Ulnar head prosthesis system

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 extending about a circumference thereof with a second diameter greater than the first diameter to define at least one attachment shoulder extending about the complete circumference of the bore;
• 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 distal end of the stem has an extended portion defined between the locking flange and a distal end surface.

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 defining a bore end surface and a bore opening opposite thereto;
• and
• a stem having a stem body extending axially between a proximal end configured for implantation in a target bone and a distal end configured to be received axially into the attachment bore opening, the distal end having a distal end surface with at least one projection extending therefrom and configured such that when the distal end is received in the attachment bore, the at least one projection penetrates the bore end surface such that the head material deforms about the at least one projection and prevents relative rotation between the head and the stem.

An ulnar prosthesis assembly comprising:

• a head with a curved surface extending between opposed ends, one of the ends having an ulnar styloid prominence or process with one or more through holes for reattachment of stabilizing soft tissues, the other end having an attachment bore defined therein and having a bore axis, each of the through holes having a hole axis substantially perpendicular to the bore axis;
• 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.

An ulnar prosthesis stem comprising:

• a stem body extending along a stem axis between a proximal end configured for implantation in a target bone and a distal end adapted to be received in an attachment bore of an ulnar prosthesis head, the distal end having a locking flange extending radially therefrom about the complete circumference thereof, the locking flange having a flange axis generally parallel to the stem axis and defining a locking shoulder about the complete circumference of the stem body in a plane generally perpendicular to the stem axis and facing the proximal end.