A larger defect size and more prior surgical procedures are negatively associated with radiological outcome 10 years after tibiofemoral matrix‐induced autologous chondrocyte implantation

Abstract Purpose To investigate factors associated with radiological graft outcome 10 years after tibiofemoral matrix‐induced autologous chondrocyte implantation (MACI). Methods This retrospective study included 96 patients that underwent MACI to the medial ( n = 72) or lateral ( n = 24) femoral condyle. All patients underwent pre‐operative review, as well as 10‐year clinical and radiological review. Regression analysis assessed the contribution of baseline demographic, injury, surgical and activity (KOOS Sport and Recreation subscale) parameters, to 10‐year graft‐related MRI outcomes including: (1) the magnetic resonance observation of cartilage repair tissue (MOCART) score and (2) tissue infill (greater or less than 50% tissue infill). Results The mean 10‐year MOCART score was 2.9 ± 0.6 (out of 4.0). For tissue infill, 53.1% ( n = 51) of patients demonstrated infill at (or beyond) the adjacent native cartilage, 83.3% ( n = 80) had greater than 50% infill compared with the native cartilage, and six patients (6.3%) demonstrated graft failure (subchondral bone exposed). The KOOS Sport and Recreation subscale improved from baseline to 10‐years by a mean 44.0 points (95% CI, 38.0–50.0; p < 0.001). In the final multivariable model, defect size ( p = 0.012) and the number of prior knee procedures ( p = 0.012) were significant predictors of graft infill. The only variable that was a significant predictor of the MOCART score was defect size ( p = 0.015). Conclusion Encouraging long‐term clinical and MRI‐based outcomes were observed after MACI. A greater number of prior procedures and a larger defect size were associated with a worse long‐term MRI‐based graft outcome. This information is important in providing realistic expectations to patients on longer‐term graft survivorship. Level of Evidence Level IV.