Knee prosthesis with guided extension and flexion

摘要

An orthopaedic knee joint prosthesis (10) provides guided motion in a wide range of motion, and in both extension and flexion. In flexion, a tibial bearing component (16) shifts to a first position in which a posterior cam (36) formed in a femoral component (12) engages a tibial spine (18) coupled to a tibial component (14). Contact between the posterior cam and the spine guides the motion profile of the knee joint prosthesis throughout a wide range of flexion movement. In extension, the bearing component shifts to a second position in which an anterior cam (34) formed in the femoral component engages the spine. Contact between the anterior cam and spine guides the motion profile of the knee joint prosthesis throughout a wide range of extension. The anterior and posterior cams, mobile bearing component, and tibial component-mounted spine cooperate to facilitate guided flexion and extension of the knee joint prosthesis throughout a wide range of motion.

主权项

1. A knee joint prosthesis, comprising:
a tibial component implantable on a proximal tibia and having a proximally-facing tibial plate; a spine coupled to said tibial component and protruding proximally from said tibial plate, said spine defining an anteroposterior span; a tibial insert attachable to said tibial component, said tibial insert comprising:
an insert bearing surface in abutting, sliding engagement with said tibial plate of said tibial component;a proximal articulation surface, said articulation surface positioned opposite said insert bearing surface; andan oblong aperture formed within said tibial insert so that at least a portion of said spine passes through said oblong aperture, said oblong aperture having an anteroposterior extent larger than said anteroposterior span of said spine, whereby said tibial insert is slidable in an anteroposterior direction with respect to said tibial component; and a femoral component implantable on a distal femur and articulable with said tibial insert between an extension configuration and a flexion configuration when said tibial component and said femoral component are implanted on the tibia and the femur, respectively, said femoral component comprising:
an articular surface abutting said articulation surface of said tibial insert when said femoral component articulates with said tibial insert;an anterior cam engaged with said spine through a first range of motion from the flexion configuration to the extension configuration when said tibial component and said femoral component are implanted on the tibia and femur, respectively, said first range of motion including between 80 degrees flexion and zero degrees flexion; anda posterior cam engaged with said spine through a second range of motion from the extension configuration to the flexion configuration.