Arthroplasty systems and methods

1. A method of preparing a joint arthroplasty prosthesis for replacing at least a portion of a natural articular surface of a synovial joint, comprising:

placing a bone-contacting surface of a prosthesis against a resected or flattened bone surface along a first direction, the prosthesis further comprising an articular surface, the bone- contacting surface being configured to compliment the resected or flattened bone surface, the bone-contacting surface comprising an undercut channel extending across at least a portion of the bone-contacting surface, the articular surface replicating at least a portion of a natural articular surface of a synovial joint; and

sliding at least a portion of a rail of an anchor along the undercut channel from a first position to a second position, the anchor further comprising a blade offset from the rail and connected to the rail by a support, wherein the rail is moved from the first position to the second position along a second direction that is different than the first direction.

2. The method of claim 1 , further comprising activating a spring feature after sliding the at least a portion of the rail along the undercut channel, wherein activating the spring feature blocks movement of the rail along the undercut channel toward the first position.

3. The method of claim 1 , wherein the spring feature is a feature on the anchor, wherein the undercut channel is formed in a bone replacement component of the prosthesis, and wherein the activating of the spring feature comprises positioning the spring feature using a spring action to engage the bone replacement component.

4. The method of claim 3 , wherein the activating of the spring feature comprises at least a portion of the spring feature opening into a clearance pocket in the bone replacement component.

5. The method of claim 1 , wherein sliding the at least a portion of the rail along the undercut channel and sliding the portion of the support along the undercut channel comprise sliding the rail into the undercut channel before sliding the portion of the support into the undercut channel.

6. The method of claim 1 , wherein the blade is inclined at an acute angle relative to the bone-contacting surface when the at least a portion of the rail is in the undercut channel, wherein the acute angle opens toward a leading end of the anchor.

7. The method of claim 1 , further comprising:

attaching the prosthesis to an attachment portion of a guide tool, the guide tool further comprising a guidance portion including at least one track, wherein the attachment portion is releasably attachable to a portion of the prosthesis, and wherein the at least one track coaxially aligns with the undercut channel when the attachment portion is attached to the prosthesis;

inserting the rail into the at least one track; and

sliding the anchor toward the prosthesis.

8. The method of claim 1 , further comprising inserting at least one post that is configured to extend from the bone-contacting surface into at least one hole formed in the resected or flattened bone surface, wherein the post is located within the hole while the rail is moved along the undercut channel from the first position to the second position.

9. The method of claim 1 , further comprising sliding a portion of the support along the undercut channel, the support protruding through the bone-contacting surface, wherein a portion of the bone-contacting surface is spaced between the blade and the rail when the at least a portion of the rail and the portion of the support are sliding along the undercut channel.

10. A method of replacing at least a portion of a natural articular surface of a knee joint, comprising:

forming a resection surface on a tibial bone of the knee joint to remove a natural articular surface region comprising at least a portion of the natural articular surface of the tibial bone;

positioning a bone-contacting surface of a unicondylar tibial prosthesis against the resection surface, the bone-contacting surface complementing the resection surface;

inserting a post that extends from the bone-contacting surface of the unicondylar tibial prosthesis into a hole formed in the resection surface;

positioning an articular surface of the unicondylar tibial prosthesis to replace the removed natural articular surface region; and

installing an anchor to fix the unicondylar tibial prosthesis to the tibial bone;

wherein installing the anchor comprises:

sliding at least a portion of a rail of the anchor along an undercut channel of the unicondylar tibial prosthesis, the undercut channel extending across at least a portion of the bone-contacting surface;

sliding at least a portion of a blade of the anchor from a first position to a second position, the blade being disengaged from the tibial bone in the first position, and the blade being engaged with the tibial bone in the second position, wherein portions of the bone-contacting surface and the resection surface are situated between the blade and the rail during at least part of the sliding of the blade from the first position to the second position; and

sliding a portion of a support of the anchor along the undercut channel and the tibial bone, the support connecting the blade to the rail.

11. The method of claim 10 , wherein installing the anchor further comprises activating a spring feature after sliding the at least a portion of the rail along the undercut channel, wherein activating the spring feature inhibits movement that would reverse the sliding of the at least a portion of the rail along the undercut channel.

12. The method of claim 11 , wherein the spring feature is a feature on the anchor, wherein the undercut channel is formed in a bone replacement component of the unicondylar tibial prosthesis, and wherein the activating of the spring feature comprises positioning the spring feature using a spring action to engage the bone replacement component.

13. The method of claim 10 , further comprising:

attaching the unicondylar tibial prosthesis to an attachment portion of a guide tool, the guide tool further comprising a guidance portion including at least one track, wherein the attachment portion is releasably attachable to a portion of the unicondylar tibial prosthesis, and wherein the at least one track coaxially aligns with the undercut channel when the attachment portion is attached to the unicondylar tibial prosthesis;

inserting the rail into the at least one track; and

sliding the anchor toward the unicondylar tibial prosthesis.

14. The method of claim 13 , wherein at least one post extends from the bone-contacting surface and into at least one hole in the resection surface, wherein the post is located within the hole while at least one of the rail, the blade, and the support of the anchor are moved from the first position to the second position.

15. A method of preparing a joint arthroplasty prosthesis for replacing at least a portion of a natural articular surface of a synovial joint, comprising:

placing a bone-contacting surface of a prosthesis against a resected or flattened bone surface, the prosthesis further comprising an articular surface, the bone-contacting surface being configured to compliment the resected or flattened bone surface, the bone-contacting surface comprising an undercut channel extending across at least a portion of the bone-contacting surface, the articular surface replicating at least a portion of a natural articular surface of a synovial joint;

inserting a post that extends from the bone-contacting surface of the prosthesis into a hole formed in the resected or flattened bone surface; and

sliding at least a portion of a rail of an anchor along the undercut channel from a first position to a second position, the anchor further comprising a blade offset from the rail and connected to the rail by a support

wherein the post is inserted into the hole along a first direction and the at least a portion of the rail is moved from the first position to the second position along a second direction that is different than the first direction.

16. The method of claim 15 , further comprising activating a spring feature after sliding the at least a portion of the rail along the undercut channel, wherein activating the spring feature inhibits movement of the rail that would reverse the sliding of the at least a portion of the rail along the undercut channel.

17. The method of claim 16 , wherein the spring feature is a feature on the anchor, wherein the undercut channel is formed in a bone replacement component of the prosthesis, and wherein the activating of the spring feature comprises positioning the spring feature using a spring action to engage the bone replacement component.

18. The method of claim 17 , wherein the activating of the spring feature comprises at least a portion of the spring feature opening into a clearance pocket in the bone replacement component.

19. The method of claim 15 , wherein sliding the at least a portion of the rail along the undercut channel and sliding the portion of the support along the undercut channel comprise sliding the rail into the undercut channel before sliding the portion of the support into the undercut channel.

20. The method of claim 15 , further comprising sliding a portion of the support along the undercut channel, the support protruding through the bone-contacting surface, wherein a portion of the bone-contacting surface is spaced between the blade and the rail when the at least a portion of the rail and the portion of the support are sliding along the undercut channel.

21. The method of claim 10 , wherein installing the anchor is performed before positioning the articular surface.

22. The method of claim 10 , wherein positioning the articular surface is performed before installing the anchor.

23. The method of claim 10 , wherein the post is inserted into the hole along a first direction and the blade is inserted into the tibial bone along a second direction that is different than the first direction.