Dissociation of Bipolar Hemiarthroplasty of the Hip and Review of Literature

Abstract

Component dissociation after a bipolar hemiarthroplasty is an uncommon complication that usually necessitates reoperation due to difficulties in closed reduction. To our knowledge, only a few cases have been published in the recent literature. We present a case of disassembly location of in a 68-year-old woman who underwent bipolar hemiarthroplasty 10 years ago due to a left hip femoral neck fracture. She began complaining about pain and difficulty to bear weight after an unintentional internal rotation movement of her left hip. The initial radiographs showed the disassembly of the bipolar hip prosthesis, and the patient underwent conversion to total hip arthroplasty. We conducted a literature review to explain the potential causes and mechanisms.

Keywords: Bipolar hemiarthroplasty; Disassembly; Dissociation; Inner head displacement.

Figure 1

Patient’s initial postoperative anteroposterior radiograph of a left hip bipolar hemiarthroplasty.

Figure 2

Anteroposterior radiograph demonstrating a dissociation of a left hip bipolar hemiarthroplasty. The outer head is in extreme varus position (arrow)—osteoarthritic changes of the acetabulum.

Figure 3

Retrieved bipolar component and femoral head (a). No macroscopic wear was found at the articulating surface of the polyethylene insert (b). Excessive wear was found at the slots and groove of the polyethylene that contributed to the locking mechanism (c).

Figure 4

Postoperative anteroposterior radiograph after conversion of the bipolar hemiarthroplasty to total hip arthroplasty.

Figure 5

Anteroposterior radiograph of the left hip at 1-month follow-up after conversion to a total hip arthroplasty.