A comparison of the funtional performance of patients with Charnley and Müller total hip replacement. A two-year follow-up of eighty-nine cases.

Measurements of functional performance in 35 cases with Charnley total hip replacement were compared with those of 54 cases with Müller replacement before surgery and at 6- and 24-month follow-up intervals. The measurements included strength of the hip abductor and adductor muscles, hip motion, the amount of weight borne on the involved limb during standing posture, multiple components of free-speed and fast walking, and force applied to canes and crutches. Both replacement groups improved significantly in most components of function. In fact, both groups reached or nearly reached the lower limits of normal variability in weight-bearing ability, cadence, and some components which relate to smoothness of walking performance. The groups with Müller and Charnley replacement differed most in some components of range of hip motion, hip muscle strength, and lateral lurching during walking.