Midterm Outcomes of Patellofemoral Osteochondral Allograft Transplantation: A Comparison of Patellar, Trochlear, and Bipolar Grafts

Background: There are few studies reporting the midterm outcomes of osteochondral allograft (OCA) transplantation for chondral lesions in the patellofemoral joint, particularly in patients who are not receiving a high rate of concomitant realignment procedures. Purpose: To report clinical outcomes among patients undergoing OCA transplantation of the patellofemoral joint, and compare differences between patellar, trochlear, and bipolar (patellar and trochlear) grafts. Study Design: Case series; Level of evidence, 4. Methods: The authors identified 127 knees that underwent OCA transplantation in the patellofemoral compartment (51 patella, 47 trochlea, 29 bipolar patella and trochlea). A concomitant tibial tubercle osteotomy was performed in 5 knees (4%). Reoperations were documented, and OCA failure was defined as any reoperation that involved removal of the allograft. International Knee Documentation Committee (IKDC) subjective knee score, Knee injury and Osteoarthritis Outcome Score (KOOS), and satisfaction were assessed preoperatively and postoperatively with a minimum 2-year follow-up. Results: Reoperations occurred in 49 knees (39%) at a median time to first reoperation of 1.9 years, and did not differ among patellar (47%), trochlear (30%), and bipolar (38%) grafts ( P = .214). OCA failures occurred in 20 knees (16%) at a median of 4.4 years postoperatively. The failure rates for trochlear (9%), patellar (20%), and bipolar grafts (21%) did not differ ( P = .227). Graft survivorship rates at 5 and 10 years were 91% and 82%, respectively (85% and 78% for patellar grafts, 100% and 93% for trochlear grafts, and 87% and 68% for bipolar grafts ( P = .120). Among grafts in situ, the mean follow-up duration was 7.5 years (range, 2-19 years). Patients had significant improvements in IKDC and KOOS values at the latest follow-up (all P < .05), with no statistically significant differences among groups. Overall, 77% of cases reported being satisfied with the OCA transplantation (80% in the patellar group, 78% in the trochlear group, and 68% in the patellar and trochlear group; P = .555). Conclusion: Patients undergoing patellofemoral OCA transplantation exhibited high survival rates at 5 and 10 years, along with improved patient-reported outcomes when performed without concomitant tibial tubercle osteotomy. Trochlear grafts had greater survivorship than isolated patellar or bipolar grafts, and outcomes were comparable to those of OCA transplantation performed in the femoral condyles.