PROBLEM TO BE SOLVED: To spread a notch while simply preventing backward tilting of a bone.SOLUTION: A bone spreading device 1 comprises: a pair of swing members 3, 4 connected in a swingable manner around a shaft line A of a hinge part 2； a pair of opening/closing members 5, 6 that are to be inserted into a notch formed on a bone and be separated by relative swinging around shaft lines B1, B2 of the swing members 3, 4 to spread the notch； and opening/closing mechanisms 7, 8 for relatively swinging the swing members 3, 4 around the shaft line A. The respective opening/closing members 5, 6 comprise contact faces 5b, 6b that are to come into contact with cut sections of the bone in a state of being inserted into the notch and have a shape for making a distance between the contact faces 5b, 6b larger on the back side of the bone than on the front side thereof.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】骨の後傾を簡易に防止しながら切込みを開大する。【解決手段】ヒンジ部２の軸線Ａ回りに揺動可能に連結された一対の揺動部材３，４と、骨に形成された切込みに挿入され、揺動部材３，４の軸線Ｂ１，Ｂ２回りの相対的な揺動によって離間させられることにより、切込みを開大する一対の開閉部材５，６と、揺動部材３，４を軸線Ａ回りに相対的に揺動させる開閉機構７，８とを備え、各開閉部材５，６が、切込みに挿入された状態で骨の切断面に接触する接触面５ｂ，６ｂを備えるとともに、接触面５ｂ，６ｂ間の距離が、骨の前側よりも後側において大きくなる形状を有する骨開大デバイス１である。【選択図】図１
