HIP-ARTHROPLASTY USING THE CEMENTLESS CLS STEM - A 2-4-YEAR EXPERIENCE

Fifty-one Cementless Spotorno (CLS, Protek A. G., Berne) stems were im planted in 43 patients with either a Harris Galante (Zimmer, Warsaw, I N) socket or bipolar head. Patients were evaluated at a mean of 31 mon ths. Eighty percent of the hips were in patients who were less than 50 years of age or weighed more than 80 kg. The CLS stem achieved initia l stability by wedging a proximally fluted, straight stem into a retai ned bed of femoral trabecular and cortical bone. Distal canal fill was avoided. The postoperative mean Harris hip score was 95. Eighty perce nt of the hips were rated excellent, 16% good, 2% fair, and 2% poor. N o stem required revision. Six percent had slight, occasional thigh pai n. No patient had mild, moderate, or severe thigh pain. Six percent ha d a limp related to the operated hip. Fifty-three percent of the hips developed a radiographic appearance of bone apposition at the stem tip . Fifty-five percent of the hips had some reduction in proximal bone d ensity. These changes suggested that as bone remodeling occurred, the initial proximal load transfer situation expected from the CLS stem de sign changed to include some distal load transfer resulting in proxima l stress shielding. Ninety-four percent of the hips had either no chan ge in femoral bone density or only patchy loss of density isolated to zone 7. A high dislocation rate was attributed to an unfavorable head- to-neck diameter ratio, a valgus neck shaft angle, and a patient popul ation capable of excellent hip motion.