Artificial intervertebral disc implant

Abstract

The invention relates to an artificial intervertebral disc for placement between adjacent vertebrae. The artificial intervertebral disc is preferably designed to restore disc height and natural disc curvature, allow for a natural range of motion, absorb shock and provide resistance to motion and axial compression. Furthermore, the intervertebral disc may be used in the cervical, the thoracic, or the lumbar regions of the spine. The artificial intervertebral disc may include either singularly or in combination: an interior including at least one spring member preferably incorporating an arcuate surface member, a flexible core, the flexible core preferably being a slotted core, a ring spring, a winged leaf spring, a leaf spring, or the articulating member preferably being attached to one of the endplate by an intermediate shock absorbing element. Moreover, the interior may include a fluid; a valve for injecting fluid into the interior of the disk; a central region having a stiffness that is preferably greater than the stiffness of the outer regions thus enabling the disc to pivot about the central region. The central pivot may be formed by a center opening, a central chamber, an inner core or a central cable.

1 . An intervertebral disc for placement between first and second vertebrae comprising:
 a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra;   a second endplate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra;   a leaf spring having first and second resilient ends, configured to engage the second endplate, and a length, the leaf spring further comprising a central body having first and second surfaces, the first surface comprising an articulating surface.   
   
   
       2 . The intervertebral disc according to  claim 1 , wherein the second endplate further comprises a recess having a length smaller than the leaf spring length, wherein when the leaf spring engages the second endplate so that the first and second resilient ends are supported on the inner surface of the endplate and the central body is positioned over the endplate recess, at least a portion of the central body may move into the recess when a compressive force is applied to the leaf spring first surface allowing the second surface to contact the recess surface. 
   
   
       3 . The intervertebral disc according to  claim 2 , the recess further comprising a recess surface, the leaf spring second surface and the recess surface configured to define a gap therebetween so that when a predetermined compressive force is applied to the leaf spring first surface the leaf spring second surface contacts at least a portion of the recess surface. 
   
   
       4 . The intervertebral disc according to  claim 2 , wherein the central body and the recess are configured so that the leaf spring may translate in at least one direction with respect to the second end plate. 
   
   
       5 . The intervertebral disc according to  claim 1 , wherein the first endplate further comprises an inner surface having an articulating surface configured to correspond with the leaf spring articulating surface. 
   
   
       6 . The intervertebral disc according to  claim 5 , wherein the articulating surfaces are configured to allow the leaf spring to articulate, and to translate, relative to the first endplate. 
   
   
       7 . The intervertebral disc according to  claim 1 , further comprising a membrane disposed between the first and second endplates. 
   
   
       8 . The intervertebral disc according to  claim 7 , further comprising a membrane disposed between the upper and lower endplates, the membrane encapsulating at least the leaf spring. 
   
   
       9 . The intervertebral disc according to  claim 7 , wherein the endplates and membrane define an interior volume, the volume being at least partially filled a fluid. 
   
   
       10 . An intervertebral disc for placement between first and second vertebrae comprising:
 an upper endplate for contacting the first vertebra;   a lower endplate for contacting the second vertebra; and   at least first and second cable elements disposed therebetween; wherein the first and second cable elements each has a length, the length of the first cable element being substantially shorter than the length of the second cable element.   
   
   
       11 . An intervertebral disc according to  claim 10 , wherein at least one of the endplates includes at least one bore, the at least one cable element is associated with the at least one bore. 
   
   
       12 . An intervertebral disc according to  claim 11 , the disc further comprising a plurality of peripheral cable elements disposed between the upper and lower endplates, each peripheral cable element further having a length, wherein the first cable element comprises a center cable element, and the length of each peripheral cable element is substantially greater than the length of the center cable element. 
   
   
       13 . An intervertebral disc for placement between first and second vertebrae comprising:
 a first endplate having a first inner surface and a first outer surface, the first outer surface contacting the first vertebra, the inner surface including a first curved articulating surface;   a second endplate having a second inner surface and a second outer surface, the second outer surface contacting the second vertebra;   an elastic membrane operatively coupled to the first and second endplates;   a medial articulating member operatively coupled to the second endplate, the articulating member including a second curved articulating surface for contacting the first curved articulating surface;   a shock absorbing layer located between the medial articulating member and the second endplate.