| 摘要 |
PURPOSE: To sufficiently fix even a bone of irregular shape by providing a spacer having one side tightly placed on a rod type member and a recess at the other side for fitting the spherical and projected cutout lower part of a screw head. CONSTITUTION: Each screw 4 to be inserted is provided with a spacer 7, and this spacer 7 is placed on a rod type member 1 not faced to a bone, thereby acting as the bearing of the screw 4. Also, the screw 4 has a spherical cutout part 6 below the head 5 thereof for fitting to a spherical cutout recess 8 formed on the spacer 7. in addition, the recess 8 and the cutout part 6 are formed to have the same radius. As a result, the screw 4 can be screwed to a bone tissue at an angle within the spatial range of approximately±20 degrees. In this case, the whole of the screw head 5 on the spacer 7 is sufficiently placed on the rod type member 1 via the spacer 7, thereby providing a substantially improved fixed state.
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