A retrospective review published in the Journal of Orthopaedic Trauma (May/June 2008; Volume 22, Issue 5) examined patients with low-energy femoral shaft fractures admitted to a Level I trauma center between January 2002 and March 2007. Low-energy fractures are fractures that occur with minimal or no trauma and are unusual in otherwise healthy bone.
The investigators identified 70 low-energy femoral fractures. The study population included 59 women and 11 men, with an average age of 74.7 years. Of these patients, 25 (36%) were being treated with alendronate, a bisphosphonate medication commonly prescribed for osteoporosis.
Among the 25 patients taking alendronate, 19 (76%) exhibited a distinctive fracture pattern involving the femoral shaft. These fractures were typically simple, transverse fractures associated with a unicortical “beak” and localized cortical thickening, suggesting altered bone remodeling. In contrast, this fracture pattern was observed in only one patient (2%) who was not receiving alendronate therapy.
Bone is a living tissue that undergoes continuous remodeling through coordinated processes of breakdown (resorption) and rebuilding (formation). In many adults—particularly postmenopausal women—bone resorption can exceed bone formation over time. Bisphosphonates, such as alendronate (Fosamax), risedronate (Actonel), and ibandronate (Boniva), are designed to slow bone resorption and reduce fracture risk.
However, suppressing bone turnover for long periods may have unintended consequences. One concern raised by this and other studies is that microscopic stress fractures, which normally occur and are repaired during routine remodeling, may accumulate when bone turnover is excessively suppressed. Over time, this may contribute to atypical fracture patterns in weight-bearing bones such as the femur.
Another recognized complication of long-term bisphosphonate use is osteonecrosis of the jaw, a rare but serious condition in which bone tissue fails to heal and undergoes necrosis, often following dental procedures.
