Atypical femoral fractures related to bisphosphonate use: a comprehensive review of 19 patients

Abstract

BACKGROUND: Atypical femur fracture is a rare complication of bisphosphonate treatment, which is widely used for the prevention of osteoporotic fractures. This study aims to report clinical and radiological features and outcomes of surgically treated atypical femur fractures related to bisphosphonates. METHODS: We retrospectively reviewed patients with the diagnosis of atypical femur fracture who were under bisphosphonate treatment and who were surgically treated in our clinic between January 2009 and December 2017. Patients who met the atypical femur fracture criteria defined by the American Society for Bone and Mineral Research were included in this study. Radiological features of the fractures, bisphosphonate treatment and duration, prodromal clinical and radiological findings were evaluated. Outcome measures included perioperative results, clinical and radiological outcomes and mobilization status. RESULTS: In this study, 19 patients were enrolled. Mean age of the patients was 69.6 years (range: 60.8-85.1) and the mean follow-up was 33.8 months (range: 13-104). Mean bisphosphonate use duration was 8.65 years (range: 3-18). Four patients had bilateral fractures. Eight of 23 fractures were subtrochanteric and 15 were diaphyseal. Twenty-one fractures were treated with an intramedullary nail, one fracture with a locked compression plate and one fracture with cephalomedullary nail. Union was observed in 15 fractures within the first six months. There was a delayed union in four fractures and non-union in four fractures. Mean union time was 5.1 months (range: 2-9). While seven patients preserved their preoperative mobilization status, 12 patients showed regression after the fracture. CONCLUSION: This study suggests that atypical femur fractures may have prodromal signs and that their management is complex due to high complication and nonunion rates.

Does the Nonunion Rate of Atypical Femoral Fractures Differ According to Fracture Site?: A Meta-Analysis

“…1 ). Among 29 studies, 11 cohort articles included both sites of AFF (subtrochanteric and midshaft), 7 13 16 17 18 19 20 21 22 23 24) 9 cohort studies reported outcomes after surgery of subtrochanteric AFFs, 6 9 10 11 14 25 26 27 28) and 9 single cohort studies reported midshaft AFF. 8 12 15 29 30 31 32 33) The overall incidence of nonunion was 10.3% (77 / 742) in total, 17.5% (52 / 297) in the subtrochanteric AFFs group, and 5.6% (25 / 445) in the midshaft AFFs group ( Table 1 ).…”

“…Although bisphosphonates are known to have a relation to AFF, this may suggest that other factors play a greater role in the healing process of these fractures such as malreduction, which may decrease the contact area between the main fragments. 7 14 19) However, cessation of bisphosphonate after surgery of AFF should be recommended according to the guidelines of American Society for Bone and Mineral Research. 40) …”

“… 43 44) Lateral bowing of the femur was associated with difficulties in choosing the fixation material in AFF, so mastering one of them is essential for clinicians. 7 9 19 29) …”

Histopathological Finding of Microdamage Accumulation in Atypical Subtrochanteric Femoral Fracture

“…BPs inhibit bone resorption and formation. Recently, many cases of AFF caused by the application of low energy have been reported [1][2][3]. Severely suppressed bone turnover (SSBT) is also reported as one of the main causes of AFF [1,4,5].…”