The Knee
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To determine the efficacy of autologous chondrocyte implantation (ACI) in treating focal chondral defects of the knee, we reviewed the 2-year treatment outcome of ACI in 53 patients (72 lesions) through clinical evaluation, MRI, second-look arthroscopy and biopsies obtained. Improvement in mean subjective score from preoperative (37.6) to 12 months (56.4) and 24 (60.1) months post-ACI were observed. Knee function levels also improved [86% International Cartilage Repair Society (ICRS) III/IV to 66.6% I/II] from preoperative period to 24 months postimplantation. ⋯ At 24 months, further improvements to 97%, 97%, 95.6% and 92.6%, respectively, were observed. Second-look arthroscopy carried out in 22 knees (32 lesions) demonstrated all grafts to be normal/nearly normal based on the International Cartilage Repair Society (ICRS) visual repair assessment while core biopsies from 20 lesions demonstrated 13 grafts to have hyaline/hyaline-like tissue. Improvement in clinical and MRI findings obtained from second-look arthroscopy and core biopsies evaluated indicate that, at 24 months post-ACI, the resurfaced focal chondral defects of the knee remained intact and continued to function well.