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.

Purpose of the study: Implantation of a total hip arthroplasty (THA) for major misalignment is a difficult procedure and few results have been published. In the 1950s to 1970s, supra-trochanteric osteotomy was proposed for sequelar osteoarthritis of congenital hip dislocation. Subsequent degradation 20 to 30 years later can lead to neo-osteoarthritis of the joint with an effect on hip alignment and overall balance between the knee and the spine. We present a prospective consecutive series of 60 THA performed from 1991 to 2003on hips with Milch and Schanz osteotomies.

Material and methods: The objective was to reconstruct an anatomic hip joint by femoral re-alignment de-osteotomy, inferior displacement of the hip joint to enable insertion of an implant with a correctly position center of rotation and normal muscle lever arms. The technique was novel because of the direct approach to the subtrochanteric angle. The step by step procedure enabled insertion of the prosthesis without trochanterotomy. Overall recovery was long, often 12 to 18 months. There were 47 patients 60 hips) with at least 18 months follow-up. None of the patients were lost to follow-up.

Results: Results were available for 54 hips (three deaths, six hips). Mean follow-up was eight years. Outcome was good (patient satisfaction, normal x-ray) for 77%. Twelve hips presented poor clinical and radiological results due to loosening and mobilization of the femoral implant with or without nonunion of the deosteotomy. Ten hips were revised at mean five years via a femoral access for insertion of a press-fit distally locked prosthesis with graft of the nonunion (with acetabular replacement in one hip). The outcome was good at last follow-up for nine of these hips. One repeated revision gave satisfactory results.

Discussion: The only factors of risk of failure were related to femoral re-alignment and absence of trochanterotomy. A lesser risk of nonunion was related to the technique used for osteotomy, osteosynthesis and grafting. The use of a non-cemented implant with a solid primary stability and in certain cases a custom-made implant can be discussed for selected patients.