System and method for determining an optimal type and position of an implant

1. A computer-assisted orthopaedic surgery system comprising:

a device for generating a three dimensional geometrical surface model of a first bone;

a database containing three dimensional implant models of a plurality of implants; and

a computer configured to

select from the database a first implant and display on a screen the three dimensional implant model of the first implant,

determine a degree of fit of the selected first implant to the first bone by superimposing on the screen an implant model of the first implant on top of the model of the first bone, and

visually represent the degree of fit on the screen by a color map, wherein various colors of the color map represent various distances the implant model of the first implant departs from the model of the first bone.

2. The system of claim 1 , wherein the implant model of the first implant is selected from the database to have an optimal fit to the model of the first bone based on specific target criteria that is entered by the user.

3. The system of claim 2 , wherein the target criteria are one or more criteria selected from the group consisting of: geometrical criteria; matching criteria; functionality criteria; and morphology matching criteria.

4. The system of claim 1 , wherein each implant model stored in the database is in the form of a three dimensional meshed surface.

5. The system of claim 1 , wherein the implant model is depicted on the screen with a first color and the model of the first bone is depicted on screen with a second color that is different from the first color and is visually distinguishable therefrom.

6. The system of claim 1 , wherein the implant model is depicted on the screen with a first transparency and the model of the first bone is depicted on screen with a second transparency that is different from the first transparency and provides two visually distinguishable objects.

7. The system of claim 2 , wherein the computer is configured based on the generation of the model of the first bone to determine which areas, if any, of the first bone are worn or pathological and these areas are displayed on the screen so that the areas are visually distinguishable from both the other normal areas of the first bone and the implant model.

8. The system of claim 7 , wherein the computer weights or completely excludes the areas of the first bone that are worn or pathological less than the normal areas in optimizing the fit.

9. The system of claim 7 , wherein the areas of the first bone that are worn or pathological are depicted in a different color or transparency relative to the normal areas.

10. The system of claim 1 , wherein the three dimensional geometrical surface model of the first bone is provided by image-free means.

11. The system of claim 1 , wherein differences between the implant model of the first implant superimposed on the model of the first bone are highlighted with the color map in which areas where the two models depart the greatest are graphically depicted with a first color intensity and areas where the two models depart the least are graphically depicted with a second color intensity that is less than first color intensity.

12. The system of claim 1 , wherein differences between the implant model of the first implant superimposed on the model of the first bone are highlighted with the color map in which areas where the two models depart the greatest are graphically depicted with a first color and areas where the two models depart the least are graphically depicted with a second color that is less than first color.

13. The system of claim 1 , wherein the differences between the two models reflect a distance of separation between the two models in localized areas, such that the greater the degree of separation, the less optimal the fit between the two models.

14. A computer-assisted orthopaedic surgery system for joint reconstruction or resurfacing comprising:

a position determining device capable of tracking the movement of at least one bone of a joint;

a computer configured to

determine a global morphology of the at least one bone,

determine which areas of the global morphology are pathologic and which are normal,

determine an optimal location of an implant to be implanted in the at least one bone,

compare the normal bone morphology to external surfaces of an implant selected from a database of available implants in order to determine an optimal implant type and size,

determine a degree of fit of the selected implant by comparing the selected implant to the normal bone morphology of the at least one bone, and

visually represent the degree of fit on a display by a color map, wherein various colors of the color map represent various distances the selected implant departs from the at least one bone.

15. The system of claim 1 , wherein the first bone is a femur and the database of implants include femoral components of a total or partial knee replacement.

16. The system of claim 3 , wherein the morphology matching criteria includes areas of a femoral trochlear groove.