Introduction: Total hip arthroplasty is problematical in the case of high hip dislocation. To reposition the hip, a femoral shortening osteotomy is necessary in order to prevent damage to the neurovascular structures. This paper describes the implantation of a small threaded cup and a cementless straight stem using a simple technique with a simultaneous, derotating and shortening osteotomy for the femur.
Materials and Methods: In this study, 30 cementless primary total hip arthroplasties were performed in 27 patients with high hip dislocation, and clinically assessed at a mean follow-up of 5.1 years. Acetabular reconstruction was done with a cementless threaded cup, whereby the cup was medialized to ensure that at least one thread was anchored in the bone in order to achieve good primary stability. All radiographs were analyzed retrospectively.
Results: A femoral shortening osteotomy was performed in all cases. The average duration of surgery was 116 minutes. One cup loosening and one stem loosening was observed. Kaplan-Meier survivorship analysis, with aseptic radiological loosening as the endpoint, predicted a survival rate of 96,6% at 5.1 years for the acetabular component and 96.6% for the stem. The mean Harris hip score for the unrevised hips improved from 28.7 points preoperatively to 81.2 points postoperatively. Femur fractures, pseudoarthroses, paresis and deep infections were not found.
Conclusion: The surgical technique described enables the initial stable fixation of a threaded cup in the small acetabulum and of a standard prosthesis without additional osteosynthesis for the performed osteotomy. Additional advantages include a shorter duration of surgery, a lower complication rate and a more rapid consolidation of the osteotomy in comparison to other techniques. Despite a patient group with a low average age and comparatively high daily activity, hip reconstruction with a cementless, threaded cup and the use of a cementless, straight stem without additional osteosyn-thesis has produced a good mid-term outcome.
