Hip Abductor Activity of Patients with Osteoarthritis of Hip Joint in the Standing Phase of Walking

Abstract

The purpose of this study was to compare the hip abductor activity in the early, middle and late standing phases of walking between patients with osteoarthritis of hip joint and healthy subjects. Ten female patients with osteoarthritis of hip joint (average age: 38.4 ± 12.7 years) and ten healthy females (average age: 42.8 ± 7.9 years) participated in the study. Subjects walked freely, and the electromyogram of hip abductors and signals from the foot switches of toes and heels were recorded. The integral value of hip abductor activities in the early, middle and late standing phases were obtained from the signals. In all subjects, the electromyographic integral value became greater in order of the early, middle and late phases. Patients showed significantly greater electromyographic integral values in the middle (p<0.05) and late (p<0.01) phases compared with healthy subjects. In most patients, muscle activity tended to be insufficient in the early phase, thereby remaining in the late phase. This difference in muscle activity between patients with osteoarthritis of hip joint and healthy subjects may be ascribed not only to a decrease in abductor strength of hip joint, but also to a decrease in strength of muscles around hip joint and deterioration in coordinated activities between abductor and muscles around hip joint.