Shoulder prosthesis

1. Stemless shoulder prosthesis comprising a fixation device for fixing the prosthesis to a resected humerus bone,

the fixation device comprising a base portion and anchoring means, the base portion having a distal side adapted to contact a resection plane of the bone and a proximal side for carrying a humeral head, and the anchoring means being connected to the distal side of the base portion and adapted to fix the prosthesis to the bone,

wherein the anchoring means define a central axis,

wherein the anchoring means comprise a plurality of protrusions projecting from the base portion, each protrusion extending between an inner end and an outer end, the inner end being closer to the central axis than the outer end; and

wherein the protrusions define a free central space around the central axis and,

wherein the protrusions are provided at their outer ends with wings.

2. Stemless shoulder prosthesis according to claim 1 ,

wherein the inner ends of the protrusions define the free central space.

3. Stemless shoulder prosthesis according to claim 1 ,

wherein the free central space has the shape of a cone widening from the distal side of the base portion and/or

wherein the inner ends of the protrusions diverge from each other.

4. Stemless shoulder prosthesis according to claim 1 , wherein the protrusions are formed as ribs, blades or fins.

5. Stemless shoulder prosthesis according to claim 1 , wherein each protrusion has a height measured from the distal side of the base portion, the height of the protrusion increasing or remaining constant from the outer end towards the free central space, in particular wherein each protrusion has a minimum height at its outer end.

6. Stemless shoulder prosthesis according to claim 1 , wherein at least one protrusion is provided with at least one opening.

7. Stemless shoulder prosthesis according to claim 1 , wherein each protrusion comprises a distal edge which is formed at least partly as a cutting edge.

8. Stemless shoulder prosthesis according to claim 1 , wherein at least one pair of neighboring protrusions is connected by a web, wherein the web extends between the inner ends of the protrusions.

9. Stemless shoulder prosthesis according to claim 1 , wherein the base portion has openings, the openings being arranged between the protrusions.

10. Stemless shoulder prosthesis according to claim 1 , wherein the base portion comprises a plate.

11. Stemless shoulder prosthesis comprising a fixation device for fixing the prosthesis to a resected humerus bone,

the fixation device comprising a base portion and anchoring means, the base portion having a distal side adapted to contact a resection plane of the bone and a proximal side for carrying a humeral head, and the anchoring means being connected to the distal side of the base portion and adapted to fix the prosthesis to the bone,

wherein the anchoring means define a central axis,

wherein the anchoring means comprise a plurality of protrusions projecting from the base portion, each protrusion extending between an inner end and an outer end, the inner end being closer to the central axis than the outer end; and

wherein the protrusions define a free central space around the central axis,

wherein at least one pair of neighboring protrusions is connected by a web, wherein the web extends between the inner ends of the protrusions,

wherein the web is provided with a cutting edge,

and wherein the cutting edge of the web merges into cutting edges of the neighboring protrusions.

12. Stemless shoulder prosthesis according to claim 11 ,

wherein the protrusions and the web have a height measured from the distal side of the base portion, the height of the web being smaller than the height of the protrusions.

13. Stemless shoulder prosthesis according to claim 11 , wherein the web is provided with at least one opening.

14. Stemless shoulder prosthesis according to claim 11 , wherein the protrusions are provided at their outer ends with wings.

15. Stemless shoulder prosthesis comprising a fixation device for fixing the prosthesis to a resected humerus bone,

the fixation device comprising a base portion and anchoring means, the base portion having a distal side adapted to contact a resection plane of the bone and a proximal side for carrying a humeral head, and the anchoring means being connected to the distal side of the base portion and adapted to fix the prosthesis to the bone,

wherein the anchoring means define a central axis,

wherein the anchoring means comprise a plurality of protrusions projecting from the base portion, each protrusion extending between an inner end and an outer end, the inner end being closer to the central axis than the outer end; and

wherein the protrusions define a free central space around the central axis, and

wherein the base portion comprises a radially outer ring, a radially inner portion and radial spokes extending between the outer ring and the inner portion.

16. Stemless shoulder prosthesis according to claim 15 , wherein each protrusion extends radially from the outer end to the inner end.

17. Stemless shoulder prosthesis according to claim 15 ,

wherein the inner ends of the protrusions define the free central space.

18. Stemless shoulder prosthesis according to claim 15 ,

wherein the free central space has the shape of a cone widening from the distal side of the base portion and/or

wherein the inner ends of the protrusions diverge from each other.

19. Stemless shoulder prosthesis according to claim 15 , wherein the protrusions are formed as ribs, blades or fins.

20. Stemless shoulder prosthesis according to claim 15 , wherein each protrusion has a height measured from the distal side of the base portion, the height of the protrusion increasing or remaining constant from the outer end towards the free central space, in particular wherein each protrusion has a minimum height at its outer end.