Patellar Osteochondral Allograft Transplantation Yields Clinically Meaningful Improvement in 2-Year Patient-Reported Outcomes.

PURPOSE: To assess the outcomes of patellar osteochondral allograft (OCA) transplantation and access the effect of preoperative indications and patient characteristics on outcomes.

METHODS

Primary patellar OCA transplantation cases were retrospectively identified from a single surgeon from August 2017 and August 2021, all using grafts preserved with the Missouri Osteochondral Allograft Preservation technique. Patients with less than 2 years of follow-up were excluded. Variables collected included demographics, previous surgical and concomitant procedures, primary pathology and indications, graft size and location, range of motion, Magnetic Resonance Observation of Cartilage Repair Tissue 2.0 scores, patient-reported outcome measures, and reoperations. Primary pathology and unipolar versus bipolar grafting subgroups were analyzed. Preoperative and postoperative comparison was analyzed via paired sample t tests. Subgroups were compared using independent t tests for nonpaired continuous variables, with χ2 and Fisher exact tests used for categorical data. Statistical significance was set at P < .05.

RESULTS

Twenty-eight cases (16 unipolar patellar OCA transplantation, 12 bipolar transplantation) met both inclusion and exclusion criteria, with a mean age of 31.0 ± 10.3 years, a mean body mass index of 30.0 ± 5.6, and a mean follow-up of 3.6 ± 1.4 years (range 2.3-5.8 years). Eighteen knees presented with lateral patellar instability, 9 with patellofemoral (PF) chondrosis, and 1 with juvenile osteochondritis dissecans. Three knees (10.7%) in total were converted to total knee arthroplasty, all of which occurred in the setting of PF chondrosis. OCA transplantation improved International Knee Documentation Committee (IKDC; 36.6-71.9; P < .001), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (49.8-77.5; P = .001), Short-Form 12 Physical Health Survey (33.5-45.3; P = .002), and Veterans RAND 12 Physical Health Survey (34.5-49.6; P < .001) scores at 2-years. The IKDC, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Short-Form 12 Physical Health Survey, and Veterans RAND 12 Physical Health Survey thresholds (0-100) and percentages for achieving minimal clinically important difference were 18.75 (70.6%), 18.76 (73.5%), 11.90 (73.5%), and 13.56 (61.8%), respectively. Age and body mass index had strong negative correlations with IKDC scores in knees with PF chondrosis (r = -0.903; P < .01 and r = -0.875; P = .010 respectively). Bipolar transplantation for "kissing" lesions had larger improvements in IKDC scores than unipolar cases (+54.6 vs +24.1; P = .007).

CONCLUSIONS

Patellar OCA transplantation resulted in overall improvement in PROs with an 11% rate of conversion to total knee arthroplasty at 2-years follow-up.

LEVEL OF EVIDENCE: Level IV, therapeutic retrospective case series.