Autologous Chondrocyte Implantation in Cartilage Lesions of the Knee

Abstract

Background Various treatment options are available for articular cartilage lesions, but controversy exists regarding the quality of the repair tissue and the durability of the results posttreatment. Noninvasive techniques are needed for the assessment of the repair tissue. Hypothesis Magnetic resonance imaging (MRI) with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) can give valuable information regarding the quality and quantity of the repaired cartilage lesion. Study Design Cohort study; Level of evidence, 3. Methods Thirty-six knees in 31 patients were assessed 9 to 18 years after treatment with autologous chondrocyte implantation (ACI). All patients had isolated lesions. The knees were clinically evaluated with the Knee injury and Osteoarthritis Outcome Score and the dGEMRIC technique. The T1 value was measured for 2 regions of interest (ROIs), 1 in the repair tissue area (ROI 1) and 1 in the surrounding cartilage (ROI 2), giving information of the content of proteoglycans. Results The average T1 value in ROI 1 was 467.5 milliseconds and in ROI 2, 495.3 milliseconds, which yielded no significant difference, thus suggesting comparable levels of proteoglycans in the repair tissue and surrounding cartilage. Intralesional osteophytes were in 64% of the lesions, mainly in younger patients with osteochondritis dissecans lesions or a history of subchondral bone surgeries. Medium or large bone marrow edema was found in 14% of the knees and subchondral cysts, in 39%. There was no correlation between the KOOS and any MRI findings. Conclusion Magnetic resonance imaging with dGEMRIC gives valuable information for the macroscopic appearance and micro-molecular quality of the repair tissue after ACI. Nine to 18 years posttreatment, the quality of the repair tissue is similar to the surrounding normal cartilage, although intralesional osteophytes, subchondral cysts, and bone marrow edema were common. The defect area is restored in most patients. However, there was no correlation between the dGEMRIC values and the KOOS outcomes.