Purpose: Dislocation is the second most common cause of failure, after implant loosening, in revisional THA (Total hip arthroplasty), and its evaluation and treatment still remain controversial issue. This study was undertaken to evaluate the risk factors after THA using the posterolateral approach and posterior soft tissue repair. Materials and Methods: Between January 1998 and May 2003, 211 consecutive primary total hip replacement arthroplasties using the posterolateral approach and posterior soft tissue repair were performed by the same surgeon. To compare the dislocation groups (6 cases) with the non-dislocation groups (205 cases), we randomized 120 of the non-dislocation cases. The risk factors for hip dislocation were categorized into patient factors and surgical factors. Patient factors included gender, age, preoperative diagnosis, underlying systemic disease, and alcoholic history. Surgical factors included position of the component (acetabular version and inclination, femoral anteversion), leg length discrepancy, and sum of anteversions of the cup and stem. Their parameters were measured on postoperative radiographs. Statistics were performed with Fishe`s Exact test and T test. Results: Dislocations occurred at an overall incidence rate of 2.8% (6/211cases). There were 4 (1.9%) cases of anterior dislocations and 2 (0.9%) cases of posterior dislocations. Dislocations occurred on average at postoperative day 6.1 and all dislocated hips were reduced with the closed method, except for one case that was treated surgically. There was no statistical significance in patient factors between the two groups, except for neurologic disease and alcoholic history. However, the sum of the acetabular and femoral anteversions in the anterior dislocation group was larger than that of the non-dislocation group by approximately 19 degrees. Conclusion: Our results demonstrated that by using the posterior approach and repair of soft tissue, the posterior dislocation rate after total hip replacement arthroplasty can be reduced and the sum of the acetabular and femoral anteversions had more influence on dislocations after THAs than did either anteversion alone.
Acetabulum ; Alcoholics ; Arthroplasty ; Arthroplasty, Replacement, Hip* ; Diagnosis ; Dislocations ; Hip Dislocation* ; Hip* ; Humans ; Incidence ; Leg ; Risk Factors*