Problem to be solved: to provide a method of designing a semi custom intervertebral spacer.A three-dimensional orthogonal coordinate system is set in a three-dimensional X-ray projection image of a patient's spine.The first and second free curves fitted to the x-z plane and the intersection of the head end plate and the tail end plate between the object vertebra and the tail end plateThe third and fourth free curves conforming to the intersection of the Y-Z plane and the head end plate and the tail end plate between the object vertebra, respectively, andA vector image data relating to a fifth free curve determining the contour of the intervertebral spacer on the X-Y plane is obtained.Using the vector image data, the first to fifth free curves are rearranged in a three-dimensional Cartesian coordinate system independently of the three-dimensional X-ray projection image, and the head end plate surface, tail end plate surface, and side surface of the intervertebral spacer are generated based on the locus when the free curve is moved in the coordinate system. An intervertebral spacer is formed from these three surfaces.Diagram【課題】セミカスタムメイドの椎間スペーサーを設計する方法を提供する。【解決手段】患者の脊椎の三次元Ｘ線投影画像内に三次元直交座標系を設定し、Ｘ－Ｚ平面と対象椎体間の頭側終板及び尾側終板との交線にそれぞれ適合した第１及び第２の自由曲線と、Ｙ－Ｚ平面と対象椎体間の頭側終板及び尾側終板との交線にそれぞれ適合した第３及び第４の自由曲線と、Ｘ－Ｙ平面上における椎間スペーサーの輪郭を決定する第５の自由曲線とに関するベクトル画像データを取得する。ベクトル画像データを用いて、三次元Ｘ線投影画像とは独立に設定した三次元直交座標系内に第１～第５の自由曲線を再配置し、それらの自由曲線を座標系内で移動させたときの軌跡に基づいて、椎間スペーサーの頭側終板面、尾側終板面及び側面を生成し、それら３つの面から椎間スペーサーを画成する。【選択図】図１
