Unipolar versus bipolar hemiarthroplasty: functional outcome after femoral neck fracture at a minimum of thirty-six months of follow-up.

OBJECTIVES

This investigation was undertaken to compare a series of elderly individuals who sustained a displaced femoral neck fracture treated with either a cemented bipolar prosthesis or a cemented modular unipolar prosthesis.

DESIGN

A retrospective review of prospectively collected data.

SETTING

Hospital-based tertiary care orthopaedic trauma practice.

PATIENTS AND PARTICIPANTS

Two hundred eighty-one community dwelling elderly patients sixty-five years of age or older who sustained a displaced femoral neck fracture (Garden Types III-IV) and underwent primary prosthetic replacement.

INTERVENTION

One hundred one patients received a cemented bipolar prosthesis and 180 received a cemented modular unipolar prosthesis.

MAIN OUTCOME MEASUREMENTS

The study was designed to determine whether there were any significant differences in: (a) the rate of prosthetic dislocation, postoperative medical and wound complications, or need for revision surgery, and (b) the functional outcome, including the incidence of hip pain and recovery of preinjury levels of ambulatory status and activities of daily living, at a minimum of thirty-six months of follow-up.

RESULTS

The two groups of patients did not differ in preinjury characteristics (age, sex, American Society of Anesthesiologist rating of operative risk, number of comorbidities, fracture type, activities of daily living, ambulatory status). There were no significant differences in the rates of postoperative medical or wound complications or dislocation. Ninety-two patients died during the period of study. Forty patients were lost to follow-up or refused to participate. Consequently, 149 patients were followed for a minimum of thirty-six months. Functional ability was compared between both groups with regard to recovery of ambulatory status and activities of daily living, as well as the incidence of hip pain at a minimum of thirty-six months of follow-up. No significant differences were found between the unipolar and bipolar groups.

CONCLUSION

Based on the results of this study, there does not appear to be any advantage to the use of a bipolar endoprosthesis in the management of displaced femoral neck fractures in the elderly. Furthermore, the extra cost of bipolar endoprostheses does not seem to warrant its use.