Study design: Cross-sectional.
Objective: To determine the association between hip and ankle range-of-motion measures, as well as measures of hip muscle strength, with measures of quality of lower extremity movement, as assessed visually during the lateral step-down test in healthy women.
Background: Altered lower extremity movement pattern consisting of excessive femoral adduction and internal rotation, leading to excessive knee valgus alignment, is associated with increased risk of knee ligament injury, as well as patellofemoral pain syndrome. Previous investigations of lower extremity kinematics, using 3-dimensional motion analysis systems, document an inconsistent association between hip muscle strength and lower extremity movement pattern. Currently, it is unknown whether differences in hip muscle strength or other physical measures exist among women with differing quality of lower extremity movement as assessed by visual observation.
Methods: Two physical therapists assessed the quality of movement during the lateral step-down among 29 healthy women (mean ± SD age, 24.3 ± 3.2 years). Subjects were instructed on the optimal movement pattern prior to performing the test. The quality of movement was categorized as "good" or "moderate," based on a previously established 6-point scale. Several measures of hip strength (handheld dynamometer) and hip and ankle range of motion (fluid-filled inclinometer and universal goniometer) were also assessed. Differences in strength and range-of-motion measures between women with good and women with moderate quality of movement were assessed with a Mann-Whitney U test.
Results: Both examiners found decreased ankle dorsiflexion range of motion, as measured with the knee bent (P<.05 and P<.01 for examiner 1 and 2, respectively) and in weight bearing (P<.001 and P<.01 for examiner 1 and 2, respectively) among women with a moderate quality of movement compared to women with a good quality of movement on the lateral step-down test.
Conclusion: Following receipt of instructions on optimal lower extremity movement pattern, women who demonstrate a moderate quality of movement, as assessed visually during the lateral step-down test, exhibit decreased ankle dorsiflexion range of motion compared to women with a good quality of movement. Clinicians should consider evaluating ankle dorsiflexion range of motion when observing an altered lower extremity movement pattern during the lateral step-down test.