Osteochondral Allograft Transplant of the Patella Using Femoral Condylar Allografts: Letter to the Editor

Abstract

OCA) transplantations are a useful treatment for International Cartilage Repair Society (ICRS) grade 3 to 4 focal chondral defects (FCD) of the knee. Prior case series have demonstrated high success rates after this procedure. Despite having slightly inferior outcomes compared to their tibiofemoral counterpart, patellar OCA transplantations can significantly improve patientreported outcomes (PROs), with 10-and 15-year survivorships of 78.1% and 55.8%, respectively. 5,6 For this reason, patellar OCAs are becoming increasingly popular as a joint preservation option, but grafts remain more scarce than distal femoral condyle grafts.We congratulate Lin et al 10 on their recent study entitled "Osteochondral Allograft Transplant of the Patella Using Femoral Condylar Allografts: Magnetic Resonance Imaging and Clinical Outcomes at Minimum 2-Year Follow-up." In this case series, minimum 2-year follow-up PROs and minimum 6month postoperative magnetic resonance imaging (MRI) findings were assessed in 25 and 20 patients, respectively, who underwent OCA to the patella or patella and trochlea using a femoral condyle allograft (FCA). The rationale for this approach is based on the scarcity of patellar grafts compared to that of the femoral condyle. Along with this, many lateral femoral condyles are wasted because transplants in that compartment are less common. Therefore, the use of FCA for patellar OCA might improve the ability to treat patients in a timely manner. In the study, patients demonstrated significant improvements in both pain-and function-related PROs, with differences in IKDC and Knee Outcomes Survey-Activities of Daily Living scores above the previously defined minimal clinically important difference values. In addition, MRI analysis demonstrated that the mean total Osteochondral Allograft MRI Scoring System (OCAMRISS) score was 9.1 (range of 7-11), with the majority of grafts having 76%-100% cartilage fill and osseous integration. These imaging findings provide insightful and promising results on the postoperative status of the graft, perhaps even more so than PROs, which are a blunter instrument of operative success. The Lin et al article adds to the limited literature on patellar OCA transplantation and suggests short-term patient success.Although the results of this study are promising, we have some reservations for orthopaedic surgeons who are