PROSTHESIS INCLUDING BALL AND SOCKET ARRANGEMENT
FIG7A is a section view along line 7A-7A of FIG7
A closer look at FIG7A shows that the sides of the legs 52, 54 taper outwardly and that the sides of the grooves 62, 64, which receive the legs 52, 54, taper inwardly with a mating taper. When the legs 52, 54 are received in the grooves 62, 64, as shown in FIG7A, the tapered surfaces of the grooves 62, 64 partially overlie and contact the mating outer surfaces of the legs 52, 54, which prevents the legs 52, 54 from moving outwardly, in the "Y" direction, away from their respective grooves 62, 64. As soon as the legs 52, 54 are received in the grooves 62, 64, the legs 52, 54 are prevented from moving in any direction other than the X direction relative to the grooves. And once the fastener pin 78 is threaded into the prosthesis 10*, the legs 52, 54 also are prevented from moving in the first direction "X", thereby fixing the cap 48 relative to the base 50* in every direction.
section view
80
openings
48
cap
18
ball
62
grooves
34
mounting leg
52
legs leg
78
pin
66
inner surface
50
base
54
second leg
60
projections grooves
68
pin
['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.', '7. A prosthesis for replacing a mammalian joint as recited in claim 4, 5 or 6, wherein the base defines a mounting leg (34) projecting away from the socket for mounting the socket on a bone, the first and second leg openings are adjacent to said mounting leg, and the remainder of the outer surfaces of said base and cap are smooth and nearly continuous, in order to minimize the opportunity for the prosthesis to catch on or interfere with ligaments when the prosthesis is installed.', '8. A prosthesis for replacing a mammalian joint as recited in any preceding claim, wherein each of said first and second grooves lies on the inner surface of the respective cap or base member on which the respective groove is located.']