THE USE OF A DUAL-ARTICULATION ACETABULAR CUP SYSTEM TO PREVENT DISLOCATION AFTER TOTAL HIP ARTHROPLASTY. ANALYSIS OF 384 CASES AT A MEAN FOLLOW-UP OF 15 YEARS

Abstract

Background: Implant instability is a major complication of total hip arthroplasty. The concept of dual articulation invented by Prof. Bousquet in 1974 is now increasingly recognized in Europe. This concept has proved to provide high stability after total hip arthroplasty revision, and to successfully address chronic instability after total hip arthroplasty. The aim of our study was to evaluate the incidence of prosthetic instability in a consecutive homogeneous series of three hundred and eighty four hips primary cases with a mean follow-up of fifteen years.

Methods: Three hundred and eighty four hips have been implanted with a dual articulation acetabular cup system. This system consists of a cementless acetabular shell, and a polyethylene liner which freely rotates within the shell and positively captures the prosthetic head. It was a consecutive and homogeneous series of cases. Only primary cases were included in the study. A final evaluation was performed at the last follow-up. Implant survival was evaluated using the Kaplan-Meier method (p< 0.05), with surgical revision for aseptic loosening as the endpoint for failure. We have evaluated the incidence of instability by prospectively listing all the episodes of implant instability.

Results: At the last follow-up, 6 patients could not be located and 92 were deceased.

Mean follow-up was 15.3 years. The mean Merle d’Aubigner hip score was 16.3±1.8 at the latest follow-up. There was no early or late instability. Radiologically, there were 31% of severe granuloma formation extending beyond zones I and VII. However, granuloma remained asymptomatic in all of the cases and did not require surgical revision of the femoral component. On the acetabular side, late complications occurred: aseptic loosening (3.3%), intra-prosthetic dislocation (3.6%), polyethylene wear that required replacement of the liner (1.8%). Survival of dual-articulation acetabular system with surgical revision for aseptic loosening as the end-point for failure was 96.4% at 15 years and 94.9% at 18 years postoperatively (p< 0.05).

Conclusion: Our consecutive homogeneous series proves the good long-term behaviour of dual-articulation acetabular components in primary arthroplasty. Their excellent survivorship rate at 18 years increases our confidence in this concept. Considering the absence of episodes of prosthetic instability in our series, we can rightly claim that the goal of decreasing instability has been achieved.