Retention of all-polyethylene acetabular components after femoral revision of a cemented total hip replacement.

BACKGROUND

This study was undertaken to provide a basis for decision-making when a well-fixed cemented cup is encountered at the time of a revision of a femoral component of a total hip replacement. It may be beneficial to retain the cup in some instances and thus reduce morbidity, complications, blood loss, operative time, and cost.

METHODS

All patients who had a revision of the femoral component and retention of an all-polyethylene acetabular component from 1971 to 1996 were identified. Three hundred and seventy-four patients with a total of 395 cemented total hip replacements fit the inclusion criteria. The gender, date of and age at the index surgery, type of acetabular implant, and time of and reason for the revision of the femoral component were reviewed. The time to subsequent cup revision or latest surveillance was noted. The average age (and standard deviation) was 66.5 +/- 11.8 years at the time of the femoral revision, which was performed at an average of 8.0 +/- 4.4 years after the primary arthroplasty. For the purposes of this study, the end point for survival of the acetabular component was cup revision for any reason.

RESULTS

At the time of the latest follow-up, at an average of nine years after the femoral revision and 17.3 years after the primary arthroplasty, 342 (86.6%) of the 395 cups remained in situ. Fifty-three cups (13.4%) in fifty-two patients had been revised, at an average of 10.0 +/- 5.7 years after the femoral revision and 16.7 +/- 5.3 years after the primary arthroplasty. The rate of survival of the retained acetabular components was 96.9% at five years, 89.3% at ten years, and 78.7% at fifteen years after the femoral revision and was 95.1% at fifteen years and 87.1% at twenty years after the primary arthroplasty. Increased age (p < 0.0001) and a shorter time-interval (less than 7.5 years) between the primary arthroplasty and the femoral revision (p = 0.05) were significantly associated with an increased likelihood of survival free of cup revision. Femoral head size, acetabular component design, gender, and primary diagnosis did not affect prosthetic survival in this sample of patients.

CONCLUSIONS

The likelihood of survival of the unrevised cup was associated with patient age and duration of implantation, with the age of the patient being the more dominant factor predicting failure of the acetabular component.