Cementless acetabular fixation has demonstrated superior long-term durability in total hip replacement, but most series have studied implants with porous metal surfaces. We retrospectively evaluated the results of 100 consecutive patients undergoing total hip replacement where a non-porous Allofit component was used for primary press-fit fixation. This implant is titanium alloy, grit-blasted, with a macrostructure of forged teeth and has a biradial shape. A total of 81 patients (82 hips) were evaluated at final follow-up at a mean of 10.1 years (8.9 to 11.9). The Harris Hip Score improved from a mean 53 points (23 to 73) pre-operatively to a mean of 96 points (78 to 100) at final review. The osseointegration of all acetabular components was radiologically evaluated with no evidence of loosening. The survival rate with revision of the component as the endpoint was 97.5% (95% confidence interval 94 to 100) after 11.9 years. Radiolucency was found in one DeLee-Charnley zone in four acetabular components. None of the implants required revision for aseptic loosening. Two patients were treated for infection, one requiring a two-stage revision of the implant. One femoral stem was revised for osteolysis due to the production of metal wear debris, but the acetabular shell did not require revision. This study demonstrates that a non-porous titanium acetabular component with adjunct surface fixation offers an alternative to standard porous-coated implants.

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From 1973 to 1976, McKee-Farrar total hip arthroplasties were performed in the Orthopaedics Department at the Centre of Pulmology. In the present study, only patients with a complete record of radiological changes at the bone/implant or bone/cement interface were evaluated. A series of 81 patients with 100 total hip prostheses in situ according to the Mayo Clinic hip score and 36 patients who had undergone 36 revision operations were studied. The design of the metal cup with metal studs at the outer surface has a favourable effect on the stability of the implant/cement combination: loosening at the implant/cement interface did not occur in any of these cases and there were few cement fractures. In spite of the metal-to-metal combination, abrasion is slight and there is no danger of metallosis.

A retrospective study of the first consecutive 111 cementless Zweymüller Stems has been performed. 56 cases have been followed clinically and radiologically with an interval of 10-11 years. The average harris hip score was 90.7 pts, the cumulative success rate of the stem was 97.96% after 10-11 years. The frequency of bony reactions around the stem and their changes during the course of time could be followed in 40 implants with a complete radiologic documentation at 5 and 10 years postoperative. Hypertrophic changes of the bone around the tip of the stem remained unchanged from the fifth to the tenth year but there was an increase of proximal lucencies (27% at 5 yrs, 35 at 10 yrs), widening of the calcar (20% at 5 yrs, 25% at 10 yrs) and stress shielding (30% at 5 yrs, 47% at 10 yrs).

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