Osteochondral Allograft Transplantation as a Salvage Procedure After Failed Index Cartilage Surgery of the Knee: A Systematic Review

Background: Osteochondral allograft transplantation (OCA) is well established as a viable chondral restoration procedure for the treatment of symptomatic, focal chondral defects of the knee. The efficacy of secondary OCA in the setting of failed index cartilage repair or restoration is poorly understood. Purpose: To evaluate radiographic and clinical outcomes, failures, and reoperations after OCA after failed index cartilage repair or restoration of the knee. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review was conducted in accordance with the 2020 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A literature search was conducted by querying PubMed, MEDLINE, Scopus, the Cochrane Database for Systematic Reviews, and the Cochrane Central Register for Controlled Trials databases from inception through September 2023 to identify studies reporting on outcomes of patients undergoing OCA after failed index chondral repair or restoration. Results: A total of 6 studies, entailing 349 patients, met inclusion criteria. The mean patient age was 34.6 ± 10.2 years. The mean chondral defect size at the time of secondary OCA was 5.8 cm 2 (range, 4.0-9.5 cm 2 ), and the most common defect location was the medial femoral condyle (53.6%; n = 171/319). The most common index chondral procedures were marrow stimulation (73.8%; n = 256/347 patients), OCA (11.8%; n = 41/347), and autologous chondrocyte implantation (4.9%; n = 17/347). The overall failure rate after secondary OCA was 16.6% (95% CI, 8.8%-24.4%). The overall reoperation rate was 42.8% (95% CI, 31.7%-53.9%). Failure and reoperation rates were associated with increasing chondral defect size ( P < .01). Defects 9-10 cm 2 had a reoperation rate of 67% and a failure rate of 39%. The 5-year survival rate after secondary OCA was 79% to 87.8%, and the 10-year survival rate was 61% to 82%. A total of 42 clinical outcome scores were reported, and 71.0% (n = 22/31) of patient-reported outcome measures yielded significant improvement from preoperative to postoperative levels for patients undergoing secondary OCA. Conclusion: After index chondral surgery, the overall failure rate after secondary OCA was 16.6%, with an overall reoperation rate of 42.8%. The majority of clinical outcomes reported suggest improvement when compared with preoperative values. Larger chondral defects may be associated with higher rates of failure and reoperation.