Etiologic factors associated with anterior knee pain in distance runners

Purpose: The objectives of this study were 1) to examine the differences between a noninjured (C) cohort of runners (N = 70) and runners afflicted with anterior knee pain (AKP) according to selected training, anthropometric, rearfoot motion, ground reaction force, and muscular strength and endurance variables; 2) to explore multivariate relationships among these measures in the well and injured groups; and 3) to develop specific hypotheses concerning risk factors for injury that will later be tested in a prospective clinical study. Methods: High speed videography (200 frames s(-1)), a force platform (500Hz). and a Cybex II+ isokinetic dynamometer were used to assess rearfoot motion, ground reaction forces, and knee muscular strength and endurance, respectively. A linear discriminant function was performed on each of the five categories of variables and revealed 19 significant (P less than or equal to 0.05) predictors. These variables were then combined and a final discriminant function analysis was performed. Results: Pronation through the first 10% of stance, arch index, shoe mileage, and extension peak torque were the best overall (P less than or equal to 0.05) predictors. The AKP group had smaller mean values on all four significant predictors. Conclusion: With the exception of shoe mileage, which is likely a response to rather than a risk factor for AKP, these results should prove useful to clinicians in identifying runners at risk for anterior knee pain.