Ceramic-ceramic in total hip arthroplasty. An analysis of 7-13 year survival rate

After 7-13 years, the long-term results of primary replacement of the hip joint by total cemented arthroplasty, with a head and acetabulum in high-density alumina, and a stem in chrome-cobalt alloy in a series of 38 patients were analyzed. The age of the patients ranged from 36 to 76 years (mean 55 years). The patients were monitored annually, by both clinical-radiographic follow-up and by an interview over the telephone (pain, independence walking, degree of hip flexion). The presence of a correlation between loosening of the implant and several clinical parameters (age, sex, diagnosis) and radiographic parameters (orientation, height and lateralization of the acetabular cup, rotation center of the implant, position of the femoral stem) were searched for. Data concerning 35 of the 43 prostheses implanted were gathered. The data were analyzed by the survival curve with an actuarial method, log-rank test and chi square test. The differences were considered significant for p < 0.05. There were no clinical or radiographic signs of loosening of the femoral prosthetic component. Instead, the acetabular cup was loosened in 7 cases. An implant was removed because of infective complications 6 months after surgery. The cumulative percentage of survival of the implant after 13 years was 81.2%. There was no statistically significant correlation between loosening of the implant and the parameters considered. Despite the favorable mechanical features of bioceramics, the acetabular component proved to be the weak point of the implant. The authors believe that only the introduction of new concepts of acetabular fixation could contribute to a significant increase in the survival rate for ceramic-ceramic.