Between November 2000 and April 2001 31 patients with unilateral coxarthrosis were assessed in order to determine strength of the hip abductors and hip mobility 2 days prior surgery, 10 and 14 days post surgery. All patients underwent total hip replacement though an antero-lateral approach. It was found that maximal and average muscle strength decreased during the first 2 weeks post-op, with concomitant increase in time needed to achieve full muscle strength and hip mobility.