Femoral stress fractures associated with long-term bisphosphonate treatment

Abstract

Background: Recent studies have described unique clinical and radiographic characteristics of femoral stress fractures or low-energy fractures associated with long-term bisphosphonate therapy. However, it is unclear whether these fractures require subsequent surgery after the initial treatment.

Questions/purposes: We performed a cohort analysis of bisphosphonate-associated femoral stress fractures to (1) confirm the unique clinical and radiographic findings compared with existing literature, (2) determine whether any patients with completed fractures had no preexisting transverse stress fracture lines, (3) assess the need for additional surgical procedures, and (4) determine whether the hospital length of stay (LOS) differed for patients with prophylactic fixation of stress fractures versus fixation of completed fractures.

Methods: We retrospectively reviewed 16 patients with 24 diaphyseal and subtrochanteric femoral stress fractures (14) or low-energy fractures (10) who had been on bisphosphonates for 3 to 10 years. Data included demographics, symptoms, medication history, radiographic characteristics, treatment parameters, LOS, and outcome. Minimum followup was 9 months (average, 44.0 months; median, 31 months; range, 9-112 months).

Results: All patients had clinical and radiographic findings similar to those reported in the literature. Two of four patients sustained completed fractures after radiographs failed to reveal transverse lateral fracture lines. None of the 14 prophylactically treated impending fractures progressed or required additional surgery; however, in five of 10 femurs treated after fracture completion, six additional surgeries were performed. The average hospital LOS was shorter in patients who underwent prophylactic fixation (3.8 days) than in patients treated for completed fractures (5.6 days).

Conclusions: Bisphosphonate-associated stress fractures and completed fractures are unique, possessing subtle characteristic radiographic features. Completed fractures may occur through the thickened bone in the absence of an appreciable transverse stress fracture line. Our observations suggest prophylactic reconstruction nail fixation may avoid fracture completion and may be associated with a shorter hospital LOS and less morbidity than treatment of completed fractures.

Level of evidence: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.