Quadriceps muscle weakness after anterior cruciate ligament reconstruction: A risk factor for knee osteoarthritis?

OBJECTIVE: To identify risk factors for knee osteoarthritis (OA) 10-15 years after anterior cruciate ligament (ACL) reconstruction. We hypothesized that quadriceps muscle weakness after ACL reconstruction would be a risk factor for radiographic and symptomatic radiographic knee OA 10-15 years later. METHODS: Subjects with ACL reconstruction (n=258) were followed for 10-15 years. Subjects with unilateral injury at the 10-15-year followup were included in the present study. Outcomes included the Cincinnati knee score, knee joint laxity, hop performance, and isokinetic muscle strength tests at 6 months, 1 year, and 2 years postoperatively. At the 10-15-year followup, radiographs were taken and graded according to the Kellgren/Lawrence classification (range 0-4). RESULTS: Of the 212 subjects (82%) assessed at the 10-15-year followup, 164 subjects had unilateral injury. The mean±SD age at ACL reconstruction was 27.4±8.5 years. Increased age (odds ratio [OR] 1.06, 95% confidence interval [95% CI] 1.01-1.11) and meniscal injury and/or chondral lesion (OR 2.05, 95% CI 1.00-4.20) showed significantly higher odds for radiographic knee OA. Low self-reported knee function 2 years postoperatively (OR 0.95, 95% CI 0.92-0.98) and loss of quadriceps strength between the 2-year and the 10-15-year followup (OR 1.00, 95% CI 1.00-1.01) showed significantly higher odds for symptomatic radiographic knee OA. Quadriceps muscle weakness after ACL reconstruction was not significantly associated with knee OA. CONCLUSION: This study detected no association between quadriceps weakness after ACL reconstruction and knee OA as measured 10-15 years later.