Abstract: A ball-and-socket joint prosthesis developed for the shoulder has one component in the form of a ball connected through a neck to a stem, a first cup engaged with the ball in a snap fit which is held captive by a first clip connected round the cup, and a second cup releasably engaged around the remainder of the ball. The second cup is slotted from its rim to accommodate the first component neck and so predetermine the relative positions of these parts, and the second cup rim is complementary with that of the first cup to predetermine the relative positions of the cups around the ball. The resultant assembly therefore fixes the relative positions of the one component and first cup to facilitate securement of these parts, while keeping the articular surfaces free of cement, and the second cup is removed after securement to leave a stable captive ball-and-socket joint.

Abstract: An endoprosthetic elbow joint device has a humeral component in the form of two like frusto-cones coaxially connected at their narrow ends and with their wider ends mutually convergently inclined to wedge into the intracondylar notch in the humerus when resected. This component is secured with cement, the component end faces being provided with a relieved structure of grooves or ribs extending in the relevant directions of inclination. The device also has an ulnar component of less than semi-circular toroidal form with its radially inner face complementary to and engaged with the above double cone. Again cement fixation is used in the ulna with a suitable relieved structure to key the component. Preferably this structure includes a chordally-directed groove to allow passage of a bone screw longitudinally through the olecranon so that the latter can be detached to expose the implantation site and thereafter reattached.