Methods and Devices for Knee Joint Replacement with Anterior Cruciate Ligament Substitution

Abstract

Methods and devices are provided for knee joint replacement with anterior cruciate ligament (ACL) substitution. Generally, the methods and devices can allow a knee joint to be partially or totally replaced in conjunction with substitution of the knee joint's ACL. In one embodiment, a knee replacement prosthesis can include a medial or lateral femoral implant, a femoral intercondylar notch structure, a medial or lateral tibial insert, and an ACL-substitution member. The ACL-substitution member can be configured to engage with the femoral intercondylar notch structure during a full range of knee motion and/or during only early knee flexion.

What is claimed is: 
     
         1 . A medical device, comprising:
 a tibial implant having an inferior surface and an opposite, superior surface, the inferior surface being configured to be fixed to a tibia of a patient;   a femoral implant mateable to the tibial implant and having an inferior surface and an opposite, superior surface, the superior surface being configured to be fixed to a femur of the patient, and the tibial implant being configured to articulate relative to the femoral implant when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur;   a femoral intercondylar notch coupled to the femoral implant; and   a post extending from the superior surface of the tibial implant near an edge thereof such that the post simulates an anterior cruciate ligament (ACL) when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur,   wherein a mediolateral distance measured from a medial or lateral surface of the post to an adjacent surface of the femoral intercondylar notch is less than a second mediolateral distance measured from the medial or lateral surface of the post to an adjacent surface of the femoral intercondylar notch, the second measurement being taken at a more posterior location on the post than the first measurement.   
     
     
         2 . The device of  claim 1 , wherein the mediolateral distance is measured with the femoral component oriented at or near full extension relative to the tibia 
     
     
         3 . The device of  claim 1 , wherein the tibial implant has medial and lateral compartments, the lateral compartment being configured to be seated on a lateral surface of the tibia such that the lateral surface is substantially covered by the lateral compartment, and the medial compartment being configured to be seated on a medial surface of the tibia such that the medial surface is substantially covered by the medial compartment. 
     
     
         4 . The device of  claim 1 , wherein the post is integrally formed with the tibial implant. 
     
     
         5 . The device of  claim 1 , wherein the post is a discrete element configured to couple to the tibial implant. 
     
     
         6 . The device of  claim 1 , wherein the post is configured to articulate relative to the femoral intercondylar notch. 
     
     
         7 . A medical device, comprising:
 a tibial implant having an inferior surface and an opposite, superior surface, the inferior surface being configured to be fixed to a tibia of a patient;   a femoral implant rateable to the tibial implant and having an inferior surface and an opposite, superior surface, the superior surface being configured to be fixed to a femur of the patient, and the tibial implant being configured to articulate relative to the femoral implant when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur; and   a post extending from the superior surface of the tibial implant near an edge thereof such that the post simulates an anterior cruciate ligament (AOL) when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur, a medial or lateral surface of the post being angled in the transverse plane away from the adjacent femoral intercondylar notch such that distance between the said medial/lateral surface of the post and the adjacent femoral intercondylar notch is greater at a posterior location than at an anterior location on the post,   
     
     
         8 . The device of  claim 7 , wherein the mediolateral distance is measured with the femoral component oriented at or near full extension relative to the tibia 
     
     
         9 . The device of  claim 7 , wherein the tibial implant has medial and lateral compartments, the lateral compartment being configured to be seated on a lateral surface of the tibia such that the lateral surface is substantially covered by the lateral compartment, and the medial compartment being configured to be seated on a medial surface of the tibia such that the medial surface is substantially covered by the medial compartment. 
     
     
         10 . The device of  claim 7 , wherein the post is integrally formed with the tibial implant. 
     
     
         11 . The device of  claim 7 , wherein the post is a discrete element configured to couple to the tibial implant. 
     
     
         12 . The device of  claim 7 , further comprising a femoral notch structure coupled to the femoral implant, the femoral notch structure being configured to prevent the post from impinging on a lateral surface of the femur through a full range of knee flexion when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur,
 wherein the post is configured to articulate relative to the femoral notch structure.   
     
     
         13 . A medical device, comprising:
 a tibial implant having an inferior surface and an opposite, superior surface, the inferior surface being configured to be fixed to a tibia of a patient;   a femoral implant mateable to the tibial implant and having an inferior surface and an opposite, superior surface, the superior surface being configured to be fixed to a femur of the patient, and the tibial implant being configured to articulate relative to the femoral implant when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur; and   a post extending from the superior surface of the tibial implant near an edge thereof such that the post simulates an anterior cruciate ligament (ACL) when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur, a medial and/or lateral surface of the post designed such that a mediolateral distance between a medial and/or lateral surface of the post and a longitudinal plane is greater at a superior location on the post than at an inferior location on the post, the longitudinal plane being perpendicular to the transverse plane, and being oriented along a longitudinal length of the post measured along a line from an anterior edge to a posterior edge of the post.   
     
     
         14 . The device of  claim 13 , wherein the mediolateral distance is measured with the femoral component oriented at or near full extension relative to the tibia. 
     
     
         15 . The device of  claim 13 , wherein such a reduction in mediolateral distance at a superior location on the post relative to an inferior location begins at or below the level of a distal bony resection of the medial/lateral femoral condyle. 
     
     
         16 . The device of  claim 13 , wherein the post is integrally formed with the tibial implant. 
     
     
         17 . The device of  claim 13 , wherein the post is a discrete element configured to couple to the tibial implant. 
     
     
         18 . The device of  claim 13 , further comprising a femoral notch structure coupled to the femoral implant, the femoral notch structure being configured to prevent the post from impinging on a lateral surface of the femur through a full range of knee flexion when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur, wherein the post is configured to articulate relative to the femoral notch structure. 
     
     
         19 . A medical device, comprising:
 a tibial implant having an inferior surface and an opposite superior surface, the inferior surface configured to be fixed to a tibia of a patient;   a femoral implant mateable to the tibial implant and having an inferior surface and an opposite superior surface, the superior surface configured to be fixed to a femur of the patient, and the tibial implant configured to articulate relative to the femoral implant when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur; and   a post extending from the superior surface of the tibial implant near an edge thereof such that the post simulates an anterior cruciate ligament (ACL) when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur;   wherein a bone facing surface of the femoral component is raised near an anterior aspect of a femoral notch relative to surfaces near the medial and/or lateral aspects of the femoral notch.   
     
     
         20 . A medical device, comprising:
 a tibial implant having an inferior surface and an opposite superior surface, the inferior surface configured to be fixed to a tibia of, a patient;   a femoral implant mateable to the tibial implant and having an inferior surface and an opposite superior surface, the superior surface configured to be fixed to a femur of the patient, and the tibial implant configured to articulate relative to the femoral implant when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur; and   a post extending from the superior surface of the tibial implant near an edge thereof such that the post simulates an anterior cruciate ligament (ACL) when the tibial implant is fixed to the tibia and the femoral implant is fixed to the femur an anterior surface of the tibial insert being angled anteriorly relative to a plane perpendicular to the tibial insert base.