Void filling joint prosthesis and associated instruments

1. A method of preparing a distal femur for receipt of a prosthesis comprising:

reaming through a distal end of the femur along an intramedullary axis thereof to form a central void;

reaming through the distal end of the femur adjacent the central void to form a first offset void; and

reaming through the distal end of the femur adjacent the central void to form a second offset void, wherein the first and second offset voids intersect the central void to form a continuous void configured to receive a void filler prosthesis in a press-fit manner.

2. The method of claim 1 , wherein reaming the first and second offset voids includes using a conical reamer.

3. The method of claim 1 , wherein reaming the central void includes reaming through the distal femur into an intramedullary canal thereof with a first reamer and reaming over the first reamer with a second reamer to form an opening in the distal femur larger than an opening formed by the first reamer.

4. The method of claim 1 , further comprising:

inserting a reamer guide assembly into the central void so that a portion of the reamer guide assembly extends from the central void, the reamer guide assembly having a longitudinal axis and first and second openings extending therethrough, the first and second openings each defining a guide axis offset from the longitudinal axis of the reamer guide.

5. The method of claim 4 , wherein reaming the first offset void includes driving a reamer along the guide axis defined by the first opening into the distal end of the femur.

6. The method of claim 5 , further comprising:

inserting the reamer into the first opening prior to reaming the first offset void by passing a shaft of the reamer through a first slot in a side of the reamer guide assembly that communicates with the first opening.

7. The method of claim 6 , further comprising:

inserting the reamer into the second opening by passing the shaft of the reamer through a second slot in a side of the reamer guide assembly that communicates with the second opening, and

driving the reamer along the guide axis defined by the second opening into the distal end of the femur.

8. The method of claim 7 , further comprising:

inserting a stabilizer member into the first offset void prior to reaming the second offset void so that the stabilizer member is coupled to the reamer guide assembly and extends from the first opening of the reamer guide assembly into the first offset void.

9. The method of claim 6 , further comprising sliding a bushing disposed over the shaft of the reamer into the first opening once the reamer shaft is disposed within the first opening, the bushing having an external dimension substantially corresponding to an internal dimension of the first opening so as to constrain movement of the bushing transverse to the guide axis of the first opening.

10. The method of claim 8 , wherein reaming the first offset void includes sliding the reamer relative to the bushing while the bushing remains disposed within the first opening.

11. A method of implanting a void filler prosthesis into a femur comprising:

reaming through a distal end of the femur along an intramedullary axis thereof to form a central void;

reaming through the distal end of the femur adjacent the central void to form a first offset void;

reaming through the distal end of the femur adjacent the central void to form a second offset void; and

implanting a void filler prosthesis into the distal end of the femur so that a central portion and first and second offset portions of the void filler prosthesis are disposed in the central, first offset, and second offset voids, respectively.

12. The method of claim 11 , wherein implanting the void filler prosthesis includes directly abutting bone within first and second offset voids with porous surfaces the first and second offset portions of the void filler prosthesis, the porous surfaces being configured to promote bone growth therein.

13. The method of claim 11 , wherein implanting the void filler prosthesis includes aligning an opening that extends through the entirety of the central portion with an intramedullary canal of the femur.

14. The method of claim 11 , wherein reaming the first and second offset voids is performed by one or more conical reamers and the first and second offset portions of the void filler are correspondingly shaped so as to be received within the first and second offset voids in a press-fit manner.

15. A method of performing a revision arthroplasty of a distal femur comprising:

removing a first femoral prosthesis previously implanted on a distal end of the femur;

reaming through the distal femur along an intramedullary axis thereof to form a central void;

reaming through the distal femur adjacent the central void to form a first offset void;

reaming through the distal femur adjacent the central void to form a second offset void;

inserting a void filler prosthesis into the distal femur so that a central portion and first and second offset portions of the void filler prosthesis are disposed in the central, first offset, and second offset voids, respectively; and

implanting a second femoral prosthesis having an articular surface onto the distal end of the femur and over the void filler prosthesis.

16. The method of claim 15 , wherein implanting the second femoral prosthesis includes inserting a stem connected to the femoral prosthesis into the femur through an opening in the central portion of the void filler prosthesis.

17. The method of claim 15 , wherein implanting the second femoral prosthesis includes inserting a cam box thereof into a space disposed between the first and second offset portions of the void filler prosthesis.

18. The method of claim 17 , wherein implanting the second femoral prosthesis includes placing cement between the cam box and inner surfaces of the first and second offset portions of the void filler prosthesis.

19. The method of claim 18 , wherein the inner surfaces of the first and second offset portions are terraced to promote cemented fixation between the void filler prosthesis and second femoral prosthesis.

20. The method of claim 15 , further comprising:

inserting a reamer guide assembly into the central void so that a portion of the reamer guide assembly extends from the central void, the reamer guide assembly having a longitudinal axis and first and second openings extending therethrough, the first and second openings each defining a guide axis offset from the longitudinal axis of the reamer guide, and

driving a reamer through the first and second openings along the respective guide axes thereof into the distal femur to form the first and second offset voids.