Mobile bearing knee prosthesis

Abstract

In one embodiment of the present invention a mobile bearing knee prosthesis may include an interface (e.g., a spherical radius interface) comprised of a concave superior surface on a tray and a convex inferior surface on a tibial insert. In another embodiment of the present invention a mobile bearing knee prosthesis may include an interface (e.g., a spherical radius interface) comprised of a convex superior surface on a tibial tray and a concave inferior surface on a insert. In another embodiment of the present invention a mobile bearing knee prosthesis may include a bi-concave interface (e.g., having a “wave” like surface geometry). This “wave” like surface geometry may be at the second bearing (i.e., at the interface between a tibial insert and a tray in the mobile bearing knee as opposed to the interface between the tibial insert and a femoral component).

1 . A mobile bearing knee prosthesis, comprising:
 a tibial tray for interfacing with a tibia of a patient; and   a tibial insert disposed adjacent the tibial tray;   wherein the tibial insert is capable of movement relative to the tibial tray and the movement of the tibial insert relative to the tibial tray includes at least pivotal movement;   wherein the pivotal movement is around an axis of rotation defined by a post extending from a bottom surface of the tibial insert into a hole provided on an upper surface of the tibial tray;   wherein the hole provided on the upper surface of the tibial tray is provided at a substantially circular raised location;   wherein the substantially circular raised location curves downward away from the hole along both a medial-lateral axis of the tibial tray and an anterior-posterior axis of the tibial tray;   wherein at least a portion of a medial edge of the tibial tray and at least a portion of a lateral edge of the tibial tray curve upward as the medial edge and the lateral edge are approached; and   wherein the bottom surface of the tibial insert is configured to be substantially complementary to the top surface of the tibial tray when the tibial insert and the tibial tray are aligned in both the medial-lateral axis and the anterior-posterior axis.   
   
   
       2 . The mobile bearing knee prosthesis of  claim 1 , wherein an upper surface of the tibial insert is configured to receive a femoral component which interfaces with a femur of the patient. 
   
   
       3 . The mobile bearing knee prosthesis of  claim 1 , further comprising a mechanism for providing at least one of rotational control and rotational constraint to movement of the tibial insert relative to the tibial tray. 
   
   
       4 . The mobile bearing knee prosthesis of  claim 3 , wherein the mechanism for providing at least one of rotational control and rotational constraint to movement of the tibial insert relative to the tibial tray comprises a cross-pin disposed within the hole and a groove disposed on the post, wherein the cross-pin is received within the groove. 
   
   
       5 . The mobile bearing knee prosthesis of  claim 3 , wherein the mechanism for providing at least one of rotational control and rotational constraint to movement of the tibial insert relative to the tibial tray comprises at least a first tab disposed along the medial edge of the tibial tray and at least a second tab disposed along the lateral edge of the tibial tray, wherein the first tab contacts the tibial insert to provide at least one of the rotational control and the rotational constraint during rotation in a first direction and the second tab contacts the tibial insert to provide at least one of the rotational control and the rotational constraint during rotation in a second direction. 
   
   
       6 . The mobile bearing knee prosthesis of  claim 5 , wherein the first tab includes a first undercut for receiving a first edge of the tibial insert and the second tab includes a second undercut for receiving a second edge of the tibial insert. 
   
   
       7 . The mobile bearing knee prosthesis of  claim 1 , further comprising a mechanism for substantially preventing lift-off of the tibial insert from the tibial tray. 
   
   
       8 . The mobile bearing knee prosthesis of  claim 7 , wherein the mechanism for substantially preventing lift-off of the tibial insert from the tibial tray comprises a raised portion on the post cooperating with an indentation in a portion of the tibial tray defining the hole therein. 
   
   
       9 . The mobile bearing knee prosthesis of  claim 7 , wherein the mechanism for substantially preventing lift-off of the tibial insert from the tibial tray comprises at least a first tab disposed along the medial edge of the tibial tray and at least a second tab disposed along the lateral edge of the tibial tray, wherein the first tab includes a first undercut for receiving a first edge of the tibial insert and the second tab includes a second undercut for receiving a second edge of the tibial insert. 
   
   
       10 . The mobile bearing knee prosthesis of  claim 1 , wherein at least one of the hole and the post is substantially circular. 
   
   
       11 . The mobile bearing knee prosthesis of  claim 1 , wherein the hole and the raised location are disposed at a substantially central location along the medial-lateral axis of the tibial tray. 
   
   
       12 . The mobile bearing knee prosthesis of  claim 1 , wherein the hole and the raised location are disposed at a substantially central location along the anterior-posterior axis of the tibial tray. 
   
   
       13 . The mobile bearing knee prosthesis of  claim 1 , wherein the upper surface of the tibial tray comprises metal and the lower surface of the tibial insert comprises polyethelene. 
   
   
       14 . The mobile bearing knee prosthesis of  claim 13 , wherein the tibial tray is formed of metal and the tibial insert is formed of polyethelene. 
   
   
       15 . A mobile bearing knee prosthesis, comprising:
 a tibial tray for interfacing with a tibia of a patient; and   a tibial insert disposed adjacent the tibial tray;   wherein the tibial insert is capable of movement relative to the tibial tray and the movement of the tibial insert relative to the tibial tray includes at least pivotal movement;   wherein the pivotal movement is around an axis of rotation defined by a first cooperating element associated with a bottom surface of the tibial insert and a second cooperating element associated with an upper surface of the tibial tray;   wherein the second cooperating element is provided at a substantially circular raised location on the upper surface of the tibial tray;   wherein the substantially circular raised location curves downward away from the second cooperating element along both a medial-lateral axis of the tibial tray and an anterior-posterior axis of the tibial tray;   wherein at least a portion of a medial edge of the tibial tray and at least a portion of a lateral edge of the tibial tray curve upward as the medial edge and the lateral edge are approached; and   wherein the bottom surface of the tibial insert is configured to be substantially complementary to the top surface of the tibial tray when the tibial insert and the tibial tray are aligned in both the medial-lateral axis and the anterior-posterior axis.   
   
   
       16 . The mobile bearing knee prosthesis of  claim 15 , wherein an upper surface of the tibial insert is configured to receive a femoral component which interfaces with a femur of the patient. 
   
   
       17 . A mobile bearing knee prosthesis, comprising:
 a tibial tray for interfacing with a tibia of a patient; and   a tibial insert disposed adjacent the tibial tray;   wherein the tibial insert is capable of movement relative to the tibial tray and the movement of the tibial insert relative to the tibial tray includes at least pivotal movement;   wherein the pivotal movement is around an axis of rotation provided by a first cooperating element associated with a bottom surface of the tibial insert and a second cooperating element associated with a top surface of the tibial tray;   wherein the tibial tray includes at least a first diamond bearing surface;   wherein the tibial insert includes at least a second diamond bearing surface; and   wherein at least a portion of the first diamond bearing surface and at least a portion of the second diamond bearing surface bear against one another.   
   
   
       18 . The mobile bearing knee prosthesis of  claim 17 , wherein an upper surface of the tibial insert is configured to receive a femoral component which interfaces with a femur of the patient. 
   
   
       19 . The mobile bearing knee prosthesis of  claim 17 , wherein the first diamond bearing surface includes a plurality of diamonds. 
   
   
       20 . The mobile bearing knee prosthesis of  claim 17 , wherein the second diamond bearing surface includes a plurality of diamonds. 
   
   
       21 . The mobile bearing knee prosthesis of  claim 17 , wherein the first diamond bearing surface includes a plurality of diamonds and the second diamond bearing surface includes a plurality of diamonds. 
   
   
       22 . The mobile bearing knee prosthesis of  claim 21 , wherein at least one of the diamonds of the first diamond bearing surface extends beyond the other diamonds of the first diamond bearing surface such that the raised diamond cooperates with at least a portion of the second diamond bearing surface to provide rotational constraint to movement of the tibial insert relative to the tibial tray. 
   
   
       23 . The mobile bearing knee prosthesis of  claim 21 , wherein at least one of the diamonds of the second diamond bearing surface extends beyond the other diamonds of the second diamond bearing surface such that the raised diamond cooperates with at least a portion of the first diamond bearing surface to provide rotational constraint to movement of the tibial insert relative to the tibial tray.