Clinical and Radiographic Outcomes After Treatment of Patellar Chondral Defects: A Systematic Review

Context: There is currently no evidence-based consensus on how to treat a full-thickness, symptomatic articular cartilage injury of the patella, although numerous treatment options are available. Objective: To systematically evaluate the functional outcomes after operative treatment of patellar cartilage lesions. Our secondary purpose was to evaluate radiographic outcomes after treatment. Data Sources: PubMed, Cochrane, and Embase Study Selection: Studies published between January 1, 1990 and December 31, 2018 that included patient-reported functional outcomes for patients after operative treatment of patellar chondral defects at a minimum 2-year follow-up were included. Study Design: Systematic review. Level of Evidence: Level 4. Data Extraction: MINORS (Methodological Index for Non-Randomized Studies) score, level of evidence, sample size, demographic data, follow-up data, intervention, functional outcome scores, and magnetic resonance imaging (MRI) data were collected. Results: The review identified 10 studies and 293 patients receiving cartilage restoration procedures for patellar chondral defects with extractable clinical and radiographic results and data on complications and reoperations. All treatments (autologous chondrocyte implantation [ACI], matrix-induced ACI [MACI], autologous osteochondral transplantation [AOT]) utilized in the management of patellar chondral lesions, with the exception of isolated particulated juvenile articular cartilage, demonstrated statistically significant improvements in functional outcome scores compared with preoperative measurements at a minimum of 2-year follow-up. Postoperative MRIs were obtained in 6 studies and found that regardless of treatment, moderate-to-complete infill of patellar cartilage lesions was seen in the majority of patients. While failure rates were low for the various treatment modalities, rates of reoperation were substantial, with up to 40% to 60% reoperation rate seen after ACI. Conclusion: Patients treated with ACI, MACI, and AOT all demonstrated statistically significant improvements in functional outcome scores with radiographic evidence of healing at minimum of 2-year follow-up. Evidence is insufficient to recommend one particular treatment over another.