This study’s objective was to examine the association of quadriceps strength symmetry and surgical status (ACL reconstruction or nonoperative management) with early clinical knee OA 5 years after ACL injury or reconstruction.

204/300 athletes were analyzed five years after ACL injury or reconstruction (ACLR). Quadriceps strength was measured and reported as a limb symmetry index. We identified participants with early clinical knee OA using criteria that two of four Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales score ≤85% (Luyten et al. 2018). We calculated odds ratios (OR) and 95% confidence intervals (CI) using logistic regression, adjusted for age, sex, meniscal injury, and BMI, to examine the associations between quadriceps strength and surgical status with clinical knee OA. 21% of participants met the KOOS criteria for clinical knee OA (Luyten et al., 2018). For every 1% increase in quadriceps limb symmetry index, there was 4% lower odds of clinical OA (adjusted OR 0.96, 95% CI 0.93‐0.99) at five years. Surgical status was not associated with clinical knee OA (adjusted OR 0.58, 95% CI 0.23, 1.50).

In conclusion, more symmetrical quadriceps strength, but not surgical status, five years after ACL injury or reconstruction was associated with lower clinical knee OA odds.