Sage Publications for the American Orthopaedic Society for Sports Medicine
The American Journal of Sports Medicine vol:37 issue:suppl 1 pages:42S-49S
BACKGROUND: Characterized chondrocyte implantation results in superior structural repair compared with microfracture, but may be associated with a slower recovery of physical activity levels due to the arthrotomy. HYPOTHESES: Our hypotheses were that (1) microfracture results in increased activity levels over 2 years after surgery compared with characterized chondrocyte implantation, (2) patients with high preinjury activity levels have a better functional outcome, and (3) high levels of low-load activities after surgery improve functional outcome. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Sixty-seven patients with local cartilage defects (mean size, 2.4 cm(2); standard deviation, 1.5 cm(2)) of the femoral condyle underwent characterized chondrocyte implantation (n = 33) or microfracture (n = 34), followed by an identical rehabilitation protocol. Activity levels (assessed using the Activity Rating Scale) and functional outcome were determined at baseline, and 1 and 2 years after surgery. Functional outcome was based on the pooled symmetry index (derived from isokinetic knee extension strength and 3 one-legged hop tests). Patients' participation in low-load activities during the first 3 months after surgery was assessed using rehabilitation data. Mixed linear model analyses and Wilcoxon rank sum tests were used. RESULTS: Activity levels in patients treated with characterized chondrocyte implantation and microfracture were comparable at 1 and 2 years after surgery. Preinjury activity levels showed no relationship to functional outcome. Lack of postoperative low-load activities resulted in a significantly worse functional outcome (mean pooled symmetry index 78.2%) compared with high levels of postoperative surgery low-load activities (mean pooled symmetry index 92.4%). CONCLUSION: Despite differences between the characterized chondrocyte implantation and microfracture procedures, patients' activity levels were comparable at 2 years after surgery. Lack of low-load activities after surgery adversely affected functional outcome.