Asymmetry in Muscle Strength, Dynamic Balance, and Range of Motion in Adult Symptomatic Hip Dysplasia

Abstract

Hip dysplasia (HD) is a typical developmental abnormality of the hip joint, and discomfort is often found in adulthood. This study compared patients with symptomatic HD in muscle strength, dynamic balance, and range of motion (ROM) with healthy individuals. Patients included those who complained of unilateral pain although the lateral center edge angle (LCEA) exhibited bilateral abnormality. Participants (n = 95; men: 46, women: 49) were divided into symptomatic and asymptomatic sides, and a healthy group without a history of hip joint disease (n = 70; men: 30, women: 40) was compared. Hip flexion, extension, abduction, and adduction were performed at an angular velocity of 30°/s using an isokinetic strength test device. The Y-balance test was conducted to measure dynamic balance, and ROM was measured using an electronic goniometer to evaluate flexion, extension, adduction, abduction, and internal and external rotations. In addition, the pain visual analog scale (VAS) and hip and groin outcome scale (HAGOS), a subjective evaluation of the hip joint, were evaluated. ROM (flexion, abduction, internal rotation, and external rotation) was significantly decreased in the HD symptomatic sides of men and women compared to those of the healthy group and the asymptomatic side, and the dynamic balance, flexion, and abduction muscle strength were also lower on the symptomatic sides. Although the LCEA of the HD asymptomatic side was lower than that of the healthy group, there were no significant differences in VAS, flexion, extension, abduction ROM, and extension strength compared to those of healthy individuals. In conclusion, patients with HD were mostly bilateral, and on the symptomatic side, there was a decrease in ROM, dynamic balance, and muscle strength; however, on the asymptomatic side, the function was relatively close to normal.