PROBLEM TO BE SOLVED: To provide an osteotomy instrument easily cutting off the acetabuli into a substantially spherical shape.SOLUTION: An osteotomy instrument 10 includes a blade 12, a holding member 14, an oscillation mechanism 16, and a guide member 18. The blade 12 has a thin-plate-like shape, has a partial shape of the spherical surface and moves along the spherical surface. The holding member 14 holds the blade 12 at an end side with respect to the center of the blade 12. The oscillation mechanism 16 oscillates the blade 12 along both directions of the blade 12. Both ends of the holding member 14 are mounted on the guide member 18. The guide member 18 is rotated about a rotating axis BL passing through the center of the spherical surface along which the blade 12 moves, and is so configured that the holding member 14 linearly moves in a great-circle direction including an intersection of the rotating axis BL and the spherical surface. The longitudinal length of the blade 12 is not less than 1/4 and not more than 1/2 of the circumference of the great circle.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2016,JPO&INPIT【課題】寛骨臼をほぼ球状に容易に切り離す骨切り工具を提供する。【解決手段】骨切り工具10は、刃12と、保持部材14と、振動機構16と、ガイド部材18とを備えている。刃12は、薄板状で球面の一部の形状を備え、この球面に沿って移動する。保持部材14は、刃12の中心より端側で刃12を保持する。振動機構16は、刃12の面方向に沿って刃12を振動させる。保持部材14の両端は、ガイド部材18に装着されている。ガイド部材18は、刃12が移動する球面の中心を通る回転軸BLで回転し、保持部材14が回転軸BLとこの球面の交点を含む大円方向に直線状に移動できるように構成されている。刃12の長手方向の長さは、この大円の周の長さの1/4以上1/2以下である。【選択図】図1
