Restoration of hip architecture with bipolar hemiarthroplasty in the elderly: does it affect early functional outcome?

INTRODUCTION: Reconstruction of the anatomic architecture correlates with functional outcome in patients receiving elective total hip arthroplasty. In theory similar rules should apply for bipolar hemiarthroplasty in femoral neck fractures. The influence of anatomic restoration after bipolar hemiarthroplasty on short-term clinical and functional outcome is explored in this study.

PATIENTS AND METHODS: Patients receiving bipolar hemiarthroplasty for intracapsular femoral neck fractures between 2010 and 2012 were included into a retrospective cohort study. Radiologic and functional outcome parameters were recorded during the acute care phase and geriatric rehabilitation. Postoperative mobilization data were recorded and co-morbidities documented for each case. Outcome parameters were obtained during geriatric rehabilitation: Barthel index, Tinetti score, Timed up and go test, Mini-Mental State Examination. The FO-ratio (ratio of femoral offset to the body weight lever arm), HC-ratio (ratio of the height of the hip center to the pelvic height) and the BWLA ratio (ratio of the body weight lever arm to the pelvic height) were obtained from postoperative radiographs.

RESULTS: A total of 193 patients with a median age of 84 (IQR = 78-94, 72% female) were analyzed. The in-hospital mortality rate was 5.7%. There was a high proportion of patients with prior co-morbidities (96% with at least one co-morbidity). During rehabilitation the Barthel index improved significantly (p < 0.001) from 40 to 55. The median Tinetti score on rehabilitation discharge was 15.5 (IQR = 10-19.5). The patients significantly improved in the timed up and go test from a median of 22 to 19 s. A significant difference (p < 0.001) was found comparing the FO ratios of the operated vs. non-operated side. None of the radiographic measures, representing the reconstructed anatomic hip geometry, significantly influenced the clinical and geriatric outcome.

CONCLUSIONS: Applying the short-term functional outcome scores used in this study, optimized anatomic restoration in hemiarthroplasty may not be a major influencing factor in a cohort of elder, multi-morbid patients.