Bone Abstracts

Background: Atypical fractures (AF) of femoral shaft have distinct radiologic features and are probably related to prolonged bisphosphonate (BP) exposure. They are currently considered to be insufficiency fractures occurring in osteoporotic bone. After initial damage, the repair process calls for accelerated remodeling, but the later is prevented by BP accumulation on the remodeling site. Thus, the fracture expands instead of healing. The management is not postulated, but anabolic treatment makes sense and a few case reports regarding teriparatide use have been published. Long-term follow-up data is lacking. The aim of this report was to summarize our experience with AF patients – clinical characteristics, treatment and outcomes.

Patients: Seven female patients were followed prospectively since 2008. The median age was 66. All of them were BP exposed, and mean treatment duration was 8 years. Two patients were steroid treated. The majority (57%) sustained osteoporotic fractures prior to the index event. None smoked. Their vitamin D levels were >20 ng/ml, in all. Bone density prior to AF was in the osteoporotic range: lumbar spine T-score − 3.48+1.1 and femoral neck− 2.9±1.

Results: Three patients presented with complete shaft fracture, four had lateral cortex incomplete fractures (one of those bilateral). Bisphosphonate was discontinued in all patients and six (85%) were offered teriparatide (TPT) treatment. Two patients with lateral cortex incomplete fractures progressed to a complete fracture while on TPT. Median follow-up was 48 months. Hip bone density was significantly improved. None sustained another fracture.

Conclusions: AF occurred in high risk patients. In our small cohort, TPT failed to prevent incomplete fracture progression in half of the participants. Anabolic treatment was effective in terms of bone density improvement.