Clinical Outcomes following the Microfracture Procedure for Chondral Defects of the Knee: A Longitudinal Data Analysis

The purpose of this study was to evaluate long-term outcome, following microfracture of the knee in a large patient group, using a random-effect model for longitudinal data analysis. There were 350 subjects (males, 55%; females, 65%) who underwent knee microfracture by a single surgeon between 1992 and 2002. Mean age was 48 years (range, 12-76 years). Subjective questionnaires were collected from patients at 1 year postsurgery and each consecutive year thereafter. Of treated chondral lesions, 53% were traumatic lesions, and 47% were degenerative. Average initial follow-up was 4 years (range, 1-12 years). Outcome variables included Lysholm score and Tegner activity scale. Analysis showed that Lysholm score improved during the first 2 years following microfracture. After 2 years, the score remained steady with a slight decline but remained above preoperative level through the study period. There was no significant difference in the improvement of outcome over time between men and women (P > 0.05). There was no significant difference in improvement of outcome over time between degenerative and traumatic chondral lesions (P > 0.05). Subjects with traumatic lesions demonstrated a significant difference in trajectory of Lysholm scores over time by age (≤45 years, >45 years) (P = 0.04). This study showed that there was no difference in improvement in outcome following microfracture between men and women or between degenerative and traumatic chondral lesions. However, there were age-dependent differences in the improvement in outcome over time.