Autologous chondrocyte implantation: prospective MRI evaluation with clinical correlation.

PURPOSE: This study was done to assess the progression of cartilage repair after autologous chondrocyte implantation (ACI) with magnetic resonance imaging (MRI) and to correlate the findings with the clinical outcome. MATERIALS AND METHODS: Forty-one patients (mean age 30 years) affected by chondral defects of the knee (27 patients) and ankle joint (14 patients) who underwent arthroscopic autologous osteochondral grafting were studied 6 months and 1 year postoperatively with MRI. Cartilage repair after chondrocyte implantation was studied by assessing the degree of defect filling, graft integration, graft signal intensity, integrity of the subchondral lamina and trabecular oedema underneath the graft. MR findings were correlated with clinical data. RESULTS: Postoperative MRI evaluation at 6 months demonstrated complete filling of the osteochondral defect in 12/41 cases, complete integration in 18/41, mild hyperintensity in 28/41, intact subchondral lamina in 38/41 and trabecular oedema in 11/41. Postoperative MRI evaluation at 1 year demonstrated complete filling of the osteochondral defect in 9/41 patients, complete integration in 22/41, mild hyperintensity in 23/41, intact subchondral lamina in 36/41 and trabecular oedema in 8/41. Filling of the osteochondral defect and incomplete integration, nonintact subchondral lamina, high signal intensity and absence of oedema were found to correlate with worse clinical-functional outcomes. CONCLUSIONS: MRI shows direct prognostic signs of the clinical outcome of ACI.