Atypical Versus Typical Subtrochanteric Femoral Fractures

Abstract

Background: The purpose of the present study was to evaluate differences in demographic features and clinical outcomes between patients who sustained a typical versus atypical subtrochanteric femoral fracture. Methods: We reviewed the records for a cohort of consecutive patients who had undergone operative treatment of a subtrochanteric femoral fracture. Fractures were classified as either “typical” or “atypical” on the basis of the criteria of the American Society for Bone and Mineral Research (ASBMR). All patients were treated with a similar surgical algorithm and postoperative protocol. Groups were compared on the basis of demographic features, injury characteristics, operative quality measures, postoperative complications and outcomes, and radiographic time to healing. Comparative analyses were performed to compare the typical and atypical cohorts. Results: Of 220 subtrochanteric fractures, 165 (75.0%) were classified as typical and 55 (25.0%) were classified as atypical. The atypical cohort was predominately female and more likely to have bisphosphonate usage (odds ratio [OR], 7.975; [95% confidence interval (CI), 3.994-15.922]; p < 0.001) and fractures with lower-energy mechanisms (p < 0.001). Patients in the atypical cohort were more likely to be treated with a 10-mm cephalomedullary nail (CMN) (OR, 2.100 [95% CI, 1.119-3.939]; p = 0.020), whereas patients in the typical cohort were treated more frequently with an 11-mm CMN (OR, 0.337 [95% CI, 0.168-0.674]; p = 0.002). There were no differences between the groups in terms of other operative parameters; however, anatomic fracture reduction in neutral lateral alignment was achieved more frequently in the typical cohort (OR, 0.438 [95% CI, 0.220-0.875]; p = 0.018). There were no differences between the groups in terms of hospital quality measures, mortality rates, readmission rates, or complication rates (including implant failure [broken screw or nail] and fracture nonunion) (p = 1.00). Interestingly, there was no significant difference between the groups in terms of time to radiographic healing (260.30 ± 187.97 days in the typical group, compared with 246.40 ± 116.33 days in the atypical group) (OR, 0.999 [95% CI, 0.997-1.002]; p = 0.606). Conclusions: Despite differences in terms of demographic and injury characteristics, patients who sustain a subtrochanteric femur fracture can expect similar outcome profiles regardless of fracture type. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.