising but limited.  These researchers examined the available literature on the etiology, diagnosis, and reported outcomes associated with OCD of the capitellum and the use of OAT for its treatment.  They carried out a comprehensive literature search.  Unique and customized search strategies were formulated in PubMed, Embase, Scopus, Web of Science, and CENTRAL.  Combinations of keywords and controlled vocabulary terms were used to cast a broad net.  Relevant clinical, biomechanical, anatomic and imaging studies were reviewed along with recent review articles, and case series.  A total of 43 articles from the initial literature search were found to be relevant for this review.  The majority of these articles were either review articles, clinical studies, anatomic or imaging studies or biomechanical studies.  The authors concluded that current evidence suggested that OAT may lead to better and more consistent outcomes than previously described methods for treating large OCD lesions of the capitellum; however, long-term follow-up is needed to better characterize OAT as a treatment strategy in OCD of the elbow.

Kirsch et al (2017) determined the rate of return-to-play and identified lesion or osteochondral graft characteristics that may influence the return to competitive athletics after OAT for symptomatic OCD lesions.  These investigators carried out a systematic review according to the PRISMA guidelines.  A duplicate search of PubMed, Embase, Scopus, Web of Science, and CENTRAL databases was performed, beginning from the database inception dates through July 2016, for all articles evaluating the return-to-play after OAT for OCD lesions of the capitellum.  A methodological quality assessment was completed for all included studies.  Patient demographics, osteochondral lesion and graft characteristics, the number of patients, and timing of return to competitive activity were collected and evaluated.  Association between graft size/number, the time to osseous healing, and return to sport was evaluated.  A total of 7 articles met the inclusion criteria.  All included studies were case series of moderate quality with a mean Methodological Index for Non-Randomized Studies score of 12/16.  Overall, 94 % (119/126) of patients undergoing OAT for OCD lesions of the capitellum successfully returned to competitive sports.  The mean reported time for unrestricted return to athletic competition after OAT was 5.6 months (range of 3 to 14 months).  The authors concluded that current best evidence suggested that OAT is successful in treating advanced OCD lesions of the capitellum and returning athletes to high-level competition.  Evidence supporting the association between the size and number of grafts used and the time to osseous healing and return to sport is currently limited.  The assessment of the time to return to athletic competition was limited because of variable surgical technique, post-operative rehabilitation protocols, and outcome assessment.  Level of Evidence = IV.

Sato et al (2018) stated that costal osteochondral grafting is a technique to achieve anatomical and biological repair of articular defects.  Some small series of clinical applications of this procedure for advanced OCD of the humeral capitellum, with short-term follow-up, have been reported; however, longer-term outcomes remained unclear.  These researchers clarified longer-term clinical outcomes of costal osteochondral autografts in the treatment of advanced OCD of the humeral capitellum.  A total of 72 patients with an osteochondral defect of the humeral capitellum were treated with costal osteochondral autograft and followed for a minimum of 3 years (mean follow-up of 57 months; range of 36 to 147 months).  The mean patient age was 14.3 years.  Clinical outcomes, including elbow ROM, Timmerman and Andrews clinical rating score, donor-site morbidity, responses to a questionnaire regarding a return to sporting activities, and radiographic findings, were evaluated.  The mean elbow range of extension/flexion increased significantly, from -21°/122° pre-operatively to -4°/136° post-operatively (p < 0.001).  The mean clinical rating score improved significantly, from 101 to 190 by the latest follow-up (p < 0.001).  The overall clinical score-based assessment was excellent for 60 patients, good for 9, and fair for 3; 70 of the 72 patients returned to their original sport.  The remaining 2 patients had changed sporting activities before surgery and did not return to baseball, despite satisfactory clinical results.  The authors concluded that costal osteochondral autograft successfully achieved anatomical and biological reconstruction in the treatment of advanced OCD of the humeral capitellum.  Level of Evidence = IV.

Yamagami et al (2018) stated that for treatment of advanced elbow OCD, they have used surgical treatment.  Although favorable treatment outcomes have been reported for centrally located OCD, treatment outcomes are generally questionable; and the choice of surgical method is controversial for laterally located OCD.  In a retrospective, cohort study, these researchers examined the treatment outcomes based on lesion location.  Subjects were 30 young male athletes (mean age of 14 years) who underwent surgical treatment of elbow OCD and were monitored for more than 1 year.  Osteochondral autografts harvested from the knee were transplanted to centralized (13 patients) or lateral localized (9 patients) OCD lesions.  For lateral widespread (8 patients) OCD lesions, a detached osteochondral fragment was fixed using small osteochondral plugs.  When the remaining cartilage defect was large after fragment fixation, a large-sized osteochondral plug was transplanted to the defect.  Treatment outcomes were evaluated by the JOA score, elbow ROM, and radiographic findings.  The JOA score significantly improved in patients with centralized, lateral localized, and lateral widespread types of OCD; ROM significantly improved in patients with centralized and lateral localized, and they returned to playing sports within 6 months.  However, patients with lateral widespread OCD exhibited no significant ROM improvement; and returning to sports was difficult for 3 patients because of poor osseous integration of the fixed osteochondral fragment.  The authors concluded that OAT provided favorable outcomes for centralized and lateral localized elbow OCD lesions; however, for lateral widespread OCD lesions, reconstruction of the entire capitellar lesion area may be necessary.  Level of Evidence = III.

Maruyama et al (2018) noted that OCD of the humeral capitellum is a critical elbow injury in adolescent overhead throwing athletes; however, its etiology remains unknown.  Medical examinations using ultrasonography (US) found that the prevalence of capitellar OCD among adolescent baseball players was approximately from 1 % to 3 %.  A plain antero-posterior (AP) radiograph with the elbow in 45° of flexion is essential for the diagnosis of an OCD lesion.  The stability of OCD lesions is evaluated on plain radiographs, computed tomography (CT), and MRI.  Imaging features of the unstable lesions are an epiphyseal closure of the capitellum or a lateral epicondyle, a displaced fragment, or irregular contours of the articular surface and a high signal interface on T2-weighted MRI.  A stable lesion has the potential to be healed with conservative treatment.  By contrast, surgical treatment should be considered if there is no radiographic improvement within 3 months.  Furthermore, surgery should be performed for the lesions that cause pain during daily activities, have a locking phenomenon, or which are assessed by imaging as obviously unstable.  Arthroscopic debridement/loose body removal can be carried out for small lesions (less than or equal to 1.2 cm in diameter).  For large lesions (greater than 1.2 cm), preservation and/or reconstruction of the articular surface should be selected, such as bone-peg fixation of the lateral part of the fragment and OAT from the knee.  In the future directions, there is no comparative study of OAT from the knee and rib.  In addition, little is known about its long-term outcome, or resulting OA.  A recent meta-analysis showed that grafts harvested from the knee may lead to donor site morbidity (7.8 %); thus, a novel cartilage tissue engineering approach is anticipated.

In a systematic review, Logli and colleagues (2020) examined the outcomes and complications of OAT and OCA for the surgical treatment of capitellar OCD.  These investigators carried out a literature search across 3 data-bases (PubMed, Cochrane, and CINAHL [Cumulative Index to Nursing and Allied Health Literature]) from data-base inception through December 2019 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.  Individual study quality was assessed using the Methodological Index for Non-randomized Studies (MINORS) scale.  Studies were published between 2005 and 2019.  A total of 18 studies consisting of 446 elbow OCD lesions treated with OAT surgery were included.  There was a single OCA study eligible for inclusion.  Patient ages ranged from 10 to 45 years.  Of the OAT studies, 4 used autologous costal grafts whereas the remainder used autografts from the knee.  Outcome measures were heterogeneously reported.  A significant improvement in Timmerman-Andrews scores from pre-operatively to post-operatively was reported in 9 of 10 studies.  Return-to-play rates to the pre-injury level of competitive play ranged from 62 % to 100 % across 16 studies.  Significant improvement in motion, most often extension, was noted in most studies.  Reported complication, re-operation, and failure rates ranged from 0 % to 11 %, 0 % to 26 %, and 0 % to 20 %, respectively.  When used, knee autografts resulted in low donor-site morbidity (Lysholm scores, 70 to 100).  The authors concluded that OAT surgery for large, unstable OCD lesions of the capitellum reliably produced good outcomes, few complications, and a high rate of return to competitive play.  Complications were relatively uncommon, and donor-site morbidity was low.  Less was known regarding the performance of OCA given the paucity of available literature.  Level of Evidence = IV.

The authors stated that this systematic review had several drawbacks.  First, all reviews of this nature were inherently limited by the quality of evidence of their composite studies.  Although most studies included in this review were of Level IV evidence, the mean MINORS scores were reasonably good.  Heterogeneity of individual study characteristics, patients, reported outcomes, and imaging and surgical techniques was an additional drawback.  Potential areas of bias include selection of the included studies and reporting of the outcome measures in a qualitative fashion given an inability to perform formal meta-analyses.

Bae and associates (2020) stated that OATS has been advocated for unstable OCD lesions of the adolescent capitellum, although limited information is available regarding clinical and radiographic results in North American patients.  These researchers hypothesize that single-plug OATS is safe and effective in alleviating pain and restoring function in unstable OCD.  A total of 28 patients with unstable OCD treated with single-plug OATS were evaluated.  Mean age at surgery was 14.2 years; there were 14 males.  Etiology of OCD was presumed to be sports participation, including baseball (n = 5) and gymnastics (n = 11).  Indications for surgery included unstable, deep OCD lesions; 2 lesions were uncontained, and 3 patients (11% ) had OATS after failed prior surgery.  OATS was performed by an anconeus muscle-splitting approach; donor grafts were harvested from the lateral femoral condyle by small arthrotomy.  Functional outcomes were quantified using the Timmerman instrument.  Median clinical and radiographic follow-up was 6.3 months (range of 5.0 to 27.0) and 5.7 months (range of 5.0 to 26.7), respectively.  Furthermore, all patients returned functional questionnaires at a median of 9 months post-operatively (range of 5 to 27 months).  Of the 26 patients who reported pre-operative tenderness, 19 (73 %) patients had no tenderness at most recent clinical follow-up (p = 0.02).  Of 18 patients with restricted elbow motion pre-operatively, 13 had achieved full ROM (p = 0.10).  Both elbow flexion and extension improved significantly [flexion: median change (inter-quartile range [IQR]) = 10 degrees (0 to 10 degrees), p = 0.009; extension: 0 degree (-5 to 0 degrees), p < 0.001).  On post-operative MRI, 86 % (p < 0.001) of elbows had restoration of articular congruity and 93 % had complete graft incorporation.  Objective [median change (IQR) = 5 degrees (0 to 15 degrees)], subjective [25 degrees (15 to 40 degrees)], and overall [35 degrees (15 to 45 degrees)] Timmerman scores improved significantly (p = 0.001, p < 0.001, and p < 0.001, respectively).  Of the 13 patients with greater than 6 months follow-up, 9 patients (69 %) had returned to their primary sport (p = 0.27) and 100 % had returned to general sports participation.  There were no post-operative complications.  At final follow-up, all donor knees were asymptomatic with full ROM and strength.  The authors concluded that single-plug OATS was safe and effective in improving pain and elbow function in adolescents with unstable OCD, with high return to sports rates and little donor-site morbidity.  Level of Evidence = IV.

Chen et al (2020) stated that with an increase in single-sport specialization, elbow injuries have become increasingly common in the pediatric and adolescent population; and OCD of the elbow frequently requires intervention yet can be difficult to treat given high patient activity demands.  These researchers examined therapeutic options, failure rates, and provided strategies for successful revision surgery.  Patients at high risk for the development of this condition are involved in high-demand upper extremity activity such as baseball or gymnastics.  Therapeutic options include non-operative management, drilling, fixation, loose body removal/microfracture, OAT, and osteochondral allograft.  Cartilage preservation procedures (i.e., OAT) have a significant advantage in terms of clinical and radiographic healing compared with fixation or microfracture.  Capitellar OCD lesions afflict a large number of adolescent athletes today and will likely continue increasing in number from sports-related injuries.  It is critical to recognize and treat these lesions in a timely and appropriate fashion to optimize clinical outcomes.  When faced with failure of healing, surgeons must critically analyze reasons for failure including post-operative compliance, return to high-demand sporting activity, fixation of non-viable fragments, use of microfracture, alignment, and concomitant pathology.  The authors concluded that osteochondral lesions of the elbow in the pediatric and adolescent population remain difficult entities to treat for the orthopedic surgeon.  Careful counseling in regard to participation in post-operative high-demand activity is critical.  Furthermore, minimizing primary treatment failure can maximize patient outcome.  Avoidance of fixation of large osteochondral fragments, limited use of loose body removal / microfracture, and minimizing OATS procedures in uncontained/lateral lesions are critical.  If treatment failure does occur and patient compliance/post-operative rehabilitation has been optimized, aggressive cartilage restoration with OATS and recognition of pathologic alignment with osteotomy as needed, along with treatment and identification of radial head and ligamentous pathology, are paramount.

Sayani et al (2021) stated that the optimum management of OCD of the capitellum is a widely debated subject.  In a systematic review, these researchers examined the effectiveness of different surgical modalities and non-operative treatment of OCD as assessed by radiological and clinical outcomes and return to sports.  They carried out a review of all treatment studies published between January 1975 and June 2020 following the PRISMA guidelines.  A total of 76 clinical studies, including 1,463 patients, were suitable for inclusion.  Aggregate analysis and subgroup analysis of individual patient data were carried out to compare the functional and radiographic outcomes between the various non-operative and surgical treatment options for capitellar OCD.  A unified grading system (UGS; grades 1 to 4) was developed from existing validated classification systems to allow a comparison of patients with similar-grade OCD lesions in different studies according to their treatment.  Patient-level data were available for 352 patients.  The primary outcome measures of interest were patient-reported functional outcome, ROM, and return to sports after treatment.  The influences of the capitellar physeal status, location of the lesion, and type of sports participation were also assessed.  Each outcome measure was evaluated according to the grade of OCD and treatment method (debridement/microfracture, fragment fixation, OATS, or non-operative treatment).  No studies reported elbow scores or ROM for non-operatively treated patients.  All surgical modalities resulted in significantly increased post-operative ROM and elbow scores for stable (UGS grades 1 and 2) and unstable lesions (UGS grades 3 and 4).  There was no significant difference in the magnitude of improvement or overall scores according to the type of surgery for stable or unstable lesions.  Return to sports was superior with non-operative treatment for stable lesions, whereas surgical treatment was superior for unstable lesions.  Patients with an open capitellar physis had superior ROM for stable and unstable lesions, but there was no correlation with lesion location and the outcomes of OATS versus fragment fixation for high-grade lesions.  The authors concluded that non-operative treatment was similar in outcomes to surgical treatment for low-grade lesions, whereas surgical treatment was superior for higher grade lesions.  Moreover, these researchers stated that there is currently insufficient evidence to support complex reconstructive techniques for high-grade lesions compared with microfracture/debridement alone.

Furthermore, an UpToDate review on “Management of osteochondritis dissecans (OCD)” (Hergenroeder and Harvey, 2022) states that “The operative management of OCD is based upon case series and expert opinion.  Evidence that compares outcomes among the different types of operative treatment is lacking”.  Osteochondral autograft transplantation (OAT) is not listed in the “Summary and Recommendations” of this UTD review.

Mosaicplasty / Osteochondral Autograft in the Treatment of Osteochondral Defects of the Talus

Easley and Scranton (2003) stated that long-term outcome of the OATS procedure for osteochondral lesions of the talus is not yet available.

Aurich and colleagues (2008) noted that ankle sprains are one the most common injuries of the lower limb. Fractures, ligamentous lesions, and cartilaginous damage are often associated. Nevertheless, the injury is often mis-judged and concomitant chondral lesions are assessed late. In the case of a symptomatic osteo-cartilaginous lesion of the talus, which can be illustrated by MRI or X-ray, operative intervention is indicated. Methods such as microfracturing, mosaicplasty, and autologous chondrocyte transplantation (ACT) are in clinical use. The latter is well-known and being established as the treatment of choice for large cartilage defects in the knee. Due to the good results in the knee and the technological improvements (three-dimensional tissue constructs seeded with autologous chondrocytes) this method is being increasingly applied for cartilage lesions of the talus. In contrast to the mosaicplasty, donor site morbidity is low and the size of the defect is not a limiting factor. The current studies about ACT of the talus show a stable repair of the defect with mostly hyaline-like cartilage and high patient satisfaction. Therefore, the procedure can be recommended for lesions less than 1 cm2. Concomitant treatment of post-traumatic deformities (malalignment), ligamentous instabilities, and especially the reconstruction of bony defects are compulsory.

In a systematic review, Magnussen et al (2008) examined if ACT or osteochondral autograft transfer yields better clinical outcomes compared with one another or with traditional abrasive techniques for treatment of isolated articular cartilage defects and if lesion size influences this clinical outcome. These researchers performed a literature search and identified 5 randomized, controlled trials and 1 prospective, comparative trial evaluating these treatment techniques in 421 patients. The operative procedures included ACT, osteochondral autograft transfer, matrix-induced ACT, and microfracture. Minimum follow-up was 1 year (mean of 1.7 years; range of 1 to 3 years). All studies documented greater than 95 % follow-up for clinical outcome measures. No technique consistently had superior results compared with the others. Outcomes for microfracture tended to be worse in larger lesions. All studies reported improvement in clinical outcome measures in all treatment groups when compared with pre-operative assessment; however, no control (non-operative) groups were used in any of the studies. The authors stated that a large prospective trial investigating these techniques with the addition of a control group would be the best way to definitively address the clinical questions.

Steman and colleagues (2019) noted that OCDs of the talus are found subsequent to ankle sprains and ankle fractures.  While many surgical options are available, there is no clear evidence on return-to-sport (RTS) times and rates.  In a systematic review, these researchers summarized RTS times and rates for talar OCDs treated by various surgical techniques.  The literature from January 1996 to November 2018 was screened, and identified studies were divided into 7 different surgical treatment groups.  The RTS rate, with and without associated levels of activity, and the mean time to RTS were calculated per study.  When methodologically possible, a simplified pooling method was used to combine studies within 1 treatment group.  Study bias was assessed using the MINORS scoring system.  A total of 61 studies including 2,347 talar OCDs were included.  The methodological quality of the studies was poor.  There were 10 retrospective case series (RCSs) that examined bone marrow stimulation in 339 patients, with a pooled mean rate of RTS at any level of 88 % (95 % CI: 84 % to 91 %); 2 RCSs examining internal fixation in 47 patients found a pooled RTS rate of 97 % (95 % CI: 85 % to 99 %), 5 RCSs in which autograft transplantation was performed in 194 patients found a pooled RTS rate of 90 % (95 % CI: 86 % to 94 %), and 3 prospective case series on ACI in 39 patients found a pooled RTS rate of 87 % (95 % CI: 73 % to 94 %).  The rate of return to pre-injury level of sports was 79 % (95 % CI: 70 % to 85 %) for 120 patients after bone marrow stimulation, 72 % (95 % CI: 60 % to 83 %) for 67 patients after autograft transplantation, and 69 % (95 % CI: 54 % to 81 %) for 39 patients after ACI.  The mean time to RTS ranged from 13 to 26 weeks, although no pooling was possible for this outcome measure.  The authors concluded that different surgical options for talar OCDs allowed for adequate RTS times and rates; RTS rates decreased when considering patients' return to pre-injury levels versus return at any level.  Level of Evidence = IV.

The authors stated that this review had several drawbacks.  The 2 most important drawbacks were the high number of methodologically low-quality studies that were included and the substantial heterogeneity in the methodology of the included studies.  Heterogeneity was also observed in the used outcome measures.  Some studies reported outcomes other than the RTS rate and the mean time to RTS, reporting scores from various outcome measures instead.  Thus, not all studies could be taken into account when calculating the RTS rate and the mean time to RTS, which rendered the results of return to pre-injury level and mean time to RTS under-reported and subsequently left a possibility for the results being subject to reporting bias.  Furthermore, it was not possible to perform a formal meta-analysis.  Instead, a simplified pooling method was used for studies with the same methodology that reported outcomes after performing the same treatment technique.  As the pooled studies were all of methodologically low quality, the evidence retrieved from this simplified pooling method was based on a lower level of evidence and may contain methodological bias.  These researchers deliberately did not choose a comparative character for the present study, as RTS rates and times were highly under-reported when assessing sports outcomes, and more importantly, specific clinical indications for specific surgical therapies were highly different from one another.  Thus, it should be explicitly stated that the pooled calculated RTS rates should not be used for decision-making with respect to therapeutic options but should merely be applied to give patients an indication on the expected RTS rates and times for the different available therapeutic options.  The outcomes of the present study can therefore be utilized as a novel informative guideline on sports-specific prognosis for patients with primary and secondary talar OCDs aiming to return to (pre-injury level of) sports.

Struckmann and associates (2020) stated that talar osteochondral lesions (OCLs) lead to progressive stages of talar destruction.  Core decompression with cancellous bone grafting (CBG) is a common treatment for Berndt and Harty stages II and III.  However, in a subset of patients, talar re-vascularization may fail.  Surgical angiogenesis using vascularized medial femoral condyle (MFC) autografts may improve on these outcomes.  These 2 treatment strategies were directly compared via a prospective preliminary randomized trial including 20 subjects with talar core decompression followed by either cancellous (CBG group, n = 10) or vascularized MFC (MFC group, n = 10) bone grafting.  Outcome analysis was performed with VAS, AOFAS ankle-hindfoot score, Lower Extremity Functional Scale (LEFS), and contrast-enhanced MRI (CE-MRI) scans.  At 12 months of follow-up, the mean VAS score was reduced from 6.6 ± 2.5 pre-operatively to 4 ± 1.9 in the CBG group and from 5.2 ± 2.9 pre-operatively to 1 ± 1.1 in the MFC group (p < 0.001).  The LEFS improved from 53.4 ± 13.1 to 62.6 ± 16.2 CBG and from 53 ± 9.3 to 72.4 ± 7.4 MFC (p = 0.114).  AOFAS improved from 71 ± 12.1 to 84.1 ± 12.5 in CBG and from 70.5 ± 7.4 to 95.1 ± 4.8 in MFC (p = 0.019).  The MRI scans in the CBG group demonstrated 9 partial mal-perfusions and 1 hyper-vascularized bone graft, whereas the MFC group had 8 well-vascularized grafts incorporated into the talus and 1 partial mal-perfusion.  Vascularized MFC autografts provided superior pain relief along with improvement of physical function in patients with talar OCL stage II and III compared with CBG.  The authors concluded that to confirm these promising findings, further multi-center RCTs are needed.

Sabaghzadehand associates (2020) examined the effect of mosaicplasty on improvement of symptoms of patients with osteochondral lesions of talus.  A total of 19 patients with osteochondral lesions of talus participated in this study, who were treated with mosaicplasty.  Before and after treatment, pain (VAS), function (AOFAS), ROM and radiographic signs were evaluated.  The results of this study showed that mosaicplasty could significantly reduce pain, increase function and improve radiographic symptoms.  The ROM increased after treatment, which was non-significant.  The authors confirmed the effect of mosaicplasty on the improvement of patients with osteochondral lesions of the ankle, suggesting it as a therapeutic option.  Moreover, these researchers stated that increasing lesion size often requires more advanced regenerative or replacement techniques rather than reparative ones.  They stated that more comparative studies and RCTs are needed to ascertain which therapeutic options are more effective for certain types of lesions.

Osteochondral Autografts for the Treatment of Patellar Chondral Defects

Figueroa and colleagues (2020) noted that patellar chondral defects represent up to 34.6 % of defects found during routine arthroscopy.  Surgical management has evolved during the past 2 decades in an effort to develop techniques to replace hyaline cartilage.  At the present time, the only technique that achieves this is OAT.  Although good and excellent results have often been reported at mid-term and long-term follow-up for femoral lesions, little is known regarding isolated patellar defects.  In a retrospective, case-series study, these researchers examined clinical and imaging results of patients treated with OAT for high-grade patellar defects.  Subjects included all patients who received OAT for high-grade symptomatic patellar chondral defects between 2010 and 2018 at the authors’ institution.  The study included patients younger than 40 years of age with anterior knee pain and a grade-4 ICRS patellar chondral defect between 1 and 2.5 cm2.  Patients with surgery in other knee compartments, concomitant ACL ruptures, infection, rheumatoid arthritis, and degenerative lesions were excluded.  Six months post-operatively, all patients underwent MRI to allow assessment of graft integrity via the MOCART score to examine morphologic features and integration; WOMAC and Kujala scores were used to evaluate functional outcomes at final follow-up.  A total of 26 patients who received a patellar OAT were included.  Most patients were male (88.4 %), and the mean ± SD age was 28.5 ± 9.7 years.  Patellar chondral defects had a median size of 180 mm2 (range of 64 to 250 mm2), and patients received a median of 1 autograft (range of 1 to 3).  Functional outcomes assessed at a minimum of 1 year after surgery showed a mean Kujala score of 90.42 ± 6.7 and a mean WOMAC score of 95 ± 3.6.  MRI revealed a median MOCART score of 75 points (range of 20 to 90 points).  The authors concluded that to their knowledge, this was the largest series to-date regarding isolated patellar OAT.  At mid-term follow-up, most patients reported good and excellent results regarding symptoms and activity levels.  Most autografts showed good osseous integration and excellent filling of the chondral surface, as evidenced on MRI.  These researchers stated that OAT is a good alternative to treat high-grade patellar chondral defects, especially among young patients.  Moreover, they stated that further prospective, mid-term and long-term follow-up studies are needed to corroborate these findings, but this study provided promising results for treating surgeons. Level of Evidence = IV.

The authors stated that this study had several drawbacks.  Results could be attributable to the retrospective nature of this analysis.  These investigators did not carry out pre-operative assessment of functional scores to compare with pre-operative scores; thus, they were unable to state the magnitude of the improvement from this procedure.  In addition, more than 50 % of the subjects had concomitant surgery to correct patellar instability, which may have influenced the results.  Furthermore, these findings could be influenced by the relatively small sample size (n = 26).

Osteochondral Allograft for the Treatment of Patellar Cartilage Injuries / Lesions

Gracitelli et al (2015) stated that the treatment of patella-femoral cartilage injuries can be challenging.  Osteochondral allograft (OCA) transplantation has been used as a therapeutic option for a range of cartilage disorders.  In a case-series study, these researchers examined functional outcomes and survivorship of the grafts among patients who underwent OCA for patellar cartilage injuries.  An institutional review board (IRB)-approved OCA database was used to identify 27 patients (28 knees) who underwent isolated OCA transplantation of the patella between 1983 and 2010.  All patients had a minimum 2-year follow-up.  The mean age of the patients was 33.7 years (range of 14 to 64 years); 54 % were female; 26 (92.9 %) knees had previous surgery (mean of 3.2 procedures; range of 1 to 10 procedures).  The mean allograft area was 10.1 cm(2) (range of 4.0 to 18.0 cm(2)).  Patients returned for clinical evaluation or were contacted via telephone for follow-up.  The number and type of re-operations were assessed.  Any re-operation resulting in removal of the allograft was considered a failure of the OCA transplantation.  Patients were evaluated pre- and post-operatively using the modified Merle d'Aubigné-Postel (18-point) scale, the IKDC pain, function, and total scores, and the Knee Society function (KS-F) score.  Patient satisfaction was assessed at latest follow-up; 17 of the 28 knees (60.7 %) had further surgery after the OCA transplantation; 8 of the 28 knees (28.6 %) were considered OCA failures (4 conversions to total knee arthroplasty [TKA], 2 conversions to patella-femoral knee arthroplasty, 1 revision OCA, 1 patellectomy).  Patellar allografting survivorship was 78.1 % at 5 and 10 years and 55.8 % at 15 years.  Among the 20 knees (71.4 %) with grafts in-situ, the mean follow-up duration was 9.7 years (range of 1.8 to 30.1 years).  Pain and function improved from the pre-operative visit to latest follow-up, and 89 % of patients were extremely satisfied or satisfied with the results of the OCA transplantation.  The authors concluded that the treatment of patellar cartilage injuries remains a difficult clinical challenge regardless of the surgical intervention chosen, with relatively high re-operation and revision rates.  OCA transplantation was successful in the majority of this challenging cohort requiring major patellar resurfacing.  These investigators stated that patellar allografting was a useful salvage therapeutic option for patellar cartilage injuries.  Level of Evidence = IV.

The authors acknowledged several drawbacks that could threaten the validity of their conclusions.  The patient cohort was small (n = 28 knees).  Another drawback of this trial was the lack of a control group.  The lack of long-term radiographic follow-up was also a limitation of this study; many patients travel long distances for treatment; thus, routine check-ups were difficult to schedule.  Telephone interviews or mailings for outcome scores provided information on basic outcome measures including graft survival, re-operation, pain, and function.  These researchers used the modified Merle d’Aubigne´-Postel (18-point) scale; however, this scoring system has not been validated in the knee.  This scoring system is a simple, standardized method of retrospectively evaluating patient outcomes on an objective basis and is used commonly in the orthopedic literature.  Another drawback of this study was due to lack of a good salvage therapeutic option for young patients regarding patella-femoral arthritis.  Young patients may have to live with patella-femoral arthritis, increasing the survivorship rate.  However, these patients had lower clinical outcomes, which were represented by the lower functional outcomes in this study.  They noted that prospective studies also may give results that are more beneficial.

Gelber et al (2018) stated that the treatment of articular cartilage lesions in young patients is certainly a complex matter and subject of continuous research, especially for those located at the patella-femoral joint, given its peculiar biomechanical characteristics.  Osteochondral grafts can be of relatively small size when the defect is focal and in an area that allows good stability and consequently the graft's integration.  In case of large or multi-focal lesions, it is possible to consider an osteochondral transplantation of the entire articular surface of the patella.  These researchers presented a simple and reproducible technique to perform a patellar fresh osteochondral allograft resurfacing attempting to reduce the symptoms and delay a prosthetic implant in young patients with advanced patellar chondral injuries.  The authors concluded that the current technique is a valid option and perhaps the most appropriate non-metal alternative for invalidating anterior knee pain due to a large cartilage defect of the patella in young patients.  Although the technique is not technically demanding, the use of fresh allografts carries considerable logistics limitations.

Dekker et al (2019) noted that chondral defects of the patella-femoral joint remain a difficult-to-treat pathology with limited long-term results.  Currently available techniques to treat large or unipolar chondral defects of the patella include ACI and OAT.  Despite the recent advances in ortho-biologic adjuncts, there is no single gold-standard surgical approach to this difficult-to-treat pathology in patients who are frequently young, active, and demanding on their bodies.  The authors described a technique for OAT to the patella for an isolated patellar chondral lesion (unipolar).  Moreover, these researchers stated that with results of this technique limited to small case series and retrospectively collected data, studies that prospectively identify patients with isolated chondral defects that are followed longitudinally are needed to examine the effectiveness of this technique.

Lin et al (2020) noted that fresh OCA has good outcomes in the knee; however, donor tissue for patellar OCA is limited.  Outcomes after non-orthotopic OCA of the patella using more readily available femoral condylar allograft (FCA) tissue have not been previously reported.  In a case-series study, these researchers examined short-term MRI and minimum 2-year clinical outcomes of non-orthotopic patellar OCA using an FCA donor.  A prospective, institutional cartilage registry was reviewed to identify patients treated with patellar OCA using an FCA donor between August 2009 and June 2016.  OCA plugs were obtained from the FCA at its trochlear-condylar junction and implanted into the recipient patellar lesion.  Early post-operative MRI scans were graded by a blinded musculoskeletal radiologist using the Osteochondral Allograft MRI Scoring System (OCAMRISS).  IKDC, Knee Outcomes Survey-Activities of Daily Living (KOS-ADL), and pain VAS scores were collected pre-operatively and at minimum 2 years post-operatively, and outcomes were compared using the paired t-test.  A total of 25 patients were included for clinical outcome analysis and 20 patients for MRI analysis.  MRI scans obtained at a mean of 11.4 months (range of 6 to 22 months) post-operatively showed a mean total OCAMRISS score of 9.0 (range of 7 to 11); mean bone, cartilage, and ancillary sub-scores were 2.6, 3.7, and 2.6, respectively.  At the latest follow-up (mean of 46.5 months; range of 24 to 85 months), post-operative improvements were noted in IKDC (from 45.0 to 66.2; p = 0.0002), KOS-ADL (from 64.3 to 80.4; p = 0.0012), and VAS (from 5.1 to 3.4; p = 0.001) scores, with IKDC and KOS-ADL scores above the corresponding previously reported minimal clinically important difference.  The authors concluded that the findings of this retrospective analysis of prospectively collected registry data suggested that use of femoral condylar donor tissue for treatment of patellar chondral lesions produced good short-term clinical and MRI outcomes.  Improvements in patient-reported outcome scores and rate of complete osseous integration based on MRI were comparable with previously reported results after OCA for condylar defects.  On post-operative MRI follow-up beyond 2 years, a subset of patients had a worsening appearance on MRI scans due to worsening cartilage sub-scores.  The clinical correlation of this finding was unclear.  These researchers stated that the lack of a comparison group and retrospective nature of this study precluded direct comparison with other techniques.  They stated that further well-designed comparative studies are needed to elucidate differences between the various cartilage restoration techniques for focal patellar defects and further characterize outcomes after the use of condylar donor tissue for patellar defects.  Level of Evidence = IV.

The authors stated that this study had many important drawbacks.  Although data were prospectively collected through an institutional registry, analysis was carried out retrospectively, introducing various confounders.  Although the demographic information collected pre-operatively did not differ between the overall cohort and separate clinical and MRI groups, other possible confounders may have influenced the results of the intervention: history of patellar instability, activity level, sports participation, smoking status, or post-operative compliance with rehabilitation protocols.  There was a large loss to follow-up in both the clinical and the MRI groups, since only patients with complete outcome data at greater than 2 years or patients with MRI scans from the early post-operative period were included, which introduced participation bias.  Although the inclusion and exclusion criteria defined a distinct population and outcomes from this study were comparable with those previously reported in similar patients, there was still potential for sampling bias, as the study population was drawn from a single institution.  Furthermore, no control or comparison group was included, precluding direct comparison with other described techniques.  To capture a larger number of patients with OCA using FCA, these researchers included patients receiving treatment for bipolar lesions.  However, this study was not initially powered to draw conclusions based on the post-hoc subgroup analyses.  Larger sample size and more uniform follow-up are needed to draw conclusions regarding changes in MRI characteristics on subsequent imaging follow-up.  Specific to patellar osteochondral lesions, although the OCAMRISS score measures the lesion fill, surface congruity, and subchondral congruity, there is no standardized way of measuring the overall topography fit.  For instance, while a graft may match the host patella perfectly at the edges without any fissures or step-offs, the surface topography may still be altered; the clinical impact of this phenomenon is unknown and was not measured in this study.  Similarly, these investigators did not sub-analyze these findings based on which region of the patella was affected; although most of the lesions in this study were central, it was possible that patients with steeper patellar anatomy or particular facet lesions tended to have worse outcome after condylar allograft, and these subpopulations would be missed in this analysis.

Melugin et al (2021) analyzed the clinical outcomes, knee function, and activity level of patients after treatment of full-thickness cartilage defects involving the patella-femoral compartment of the knee with cryo-preserved osteochondral allograft.  A total of 19 patients with cartilage defects involving the patella-femoral compartment were treated.  The average age was 31 years (range of 15 to 45 years), including 12 females and 7 males.  Patients were prospectively followed using validated clinical outcome measures including Veterans RAND 12-item Health Survey (VR-12), IKDC, KOOS, and the Tegner activity scale.  Graft incorporation was evaluated by MRI or 2nd-look arthroscopy.  The cartilage defects included the patella (n = 16) and the femoral trochlea (n = 3).  Mean VR-12 scores increased from 31.6 to 46.3 (p < 0.01), mean IKDC increased from 40.0 to 69.7 (p < 0.01), mean KOOS increased from 53.9 to 80.2 (p < 0.01), and mean Tegner scores increased from 3.0 to 4.9 (p < 0.01), at average follow-up of 41.9 months (range of 24 to 62 months).  Of the 3 patients who underwent 2nd-look arthroscopy, all demonstrated a well-incorporated graft.  Mean MOCART score for the 6 patients with follow-up MRI was 62.5 (range of 25 to 85).  The re-operation rate was 21.1 % and 2 patients (12.5 %) experienced progressive patella-femoral OA requiring conversion to patella-femoral arthroplasty.  The authors concluded that patients with unipolar cartilage defects involving the patella-femoral compartment of the knee could have positive outcomes at minimum 2-year follow-up following surgical treatment with a cryo-preserved osteochondral allograft when concomitant pathology was also addressed; however, the re-operation rate was high and bipolar cartilage lesions may increase the failure rate.

The authors stated that the findings of this study should be considered with its limitations.  The series consisted of a rather small number of patients (n = 16 for the patella group); however, this was because of the fact that this was a relatively new procedure and has only been performed at the authors’ institution since 2014.  There was a high percentage of concurrent procedures in this series, which was a confounding variable, but this is standard in cartilage restoration surgery.  In fact, Brophy et al (2017) discussed the necessity of concurrent operations in their review of patella-femoral compartment cartilage restoration options.  Nevertheless, the improvements appreciated in this study likely could not be completely attributed to the presented technique as the majority of patients underwent a concurrent re-alignment procedure.  It is known that re-alignment procedures may be performed in isolation for the treatment of patella-femoral cartilage lesions.  There was no control group; and the patients were not randomized.  Despite its limitations, to the authors knowledge, this was the 1st study evaluating the 2-year minimum outcomes in patients following treatment with cryo-preserved OCA.

Biologic Augmentation for the Operative Treatment of Osteochondral Defects of the Knee

Chona et al (2021) stated that various surgical therapeutic options exist for repairing, replacing, or regenerating tissue to fill osteochondral defects.  Biologic augmentation has been increasingly studied as an adjunct in the surgical treatment of osteochondral defects of the knee in animal and human models.  In a systematic review, these researchers examined the use of PRP and bone marrow concentrate (BMC) augmentation in the surgical treatment of osteochondral knee defects and presented the outcomes.  It was hypothesized that both PRP and BMC augmentation would result in improved outcomes in osteochondral knee surgery in both animal and human models.  PubMed, Medline, and Embase were searched for studies relating to PRP or BMC and treatment of osteochondral defects of the knee, from database inception to February 1, 2020.  Included were studies that examined PRP or BMC augmentation; employed osteochondral autograft, allograft, or biologic scaffold; and treated osteochondral defects in the knee.  Data on use of PRP or BMC, outcomes assessed, and results were recorded for each publication.  Of the 541 articles identified initially, 17 were included in the final review – 5 articles studied osteochondral grafts in animals, 5 studied biologic scaffolds in animals, and 7 studied scaffolds or allografts in humans; the combined sample size was 202 patients.  Of 4 histologic scaffold studies, 3 PRP-augmented scaffold studies identified histologic improvements in regenerated cartilage in animal models, while 1 BMC study demonstrated similar improvement in histologic scores of BMC-augmented scaffolds compared with controls; 3 studies associated greater collagen type 2 and glycosaminoglycan content with PRP treatment.  Comparative studies found that both augmentations increased osteogenic proteins, including bone morphogenetic protein-2 (BMP-2) and osteoprotegerin; 2 of 3 studies on BMC-augmented osteochondral allografts reported no difference in radiographic features post-operatively.  Long-term improvement in clinical and radiographic outcomes of PRP-augmented scaffolds was demonstrated in 1 human study.  The authors concluded that animal studies suggested that biologics possess potential as adjuncts to surgical treatment of osteochondral knee defects; however, clinical data remain limited.  These researchers stated that further investigation is needed to more accurately determine the true impact of biologics on the treatment outcomes for these injuries.  Establishing standardized manufacturing methods and biochemical profiles of PRP and BMC would address the heterogeneity of biologic treatments and allow for more meaningful comparisons between studies.  Furthermore, clinical studies are limited in quantity but would likely be of substantial benefit, especially if comparisons could be made between PRP and BMC as forms of augmentation.

Osteochondral Autografts/Allografts for the Treatment of Osteochondral Lesions of the Tibial Plafond

Allahabadi et al (2021) noted that osteochondral lesions of the tibial plafond (OLTPs) remain less common than osteochondral lesions of the talus (OLTs); however, recognition of the condition has increased.  In a systematic review, these investigators examined the literature on lesion locations and treatment outcomes of OLTPs, whether in isolation or in combination with OLTs.  They carried out a literature search using the PubMed, Embase, and CINAHL databases for studies on lesion locations or with imaging or treatment outcomes of OLTPs.  Case reports and reports based on expert opinion were excluded.  Lesion locations as well as outcome measure results were aggregated.  The MINORS score was used to evaluate methodological quality when applicable.  Included in this review were 10 articles, all published in 2000 or later.  Most studies were evidence level IV, and the mean MINORS score was 8.6 (range of 8 to 10).  Overall, 174 confirmed OLTP cases were identified, and the mean patient age was 38.8 years.  Of the 157 lesions with confirmed locations, the most common was central-medial (32/157; 20.4 %).  Of 6 studies on treatment outcomes, all but 1 examined bone marrow stimulation techniques.  Microfracture of small lesions (less than 150 mm2) was the most common treatment employed.  Imaging and functional outcomes appeared favorable following treatment.  The results did not support differences in outcomes between isolated OLTPs and OLTPs with co-existing OLTs.  The authors concluded that osteochondral lesions of the distal tibia most commonly occurred at the central-medial tibial plafond.  Microfracture of small lesions was the most common treatment used, and clinical and MRI results were favorable, although data were heterogeneous.  These researchers stated that areas for future research include the following: the effect of patient factors and additional pathologies on outcomes; larger or deeper lesion treatment; more direct comparisons of outcomes between kissing or co-existing lesions and isolated lesions; and direct comparison of treatments, such as microfracture, bone marrow-derived cell transplantation (BMDCT), and osteochondral autografts/allografts.  Level of Evidence = IV.

The authors stated that this systematic review was primarily limited in the paucity of data; the variety of treatments; and the current evidence, which is largely level IV without comparison groups.  Therefore, these researchers were unable to aggregate the majority of the data or carry out any meaningful meta-analyses, and conclusions of the studies should be interpreted with caution.  The number of studies on OLTPs were also limited, with even fewer reporting on outcomes of treatment.  Those that did report outcomes were heterogeneous in the measures used and the treatment techniques.  These investigators stated that more studies are needed on OLTPs and co-existing OLTPs and OLTs to understand algorithms in and outcomes of management.  Future studies should examine factors such as the effects of age and lesion area and depth on outcomes.  Furthermore, determining the association of imaging findings with arthroscopic findings and each of these with functional outcomes would be beneficial to understand the use of the pre- and intra-operative evaluation. 

Butler et al (2021) noted that there is a paucity of data regarding OLTPs partly because they are far less common than osteochondral lesions of the talus.  In a systematic review, these investigators examined the topographical characteristics of OLTPs and outcomes following surgical intervention, while analyzing the level of evidence (LOE) and quality of evidence (QOE) of the included studies.  They carried out a systematic review of the Medline, Embase, and Cochrane Library databases in accordance with PRISMA guidelines; studies reporting clinical data for OLTPs were included.  The LOE and QOE of the included studies were assessed using a 5-level grading system and the modified Coleman Methodology Score, respectively.  Included were 20 studies with 426 OLTPs; 4 studies were LOE II and 16 studies were LOE IV.  Overall, 86.7 % of OLTPs were associated with a traumatic history and/or previous ankle sprain.  OLTPs were most commonly located in the centro-medial region of the tibial plafond (30.4 %), with the fewest number of OLTPs found in the antero-medial region of the tibial plafond (3.9 %).  In 17 of the studies, a total of 46.9 % of OLTPs were associated with co-existing osteochondral lesions of the talus.  The most frequently used surgical technique to treat OLTPs was microfracture, which resulted in good clinical outcomes at mid-term follow-up.  The authors concluded that the findings of this systematic review indicated that OLTPs were frequently preceded by ankle trauma and were often associated with co-existing osteochondral lesions of the talus.  Clinical outcomes following arthroscopic intervention appeared to produce good results in the mid-term; however, the low LOE, poor QOE, marked heterogeneity, and under-reporting of the data confounded any recommendation based on this systematic review.  Furthermore, osteochondral autografts/allografts were not discussed as therapeutic options in this systematic.  Level of Evidence = IV.


Agili-C is a cell-free, off-the-shelf implant for use in cartilage and osteochondral defects in traumatic and osteoarthritic joints.  The implant is a porous, biocompatible, and resorbable bi-phasic scaffold, consisting of inter-connected natural inorganic calcium carbonate (aragonite).

Kon et al (2021) stated that OA is considered a contraindication to most cartilage repair techniques.  Several regenerative approaches have been attempted with the aim of delaying or preventing joint replacement, with controversial results.  Currently, there is a paucity of data on the use of single-step techniques, such as cell-free biomimetic scaffolds, for the treatment of joint surface lesions (JSLs) in OA knees.  In a prospective, multi-center study, these researchers presented the 2-year follow-up clinical and radiological outcomes following implantation of a novel, cell-free aragonite-based scaffold for the treatment of JSLs in patients with mild-to-moderate knee OA.  A total of 86 patients, 60 men and 26 women, with a mean age of 37.4 +/- 10.0 years, mild-to-moderate knee OA, and a mean defect size of 3.0 +/- 1.7 cm2, were recruited at 8 medical centers according to the following criteria: radiographic mild-to-moderate knee OA (Kellgren-Lawrence grade of 2 or 3); up to 3 treatable chondral/osteochondral defects (ICRS grades of 3 and 4) on the femoral condyles or trochlea; a total defect size 7 cm2; and no concurrent knee instability, severe axial malalignment, or systemic arthropathy.  All patients were examined at baseline and at 6, 12, 18, and 24 months following implantation using the KOOS and IKDC subjective score.  Furthermore, MRI was carried out to evaluate the amount of cartilage defect filling at the repaired site.  Significant improvement on all KOOS subscales was recorded from baseline (pain: 49.6 +/- 13.1; ADL: 56.1 +/- 18.4; sport: 22.8 +/- 18.8; quality of life [QOL]: 23.5 +/- 16.5; symptoms: 55.4 +/- 19.9) to the 24 months’ follow-up (pain: 79.5 +/- 21.1 [p < 0.001]; ADL: 84.1 +/- 21.4 [p < 0.001]; sport: 60.8 +/- 31.9 [p < 0.001]; QOL: 54.9 +/- 30.4 [p < 0.001]; symptoms: 77.7 +/- 21.2 [p < 0.001]).  The IKDC subjective score showed a similar trend and improved from 37.8 +/- 14.7 at baseline to 65.8 +/- 23.5 at 24 months (p < 0.001).  MRI showed a significant increase in defect filling over time: up to 78.7 % +/- 25.3 % of surface coverage after 24 months.  Treatment failure requiring revision surgery occurred in 8 patients (9.3 %).  The authors concluded that the use of an aragonite-based osteochondral scaffold in patients with JSLs and mild-to-moderate knee OA provided significant clinical improvement at the 24-month follow-up, as reported by the patients.  These findings were associated with good cartilage defect filling, as observed on MRI.  Moreover, these researchers stated that longer term evaluations are needed to examine the durability of the outcomes to understand whether it has the potential to delay joint replacement and be considered a disease-modifying treatment method.  Level of Evidence = IV.

These researchers stated that this study suffered from a limitation due to the absence of a matched control group.  Moreover, the small amount of histological data must be acknowledged, as only 1 full specimen was available and analyzed from a patient who underwent TKA because of the progression of OA in the patella-femoral compartment.

Boffa et al (2021) analyzed the clinical results provided by multi-layer cell-free scaffolds for the treatment of knee osteochondral defects.  These investigators carried out a systematic review on PubMed, Web of Science, and Cochrane to identify studies examining the effectiveness of cell-free osteochondral scaffolds for knee lesions.  A meta-analysis was performed on studies reporting results of the IKDC and Tegner scores.  The scores were analyzed as improvement from baseline to 1, 2, and 3 years or more follow-ups.  The modified Coleman Methodology Score was used to assess the study methodology.  A total of 34 studies (1,022 patients) with a mean follow-up of 35 months was included.  Only 3 osteochondral scaffolds have been examined in clinical trials: while TruFit has been withdrawn from the market for the questionable results, the analysis of MaioRegen and Agili-C provided clinical improvements at 1, 2, and 3 years or more of follow-up (all significantly higher than the baseline, p < 0.05), although with a limited recovery of the sport-activity level.  A low rate of AEs and an overall failure rate of 7.0 % were observed; however, the overall evidence level of the available studies was limited.  The authors concluded that multi-layer scaffolds may provide clinical benefits for the treatment of knee osteochondral lesions at short- and mid-term follow-ups and with a low number of failures, although the sport-activity level obtained appeared to be limited.  Moreover, these researchers stated that further research with high-level studies is needed to confirm the role of multi-layer scaffold for the treatment of knee osteochondral lesions.

Drobnic et al (2021) reported that the 2-year results of a multi-center clinical trial that examined surgical treatment of hallux rigidus using a novel, bi-phasic, biodegradable, and cell-free aragonite-based scaffold (Agili-C, CartiHeal Ltd, Israel).  A total of 20 patients with moderate-to-severe hallux rigidus were recruited.  After thorough metatarsophalangeal joint (MTPJ-1) debridement, the scaffolds were implanted into the defect center; 8 patients received concomitant osteotomy.  Treatment outcome was followed clinically (Pain VAS, FAAM-ADL, FAAM-Sport, AOFAS-HMIS, maximum active range of extension ROM-EXT, and flexion ROM-FLEX), and by medical imaging, at 6-month intervals for 2 years; AEs were recorded throughout the study follow-up period.  Significant clinical improvement over time was observed in all evaluated parameters (screening to final evaluation averages: Pain VAS 59 to 26, FAAM-ADL 57 to 77, FAAM-Sport 39 to 66, AOFAS-HMIS 51 to 81, ROM-EXT 18° to 36°), except for ROM-FLEX.  Radiographs showed stable MTPJ-1 width over the 2 years in 17/18 cases (94 %).  MRI demonstrated progressive implant biodegradation, coupled with articular cartilage and subchondral bone regeneration, with a repair tissue defect fill of 75 % to 100 % in 14/17 (82 %) subjects at their final visit.  Revision surgery with implant removal was carried out in 2 patients.  The authors concluded that b-phasic, osteochondral, biodegradable, aragonite-based scaffold demonstrated positive clinical outcome and a good safety profile in the treatment of medium-to-advanced hallux rigidus.  According to the medical imaging, this implant has the potential to restore the entire osteochondral unit of metatarsal head.

The authors stated that the drawbacks of this study included the non-randomized design, small sample size (n = 20), concomitant procedures could improve great toe status per se, and hallux rigidus grades from 2 to 4 were included.  As this was the 1st study on the novel bi-phasic aragonite device, the main study intention was to show safety and feasibility, which was confirmed.  Power analysis indicated that the statistical power was sufficient, despite cohort size.  Furthermore, multi-variate analysis also excluded significant effect of hallux rigidus grades or concomitant osteotomies on the final study results.

Veronesia et al (2021) noted that acute or degenerative meniscus tears are the most common knee lesions.  Meniscectomy provides symptomatic relief and functional recovery only in the short- to mid-term follow-up but significantly increases the risk of OA.  For this reason, preserving the meniscus is key, although it remains a challenge.  Allograft transplants present many disadvantages, so during the past 2 decades, pre-clinical and clinical research focused on developing and investigating meniscal scaffolds.  In a systematic review, these investigators examined available evidence on biosynthetic scaffolds for meniscus regeneration both in-vivo and in clinical studies.   A total of 3 databases were searched: 46 in-vivo pre-clinical studies and 30 clinical ones were found – 16 natural, 15 synthetic, and 15 hybrid scaffolds were studied in-vivo.  Among them, only 2 were translated into clinic: The Collagen Meniscus Implant, used in 11 studies, and the polyurethane-based scaffold Actifit, applied in 19 studies.  Although positive outcomes were described in the short- to mid-term, the number of concurrent procedures and the lack of randomized trials were the major drawbacks of the available clinical literature.  Few in-vivo studies also combined the use of cells or growth factors; however, these augmentation strategies have not been applied in the clinical practice yet.  The authors concluded that current solutions offer a significant but incomplete clinical improvement, and the regeneration potential is still unsatisfactory.  Building upon the overall positive results of these “old” technologies to address partial meniscal loss, further innovation is urgently needed in this field to provide patients better joint-sparing treatment options.


The above policy is based on the following references:


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