Is microfracture of chondral defects in the knee associated with different results in patients aged 40 years or younger?

Abstract

Age-dependent studies about the clinical result after microfracture of cartilage lesions in the knee are still missing. This prospective study was performed to discover age-dependent differences in the results after microfracture over a period of 36 months. Between 1999 and 2002, 85 patients (mean age, 39 years) with full-thickness chondral lesions underwent the microfracture procedure and were evaluated preoperatively and at 6, 18, and 36 months after surgery. Depending on the patients' age (< or =40 years or >40 years) and the localization of the defects (femoral condyles, tibia, and patellofemoral joint), the patients were assigned to 6 different groups. Exclusion criteria were meniscal pathologic conditions, tibiofemoral malalignment, and ligament instabilities. Baseline clinical scores were compared with follow-up data by use of paired Wilcoxon tests for the modified Cincinnati knee score and the International Cartilage Repair Society (ICRS) score. The scores improved in all groups over the whole study period (P < .05). Patients aged 40 years or younger had significantly better results (P < .01) for both scores compared with older patients. Between 18 and 36 months after microfracture, the ICRS score deteriorated significantly (P < .05) in patients aged over 40 years whereas younger patients with defects on the femoral condyles and on the tibia showed neither a significant improvement nor a significant deterioration in the ICRS score (P > .1). Magnetic resonance imaging 36 months after surgery revealed better defect filling and a better overall score in younger patients (P < .05). The Spearman coefficient of correlation between clinical and magnetic resonance imaging scores was 0.84. The clinical results after microfracture of full-thickness cartilage lesions in the knee are age-dependent. Deterioration begins 18 months after surgery and is significantly pronounced in patients aged older than 40 years. The best prognostic factor was found to be a patient age of 40 or younger with defects on the femoral condyles. Level IV, prognostic case series.