Patent ID: 7875082

Claim:
An ulnar prosthesis assembly comprising: a head formed with a curved surface extending between opposed ends, one of the ends having an attachment bore defined therein, the attachment bore generally having a first diameter and including an attachment groove thereabout with a second diameter greater than the first diameter to define at least one attachment shoulder; and a stem having a stem body extending between a proximal end configured for implantation in a target bone and a distal end configured to be received in the attachment bore, the distal end having a locking flange extending radially therefrom, the locking flange defining a locking shoulder having a diameter greater than the first diameter such that upon receipt in the attachment bore, the locking shoulder engages the attachment shoulder wherein the stem includes a radial collar with a locking groove defined between the locking shoulder and a distal surface of the radial collar and the radial collar includes a secondary collar adjacent a proximal surface of the collar, the secondary collar having a diameter less than a diameter of the radial collar.