Dislocation after Hemiarthroplasty due to Insufficiency Fracture of the Superior Acetabulum: A Case Report

Abstract

Insufficiency fracture of the superior part of the acetabulum after hemiarthroplasty has not been reported before. Here we report a case of dislocation after hemiarthroplaty due to insufficiency fracture of the acetabulum. In our patient, insufficiency fracture of the ilium immediately above the acetabulum produced obvious evidence of compression and collapse that led to dislocation of the outer head of the femoral component. This patient had subsequently been treated with a cementless socket inserted into the fractured acetabulum. We should remember the possibility of insufficiency fracture of the superior acetabulum after hemiarthroplasty, particularly in elderly patients suffering from chronic postoperative pain and disability.

Figure 1

Radiographs show irregularity of the surface of the left acetabulum and osteoporotic changes of the superior part of the left acetabulum in comparison with the right hip. There is an obvious pseudoarthrosis of the femoral neck after internal fixation.

Figure 2

The outer head is set adequately in the acetabulum.

Figure 3

Subluxation of the outer head is apparent. The superior part of the acetabulum shows compression and the inclination of acetabular subchondral bone is increased compared with that on the right side.

Figure 4

The outer head is dislocated completely. The outer part of the subchondral bone is inclined in the superior direction.

Figure 5

There is no loosening of the acetabular component at three years after revision surgery.