Systems and methods for mobile bearing prosthetic knee

摘要

A knee prosthesis including a femoral implant, a tibial implant, a tibial insert and a cam post. The femoral implant is secured to a femur and has a cam feature and condyles. The tibial implant is secured to a tibia. The tibial insert comprises a medial cavity with a rotational axis. The tibial insert has articulating surfaces that match the contours of the condyles of the femoral implant. The tibial insert has a medial boss that aligns with the medial cavity allowing it to rotate about the rotational axis. A cam post is secured to the tibial implant and passes through a channel of the tibial insert providing anterior and posterior stops for the rotation of the tibial insert about the rotational axis. The cam post interacts with the femoral implant cam feature and, with the tibial insert, allows more anatomically correct rollback and femoral external rotation during knee flexion.

主权项

1. A knee replacement system comprising:
a tibial baseplate comprising a tibia facing surface and a superior surface, wherein the tibia facing surface is shaped to lie against a tibial resected surface; a femoral knee implant comprising a pair of condyles, a cam feature, and a bone facing side shaped to lie against a resected surface of a femur; a tibial insert comprising a baseplate facing side, a lateral articulating surface, and a medial articulating surface, wherein the baseplate facing side pivotally articulates with the superior surface, wherein the baseplate facing side defines a boss toward a medial side to provide a medially-displaced axis of rotation upon insertion of said boss into a cavity positioned medially on the superior surface, wherein the articulating surfaces are shaped and positioned to articulate with the condyles, and a channel passes through the tibial insert along a direction generally perpendicular to the baseplate facing side, wherein the channel is arc shaped to guide a rotation of the tibial insert posteriorly relative to the tibial baseplate about the medially-displaced axis of rotation; and a cam post coupled to the tibial baseplate and protruding from the superior surface and passing through the channel, wherein contact of an anterior side of the cam feature with a posterior side of the cam post during flexion of a knee joint in which the knee replacement system is implanted provides the rotation, and wherein the cam post further interacts with the channel to provide anterior and posterior stops for the rotation.