Cervical intervertebral prosthesis

Abstract

A spinal implant includes two connection plates dimensioned for connection to adjacent vertebral bodies and a hinge core. The hinge core together with one connection plate forms a hinge between a generally spherical hinge extending from the one connection plate into an opening of a generally spherical depression in the hinge core. The opening is dimensioned to be elastically deformed to allow passage of the generally spherical hinge into the generally spherical depression. The hinge core bears on a slide surface which extends substantially parallel to the direction of the other connection plate and permits relative translatory movement of the hinge core. The walled receiving area limits this relative translatory movement of the hinge core. The stability of the spinal implant with respect to laterally incident forces is increased.

1 . A spinal implant, comprising:
 a first connection plate having a first surface dimensioned to contact a first vertebral body, a second surface opposite the first surface, and a generally spherical hinge extending from the second surface;   a second connection plate having a first surface dimensioned to contact a second vertebral body, a second surface opposite the first surface, and a walled section extending from the second surface to define a receiving area; and   a hinge core dimensioned to be received at least partially within the receiving area of the second connection plate, the hinge core including an opening and a generally spherical depression extending from the opening, wherein the opening is dimensioned to be elastically deformed to allow the generally spherical hinge of the first connection plate to pass through the opening and into the generally spherical depression.   
     
     
         2 . The spinal implant of  claim 1 , wherein at least one of first and second connection plate includes a flange disposed generally perpendicularly to the connection plate with at least one aperture to receive a fixation element to aid in affixing the connection plate to the respective vertebral body. 
     
     
         3 . The spinal implant of  claim 1 , wherein the hinge core includes a base portion and a collar, the base portion positioned within the receiving area of the second connection plate and the collar extending radially outward from the base portion. 
     
     
         4 . The spinal implant of  claim 1 , wherein the hinge core is made of a non-metal material. 
     
     
         5 . The spinal implant of  claim 1 , wherein the walled section of the receiving area is rectangular. 
     
     
         6 . The spinal implant of  claim 1 , wherein the walled section of the receiving area is square. 
     
     
         7 . The spinal implant of  claim 1 , wherein the walled section of the receiving area is square, and the hinge core is dimensioned with one pair of sides which has a side length substantially corresponding to a side length of the receiving area, and one pair of sides which has a shorter side length than the side length of the receiving area. 
     
     
         8 . The spinal implant of  claim 1 , wherein the walled section of the receiving area is square, and the hinge core is dimensioned with sides that have a shorter side length than the receiving area. 
     
     
         9 . The spinal implant of  claim 1 , wherein the walled section of the receiving area and the hinge core have substantially the same dimensions. 
     
     
         10 . The spinal implant of  claim 1 , wherein the hinge core lies substantially completely inside the receiving area. 
     
     
         11 . The spinal implant of  claim 1 , wherein the generally spherical depression of the hinge core encloses the generally spherical hinge of the first connection plate within an enclosure angle of more than 180°.