末期変形性股関節症の同側に生じた大腿骨転子下骨折の3例

Subtrochanteric Fracture and Coxarthrosis in an Injured Hip. Report of 3 Cases

　変形性股関節症（OA）に生じた大腿骨転子下骨折を3例経験したので報告する．OA患者の同側に生じる大腿骨頚部骨折では，内側骨折よりも外側骨折が生じやすいと言われている．OAが存在すると大腿骨頚部と寛骨臼後面のimpingementを起こすだけの十分な可動域がないこと，大腿骨骨頭および頚部の骨硬化，さらに大腿骨の骨粗鬆化のために，外側骨折が生じやすいものとされている．今回の3症例は，非常に高齢で同様の骨折形態をとっていた．OAに加えて強い骨粗鬆化が転子下骨折の原因と考えられた．

　We report three cases of subtrochanteric fracture that occurred in a hip affected by coxarthrosis. Coxarthrosis of the hip is rarely associated with an ipsilateral intracapsular femoral neck fracture, but intertrochanteric fractures occur in hips affected by coxarthrosis. Coxarthrosis patients are susceptible to extracapsular fractures because they do not have a full enough range of motion to thrust the femoral neck against the posterior margin of the acetabulum and they have sclerosis of femoral head and neck and osteoporosis. Our three cases were in very old patients and exhibited the same fracture pattern. They suggest that severe osteoporosis in addition to coxarthrosis may cause such subtrochanteric fractures.