Lower Extremity Strength and Mechanics During Jumping in Women With Patellofemoral Pain

Context: Lower extremity (LE) weakness might be associated with altered mechanics during weight bearing in subjects with patellofemoral Pain syndrome (PFPS). Objective: To analyze LE strength, mechanics, and the association between these variables among women with and without PFPS during a simulated athletic task. Design: Case control. Setting: Motion-analysis laboratory. Subjects: 20 women with PFPS and 20 healthy women. Main Outcome Measures: Peak isometric lateral trunk-flexion, hip-abduction, hip external-rotation, knee-flexion, and knee-extension strength, as, well as hip- and knee-joint excursions and angular impulses during single-leg jumps. Results: PFPS subjects produced less hip-abduction, hip external-rotation, and trunk lateral-flexion force than the control group. The PFPS group also demonstrated greater hip-adduction excursion and hip-abduction impulses. The association between the strength Measurements and LE mechanics was low. Conclusions: Women with PFPS demonstrate specific weaknesses and altered LE mechanics. Weakness is not, however, highly correlated with observed differences in mechanics.