Outcomes of Revision Cartilage Restoration Surgery for Failed Primary Treatment of Chondral or Osteochondral Defects of the Knee: A Systematic Review

Background: Failure of primary cartilage restoration procedures of the knee that proceed to necessitating revision cartilage procedures represent a challenging clinical scenario with variable outcomes reported in previous literature. Purpose: To perform a systematic review and meta-analysis of clinical outcomes and adverse events after revision cartilage restoration procedures of the knee for failed primary cartilage procedures. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: The PubMed, OVID/MEDLINE, and Cochrane databases were queried in August 2023 for trials reporting on the outcomes of revision cartilage restoration procedures of the knee. Information pertaining to rates of failure, reoperations, graft-related complications, and patient-reported outcome measures were extracted. A meta-analysis using inverse-variance proportion models using Freeman-Tukey double-arcsine transformations and DerSimonian-Laird random-effects estimators was constructed to quantitatively describe the cumulative incidence of adverse events. Results: Sixteen studies (1361 patients; mean age, 35.7 ± 9.3 years) were included. The most frequently performed revision cartilage procedure was autologous chondrocyte implantation (ACI; n = 755 [55.5%]). The overall rate of failure was 25.1% (95% CI, 14.4%-37.3%) at a mean 6.5 years (range, 2-26 years). The majority of studies (n = 9) reported a failure rate exceeding 20%. A significant reduction in failure was observed in favor of the revision osteochondral allograft cohort (19.0% [75/395] vs 35.7% [273/764]; relative risk, 0.63; P <.0001) compared with the revision ACI cohort. The pooled all-cause reoperation event rate was 40.8%, which ranged between 18.2% and 71.4% (13 studies). Of these studies, 12 reported reoperation rates exceeding 20%, and 7 reported rates exceeding 40%. The pooled graft-related complication event rate was 27.2%, which ranged between 5.4% and 56.6% (11 studies). Notably, all analyses demonstrated considerable or moderate heterogeneity, potentially influencing the observed variability in pooled effect estimates. Conclusion: One of every 4 patients may experience a secondary failure after undergoing a revision cartilage procedure. Revision using an osteochondral allograft may confer a meaningful reduction in the risk of failure relative to revision using ACI. High rates of graft-related complications and reoperations are also frequently observed in this population, highlighting the challenge of treating patients with failed primary treatment of chondral or osteochondral defects of the knee.