PROSTHESIS INCLUDING BALL AND SOCKET ARRANGEMENT
FIG7B is a section view, similar to that of FIG7A, but for an alternate embodiment
FIG7B shows a second embodiment of the prosthesis 10'. In this embodiment, the legs 52', 54' of the cap 48' are received in grooves 62', 64' formed on the inner surface of the base. In this case, the space between the legs 52', 54' is less than in the previous embodiment, and the inner surfaces of the legs 52', 54' have a partial spherical shape and become part of the socket that is in contact with the ball 18. In this case, the ball 18 prevents the legs 52', 54' from moving inwardly, and the inner surface of the cap base 50' that contacts the outer surface of the legs 52', 54' prevents the legs 52', 54' from moving apart outwardly, in the "Y" direction. The edges of the grooves 62', 64' prevent the legs from moving in the "Z" direction.
section view
52
legs leg
84
14
screws
50
base
['1. A prosthesis (10) for replacing a mammalian joint, comprising: a first body (16), including a ball (18) mounted on a shaft; a second body (12), including a base (50) and a cap (48) which secures to the base, said base and cap each having an inner surface (56, 66) and an outer surface, with the inner surfaces of the base and cap together defining a socket which receives and traps the ball and supports the ball for rotation relative to the second body; characterized in that  one of said inner and outer surfaces of said base defines a first groove (62), and said cap has a first leg (52) projecting in a first direction and being received in said first groove by sliding into said first groove in said first direction; and further in comprising a second leg (54) and a second groove (64) lying parallel to and directly opposite said first leg and said first groove, wherein said first leg defines a first leg opening (74) having an axis extending in a direction that is cross-wise to the first direction, said second leg defines a second leg opening (76) coaxial with the first leg opening, and said base defines a base opening which is aligned with said first leg opening when the base and cap are assembled together; and a pin (78) received in said first leg opening, said second leg opening, and said base opening and extending in the cross-wise direction to secure the cap and base together so that an attempt to slide the cap and base apart from each other in the first direction applies shear forces to the pin; and means for preventing the first leg from moving outwardly away from the first groove in the cross-wise direction when the first leg is received in the first groove; wherein said means for preventing the first leg from moving outwardly away from the first groove includes at least a portion of said base contacting the outer surface of the first leg.']