Session V - Femur

Randomized Evaluation of Bipolar Versus Unipolar Hemiarthroplasty for Displaced Femoral Neck Fractures in the Elderly: Preliminary Results

Michael W. Schweppe, MD; Michael G. Vitale, MD; Iris Yaron, MD; Mauricio F. Herrera, MD; Josephine A. Sollano, MPH; Christopher B. Michelsen, MD; Melvin Rosenwasser, MD, Columbia Presbyterian Medical Center, Trauma Training Center, New York, NY

Purpose: Femoral neck fractures are among the most common injuries in patients over sixty-five and consume a major portion of healthcare resources. The bipolar hip prosthesis has theoretical advantages over the unipolar prosthesis in the treatment of these fractures. Clinical studies, however, have reached differing conclusions regarding these implants. The purpose of this study is to compare the efficacy of unipolar and bipolar hemiarthroplasty in elderly patients with displaced femoral neck fractures in terms of functional, clinical and quality of life outcomes.

Methods: This is an ongoing, single-blinded, prospective, randomized clinical trial. Seventy-four patients with a mean age of 82 years (range, 65 to 101) with displaced femoral neck fractures were randomized to undergo cemented unipolar or bipolar hemiarthroplasty. Patients who were institutionalized, nonambulatory, demented, or who had pathologic fractures or other lower extremity fractures were excluded. Pre-injury and follow-up functional status was assessed utilizing the AAOS Total Hip Outcome Evaluation Questionnaire; health-related quality of life was assessed using the SF-36 health survey.

Forty-three patients (26 women and 17 men) underwent unipolar hemiarthroplasty and 31 patients (25 women and 6 men) underwent bipolar hemiarthroplasty. The groups were equivalent in terms of age, medical comorbidities, and prefracture ambulatory and social status. Average followup was five months.

Results: There were no significant differences in in-hospital complications between the two groups. There were no in-hospital deaths. The average hospital stays were 12.2 days for the unipolar group and 9.8 days for the bipolar group. Twenty-nine of forty-three unipolar patients and Michael W. Schwepp bipolar patients were discharged directly to home. Ninety day mortality was 4.7% (2/43) in the unipolar group and 9.7% (3/31) in the bipolar group. There was one reoperation for a deep infection in the unipolar group and two reoperations for decubiti in the bipolar group. All of 16 unipolar patients and 8/11 bipolar patients followed for one year were living at home. Six of seven unipolar patients remained community ambulators at one year follow-up, as did 11/14 bipolar patients. None of these differences were statistically significant, nor were there significant differences between the two groups' preoperative and postoperative SF-36 scores.

Discussion and Conclusion: Early results of this prospective, randomized study suggest that the bipolar endoprosthesis provides no advantage in the treatment of displaced femoral neck fractures in the elderly. These results are preliminary, and the numbers of patients enrolled have not yet satisfied statistical power requirements. Further study is warranted to determine the true cost-effectiveness and relative efficacy of these two implants.