Patient specific femoral prosthesis

1. A femoral prosthesis comprising:

an elongate core body that extends along a central core body axis from a proximal core body end to a distal core body end opposite the proximal core body end, wherein the elongate core body defines a medial core body side and a lateral core body side opposite the medial core body side substantially along a medial-lateral direction that is substantially perpendicular to the central core body axis;

a neck that extends out with respect to the elongate core body; and

a porous casing that encases at least a portion of the core body, wherein the porous casing faces the core body and defines an outer casing surface opposite the core body, wherein the porous casing defines an anterior casing side and a posterior casing side opposite the anterior casing side substantially along an anterior-posterior direction that is substantially perpendicular to each of the central core body axis and the medial-lateral direction,

wherein one of the medial core body side and the lateral core body side is spaced from the anterior casing side a first distance along the anterior-posterior direction, the one of the medial core body side and the lateral core body side is spaced from the posterior casing side a second distance along the anterior-posterior direction, the other of the medial core body side and the lateral core body side is spaced from the anterior casing side a third distance along the anterior-posterior direction, and the other of the medial core body side and the lateral core body side is spaced from the posterior casing side a fourth distance along the anterior-posterior direction, wherein the first, second, third, and fourth distances are measured in a plane that is oriented substantially perpendicular to the central core body axis, and

wherein the first and fourth distances are greater than each of the second and third distances.

2. The femoral prosthesis of claim 1 , wherein the core body is elongate along a central core body axis, the neck extends out with respect to the core body along a central neck axis that defines a fixed neck angle with respect to the central core body axis, and the central neck axis defines a selectable neck angle with respect to the central outer casing axis, wherein the selectable neck angle is different than the fixed neck angle.

3. The femoral prosthesis of claim 2 , wherein the selectable neck angle ranges up to approximately 30 degrees.

4. The femoral prosthesis of claim 1 , wherein the casing defines an inner casing surface that faces the core body, and the outer casing surface is opposite the inner casing surface.

5. The femoral prosthesis of claim 4 , wherein the casing defines a medial casing side and a lateral casing side that each extend from the anterior casing side to the posterior casing side, the medial casing side is spaced from the lateral casing side along a medial direction, and the casing has a thickness at the anterior casing side that increases as the anterior casing side extends in the medial direction, the thickness being measured from the inner casing surface to the outer casing surface.

6. The femoral prosthesis of claim 5 , wherein the thickness of the casing at the posterior casing side decreases as the posterior casing side extends in the medial direction.

7. The femoral prosthesis of claim 4 , wherein the casing defines a medial casing side and a lateral casing side that each extend from the anterior casing side to the posterior casing side, the medial casing side is spaced from the lateral casing side along a medial direction, and the casing has a thickness at the anterior casing side that decreases as the anterior casing side extends in the medial direction, the thickness being measured from the inner casing surface to the outer casing surface.

8. The femoral prosthesis of claim 7 , wherein the thickness of the casing at the posterior casing side increases as the posterior casing side extends in the medial direction.

9. The femoral prosthesis of claim 4 , wherein the inner surface of the porous casing extends along a central inner casing axis that is substantially coincident with the central core body axis, and the outer surface of the porous casing extends along a central outer casing axis that intersects the central inner casing axis within an outer perimeter of the core body with respect to a side elevation view that includes the proximal core body end, the distal core body end, the medial core body side, and the lateral core body side.

10. The femoral prosthesis of claim 9 , wherein with respect to a side elevation view of the femoral prosthesis that includes the proximal core body end, the distal core body end, the medial core body side, and the lateral core body side, the thickness at a first side of the porous casing increases as the casing extends in a distal direction from the proximal core body end to the distal core body end, and the thickness at a second side of the porous casing decreases as the casing extends in the distal direction, the second side is opposite the first side.

11. The femoral prosthesis of claim 9 , wherein medial and lateral sides of the outer casing surface taper toward each other as they extend distally.

12. The femoral prosthesis of claim 1 , wherein the central core body axis is curved.

13. The femoral prosthesis of claim 1 , wherein the neck extends out with respect to the core body along a central neck axis, and the femoral prosthesis defines a neck offset from the porous casing to the neck along the central neck axis.

14. The femoral prosthesis of claim 1 , wherein the one of the medial core body side and the lateral core body side is defined by the medial core body side, and the other of the medial core body side and the lateral core body side is defined by the lateral core body side.

15. The femoral prosthesis of claim 1 , wherein the one of the medial core body side and the lateral core body side is defined by the lateral core body side, and the other of the medial core body side and the lateral core body side is defined by the medial core body side.