Study design: Controlled laboratory study.
Objectives: To compare hip and knee kinematics and pain during a single-limb squat between 3 movement conditions (usual, exaggerated dynamic knee valgus, corrected dynamic knee valgus) in women with patellofemoral pain.
Background: Altered kinematics (increased hip adduction, hip medial rotation, knee abduction, and knee lateral rotation, collectively termed dynamic knee valgus) have been proposed to contribute to patellofemoral pain; however, cross-sectional study designs prevent interpreting a causal link between kinematics and pain.
Methods: The study sample included 20 women with patellofemoral pain, who demonstrated observable dynamic knee valgus. Participants performed single-limb squats under usual, exaggerated, and corrected movement conditions. Pain during each condition was assessed using a 0-to-100-mm visual analog scale. Hip and knee frontal and transverse plane angles at peak knee flexion and pain levels were compared using repeated-measures 1-way analyses of variance. Pearson correlation coefficients were used to determine within-condition associations between kinematic variables and pain.
Results: In the exaggerated compared to the usual condition, increases were detected in hip medial rotation (mean ± SD difference, 5.8° ± 3.2°; P<.001), knee lateral rotation (5.5° ± 4.9°, P<.001), and pain (8.5 ± 10.8 mm, P = .007). In the corrected compared to the usual condition, decreases were detected in hip adduction (mean ± SD difference, 3.5° ± 3.7°; P = .001) and knee lateral rotation (1.6° ± 2.8°, P = .06); however, average pain was not decreased (1.2 ± 14.8 mm, P = 1.0). Pain was correlated with knee lateral rotation in the usual (r = -0.47, P = .04) and exaggerated (r = -0.49, P = .03) conditions. In the corrected condition, pain was correlated with hip medial rotation (r = 0.44, P = .05) and knee adduction (r = 0.52, P = .02).
Conclusion: Avoiding dynamic knee valgus may be an important component of rehabilitation programs in women with patellofemoral pain, as this movement pattern is associated with increased pain.