Outcomes of Restorative Treatment for Isolated Patellar Cartilage Lesions: A Systematic Review and Meta-analysis

Background: Patellar cartilage lesions often cause debilitating symptoms, and several treatments exist. However, most review studies have combined patellar and trochlear lesions. Purpose: To assess the outcomes of different treatments of only patellar cartilage lesions. Study Design: Systematic review; Level of evidence, 4. Methods: The PubMed, Embase, and Cochrane Library databases were searched in March 2025 for clinical studies reporting outcomes of advanced cartilage treatments beyond microfracture or chondroplasty. The inclusion criteria consisted of isolated patellar lesions (no trochlear or bipolar lesions), regardless of concomitant procedures, with a minimum 1-year follow-up and at least 10 patients. Relevant outcomes were failure, reoperation, and complication rates, and patient-reported outcome measures (PROMs). Random-effect models were used, and outcomes were reported with 95% CIs. Results: A total of 36 studies (1058 patients; mean age, 32 years; follow-up, 5.1 years) were included. Most patients underwent (matrix-induced) autologous chondrocyte implantation (MACI/ACI; mean lesion, 4.3 cm 2 ), followed by osteochondral autograft transfer (OAT/mosaicplasty; mean lesion, 1.5 cm 2 ) and autologous matrix-induced chondrogenesis (AMIC; mean lesion, 2.9 cm 2 ). Most studies were level 3 or 4 evidence and published since 2010. MACI/ACI resulted in an overall failure risk of 8.8% (4.4%-14%), a Lysholm score of 72.8 (68.7-76.8), a Kujala score of 74.8 (66.9-82.8), and an International Knee Documentation Committee (IKDC) score of 65.3 (60.7-69.9). OAT/mosaicplasty resulted in an overall failure risk of 1.7% (0.4%-6.7%), a Lysholm score of 82.7(76.1-89.3), a Kujala score of 77.6 (75.3-79.8), and an IKDC score of 84.2 (65.4-103). AMIC resulted in a failure risk of 8% (3.9%-15.9%), a Lysholm score of 87.7 (85.1-90.4), a Kujala score of 78.7 (63.9-93.5), and an IKDC score of 84.3 (73.9-94.7). Sensitivity analysis of lesions <3.5 cm 2 showed equivalent failure rates among treatments, and mean IKDC scores were 84.2 (65.4-103), 67.2 (63.1-73.1), and 89.5 (84.2-94.9) after OAT/mosaicplasty, MACI/ACI, and AMIC, respectively. Conclusion: In this systematic review with meta-analysis, overall good to excellent outcomes were observed for all identified treatments, with mean estimated failure rates <10% and PROMs ranging from 70% to 85% of the maximum score. Treatment with OAT/mosaicplasty and AMIC resulted in the highest IKDC score for patients with lesions <3.5 cm 2 .