Bipolar hemiarthroplasty of the hip has been used as a treatment modality for displaced femoral neck and intertrochanteric fractures in elderly patients, inflammatory and degenerative diseases of the hip, osteonecrosis of femoral head and limb salvage procedure after tumor resection. Because of the intrinsic stability of the biarticular structure, it is also used for treatment of recurrent dislocation after total hip replacement arthroplasty. However, despite its intrinsic stability, dislocation does occur even after bipolar hemiarthroplasty, and poor prognosis after the dislocation has been reported. So, we tried to investigate the incidence, risk factors, treatment and preventive methods of dislocation after bipolar hemiarthroplasty.

We reviewed 138 patients and 138 bipolar hemiarthroplasties retrospectively to analyze the incidence, timing, risk factors, treatment and preventive methods of the dislocation.

The incidence of dislocation was 5.8% (8/138). Female gender, intertrochanteric fracture, pre-existing neuromuscular disorders including cerebrovascular accident, long period of pre-operative and postoperative immobilization were statistically significant (P<0.05) as a risk factor. Related muscular weakness was the most significant predisposing factor for dislocation.

In order to prevent dislocation after bipolar hemiarthroplasty performed in the patients with above risk factors, we must try and encourage early operation, early ambulation, muscle strengthening exercise and application of abduction hip brace.