Humeral component of a shoulder prosthesis
A humeral component of a shoulder prosthesis encloses a stem module which has a shank and an upper shank portion with a stem support surface. A joint adapter is adapted to hold either a liner or a spherical cap. The joint adapter has an adapter support surface which interfaces with the stem support surface. Further, the stem support surface and the adapter support surface have corresponding radial arc shaped sections which allow positioning of the joint adapter against the stem module at different inclination angles. For fastening the joint adapter to the stem module, a bolt or screw is provided.
1. A humeral component of a shoulder prosthesis comprising:
a stem module comprising a shank and an upper shank portion with a stem support surface, and
a joint adapter adapted to hold either a liner or a spherical cap, the joint adapter having an adapter support surface which interfaces with the stem support surface, the joint adapter having a plurality of holes for inserting a fastening device dependent on an inclination angle corresponding to the inclination angle of a patient's humeral joint;
wherein the stem support surface and the adapter support surface have corresponding approximately radial arc shaped sections which comprise segments of a cylinder shell surface with a radius and a center axis for positioning of the joint adapter against the stem module at different inclination angles between the longitudinal axis of the stem module and the center axis of the joint adapter; and
wherein the joint adapter is fastened to the stem module.
2. The humeral component of a shoulder prosthesis according to claim 1 , wherein the stem support surface and the adapter support surface have corresponding protrusions and recesses to prevent pivoting of the joint adapter against the stem module.
3. The humeral component of a shoulder prosthesis according to claim 1 , wherein the radial arc shaped section of the stem module extends from, or within, a medial boundary to a lateral boundary of the most proximal aspect of the stem module.
4. The humeral component of a shoulder prosthesis according to claim 1 , wherein at least one hole is provided in the stem module to allow fastening of a bolt or screw in the at least one hole to fix the joint adapter at alternate positions relative to the stem module.
5. The humeral component of a shoulder prosthesis according to claim 1 , wherein a single, continuous cavity is formed from the stem module surface into the body of the stem module to hold the bolt or screw.
6. The humeral component of a shoulder prosthesis according to claim 5 , wherein the substantial portion of the cavity below the surface is greater in width from the opening at the surface.
7. The humeral component of a shoulder prosthesis according to claim 1 , wherein a ball screw is used for fastening the joint adapter to the stem module which has a threaded proximal section, and distal spherical section.
8. The humeral component of a shoulder prosthesis according to claim 1 , wherein fastening device inserted into the plurality of holes of the joint adapter comprises a bolt or screw.
9. The humeral component of a shoulder prosthesis according to claim 1 , wherein the joint adapter is cup shaped and adapted to hold a liner.
10. The humeral component of a shoulder prosthesis according to claim 9 , wherein the liner has a recessed spherical concavity which is located centrally originating from a surface.
11. The humeral component of a shoulder prosthesis according to claim 1 , wherein the joint adapter is a trunion to hold a spherical cap.
12. The humeral component of a shoulder prosthesis according to claim 11 , wherein the trunion has a substantially planar front surface opposing the adapter support surface which is intersected by a protrusion having a cavity located central to the protrusion which extends through the joint adapter.