Long-term fate of uncemented, threaded acetabular components with smooth surface treatment: minimum 10-year follow-up of two different designs

Introduction

In the 1970s and 1980s, uncemented, threaded acetabular components with smooth surface treatment were widely used in continental Europe for arthroplasty of the hip to overcome the high rate of aseptic loosening in cemented hip arthroplasty in young patients. There were several reports on short- and intermediate-term results, but information on survival in the longer term is not available at present.

Materials and methods

In a consecutive series of 320 patients, 348 threaded cups with smooth surface treatment (221 Mecring and 127 Weill) had been implanted in combination with one type of uncemented stem. Patients were followed clinically and radiographically. The mean time of follow-up was 12.4 (range 10–15) years (Mecring 11.9 years, Weill 13.3 years).

Results

In 76 hips the acetabular component had been revised (Mecring 56, Weill 20): 7 hips for infection and 69 for aseptic loosening. Of the remainder, the cup had migrated in 55 hips, and 32 hips were awaiting revision. Survival at 14 years was 63.8% (95%CI: 52.5–75.0%) for the Mecring and 76.2% (95%CI: 65.6–86.7%) for the Weill component. Radiolucent lines were present in 59 hips (31.9%). The median Harris Hip Score at follow-up was 84 points (Mecring 85, Weill 82). Radiographic loosening did not correlate with clinical outcome.

Conclusion

These results support the view that smooth, threaded acetabular components do not provide satisfactory long-term fixation and should be abandoned.