アレンドロネート長期服用例に発生した大腿骨転子下骨折の1例

Subtrochanteric Femoral Fracture in a Patient on Long-term Alendronate Therapy. Case Report

　アレンドロネート内服期間3年の76歳の女性が非外傷性大腿骨転子下骨折を来したので報告する．発症1年半前から左下肢痛を認め，翌年に単純X線像で大腿骨転子下外側に骨性隆起，MRIのT2強調画像で転子下に高信号領域を認めた．その後，突然に大腿骨転子下での斜骨折を来した．自家骨移植と骨接合術を施行して骨癒合を得た．アレンドロネート内服でリモデリングが抑制され，生理的弯曲部での転子下での微小骨折が治癒されずに完全骨折に至ったと考えられた．定期的に疼痛の有無を確認し，画像検査で異常を見落とさないことが重要である．

　A 76-year old female who had on alendronate therapy for 3 years, developed a nontraumatic subtrochanteric fracture of the left femur.　She had experienced pain in her left thigh for 18 months before the fracture.　An X-ray and MRI T2 image acquired 6 months before the fracture showed bony upheaval and high signal intensity in the subtrochanteric region.　The fracture united 5 months after placement of an intramedullary nail and an autograft.　It appeared that alendronate suppressed bone remodeling, and that failure of a micro-fracture in the femoral subtrochanteric area to heal for a long time had led to a more serious fracture.　We concluded that it is important not to overlook abnormal findings and bony reactions to micro-fracture on X-ray and MRI images.