BIPOLAR VERSUS UNIPOLAR FOR DISPLACED INTRACAPSULAR HIP FRACTURES – A PRELIMINARY REPORT.

Abstract

The purpose of this study is to evaluate the clinical outcomes between a bipolar prosthesis and a hemiprosthesis (unipolar) in the treatment of displaced intracapsular femoral neck fractures. The theoretical advantage of a bipolar prosthesis is a reduction of acetabular erosion. Movement within the prosthesis may also reduce the pain caused by movement in the acetabulum.

A prospective randomised study was conducted evaluating 40 patients over the age of 70 years, who presented with intracapsular hip fractures Garden 3 or 4, treated either with a bipolar prosthesis (medical international) or a Thompsons hemiarthroplasty. There were 20 patients in each group, and the operation was performed through a Hardinge approach by the same surgical team. All prostheses were uncemented. All patients were rehabilitated by the same Physiotherapist using the same routine. An out-patient assessment was performed at 6 weeks, checking the wound, the clinical result and doing an AP x-ray of the pelvis.

39 Patients were followed for a median period of 13 months. 1 Patient who received a Thompsons prosthesis died in hospital. The average hospital stay in patients receiving a bipolar prosthesis was 7 days, and 13 days for those who were treated with a Thompsons prosthesis. There were 2 deep infections and 1 peri prosthetic fracture in the hemiarthroplasty (Thompsons) group. 15 Of the 20 patients treated with a bipolar prosthesis returned to their pre-injury state with mild pain, and were satisfied with the procedure. Only 9 of the 19 patients in the Thompsons group returned to their pre-injury level, with 12 complaining of pain and only 4 satisfied with the procedure.

The early subjective outcome in elderly patients is difficult to assess, and the optimum realistic outcome should be a return to pre-injury function and the presence or absence of pain. This review was not blinded, and hence the assessment of results could be biased towards certain prostheses. The findings suggest that a bipolar prosthesis may give a better short term result in the elderly. The bipolar prosthesis used in this series is inexpensive, and we felt its use justified.