THE EFFECT OF THE TYPE OF CEMENT ON EARLY REVISION OF CHARNLEY TOTAL HIP PROSTHESES - A REVIEW OF 8,579 PRIMARY ARTHROPLASTIES FROM THE NORWEGIAN ARTHROPLASTY REGISTER

We studied the survival of 8579 Charnley prostheses, in 7922 patients, according to the different types of cement that had been used. All of the patients had had a primary total hip replacement for primary coxa rthrosis. The mean duration of follow-up was 3.2 years (range, zero to 6.4 years). The data were collected from the national Norwegian Arthr oplasty Register. The duration of survival was defined as the time to revision due to aseptic loosening. The Kaplan-Meier estimate of surviv al at 5.5 years for the 1226 femoral components that had been implante d with low-viscosity cement was 94.1 per cent (95 per cent confidence interval, 92.1 to 96.2 per cent), compared with 98.1 per cent (95 per cent confidence interval, 97.5 to 98.6 per cent) for the 6589 componen ts that had been implanted with high-viscosity cement (p < 0.0001). Th e remaining 764 femoral components had been implanted with Boneloc cem ent, which was classified as neither high nor low-viscosity, and these components were considered as a separate group in the analyses. The B oneloc cement had been used for only three gears, and the two-year sur vival rate of these prostheses was 95.5 per cent (p < 0.0001). The cem ent contained an antibiotic in 2801 (42 per cent) of the hips in which the femoral component had been implanted with high-viscosity cement, compared with only thirty (2 per cent) of those in which it had been i mplanted with low-viscosity cement. With restriction of the comparison to cement without an antibiotic, and with adjustment for the age and sex of the patient, with use of the Cox proportional-hazards model the femoral components that had been implanted with low-viscosity cement had a rate of revision that was 2.5 times greater (95 per cent confide nce interval, 1.6 to 3.8 times) than that for the components that had been implanted with high-viscosity cement, and those that had been imp lanted with Boneloc cement had a rate that was 8.7 times greater (95 p er cent confidence interval, 5.1 to 14.8 times). The addition of an an tibiotic to the high-viscosity cement improved the Kaplan-Meier estima te of survival, at 5.5 years, from 97.7 to 98.7 per cent for the femor al components (p = 0.06) and from 99.2 to 99.6 per cent for the acetab ular components (p = 0.07). The rate of survival of the acetabular com ponents at 5.5 years was higher than 99 per cent in association with a ll types of cement. There was no significant difference in the rates o f failure between the low and high-viscosity cement. However, the acet abular components that had been implanted with Boneloc cement had a cu mulative rate of revision of 1.2 per cent at two years, compared with 0.2 per cent for the other components (p < 0.001).