Analysis of Defect Size and Ratio to Condylar Size With Respect to Outcomes After Isolated Osteochondral Allograft Transplantation

Autologous Osteochondral Grafts for Knee Osteochondral Diseases Result in Good Patient-Reported Outcomes in Patients Older Than 60 Years

Purpose

This study aims to examine the clinical autologous osteochondral grafts (AOG) outcomes for knee osteochondral diseases at operative ages >60 years, and to determine whether patients are able to sit straight in Japanese style after AOG.

Methods

All patients who underwent AOG for knee osteochondral diseases between November 2001 and April 2018 were retrospectively identified. The inclusion criteria were AOG only without osteotomy, operative ages between 60 and 79 years, >2 years of follow-up, and involved femorotibial angle between 169° and 179° (normal alignment). Patients who underwent osteotomy to improve knee alignment and patients with inflammatory diseases such as rheumatoid arthritis were excluded. The patients' knee symptoms and their clinical outcome were evaluated according to the criteria of the knee scoring system of the Japanese Orthopedic Association (JOA), International Knee Documentation Committee (IKDC) subjective score, and the ability of straight sitting in Japanese style.

Results

This study enrolled 57 cases and 60 knee joints during the study period. The follow-up ratio was 85.1%. Moreover, 14 men and 43 women and 29 right and 31 left knee joints were included in this study. The mean operative age and mean follow-up period were 67.8 years (range 60-76 years) and 81.1 months (range 24-167 months), respectively. In addition, the study involved 30 cases and 32 knee joints (60s group), and 27 cases and 28 knee joints (70s group). Moreover, 34 cases and 36 knee joints had osteonecrosis (ON group), and 23 cases and 24 knee joints had cartilage injury (CI group). The IKDC subjective and JOA scores in both the 60s and 70s groups showed significant differences: 2 years after AOG ＞at the follow-up period, ＞at the preoperative period. The scores in both the CI and ON groups showed similar significant differences. Furthermore, 8.3% and 53.5% of the patients could sit straight in Japanese style at the preoperative period and 2 years after AOG, respectively.

Conclusion

Even if the patient's operative age was >60 years, the AOG only for their knee osteochondral diseases had good clinical outcomes, including the ability to sit straight in Japanese style.

Level of Evidence

IV, Therapeutic case series Key words: autologous osteochondral grafts, aged patients, clinical outcome, knee joint, straight sitting in Japanese style.

Characteristics and Clinical Outcomes After Osteochondral Allograft Transplantation for Treating Articular Cartilage Defects: Systematic Review and Single-Arm Meta-analysis of Studies From 2001 to 2020

Background

Osteochondral allograft transplantation (OCA) treats symptomatic focal cartilage defects with satisfactory clinical results.

Purpose

To comprehensively analyze the characteristics and clinical outcomes of OCA for treating articular cartilage defects.

Study Design

Systematic review; Level of evidence, 4.

Methods

We searched Embase, PubMed, Cochrane Database, and Web of Science for studies published between January 1, 2001, and December 31, 2020, on OCA for treating articular cartilage defects. Publication information, patient data, osteochondral allograft storage details, and clinical outcomes were extracted to conduct a comprehensive summative analysis.

Results

In total, 105 studies involving 5952 patients were included. The annual reported number of patients treated with OCA increased from 69 in 2001 to 1065 in 2020, peaking at 1504 cases in 2018. Most studies (90.1%) were performed in the United States. The mean age at surgery was 34.2 years, and 60.8% of patients were male and had a mean body mass index of 26.7 kg/m2. The mean lesion area was 5.05 cm2, the mean follow-up duration was 54.39 months, the mean graft size was 6.85 cm2, and the number of grafts per patient was 54.7. The failure rate after OCA was 18.8%, and 83.1% of patients reported satisfactory results. Allograft survival rates at 2, 5, 10, 15, 20, and 25 years were 94%, 87.9%, 80%, 73%, 55%, and 59.4%, respectively. OCA was mainly performed on the knee (88.9%). The most common diagnosis in the knee was osteochondritis dissecans (37.9%), and the most common defect location was the medial femoral condyle (52%). The most common concomitant procedures were high tibial osteotomy (28.4%) and meniscal allograft transplantation (24.7%). After OCA failure, 54.7% of patients underwent revision with primary total knee arthroplasty.

Conclusion

The annual reported number of patients who underwent OCA showed a significant upward trend, especially from 2016 to 2020. Patients receiving OCA were predominantly young male adults with a high body mass index. OCA was more established for knee cartilage than an injury at other sites, and its best indication was osteochondritis dissecans. This analysis demonstrated satisfactory long-term postoperative outcomes.

Isolated Osteochondral Autograft Versus Allograft Transplantation for the Treatment of Symptomatic Cartilage Lesions of the Knee: A Systematic Review and Meta-analysis

BACKGROUND

Focal cartilage lesions of the knee remain a difficult entity to treat. Current treatment options include arthroscopic debridement, microfracture, autograft or allograft osteochondral transplantation, and cell-based therapies such as autologous chondrocyte transplantation. Osteochondral transplantation techniques restore the normal topography of the condyles and provide mature hyaline cartilage in a single-stage procedure. However, clinical outcomes comparing autograft versus allograft techniques are scarce.

PURPOSE

To perform a comprehensive systematic review and meta-analysis of high-quality studies to evaluate the results of osteochondral autograft and allograft transplantation for the treatment of symptomatic cartilage defects of the knee.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 2.

METHODS

A comprehensive search of the literature was conducted using various databases. Inclusion criteria were level 1 or 2 original studies, studies with patients reporting knee cartilage injuries and chondral defects, mean follow-up ≥2 years, and studies focusing on osteochondral transplant techniques. Exclusion criteria were studies with nonknee chondral defects, studies reporting clinical outcomes of osteochondral autograft or allograft combined with other procedures, animal studies, cadaveric studies, non-English language studies, case reports, and reviews or editorials. Primary outcomes included patient-reported outcomes and failure rates associated with both techniques, and factors such as lesion size, age, sex, and the number of plugs transplanted were assessed. Metaregression using a mixed-effects model was utilized for meta-analyses.

RESULTS

The search resulted in 20 included studies with 364 cases of osteochondral autograft and 272 cases of osteochondral allograft. Mean postoperative survival was 88.2% in the osteochondral autograft cohort as compared with 87.2% in the osteochondral allograft cohort at 5.4 and 5.2 years, respectively (P = .6605). Patient-reported outcomes improved by an average of 65.1% and 81.1% after osteochondral autograft and allograft, respectively (P = .0001). However, meta-analysis revealed no significant difference in patient-reported outcome percentage change between osteochondral autograft and allograft (P = .97) and a coefficient of 0.033 (95% CI, -1.91 to 1.98). Meta-analysis of the relative risk of graft failure after osteochondral autograft versus allograft showed no significant differences (P = .66) and a coefficient of 0.114 (95% CI, -0.46 to 0.69). Furthermore, the regression did not find other predictors (mean age, percentage of female patients, lesion size, number of plugs/grafts used, and treatment location) that may have significantly affected patient-reported outcome percentage change or postoperative failure between osteochondral autograft versus allograft.

CONCLUSION

Osteochondral autograft and allograft result in favorable patient-reported outcomes and graft survival rates at medium-term follow-up. While predictors for outcomes such as mean age, percentage of female patients, lesion size, number of plugs/grafts used, and treatment location did not affect the comparison of the 2 cohorts, proper patient selection for either procedure remains paramount to the success and potentially long-term viability of the graft.

Revision Lateral Femoral Condyle Osteochondral Allograft Transplantation With the Snowman Technique After Failed Previous Oblong Osteochondral Allograft

Osteochondral allograft transplantation provides components of both cartilage and subchondral bone and can be used in large and multifocal defects where autologous procedures are limited by donor-site morbidity. Osteochondral allograft transplantation is particularly appealing in the management of failed cartilage repair, as larger defects and subchondral bone involvement are often present, and the use of multiple overlapping plugs might be considered. The described technique provides our preoperative workup and reproducible surgical approach for patients who have undergone previous osteochondral transplantation with graft failure and are young, active patients who would not be otherwise suited for a knee arthroplasty procedure.

Variability in the Processing of Fresh Osteochondral Allografts

The indications for fresh osteochondral allograft continue to increase. As a result, variations in graft processing and preservation methods have emerged. An understanding of these techniques is important when evaluating the optimal protocol for processing fresh osteochondral allografts prior to surgical implantation. The aim of this study is to review the literature and understand various tissue processing protocols of four leading tissue banks in the United States. Donor procurement, serological and microbiological testing, and storage procedures were compared among companies of interest. Similarities between the major tissue banks include donor screening, aseptic processing, and testing for microorganisms. Variability exists between these companies with relation to choice of storage media, antibiotic usage, storage temperature, and graft expiration dates. Potential exists for increased chondrocyte viability and lengthened time-to-expiration of the graft through a protocol of delicate tissue handling, proper choice of storage medium, adding hormones and growth factors like insulin growth factor-1 (IGF-1) to serum-free nutrient media, and storing these grafts closer to physiologic temperatures.

Inconsistent Reporting of Preauthorization Medical Criteria for Osteochondral Allograft Transplantation Surgery

BACKGROUND

Although osteochondral allograft (OCA) transplantation has been a standard treatment for patients with osteochondral lesions, there is a disagreement in commercial payers' medical criteria regarding the definition of medical suitability and thus authorization for OCA transplantation. The primary goal of this study was to understand where consensus between a committee of experienced cartilage restoration surgeon scientists and payer policies existed and where there was significant disagreement.

METHODS

U.S. private payers were identified by reviewing health insurance market research literature. Medical criteria were then obtained from publicly available payer medical polices. A literature review was conducted to identify supporting evidence for consensus statements based on private payer medical criteria. The MOCA (Metrics of Osteochondral Allograft) Committee, 30 experienced surgeons and subject-matter experts in OCA transplantation, used a Likert scale of 1 (strongly disagree) to 5 (strongly agree) to rank each statement. The extent of agreement and disagreement among participants was measured for each statement. Consensus was defined as agreement or disagreement of >75%.

RESULTS

Fifty-seven statements regarding relevant medical criteria for OCA transplantation were included in the survey. All 30 MOCA Committee members completed the survey (100% response rate). Over half of the statements (52.6%) did not reach consensus. Of the remaining 27 statements that reached consensus, respondents agreed or strongly agreed with 16 statements, and disagreed or strongly disagreed with 11 statements. Inconsistent voting was observed for statements related to osteoarthritis, inflammation, and degenerative changes.

CONCLUSIONS

Commercial payers are not consistent in the medical criteria used to define patient eligibility for authorization of OCA transplantation. In contrast, an expert panel of cartilage surgeons reached a consensus that OCA transplantation was clearly suitable for a variety of specific indications. This study demonstrates the need to standardize medical criteria for cartilage restoration based on the most current literature, as well as in conjunction with experienced cartilage restoration experts.

LEVEL OF EVIDENCE

Therapeutic Level V . See Instructions for Authors for a complete description of levels of evidence.

Males and Females Exhibit Comparable Outcomes Following Treatment of Osteochondritis Dissecans Lesions of the Knee: A Systematic Review

PURPOSE

The purpose of this study was to evaluate the impact of patient sex on outcomes after treatment of osteochondritis dissecans (OCD) lesions of the knee through a systematic review of current evidence.

METHODS

This review was conducted according to the PRISMA guidelines using the PubMed, PubMed Central, Embase, Ovid Medline, Cochrane Libraries, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases. Relevant outcomes included functional (e.g., International Knee Documentation Committee and Subjective Knee Evaluation, Lysholm Knee Score) and clinical outcomes (e.g., symptom/pain resolution, reoperation rates) for males and females after operative or nonoperative treatment of knee OCD lesions.

RESULTS

Ten articles with a total of 691 (73%) males and 260 (27%) females were included. Mean age ranged from 11.3 ± 2.1 years to 34.5 ± 10.3 years, and follow-up ranged from 6 months to 16.3 years. In four studies reporting functional outcomes, no significant differences were found between males and females in any metric assessed (all P > .05). Seven studies reported clinical outcomes after treatment of knee OCD lesions. One study determined males were more likely to have a successful nonoperative outcome than females (OR: 1.85, 95% CI: 1.00-3.40). Another study found males had a lower risk of developing symptomatic knee pain following operative or nonoperative treatment at a mean 14-year follow-up (HR: 0.24; 95% CI: 0.07-0.81). The remaining 5 studies reported statistically comparable clinical outcomes between males and females (all P > .05).

CONCLUSION

The present systematic review found mostly comparable clinical and functional outcomes between males and females following treatment of knee OCD lesions. Despite sex-related differences in the prevalence of these lesions and limited evidence of differences in clinical outcomes, these data suggest that sex does not independently predict outcomes after treatment.

LEVEL OF EVIDENCE

III, systematic review of Level II and III studies.

A method for labelling lesions for machine learning and some new observations on osteochondrosis in computed tomographic scans of four pig joints

Background

Osteochondrosis is a major cause of leg weakness in pigs. Selection against osteochondrosis is currently based on manual scoring of computed tomographic (CT) scans for the presence of osteochondrosis manifesta lesions. It would be advantageous if osteochondrosis could be diagnosed automatically, through artificial intelligence methods using machine learning. The aim of this study was to describe a method for labelling articular osteochondrosis lesions in CT scans of four pig joints to guide development of future machine learning algorithms, and to report new observations made during the labelling process. The shoulder, elbow, stifle and hock joints were evaluated in CT scans of 201 pigs.

Results

Six thousand two hundred fifty osteochondrosis manifesta and cyst-like lesions were labelled in 201 pigs representing a total volume of 211,721.83 mm³. The per-joint prevalence of osteochondrosis ranged from 64.7% in the hock to 100% in the stifle joint. The lowest number of lesions was found in the hock joint at 208 lesions, and the highest number of lesions was found in the stifle joint at 4306 lesions. The mean volume per lesion ranged from 26.21 mm³ in the shoulder to 42.06 mm³ in the elbow joint. Pigs with the highest number of lesions had small lesions, whereas pigs with few lesions frequently had large lesions, that have the potential to become clinically significant. In the stifle joint, lesion number had a moderate negative correlation with mean lesion volume at r = − 0.54, p < 0.001.

Conclusions

The described labelling method is an important step towards developing a machine learning algorithm that will enable automated diagnosis of osteochondrosis manifesta and cyst-like lesions. Both lesion number and volume should be considered during breeding selection. The apparent inverse relationship between lesion number and volume warrants further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03426-x.

Association of Sex Mismatch Between Donor and Recipient With Graft Survivorship at 5 Years After Osteochondral Allograft Transplantation

BACKGROUND

Sex mismatch between donor and recipient has been considered a potential contributor to adverse outcomes after solid organ transplantation. However, the influence of sex mismatching in osteochondral allograft (OCA) transplantation has yet to be determined.

PURPOSE

To evaluate whether donor-recipient sex mismatching affects graft survival after OCA transplantation.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In this review of prospectively collected data, patients who underwent OCA transplantation between November 2013 and November 2017 by a single surgeon were analyzed. Cumulative survival was assessed via the Kaplan-Meier method using log-rank tests to compare patients with similar donor groups. Multivariable Cox regression analysis adjusted for patient age, graft size, and body mass index was used to evaluate the influence of donor-recipient sex on graft survival.

RESULTS

A total of 154 patients were included: 102 (66.2%) who received OCAs from a same-sex donor and 52 (33.8%) who received OCAs from a different-sex donor. At 5-year follow-up, a significantly lower graft survival rate was observed for different-sex donor transplantation in comparison with same-sex donorship (63% vs 92%; P = .01). When correcting for age, graft size, and body mass index, donor-recipient sex-mismatch transplantation demonstrated a 2.9-times greater likelihood to fail at 5 years compared with donor-recipient same-sex transplantation (95% CI, 1.11-7.44; P = .03). A subgroup analysis showed no significant difference in graft survival between the female-to-female and female-to-male groups (91% and 84%, respectively). Conversely, male-to-male transplantation demonstrated a significantly higher cumulative 5-year survival (94%; P = .04), whereas lower survival was found with male-to-female donorship (64%; P = .04). Multivariable Cox regression indicated a 2.6-times higher likelihood of failure for the male-to-female group in comparison with the other groups (95% CI, 1.03-6.69; P = .04). Male-to-male transplantation had a tendency toward decreased likelihood of OCA failure (hazard ratio, 0.33), although without statistical significance (95% CI, 0.11-1.01; P = .052).

CONCLUSION

Mismatch between donor and recipient sex had a negative effect on OCA survival after transplantation, particularly in those cases when male donor tissue was transplanted into a female recipient.

Osteochondral Allograft for Unsalvageable Osteochondritis Dissecans in the Skeletally Immature Knee

Background:

While an excellent option for osteochondral defects in the adult knee, fresh osteochondral allograft (FOCA) in the skeletally immature adolescent knee has been infrequently studied.

Purpose:

To compare radiographic and patient-reported outcomes (PROs) in skeletally mature and immature adolescents after FOCA in the knee for treatment of unsalvageable osteochondritis dissecans (OCD).

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were 34 patients (37 knees) who underwent size-matched FOCA of the knee for unsalvageable OCD lesions. All patients were aged ≤19 years and had a minimum of 12 months of follow-up. Patient characteristics, lesion characteristics, reoperations, and PROs were evaluated and compared between patients with open physes (skeletally immature; n = 20) and those with closed physes (skeletally mature; n = 17). Graft failure was defined as the need for revision osteochondral grafting. Postoperative radiographs were analyzed at 1 year and the final follow-up for graft incorporation and classified as A (complete), B (≥50% healed), or C (<50% healed).

Results:

The mean patient age was 15.4 years (range, 9.6-17.6 years), and the mean follow-up was 2.1 years (range, 1-5.3 years). The mean graft size was 5.0 cm² and did not differ significantly between the study groups. Patients with open physes were younger (14.7 vs 16.2 years; P = .002) and more commonly male (80% vs 35%; P = .008). At the 1-year follow-up, 85% of immature patients and 82% of mature patients had radiographic healing grades of A or B. Patients with open physes were more likely to achieve complete radiographic union at 1 year (65% vs 15%; P = .007) and demonstrated better Knee injury and Osteoarthritis Outcome Score (KOOS) Daily Living (96.8 vs 88.5; P = .04) and KOOS Quality of Life (87.0 vs 56.8; P = .01) at the final follow-up. Complications were no different in either group, and graft failure occurred in only 1 skeletally mature patient with a trochlear lesion.

Conclusion:

FOCA treatment for unsalvageable OCD in the young knee may be expected to yield excellent early results. Despite the presence of open physes and immature epiphyseal osteochondral anatomy, equivalent or improved healing and PRO scores compared with those of skeletally mature patients may be expected.

Differences in Clinical and Functional Outcomes Between Osteochondral Allograft Transplantation and Autologous Chondrocyte Implantation for the Treatment of Focal Articular Cartilage Defects

Background:

Articular cartilage pathology can result from a spectrum of origins, including trauma, osteochondritis dissecans, avascular necrosis, or degenerative joint disease.

Purpose:

To compare the differences in clinical and patient-reported outcomes after autologous chondrocyte implantation (ACI) versus osteochondral allograft transplantation (OCA) in patients with focal articular cartilage defects without underlying bone loss.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A retrospective review identified patients who underwent ACI or OCA between 2008 and 2016 for isolated grades 3 and 4 articular cartilage defects without underlying bone loss. Outcome measures included the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), International Knee Documentation Committee (IKDC) evaluation, and 12-Item Short Form Health Survey–Physical Component (SF-12-P) scores. Defect location, size, complications, and rate of subsequent surgery were determined.

Results:

Overall, 148 patients were included: 82 (55%) underwent ACI and 66 (45%) underwent OCA. The mean age at the time of surgery was 31.2 years within the ACI cohort and 37.7 years within the OCA cohort (P < .001); the mean follow-up for both cohorts was 6.7 years (P = .902). Within the ACI group, 28 (34%) patients had multifocal defects, 21 (26%) had defects confined to the femoral condyles, and 33 (40%) had defects in the patellofemoral region. Within the OCA group, 23 (35%) patients had multifocal defects, 30 (46%) had confined femoral condyle lesions, and 13 (20%) had patellofemoral defects. When comparing by lesion location, there were no significant differences in KOOS JR, and IKDC scores between the ACI and OCA cohorts (P < .05). There was, however, a significant difference for SF-12-P scores for FDD trochlear lesions. In both cohorts, traumatic patellofemoral pathology demonstrated lower patient-reported outcomes and higher failure rates than degenerative lesions. The overall rate of failure, defined as graft failure with revision surgery and/or conversion to arthroplasty, was significantly greater in the OCA group (21% vs 4%; P = .002).

Conclusion:

Study results indicated that ACI provides similar outcomes to OCA with or without concomitant procedures for the treatment of symptomatic articular cartilage defects in all lesion locations and may have a lower revision rate for multifocal and condylar lesions.

Risk Factors for Failure After Osteochondral Allograft Transplantation of the Knee: A Systematic Review and Exploratory Meta-analysis

BACKGROUND

Graft failure after osteochondral allograft transplantation (OCA) of the knee is a devastating outcome, often necessitating subsequent interventions. A comprehensive understanding of the risk factors for failure after OCA of the knee may provide enhanced prognostic data for the knee surgeon and facilitate more informed shared decision-making discussions before surgery.

PURPOSE

To perform a systematic review and meta-analysis of risk factors associated with graft failure after OCA of the knee.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

The PubMed, Ovid/MEDLINE, and Cochrane databases were queried in April 2021. Data pertaining to study characteristics and risk factors associated with failure after OCA were recorded. DerSimonian-Laird binary random-effects models were constructed to quantitatively evaluate the association between risk factors and graft failure by generating effect estimates in the form of odds ratios (ORs) with 95% CIs, while mean differences (MDs) were calculated for continuous data. Qualitative analysis was performed to describe risk factors that were variably reported.

RESULTS

A total of 16 studies consisting of 1401 patients were included. The overall pooled prevalence of failure was 18.9% (range, 10%-46%). There were 44 risk factors identified, of which 9 were explored quantitatively. There was strong evidence to support that the presence of bipolar chondral defects (OR, 4.20 [95% CI, 1.17-15.08]; P = .028) and male sex (OR, 2.04 [95% CI, 1.17-3.55]; P = .012) were significant risk factors for failure after OCA. Older age (MD, 5.06 years [95% CI, 1.44-8.70]; P = .006) and greater body mass index (MD, 1.75 kg/m² [95% CI, 0.48-3.03]; P = .007) at the time of surgery were also significant risk factors for failure after OCA. There was no statistically significant evidence to incontrovertibly support that concomitant procedures, chondral defect size, and defect location were associated with an increased risk of failure after OCA.

CONCLUSION

Bipolar chondral defects, male sex, older age, and greater body mass index were significantly associated with an increased failure rate after OCA of the knee. No statistically significant evidence presently exists to support that chondral defect size and location or concomitant procedures are associated with an increased graft failure rate after OCA of the knee. Additional studies are needed to evaluate these associations.

Bone Marrow Lesions on Preoperative Magnetic Resonance Imaging Correlate With Outcomes Following Isolated Osteochondral Allograft Transplantation

PURPOSE

The purpose of this study was to investigate the role of preoperative bone marrow lesion (BML) size and location on (1) postoperative patient reported outcomes and (2) postoperative failure and time to failure after osteochondral allograft (OCA) transplantation.

METHODS

Consecutive patients from 2 senior surgeons who underwent isolated OCA transplantation to the knee from 2009-2018 were identified for the case series. Preoperative magnetic resonance imaging (MRI) was evaluated for BMLs based on 2 classification systems (Welsch et al. and Costa-Paz et al.) by 2 independent graders. BMLs associated with minimum 1-year postoperative outcomes were evaluated, and the effect of BML classification on survivorship was investigated with Kaplan-Meier curves.

RESULTS

The 77 patients who underwent isolated OCA transplantation (mean follow-up: 39.46 ± 22.67 months) and had preoperative MRIs were included. Within this cohort, 82% of patients demonstrated a BML. The preoperative Costa-Paz et al. classification was significantly positively correlated with the postoperative Visual Analog Scale, International Knee Documentation Committee and Veterans RAND 12-Item Health Survey raw scores for both graders (P < 0.05). Failure occurred in 5 of 65 (8%) patients at a mean of 22.86 ± 12.04 months postoperatively. The presence of BML alone did not significantly affect survival (P = 0.780). However, for 1 grader, the Welsch et al. classification was associated with increased risk of graft failure (P = 0.031).

CONCLUSION

Preoperative subchondral BMLs were present in 82% of patients undergoing OCA transplantation. We found that more severe BMLs based on the Costa-Paz classification, with increasing involvement in the juxta-articular surface, were correlated with higher postoperative patient-reported functional outcomes after OCA. BMLs may be associated with an increase in graft failure, but their role in this remains unclear.

LEVEL OF EVIDENCE

IV, Retrospective Case Series.

Effect of Preoperative Imaging and Patient Factors on Clinically Meaningful Outcomes and Quality of Life After Osteochondral Allograft Transplantation: A Machine Learning Analysis of Cartilage Defects of the Knee

BACKGROUND

Fresh osteochondral allograft transplantation (OCA) is an effective method of treating symptomatic cartilage defects of the knee. This restoration technique involves the single-stage implantation of viable, mature hyaline cartilage into a chondral or osteochondral lesion. The extent to which preoperative imaging and patient factors predict achieving clinically meaningful outcomes among patients undergoing OCA for cartilage lesions of the knee remains unknown.

PURPOSE

To determine the predictive relationship of preoperative imaging, preoperative patient-reported outcome measures (PROMs), and patient demographics with achievement of the minimal clinically important difference (MCID) and substantial clinical benefit (SCB) for functional and quality-of-life PROMs at 2 years after OCA for symptomatic cartilage defects of the knee.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were analyzed for patients who underwent OCA before May 1, 2018, by 2 high-volume fellowship-trained cartilage surgeons. The International Knee Documentation Committee (IKDC) subjective form, Knee Outcome Survey-Activities of Daily Living (KOS-ADL), and mental and physical component summaries of the SF-36 were administered preoperatively and at 2 years postoperatively. A total of 42 predictive models were created using 7 unique architectures to detect achievement of the MCID for each of the 4 outcome measures and the SCB for the IKDC and KOS-ADL. Data inputted into the models included sex, age, body mass index, baseline PROMs, lesion size, concomitant ligamentous or meniscal tear, and presence of "bone bruise" or osseous edema. Shapley additive explanations plot analysis identified predictors of reaching the MCID and SCB.

RESULTS

Of the 185 patients who underwent OCA for the knee and met eligibility criteria from an institutional cartilage registry, 153 (83%) had 2-year follow-up. Preoperative magnetic resonance imaging (MRI), baseline PROMs, and patient demographics best predicted reaching the 2-year MCID and SCB of the IKDC and KOS-ADL PROMs, with areas under the receiver operating characteristic curve of the top-performing models ranging from good (0.88) to excellent (0.91). MRI faired poorly (areas under the curve, 0.60-0.68) in predicting the MCID for the mental and physical component summaries. Higher body mass index, knee malalignment, absence of preoperative osseous edema, concomitant anterior cruciate ligament or meniscal injury, larger defect size, and the implantation of >1 OCA graft were consistent findings contributing to failure to achieve the MCID or SCB at 2 years postoperatively.

CONCLUSION

Our machine learning models demonstrated that preoperative MRI, baseline PROMs, and patient demographics reliably predict the ability to reach clinically meaningful thresholds for functional knee outcomes 2 years after OCA for cartilage defects. Although clinical improvement in knee function can be reliably predicted, improvements in quality of life after OCA depend on a comprehensive preoperative assessment of the patient's perception of his or her mental and physical health. Absence of osseous edema, concomitant anterior cruciate ligament or meniscal injury, larger lesion size on MRI, knee malalignment, and elevated body mass index are predictive of failure to achieve 2-year functional benefits after OCA of the knee.

Association Between Preoperative Mental Health and Clinically Meaningful Outcomes After Osteochondral Allograft for Cartilage Defects of the Knee: A Machine Learning Analysis

BACKGROUND

Fresh osteochondral allograft transplantation (OCA) is an effective method of treating symptomatic cartilage defects of the knee. This cartilage restoration technique involves the single-stage implantation of viable, mature hyaline cartilage into the chondral or osteochondral lesion. Predictive models for reaching the clinically meaningful outcome among patients undergoing OCA for cartilage lesions of the knee remain under investigation.

PURPOSE

To apply machine learning to determine which preoperative variables are predictive for achieving the minimal clinically important difference (MCID) and substantial clinical benefit (SCB) at 1 and 2 years after OCA for cartilage lesions of the knee.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were analyzed for patients who underwent OCA of the knee by 2 high-volume fellowship-trained cartilage surgeons before May 1, 2018. The International Knee Documentation Committee questionnaire (IKDC), Knee Outcome Survey-Activities of Daily Living (KOS-ADL), and Mental Component (MCS) and Physical Component (PCS) Summaries of the 36-Item Short Form Health Survey (SF-36) were administered preoperatively and at 1 and 2 years postoperatively. A total of 84 predictive models were created using 7 unique architectures to detect achievement of the MCID for each of the 4 outcome measures and the SCB for the IKDC and KOS-ADL at both time points. Data inputted into the models included previous and concomitant surgical history, laterality, sex, age, body mass index (BMI), intraoperative findings, and patient-reported outcome measures (PROMs). Shapley Additive Explanations (SHAP) analysis identified predictors of reaching the MCID and SCB.

RESULTS

Of the 185 patients who underwent OCA for the knee and met eligibility criteria from an institutional cartilage registry, 135 (73%) patients were available for the 1-year follow-up and 153 (83%) patients for the 2-year follow-up. In predicting outcomes after OCA in terms of the IKDC, KOS-ADL, MCS, and PCS at 1 and 2 years, areas under the receiver operating characteristic curve (AUCs) of the top-performing models ranged from fair (0.72) to excellent (0.94). Lower baseline mental health (MCS), higher baseline physical health (PCS) and knee function scores (KOS-ADL, IKDC Subjective), lower baseline activity demand (Marx, Cincinnati sports), worse pain symptoms (Cincinnati pain, SF-36 pain), and higher BMI were thematic predictors contributing to failure to achieve the MCID or SCB at 1 and 2 years postoperatively.

CONCLUSION

Our machine learning models were effective in predicting outcomes and elucidating the relationships between baseline factors contributing to achieving the MCID for OCA of the knee. Patients who preoperatively report poor mental health, catastrophize pain symptoms, compensate with higher physical health and knee function, and exhibit lower activity demands are at risk for failing to reach clinically meaningful outcomes after OCA of the knee.

Shorter Storage Time Is Strongly Associated With Improved Graft Survivorship at 5 Years After Osteochondral Allograft Transplantation

BACKGROUND

Current regulations surrounding the use of osteochondral allografts (OCAs) in the United States require delayed graft release after 14 days to complete infectious disease screening. With a generally accepted expiration time of 28 days in storage, a limited window from 14 to 28 days remains for implantation. Yet, the rates of graft survival and thus optimal time for transplantation within this window remain largely unknown.

HYPOTHESIS

OCAs transplanted within 19 to 24 days would have lower failure rates at 5 years than those transplanted at 25 to 27 days.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In this retrospective case series, we analyzed data from patients who underwent OCA transplantation (N = 111) by a single surgeon between February 2014 and December 2016 with at least 2-year follow-up. In total, 56 patients received early transplant grafts (storage time, 19-24 days), and 55 received late transplant grafts (storage time, 25-27 days). Survival analysis with Kaplan-Meier curves was performed using log-rank analysis to compare the groups. Multivariable Cox regression analysis was used to assess the influence of OCA storage duration on graft survival while adjusting for age and defect size. Optimal storage time cutoff associated with graft failure was identified by performing receiver operating characteristic curve analysis and calculating the area under the curve.

RESULTS

Patients in the late transplant group had a significantly lower rate of graft survival at 5 years postoperatively (70.4%) as compared with patients in the early transplant group (93.1%; P = .027). When correcting for patient age and defect size, late transplant OCAs demonstrated a 3.4-times greater likelihood of failure versus early transplant OCAs. Receiver operating characteristic analysis suggested that OCA transplantation should ideally occur before 25 days of graft storage.

CONCLUSION

OCA transplantation is a safe and successful treatment option for large osteochondral defects of the knee, with excellent rates of in situ graft survival at 5 years. Prioritizing early transplantation of OCAs to <25 days in storage improves rates of graft survival.