| 摘要 |
PROBLEM TO BE SOLVED: To improve compression strength of a bone caput ball and to widely increase strength of the bone caput ball to enable to improve working efficiency, by providing an inward narrowing taper hole and a void in a deep part on a bone caput ball made of ceramics and forming the periphery wall face of the void almost parallel to the central axis of the taper hole. SOLUTION: A bone caput ball (B) made of alumina, zirconia, etc., is rotatably accepted into an acetabulum socket. An inward narrowing taper hole (b) is bored in the bone caput ball (B). In the deeper side of the taper hole (b), a void (e) with a periphery wall face (7e1) almost perpendicular, i.e., almost in parallel with the central axis 1 of the taper hole (b), is bored. Thereby the tip end part of a stem (S) of this artificial hip joint abuts on only the taper wall face at a place deeper than 1/2 of the wall length of the taper hole (b) of the bone caput ball (B). Since the load stress applied on the abutting face between the bone caput ball (B) and the stem (S) can be distributed on the surrounding of the void (e), the compression strength of the bone caput ball (B) can be improved. |
