Ten year follow-up of a randomized trial of autologous chondrocyte implantation versus alternative forms of surgical cartilage management in the knee.

OBJECTIVE

To determine at 10 years whether ACI was superior to alternative forms of cartilage management in patients after a failed previous treatment for chondral or osteochondral defects in the knee.

METHODS

390 patients were randomly assigned to receive either ACI or alternative management. Patients aged 18-55 years with symptomatic cartilage defects who had failed one previous therapeutic surgical procedure were included. Randomization was stratified by age, defect size, defect location, chosen intended alternative treatment and baseline Lysholm knee score. The primary outcome was a patient-completed Lysholm knee score. The main secondary outcome was time to treatment failure. Analysis was performed on all available data and the intention-to-treat principle using a mixed linear model.

RESULTS

The average age was 35.4 (SD 9) years, with 64% being male. 88% of defects were femoral, and the mean defect size was 3.2 cm2 in both groups. At 10 years, 70% completed all patient Lysholm scores, however 94% provided 1 response and contributed to the analysis. The mean Lysholm score in those randomised to ACI was significantly higher (mean difference 7.3 points; 95% CI 2.5-12.1). Sensitivity analysis on the impact of further operations following treatment failure suggests a treatment effect that still favours ACI but was somewhat reduced (mean difference 3.8 points, 95%CI: -1.8-9.5). Ten-year treatment failure rates were comparable (29% and 25%, HR 1.04, 95%CI 0.69-1.6). In the ACI arm, mean scores were not affected by previous marrow stimulation, whereas in the alternative arm, mean scores were significantly worse.

INTERPRETATION: ACI results in superior knee function at 10 years follow-up compared to alternate surgical treatments. The results of ACI were not impacted by prior marrow stimulation.

REGISTRATION: International Standard Randomised Controlled Trial Number: 48911177.