A review of atypical subtrochanteric femoral fractures in Northern Ireland between 2010 and 2014

The term atypical femoral fractures most commonly occur in the subtrochanteric area. Concerns exist regarding the role of bisphosphonate treatment in their aetiology. Which surgical intervention provides the best outcome remains contentious. We reviewed all atypical subtrochanteric femoral fractures treated in Northern Ireland over 5 years, specifically investigating incidence, prodromal symptoms, association with bisphosphonates and optimal fixation methods. All subtrochanteric fractures treated in the region were identified and reviewed for atypical features. Case notes and imaging were then reviewed for each patient. A total of 364 subtrochanteric femoral fractures were identified during the 5-year study period. Twenty-six of these met the criteria for an atypical fracture (7%). Thirteen patients (50%) had presented with prodromal symptoms prior to complete fracture, six of which had radiological evidence of an incomplete fracture of the lateral cortex. Thirteen patients had a history of bisphosphonate treatment. All were treated operatively, with twenty-five cephalomedullary nails and one dynamic hip screw. Twenty-one patients had follow-up for greater than 2 months, nine of which (42.9%) achieved radiological union with a mean time to union of 297 days. Dynamically locked nails had a higher union rate than statically locked (80% versus 33.3%). Four patients required major revision surgery (15.4%). The quality of reduction was statistically significant in predicting need for revision. Atypical fractures often present with prodromal symptoms. Complete fractures are difficult to successfully manage with longer than expected times to union. Treatment with a dynamically locked, cephalomedullary with a good reduction provided the best results.