Muscle Activation Pattern of Hip Arthroplasty Patients in Walking

Abstract

This study examined the hip abductor activation pattern of 14 hip replacement patients and 10 age-matched healthy controls by measuring surface electromyography (EMG) onset and cessation times. Stride characteristics, surface EMG from bilateral gluteus medius, and 3D pelvis kinematics were evaluated during treadmill ambulation. EMG onset times were normalized with regard to the individual stride time for each gait cycle. An ANOVA revealed significantly delayed EMG onset times (p < .001) in comparing hip abductors of the operated side with the unimpaired side and the healthy controls. Between subject effects also demonstrated significant differences (p < .01) for stance duration and sagittal pelvis range of motion. No significant differences were found for EMG cessation times and angular pelvis peak-to-peak ranges in the frontal and transverse planes. The results indicated deficiencies in the hip abductor recruitment pattern of hip arthroplasty patients. Further analysis should explore whether specific exercises, or rehabilitation programs can facilitate adequate muscle activation.