The Elite-Plus stem migrates more than the flanged Charnley stem: A clinical, radiographic, and radiostereometric analysis of 114 patients with an average of 7 years follow-up

BACKGROUND AND PURPOSE: The Charnley Elite-Plus stem was introduced in 1993 as a presumed improvement of the flanged Charnley stem. We started this study in 1996 to investigate the migratory pattern of the Elite-Plus stem. PATIENTS AND METHODS: We followed 114 patients with osteoarthritis and a primary total hip replacement with the Elite-Plus stem. Mean age at the time of operation was 64 (50–76) years. The mean follow-up time was 6.5 (2–7) years. Radiographs were evaluated with respect to cementing technique, migration, and wear measured by radiostereometry (RSA). RESULTS: The stem survival was 98% (CI: 96–100) at 7 years and 92% (CI: 86–97) at 10 years. Mean migration of the femoral head was 0.35 mm (SD 0.3) medially, 0.51 mm (SD 0.6) distally, and 1.1 mm (SD 1.8) in the dorsal direction. Mean total point motion was 1.7 mm (SD 1.7). The migration of the stems stabilized after 5 years in the medial and dorsal directions, but continued to subside slightly. Migration along any of the axes was higher if the cementing technique was inferior. INTERPRETATION: Patients with a Charnley Elite-Plus stem and defects in the cement mantle or other signs of inferior implantation technique should be carefully monitored.