Proportioned surgically implantable knee prosthesis
View Patent ↗A unicompartmental knee prosthesis for implantation into a knee joint includes a body having a substantially elliptical shape in plan and a pair of contoured opposed faces including a first face and a second face, the second face including a concave surface. The prosthesis is free of fixation to a permanent location within the knee joint compartment. A peripheral edge extends between the faces and has a first side, a second side opposite the first side, and a first end and a second end opposite the first end, the body including a cusp comprising a reverse curve downward from to the first face at one of the first and second ends. A first dimension D is defined by the first end and the second end, and a second dimension F is defined by the first side and the second side. A coordinate system origin (CSO) is at an intersection of D and F, the body including a material thickness at the CSO, where the dimension F is from about 0.25 to about 1.5 of the dimension D.
1. A unicompartmental knee prosthesis for implantation into a knee joint compartment between a femoral condyle and its corresponding tibial plateau, the prosthesis comprising:
a body having a substantially elliptical shape in plan and a pair of contoured opposed faces including a first face and a second face, the first face including a convex surface comprising substantially an entirety of the first face and the second face including a concave surface, the prosthesis free of fixation to a permanent location within the knee joint compartment and configured to be translatable with respect to the tibial plateau during knee articulation;
a peripheral edge extending between the faces and having a first side, a second side opposite the first side, a first end and a second end opposite the first end, the body including a cusp comprising a reverse downward curve with respect to the first face protruding from at least one of the first and second ends for limiting translation of the prosthesis;
a first dimension D defined by the first end and the second end;
a second dimension F defined by the first side and the second side, and
a coordinate system origin (CSO) at an intersection of D and F, the body including a material thickness at the CSO, where the dimension F is from about 0.25 to about 1.5 of the dimension D,
wherein the prosthesis is implantable without requiring bone resection.
2. The prosthesis according to claim 1 wherein the second face includes an anterior to posterior radius A and the first dimension D, where D is from about 0.6 A to about 1.4 A.
3. The prosthesis according to claim 2 wherein the anterior to posterior radius A is equal to the first dimension D.
4. The prosthesis according to claim 2 wherein the second dimension F is 0.64 A.
5. The prosthesis according to claim 2 wherein the second face includes a medial to lateral radius B of from about 0.25 A to about 1.0 A.
6. The prosthesis according to claim 5 wherein the radius B is 0.68 A.
7. The prosthesis according to claim 2 further comprising:
a posterior portion; and
a posterior portion dimension E of from about 0.1 A to about 0.75 A.
8. The prosthesis according to claim 7 wherein the posterior portion dimension E=0.5 A.
9. The prosthesis according to claim 2 further comprising:
a part center location;
a medial edge; and
a width from part center location to medial edge dimension G of from about 0.096 A to about 0.48 A.
10. The prosthesis according to claim 9 wherein the width from part center location to medial edge dimension G=0.352 A.
11. The prosthesis according to claim 2 further comprising:
a posterior portion;
a posterior portion dimension E of from about 0.1 A to about 0.75 A;
a part center location;
a medial edge; and
a width from part center location to medial edge dimension G of from about 0.096 A to about 0.48 A.
12. The prosthesis according to claim 11 wherein the posterior portion dimension E=0.5 A and the width from part center location to medial edge dimension G=0.352 A.
13. The prosthesis according to claim 2 wherein the second face includes an anterior sweep radius C to accommodate relative rotation between the femoral condyle and the tibial plateau.
14. The prosthesis according to claim 13 wherein C is from about 0.5 A to about 2.0 A.
15. The prosthesis according to claim 14 wherein C=A.