Does a bipolar hemiprosthesis offer advantages for elderly patients with neck of femur fracture? A clinical trial with 261 patients

Abstract

Previous studies comparing unipolar and bipolar hemiarthroplasty for treatment of displaced intracapsular femoral neck fractures in elderly patients have often lacked methodological power and yielded conflicting clinical results. The objective of this study was to compare the clinical outcomes from each implant in a randomized cohort of elderly patients with intracapsular fracture of the femoral neck treated with a cemented hemiprosthesis. This study is a clinical trial of 261 patients (82.0 ± 7.9 years) who were randomly assigned to one of the two treatment groups: group 1 (n = 133) received a cemented bipolar implant and group 2 (n = 128) received a unipolar head with the same stem. At 12 months post-surgery, pain and functional abilities were quantified by blinded assessors using the Oxford and Harris Hip Scores, Verbal Numerical Rating Score and Six-Minute Walk. The Mann-Whitney U-test and t-test for independent samples were used to compare results between the groups (P < 0.05). There were no significant differences in any clinical scores between the groups. Results from the Six-Minute Walk indicated no difference in functional walking ability or endurance (P = 0.446) between the groups. Self-selected pain ratings also did not differ between groups (P = 0.236). Patients receiving the unipolar prosthesis had significantly reduced abduction (P = 0.0001) and internal rotation (P = 0.047) in the operated hip compared to the non-operated hip. These short-term results suggest that unipolar implants share many of the advantages of the bipolar prosthesis but can be manufactured at substantially lower cost. These implants may be appropriate for the less-active elderly patient, particularly when used with bone cement.