Dislocation after Hip Arthroplasty: Analysis of the Cause Factors

Hwang, Deuk Soo; Yune, Seung Ho; Kim, Hyeong Seong; Song, Jae Gie

Abstract

We reviewed 174 total hip arthroplasty (25 were revision procedure) and 65 bipolar hemiarthroplasty procedure followed by more than 6 months at Chungnam National University Hospital from July, 1992 to March, 1995. These were performed on 189 male and 50 female patients. We have followed up average 45.8 months and obtained following results; The dislocation rate is 3.76% (9 of 239 cases) and the dislocation rate of revision arthroplasties (16%: 4 of 25 cases) is higher than those of primary hip arthroplasties (2.6%: 5 of 214 cases). Among Nine dislocations, 8 cases (89%) were between fifth and seventh decade and all cases are men. All dislocations occured within 5 weeks postoperatively. Because 6 of 9 cases were due to poor compliance, the patient's cooperation during postoperative recovery is essential to prevent postoperative dislocation. The capsulectomy, surgical approach, or immobilization of patients after operation are unrelated to dislocaton. For the prosthetic factors, 7 cases dislocated posteriorly is appeared that the plane of the cup was between 3 and 9 degrees of anteversion, and also less than the normal range. Stable outcome without surgical operation was achieved in 7 of 9 dislocation. Among 2 patients who had recurrent dislocation after optimum conservative treatment, one had infected arthroplasty and the other had a impinged anterior thick capsule formation around the head. We concluded that the predisposing factors for dislocation after hip arthroplasty is multifactorial.