Midterm Survivorship and Clinical Outcomes in Fresh Osteochondral Allograft Transplantation for the Treatment of Large Bipolar Lesions of the Knee

Background: Fresh osteochondral allograft (OCA) transplantation is an established treatment option for patients with chondral or osteochondral lesions of the knee. Predictably positive outcomes are seen in situations of focal or isolated cartilage defects. However, OCA transplantation may also be performed in more complex joint salvage situations in young patients. Purpose: To evaluate survivorship and outcomes in patients who underwent OCA transplantation for large bipolar lesions of the knee. Study Design: Case series; Level of evidence, 4. Methods: Fresh OCAs were implanted for bipolar chondral lesions in 86 patients (89 knees) between 1983 and 2020. A total of 37 male and 52 female knees with a mean patient age of 37.9 years (range, 14.5-66.0 years) were treated. Surgical indications included degenerative chondral lesions, osteoarthritis, osteochondritis dissecans, traumatic chondral injuries, and previous failed OCAs. The clinical evaluation included the modified Merle d’Aubigné-Postel score, International Knee Documentation Committee (IKDC) score, and Knee Injury and Osteoarthritis Outcome Score (KOOS). Outcomes were collected during outpatient clinic visits or via mail. The minimum follow-up was 2 years. Additional procedures after OCA transplantation were documented. OCA failure was defined as a reoperation that involved removal of the allograft. Results: There were 81 knees (91.0%) that had undergone previous surgery, with a mean of 3.2 previous procedures (range, 1-11). The mean treated defect surface area was 16.7 cm 2 . Graft failure occurred in 31 knees (34.8%). Reoperations (including failures) occurred in 46 knees (51.7%). The mean time to failure was 4.8 years. Survivorship of the bipolar OCA was 73.8% at 5 years, 66.6% at 10 years, and 58.9% at 15 years. Among the 58 knees (65.2%) in which the OCA was still in situ, the mean follow-up was 11.3 years (range, 2.1-27.6 years). The mean modified Merle d’Aubigné-Postel score improved from 12.4 to 14.8 points; 64.3% of knees (36/56 with available data) were considered successful with a score ≥15. The mean IKDC pain score improved from 6.3 to 4.0, and the mean IKDC function score improved from 2.9 to 6.2. The KOOS symptoms, pain, activities of daily living, sports/recreation, and quality of life subscores all increased postoperatively by a mean of 19.7, 25.9, 27.1, 35.4, and 36.4, respectively. Conclusion: OCA transplantation is a salvage treatment option for large bipolar cartilage lesions of the knee with acceptable survivorship and significant clinical improvement in a challenging patient population.