Mobile bearing total joint replacement

A prosthetic joint replacement for a condylar joint comprising:

• a first prosthetic component having a bone attachment portion for attachment to a first bone of the condylar joint and having an articular surface;
• a second prosthetic component having a second bone attachment portion for attachment to a second bone of the condylar joint, said second prosthetic component further having an opposed substantially planar bearing surface, side walls projecting from said bearing surface of said second prosthetic component, each said side wall having a concave surface orthogonal to said bearing surface of said second prosthetic component, said concave surfaces defining arc segments of a single right circular cylinder of radius R.sub.t ;
• and
• a plastic bearing disposed between said first and second prosthetic components, said bearing having a first bearing surface in articular bearing engagement with the articular surface of the first prosthetic component and a second bearing surface slidably and rotatably disposed on the bearing surface of said second prosthetic component, thrust surfaces aligned orthogonally to said second bearing surface and defining arc segments of two right circular cylinders having radii R.sub.b, said radii R.sub.b being less than R.sub.t, the thrust surfaces being generated about centers that are spaced in a first direction to define a selected width for said bearing in said first direction that is greater than twice R.sub.b, but less than twice R.sub.t, for permitting sliding movement of said bearing in directions parallel to said first direction which is significantly less than sliding movement of said bearing permitted in a second direction orthogonal to said first direction.

A prosthetic joint replacement for a condylar joint comprising:

• a first prosthetic component having a bone attachment portion for attachment to a first bone of the condylar joint and having an articular surface;
• a second prosthetic component having a bone attachment portion for attachment to a second bone of the condylar joint, a pair of side walls projecting away from said bone attachment portion, each said side wall having a concave surface, said concave surfaces of said side walls facing one another, a bearing surface facing away from said bone attachment portion and extending between the respective concave surfaces of said side walls;
• and
• a single bearing disposed between said first and second prosthetic components, said bearing having a first bearing surface in articular bearing engagement with the articular surface of the first prosthetic component, a pair of convex thrust surfaces disposed between the side walls of the second prosthetic component and a second bearing surface extending continuously between the convex thrust surfaces, said second bearing surface being slidably and rotatably engaged with the bearing surface of said second prosthetic component and the convex thrust surfaces facing the respective concave surfaces of the side walls of the second prosthetic component, the convex thrust surfaces being dimensioned and configured relative to said facing concave surfaces of said side walls for all positions of said bearing on the second prosthetic component to permit substantially greater sliding movement of said bearing on said second prosthetic component along a first axis than along a second axis orthogonal to said first axis.

A prosthetic joint replacement for a condylar joint comprising:

• a first prosthetic component having a bone attachment portion for attachment to a first bone of the condylar joint and an articular surface;
• a second prosthetic component having a bone attachment portion for attachment to a second bone of the condylar joint and a substantially planar bearing surface;
• a plastic bearing disposed between said first and second prosthetic components, said bearing having a first bearing surface in articular bearing engagement with the articular surface of the first prosthetic component and a second bearing surface disposed in sliding and rotary bearing engagement on the bearing surface of said second prosthetic component;
• sliding limitation means on said second prosthetic component and said bearing for limiting sliding movement therebetween, said sliding limitation means being disposed respectively at medial and lateral sides on said second prosthetic component and said bearing;
• and
• dislocation prevention means spaced from said sliding limitation means and disposed on the respective second prosthetic component and the bearing at locations generally centrally between medial and lateral sides thereof for preventing dislocation of the bearing surface of said second prosthetic component from the second bearing surface of said plastic bearing while permitting rotary movement between said plastic bearing and said second prosthetic component.

A system of joint replacement prosthetic components for condylar joints comprising:

• a first prosthetic component attachable to a first bone of one said condylar joint, said first prosthetic component having an articular surface;
• a second prosthetic component attachable to a second bone of one said condylar joint, said second prosthetic component further having a bearing surface;
• and
• a plurality of bearings, each said bearing having a first bearing surface for articular bearing engagement with the articular surface of said first prosthetic component, each said bearing further having a second bearing surface, the second bearing surface of at least one said bearing in said system being fixedly engageable with the bearing surface of said second prosthetic component for defining a fixed bearing joint replacement, the second bearing surface of at least a second bearing in said system being rotatably engageable with the bearing surface of said second prosthetic component for defining a rotating bearing joint replacement, and the second bearing surface of at least a third bearing in said system being slidably engageable with the bearing surface of said second prosthetic component for defining a sliding bearing joint replacement.

A prosthetic joint replacement for a condylar joint comprising:

• a first prosthetic component having a bone attachment portion for attachment to a first bone of said condylar joint and having an articular surface;
• a second prosthetic component having a bone attachment portion for attachment to a second bone of said condylar joint, said second prosthetic component further having a bearing surface and medial and lateral side walls projecting from said bearing surface, each said side wall having an anterior end, a posterior end and a concave surface therebetween, said concave surfaces defining arc segments of a single right circular cylinder, a button projecting from said bearing surface at a location concentric with said concave surfaces;
• and
• a bearing disposed between the first and second prosthetic components, said bearing having a first bearing surface in articular bearing relationship with the articular surface of said first prosthetic component, a second bearing surface slidably and rotatably engaged with the bearing surface of said second prosthetic component, and medial and lateral thrust surfaces facing the respective medial and lateral side walls of the second prosthetic component, the thrust surfaces defining arc segments of two right circular cylinders which are dimensioned and disposed to permit a selected small medial-lateral sliding movement of said bearing between said side walls of said second prosthetic component and a selected substantially larger anterior-posterior sliding movement of said bearing on said second prosthetic component, a cavity extending into said second bearing surface at a location generally centrally between said thrust surfaces, said button of said second prosthetic component being slidably and rotatably engaged within said cavity.

A prosthetic joint replacement for a condylar joint comprising:

• a first prosthetic component having a bone attachment portion for attachment to a first bone of the condylar joint and having an articular surface;
• a second prosthetic component having a second bone attachment portion for attachment to a second bone of the condylar joint, said second prosthetic component further having an opposed substantially planar bearing surface, medial and lateral side walls projecting from said bearing surface of said second prosthetic component, each said side wall having an anterior end, a posterior end and a concave surface orthogonal to said bearing surface of said second prosthetic component, said concave surfaces defining arc segments of a single right circular cylinder of radius R.sub.t, a button projecting from said bearing surface at a location concentric with said concave surfaces;
• and
• a plastic bearing disposed between said first and second prosthetic components, said bearing having a first bearing surface in articular bearing engagement with the articular surface of the first prosthetic component and a second bearing surface slidably and rotatably disposed on the bearing surface of said platform, medial and lateral thrust surfaces aligned orthogonally to said second bearing surface and defining arc segments of two right circular cylinders having radii R.sub.b, said radii R.sub.b being less than R.sub.t, the thrust surfaces being spaced in a medial-to-lateral direction to define selected M-L clearances between said bearing and the respective medial and lateral side walls of said platform, said radii R.sub.b being selected relative to said radius R.sub.t and relative to said M-L clearances to permit sliding movement in anterior and posterior directions which significantly exceed the M-L clearances, a cavity extending into said second bearing surface at a location generally centrally between said thrust surfaces, said button of said second prosthetic component being slidably and rotatably engaged within said cavity.

A prosthetic joint replacement for a condylar joint comprising:

• a first prosthetic component having a bone attachment portion for attachment to a first bone of said condylar joint and having an articular surface;
• a second prosthetic component having a bone attachment portion for attachment to a second bone of said condylar joint, said second prosthetic component further having a bearing surface and first and second spaced apart side walls projecting from said bearing surface, said first and second side walls having first and second concave surfaces respectively defining arc segments of a single right circular cylinder;
• and
• a bearing disposed between the first and second prosthetic components, said bearing having a first bearing surface in articular bearing relationship with the articular surface of said first prosthetic component, a second bearing surface slidably and rotatably engaged with the bearing surface of said second prosthetic component, and first and second thrust surfaces facing the respective first and second side walls of the second prosthetic component and defining a width for the bearing, the thrust surfaces defining arc segments of two right circular cylinders having radii less than one-half the width of the bearing to permit a selected small sliding movement of said bearing in a direction parallel to said width and between said side walls of said second prosthetic component and a selected substantially larger sliding movement of said bearing on said second prosthetic component in a direction orthogonal to the width.

A system of joint replacement prosthetic components for condylar joints comprising:

• a first prosthetic component attachable to a first bone of one said condylar joint, said first prosthetic component having an articular surface;
• a second prosthetic component attachable to a second bone of one said condylar joint, said second prosthetic component further having a bearing surface;
• and
• a plurality of bearings, each said bearing having a first bearing surface for articular bearing engagement with the articular surface of said first prosthetic component, each said bearing further having a second bearing surface engageable with the bearing surface of said second prosthetic component, at least a first bearing in said plurality being configured for providing a first number of degrees of freedom of movement of said first bearing relative to said second prosthetic component and at least a second bearing of said plurality being configured for permitting a second number of degrees of freedom of movement of said second bearing relative to said second prosthetic component.