To our knowledge in medial unicompartmental knee arthroplasty (UKA) no study has specifically assessed the difference in outcome between matched gender groups. Previous unmatched gender studies have indicated more favourable results for women.

Introduction: Although a number of methods have been described to treat recurrent dislocation following total hip arthroplasty, this complication remains a challenging problem. The purpose of this retrospective study was to evaluate the minimum 2-year outcome in a consecutive series patients treated with a cemented tripolar unconstrained acetabular component for recurrent dislocation.

Patients and Methods: Fifty-one patients presenting with recurrent dislocation following primary or revision total hip arthroplasty in the absence of an identifiable curable cause were treated with a cemented tripolar unconstrained acetabular component. There were thirty-nine females and twelve males with a mean age at the time of the index procedure of 71.3 years. A single acetabular component design was used consisting of a stainless steel outer shell with grooves for cement fixation with a highly polished inner surface. This shell articulated with a mobile intermediate component with an opening diameter smaller than the 22.2-mm femoral head. No locking ring or other mean of constraint was associated.

Results: Of the fifty-one patients, forty-seven have had complete clinical and radiological evaluation data at a mean follow-up of 31.2 months (twenty-four to 56.3 months). The cemented unconstrained tripolar acetabular component restored complete stability of the hip in forty-nine patients (96%). The mean Merle d’Aubigné hip score was 15.8 ± 2.0 at the latest follow-up. Radiographic analysis revealed no or radiolucent lines less than 1 mm thick located in a single acetabular zone in forty-three of forty-seven hips (91.5%). The cumulative survival rate of the acetabular component at 36 months using revision for dislocation and/or mechanical failure as the end point was 93.3 ± 4.6% (95% confidence interval, 84.4% to 100%).

Conclusion: A cemented tripolar unconstrained acetabular component was highly effective in the treatment of recurrent dislocation with none of the complications associated with constrained devices. However, because longer term follow-up is needed to warrant that dislocation and loosening rates will not increase, the use of such a device should be limited to strict indications.