Functional recovery of noncemented total hip arthroplasty.

Eighteen patients with unilateral hip disease had noncemented total hip arthroplasty. Clinical follow-up data were complete to five years postsurgery. Gait analysis was done preoperatively, at three and six months, and at one and two years. Force plate data showed continued weakness of the operated hip in all patients at two years postsurgery. Preoperative dynamic electromyograms (EMGs) were abnormal in eight patients and showed two patterns. Stance loss seen in three patients was characterized by absence of activity of the gluteus medius and upper and lower gluteus maximus muscles. In five patients, continuous activity occurred in the tensor fascia lata, rectus femoris, and adductor longus muscles during the entire gait cycle. Postoperatively, all abnormal EMGs returned to normal. Four patients with a normal preoperative EMG developed abnormal EMG patterns postoperatively, demonstrating either a prolonged stance or stance loss pattern. All four of these hips have been revised. Although gait characteristics return to normal by two years postsurgery, weakness of the hip persists. This weakness jeopardizes the implant fixation interface. This study supports the prohibition of activities that cause high impact loading of total hip arthroplasties and suggests that a prolonged exercise program be employed postoperatively.