Femoral shaft fractures in the elderly – Role of prior bisphosphonate therapy
Introduction
There has been a recent surge in interest in bisphosphonate-related fractures and a number of studies looking into the association between low-impact fractures and the use of bisphosphonates have been published.12, 18, 19, 27, 28 Odvina et al. suggested prolonged alendronate therapy as a possible cause of the low energy non-spinal fractures in her study due to suppressed bone turnover.28 Goh et al. subsequently published a retrospective report on low-impact subtrochanteric fractures in patients on long-term alendronate therapy and proposed an association between long-term alendronate use and insufficiency fractures of the femur.12 The effects of long-term bisphosphonate use on bone metabolism still remain unclear.
Femoral shaft fractures typically occur in young adult males as a result of major trauma.26, 31 In the elderly age group, such fractures are commonly pathological fractures, with a female preponderance.17, 31 The association between low-impact femoral shaft fractures and alendronate use has recently been studied by Neviaser et al.27 and Lenart et al.19 looking at characteristic fracture patterns in this group of patients.
Our study retrospectively reviewed elderly patients admitted to our hospital with femoral shaft fractures over a 4-year period with a particular focus on patients with a history of prior bisphosphonate therapy. We predicted an association between the long-term use of bisphosphonates and low-impact femoral shaft fractures.
Section snippets
Materials and methods
The study was designed as a retrospective analysis of all elderly patients (>60 years old) with femoral shaft fractures admitted to the National University Hospital, Singapore, over a 4-year period from January 2003 to January 2007. Ethical approval from the Institutional Review Board (IRB) was obtained prior to the conduct of the study. The femoral shaft was defined as the segment of the femur lying 5 cm distal to the lesser trochanter and 8 cm proximal to the adductor tubercle4 in the study.
Results
Of the 49 patients studied, 7 had been on alendronate therapy prior to the fracture. The mean duration of alendronate use was 34.3 months (range, 24–72 months). No other types of bisphosphonates were used by any of these patients. All of these patients were females. The mean age of these 7 patients was 77.3 years (range 70–94 years).
Of these 7 patients who were previously on alendronate therapy, 4 had sustained their fractures from atraumatic mechanisms of injury, whilst 3 had sustained their
Discussion
Adynamic bone disease from prolonged use of anti-resorptive drugs like alendronate has become an area of growing research interest in recent years. Alendronate has been highly successful as a first-line therapy in the treatment of postmenopausal osteoporosis, through its inhibition of osteoclastic activity which results in increased bone mineral density.1, 3 Its efficacy has been demonstrated by the Fracture Intervention Trial (FIT), a multicenter randomised controlled study, which showed that
Conclusion
In conclusion, this is a new entity of fractures seen exclusively in patients on alendronate treatment. These fractures are usually atraumatic or from low-impact trauma and X-rays show characteristic lateral cortex thickening with a beaked appearance at the site of fracture, indicative of a previous stress fracture. It is essential to rule out underlying metabolic diseases in these patients through biochemical tests and radiographic screening of the contralateral femur. Adynamic bone disease in
Conflict of interest statement
There is no conflict of interest in the conduct of this research project. None of the authors of this paper received financial or other personal benefits from the conduct and writing of this study.
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Stress fracture of the bowed femoral shaft is another cause of atypical femoral fracture in elderly Japanese: A case series
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