Purpose: Dislocation after total hip arthroplasty (THA) is a common reason for revision. The last decade fostered a significant increase in the use of dual-mobility cups (DMCs). Here we report our study on the short-term survival rate of a cemented DMC reported to the Swedish Hip Arthroplasty Register (SHAR) compared with other cemented designs used in first-time revision due to dislocation.
Methods: During 2005-2015, 984 first-time revisions for dislocation were reported to SHAR. In 436 of these cases a cemented dual articular cup was used. During the same time period, 355 revisions performed with a standard cemented cup (femoral head size 28-36 mm) were reported to the SHAR. Patients receiving a DMC were slightly older (75 years, p = 0.005). Re-revision for all reasons was used as primary endpoint. We also anlaysed risk for re-revision of the acetabular component and re-revision due to dislocation. Kaplan-Meier implant survival and a Cox regression analyses adjusted for age and gender were performed.
Results: Implant survival at 4 years for all reasons (91% ± 3.7% vs 86% ± 4.1%, p = 0.02), and especially for re-operation because of dislocation, favours the DMC group (96% ± 3.0% vs 92% ± 3.3%, p = 0.001).
Discussion: Our findings indicate that use of a cemented DMC reduces the short- to mid-term risk of a second revision in first-time revisions compared with classic cup designs. Longer follow-up is needed to establish any long-term clinical advantages when DMCs are used in revisions performed due to dislocation.
Keywords: Dislocation; Register studies; Revision.