PROBLEM TO BE SOLVED: To prevent cracks and breakages in a thin sidewall parts of both the sides of an insertion hole by reducing the tension load acting on the parts as a result by gradually reducing compression stress in a proximal side by boring the entrance part of the insertion hole to which the maximum load acts by the moment of a lag-screw to a convex face including the periphery of the same and extending a convex face range to the upper proximal side although the insertion hole of the lag-screw intruding toward a bone head is formed in thigh bone insertion nail.SOLUTION: In the thigh bone insertion nail which is inserted into the thigh bone from the proximal side in which the insertion hole of the lag-screw in the inclination facing bone head is formed, at least the entrance part of the insertion hole is bored into the concave face including the periphery of the same and the concave face range is extended to the proximal side.COPYRIGHT: (C)2012,JPO&INPIT【課題】 大腿骨ネイルには骨頭に向けて侵入するラグスクリューの挿通孔が形成されるが、ラグスクリューのモーメントによって最大の荷重がかかる挿通孔の入口部をその周縁を含んで凹面に抉るととともに、凹面範囲を上方の近位側に延長することで、近位側の圧縮応力を漸減させ、結果として挿通孔の両側の薄い側肉部分にかかる引張荷重を軽減させてこの部分に生ずる亀裂や破断を防止する。【解決手段】 大腿骨に近位側から挿入され、骨頭に向く傾斜でラグスクリューの挿通孔を形成した大腿骨挿入ネイルにおいて、挿通孔の少なくとも入口部をその周縁を含んで凹面に抉るとともに、この凹面範囲を近位側に延長する。【選択図】 図1
