Evaluation of the Lateral Step-Down Test as a Clinical Assessment of Hip Musculature Strength

Abstract

Gluteal musculature weakness is associated with lower extremity injury and greater frontal plane knee motion. A method for functionally evaluating hip abduction and external rotation strength by observing knee motion would be beneficial for clinicians. This study evaluated the association between hip abductor and external rotation strength and knee motion. Peak isometric and eccentric hip abduction and external rotation strength were assessed in 47 healthy participants before analysis of knee kinematics during a lateral step-down test. The relationships between each strength measure and frontal plane knee kinematics were evaluated using bivariate Pearson correlation coefficients. Frontal plane knee displacement was not associated with hip musculature strength. Frontal plane knee angle at peak knee flexion was not associated with exter nal rotation or eccentric abduction strength. Isometric abduction strength was negatively correlated with peak knee flexion. Hip musculature strength is not indicative of the magnitude of frontal plane knee motion during the lateral step-down test, and this test is not recommended for clinical assessment of hip muscle strength.