The Charnley versus the Spectron hip prosthesis: clinical evaluation of a randomized, prospective study of 2 different hip implants.

Prospective, randomized studies must be performed when new surgical techniques or implants are evaluated. In this study, a new implant system was compared with the Charnley prosthesis, which over the years has been the most used hip implant in Sweden. Between 1985 and 1989, 410 hips were randomized to treatment with a Charnley or a Spectron total hip arthroplasty: 206 Charnley and 204 Spectron prostheses were implanted. The patients were operated on by a standardized procedure using a contemporary cementing technique. The patients were followed prospectively by an independent observer after 1, 3, 5 to 6, and 10 years. Harris Hip Score and patient satisfaction were recorded in the outcome evaluation. A total of 144 patients with 164 hips were deceased, and 15 patients (8 Charnley and 7 Spectron) have required a revision. Nine hips were revised because of aseptic loosening (5 Charnley stems and 4 Spectron metal-backed cups). The Charnley stem as well as the metal-backed Spectron cup had a higher risk for revision because of aseptic loosening. The Charnley ogee cup and the Spectron stem have performed remarkably well with no revision of these components. Seven Charnley prostheses dislocated, but no dislocation was recorded in the Spectron group. Survivorship calculations with a mean follow-up of 10 years revealed an overall 11-year survivorship of 94.5% +/- 3.4% (Charnley, 93.2% +/- 5.8%; Spectron, 95.9% +/- 3.0%). The clinical outcome did not differ between the 2 systems. The overall results in this old population, using a contemporary surgical technique, illustrate that cemented hip arthroplasty is an excellent treatment alternative for elderly patients.