Failure of Intramedullary Nailing for Subtrochanteric Atypical Femoral Fractures Caused by Endosteal Cortical Thickening

Financial support: This work was supported by the Academic Research Foundation of Jeju National University Institute of Medical Science in 2014. Conflict of interests: None. Purpose: Recent literature has noted incidences of subtrochanteric atypical femoral fractures (AFFs) in patients who have taken long-term bisphosphonates (BPs). Most cases of subtrochanteric AFFs have been treated with intramedullary nailing and cases of delayed union have been reported. On the other hand, there is no data available on the complications associated with endosteal thickening or cortical thickening. This study evaluated the results of surgical treatment according to the endosteal thickening of the lateral cortex in subtrochanteric AFFs. Materials and Methods: Investigation was performed at the Department of Orthopaedic Surgery, Jeju National University Hospital. The study consisted of patients with subtrochanteric AFFs, defined by the American Society for Bone and Mineral Research (ASBMR) major criteria, who underwent intramedullary nailing from March 2012 to October 2014. The cases were categorized into two groups based on the presence of endosteal thickening. The evaluation included the demographic data, radiographic data of initial reduction state, and duration of BPs. Results: The demographic data and duration of BPs were similar in the two groups. On the other hand, varus reduction (Group I: 12.5% vs. Group II: 78.9%; p=0.001), delayed union (Group I: 0% vs. Group II: 70.0%; p=0.003), nonunion (Group I: 0% vs. Group II: 47.4%; p=0.017), and union time (Group I: 5.5 months vs. Group II: 8.3 months; p<0.001) were significantly different in the two groups. Conclusion: Endosteal thickening of the lateral cortex in subtrochanteric AFFs was identified as an independent factor that decides the reduction of the fracture and nonunion. The endosteal thickening should be removed to obtain anatomical alignment for successful surgical results.