Risk Factors of Dislocation Occurring after Acetabular Component Revision

Seo, Yoo Seong; Soh, Jae Wan; Jong-Seok, Park; Yim, Soo Jae; Lee, Byung Ill

Abstract

Purpose
To analyze the causes and to prevent dislocations of the hip joint that occur in patients who underwent revisions of total hip arthroplasties by changing only the polyethylene liners and femoral heads, subsequent to primary total hip arthroplasties. Materials and Methods: We evaluated 28 patients who underwent acetabular component revisions of total hip arthroplasties subsequent to primary total hip arthroplasties. The average age of the patients was 55 years old and all 28 patients had operations through the posterolateral approach. In 17 of the cases, the acetabular cups, polyethylene liners, and femoral heads were changed; in 10 cases, just the polyethylene liners and femoral heads were changed; and in 1 case, only the polyethylene liner was changed. Results: We observed 7 cases of hip dislocations that occurred among a total of 28 cases after revisions of total hip arthroplasties. In all 7 cases, the polyethylene liners and femoral heads were changed, but not the acetabular cups. In additional, in all 7 cases of dislocation, the patients were non-compliant and started weight-bearing prematurely after revisions of the total hip arthroplasties Conclusion: We observed new dislocations in the 7 cases in which the polyethylene liners and femoral heads were changed. The main reasons were inadequate soft tissue tension and hip joint laxity. Therefore, it is necessary to increase the neck length, use elevated rim polyethylene liners, readjust the acetabular cups to their optimal positions, and apply hip abduction braces to patients early after revision of total hip arthroplasties in order to lessen the danger of dislocations.