We performed a retrospective review of all patients admitted to two large University Hospitals in the United Kingdom over a 24-month period from January 2008 to January 2010 to identify the incidence of atypical subtrochanteric and femoral shaft fractures and their relationship to bisphosphonate treatment. Of the 3515 patients with a fracture of the proximal femur, 156 fractures were in the subtrochanteric region. There were 251 femoral shaft fractures. The atypical fracture pattern was seen in 27 patients (7%) with 29 femoral shaft or subtrochanteric fractures. A total of 22 patients with 24 atypical fractures were receiving bisphosphonate treatment at the time of fracture. Prodromal pain was present in nine patients (11 fractures); 11 (50%) of the patients on bisphosphonates suffered 12 spontaneous fractures, and healing of these fractures was delayed in a number of patients. This large dual-centre review has established the incidence of atypical femoral fractures at 7% of the study population, 81% of whom had been on bisphosphonate treatment for a mean of 4.6 years (0.04 to 12.1).

This study does not advocate any change in the use of bisphosphonates to prevent fragility fractures but attempts to raise awareness of this possible problem so symptomatic patients will be appropriately investigated. However, more work is required to identify the true extent of this new and possibly increasing problem.

We carried out a retrospective review over ten months of patients who had presented with a low-energy subtrochanteric fracture. We identified 13 women of whom nine were on long-term alendronate therapy and four were not. The patients treated with alendronate were younger, with a mean age of 66.9 years (55 to 82) vs 80.3 years (64 to 92) and were more socially active. The fractures sustained by the patients in the alendronate group were mainly at the femoral metaphyseal-diaphyseal junction and many had occurred after minimal trauma. Five of these patients had prodromal pain in the affected hip in the months preceding the fall, and three demonstrated a stress reaction in the cortex in the contralateral femur.

Our study suggests that prolonged suppression of bone remodelling with alendronate may be associated with a new form of insufficiency fracture of the femur. We believe that this finding is important and indicates the need for caution in the long-term use of alendronate in the treatment of osteoporosis.

Management of bisphosphonate-associated subtrochanteric fractures remains opinion- or consensus-based. There are limited data regarding the outcomes of this fracture.

We retrospectively reviewed 33 consecutive female patients with a mean age of 67.5 years (47 to 91) who were treated surgically between May 2004 and October 2009. The mean follow-up was 21.7 months (0 to 53). Medical records and radiographs were reviewed to determine the post-operative ambulatory status, time to clinical and radiological union and post-fixation complications such as implant failure and need for second surgery.

The predominant fixation method was with an extramedullary device in 23 patients. 25 (75%) patients were placed on wheelchair mobilisation or no weight-bearing initially. The mean time to full weight-bearing was 7.1 months (2.2 to 29.7). The mean time for fracture site pain to cease was 6.2 months (1.2 to 17.1). The mean time to radiological union was 10.0 months (2.2 to 27.5). Implant failure was seen in seven patients (23%, 95 confidence interval (CI) 11.8 to 40.9). Revision surgery was required in ten patients (33%, 95 CI 19.2 to 51.2).

A large proportion of the patients required revision surgery and suffered implant failure. This fracture is associated with slow healing and prolonged post-operative immobility.

Cite this article: Bone Joint J 2014;96-B:658–64.