Importance

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Abstract

A complete shoulder joint replacement includes a metal ball and stem for securing at the upper end of the upper arm bone or humerus, with the shape of the ball being spherical at the top and of elliptical cross-section at the juncture with the surface of the upper arm bone; and a concave plastic prosthesis having a keel of generally elliptical cross-sectional configuration matching the shape of the corresponding glenoid recess in the scapula, or shoulder bone. The metal prosthesis which is secured in the upper arm or humerus has a rounded metal stem with a longitudinal rib to prevent rotation and three fins under the head to further assist fixation. The matching glenoid prosthetic replacement is elliptical, both at the articulating surface and within the glenoid recess, to conform to the natural shape of the joint. Fixation grooves encircle the fixation keel, and the keel may be clipped off at the fixation grooves to accommodate various depths of the glenoid recess in the scapula bone. The glenoid prosthesis may be either relatively open, which is the preferred configuration, or somewhat hooded, depending on the strength and development of the 'rotator cuff,' the musculature and associated ligaments and the like which hold the relatively unconstrained shoulder joint in position.

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First Claim