Comparison of Anterior and Posterior Dislocation after Total Hip Arthroplasty through the Posterior Approach

Abstract Background: Dislocation is one of the most common complications following Total Hip Arthroplasty (THA). Dislocations after THA can be divided into anterior and posterior types according to the direction of the dislocation. Reports of the difference between anterior and posterior dislocations following THA are scarce. Aims: The aim of the study is to identify the differences in risk factors and treatment between anterior and posterior dislocation following THA through the posterior approach and explored potential risk factors and effective treatment for the two types of dislocations. Methods: The study inclu4ded 1433 primary and revision THAs operated by the posterior approach at the Department of Orthopaedics of the Shengjing Hospital between 2005 and 2013. Clinical data of all patients was reviewed and analyzed. The study included an anterior dislocation group (n=5), a posterior dislocation group (n=23), and two matched control groups. Results: The dislocation rate after primary THA was 1.5% (20/1304) compared with 6.2% (8/129) for revision THA. The ratio of anterior to posterior dislocation in the entire THA cohort was 1:4.6 (5:23). There was strong association between anterior dislocation and anteversion of the acetabular cup and femoral stem, size of the femoral head, and soft tissue tension. On the other hand, a higher incidence of postoperative posterior dislocation was found to relate to soft tissue tension, revision arthroplasty, and incorrect posture. Conclusion: There are multiple factors associated with both anterior and posterior dislocation. However, the two types of dislocation have different pathologic and anatomical characteristics, as well as risk factors. It is very important to determine the true etiology of dislocation. Closed reduction and immobilization are effective treatments for most patients with either of the two dislocations before open surgery is selected.