Artificial expansile total lumbar and thoracic discs for posterior placement without supplemental instrumentation and its adaptation for anterior placement of artificial cervical, thoracic and lumbar discs

Abstract

A total artificial expansible disc having at least two pairs of substantially parallel shells, which move in multiple directions defined by at least two axes, is disclosed. Several methods for implanting the total artificial expansile disc are also disclosed. The total artificial expansile disc occupies a space defined by a pair of vertebral endplates. An expansion device moves the pairs of shells in multiple directions. A core is disposed between the pairs of shells, and the core permits the vertebral endplates to move relative to one another.

1 . A total artificial expansible disc, comprising: 
 at least two pairs of substantially parallel shells, that move in multiple directions defined by at least two axes, in order to occupy a space defined by vertebral endplates;    an expansion device that moves the pairs of shells in multiple directions; and    a core, disposed between the pairs of shells, that permits the vertebral endplates to move relative to one another.    
   
   
       2 . A total artificial expansible disc according to  claim 1  wherein the shells include a plurality of spikes that are embedded in the vertebral endplates.  
   
   
       3 . A total artificial expansible disc according to  claim 1  wherein the core is fabricated from an elastic material.  
   
   
       4 . A total artificial expansible disc according to  claim 1  wherein the core is fabricated from a material selected from a group of materials comprising rubber, silicone, or polyurethane.  
   
   
       5 . A total artificial expansible disc according to  claim 1  wherein the core includes an expandable elastomeric sheath that is molded to the inner surfaces of the shells and that can expand to substantially fill the space between the shells.  
   
   
       6 . A total artificial expansible disc according to  claim 5  wherein a curable liquefied material is injected into the sheath causing it to expand.  
   
   
       7 . A total artificial expansible disc according to  claim 6  wherein the liquefied material is selected from a group of materials comprising polycarbonateurethane, polyurethane, polyvinyl alcohol, or protein hydrogel.  
   
   
       8 . A total artificial expansible disc according to  claim 6  wherein the sheath includes a coil and a port.  
   
   
       9 . A total artificial expansible disc according to  claim 1  that further includes at least two inner shells disposed near the moveable shells, the first inner shell disposed near the outer moveable shells which form a rostral leaflet, and the second inner shell disposed near the outer moveable shells which form a caudal leaflet; the first inner shell having a trough and the second inner shell having a protruding ball that cooperates with the trough.  
   
   
       10 . A total artificial expansible disc according to  claim 9  that further includes intermediate plates disposed between the outer and inner shells.  
   
   
       11 . A total artificial expansible disc according to  claim 10  wherein the outer shells and the inner plates are made from titanium and the inner shells are made from stainless steel.  
   
   
       12 . A total artificial expansible disc according to  claim 1  that further includes at least two inner shells disposed near the moveable shells, the first inner shell disposed near the outer moveable shells which form a rostral leaflet, and the second inner shell disposed near the outer moveable shells which form a caudal leaflet; the first inner shell having a convex shape and the second inner shell having a convex shape.  
   
   
       13 . A total artificial expansible disc according to  claim 12  that further includes intermediate plates disposed between the outer and inner shells.  
   
   
       14 . A total artificial expansible disc according to  claim 10  wherein the outer shells and the inner plates are made from titanium and the inner shells are made from UHMWPE.  
   
   
       15 . A total artificial expansible disc according to  claim 1  that further includes at least two inner shells disposed near the moveable shells, the first inner shell disposed near the outer moveable shells which form a rostral leaflet, and the second inner shell disposed near the outer moveable shells which form a caudal leaflet; the first inner shell having a substantially planar shape and the second inner shell having a convex shape.  
   
   
       16 . A total artificial expansible disc according to  claim 15  that further includes an intermediate plate disposed between the outer and inner shells of the caudal leaflet.  
   
   
       17 . A total artificial expansible disc according to  claim 10  wherein the outer shells, the first inner shell and the intermediate plate are made from titanium, and the second inner convex shell is made from UHMWPE.  
   
   
       18 . A total artificial expansible disc according to  claim 1  wherein the moveable shells form a dorsal pair having rostral and caudal shells, and the moveable shells form a ventral pair having rostral and caudal shells; and wherein the dorsal pair and ventral pair move apart.  
   
   
       19 . A total artificial expansible disc according to  claim 18  wherein the moveable shells form a rostral pair having dorsal and ventral shells, and the moveable shells form a caudal pair having dorsal and ventral shells; and wherein the rostral pair and caudal pair move apart.  
   
   
       20 . A total artificial expansible disc according to  claim 19  that further includes at least one removable expansion bar moving the dorsal and ventral shells apart.  
   
   
       21 . A total artificial expansible disc according to  claim 20  that further includes at least one removable expansion bar for moving the rostral and caudal shells apart.  
   
   
       22 . A total artificial expansible disc according to  claim 21  wherein the removable expansion bars include a ratcheting mechanism.  
   
   
       23 . A total artificial expansible disc according to  claim 21  wherein the core is fabricated from an elastic material.  
   
   
       24 . A total artificial expansible disc according to  claim 1;   wherein the moveable shells form a left dorsal pair having rostral and caudal shells and a right dorsal pair having rostral and caudal shells;    wherein the moveable shells form a left ventral pair having rostral and caudal shells and a right ventral pair having rostral and caudal shells; and    wherein the left and right dorsal pairs simultaneously move apart form the left and right ventral pairs.    
   
   
       25 . A total artificial expansible disc according to  claim 20;   wherein the left dorsal pair and left ventral pair simultaneously move apart from the right dorsal pair and the right ventral pair.    
   
   
       26 . A total artificial expansible disc according to  claim 21;   wherein all the rostral shells simultaneously move apart from the caudal shells.    
   
   
       27 . A total artificial expansible disc according to  claim 1  wherein the moveable shells form a boomerang shape.  
   
   
       28 . A total artificial expansible disc according to  claim 23  wherein the expansion device controls the movement of the moveable shells with three screws disposed on a dorsal shell.  
   
   
       29 . A total artificial expansible disc according to  claim 1  wherein the expansion device includes a plurality of components that move in response to a rotational control member.  
   
   
       30 . A total artificial expansible disc according to  claim 29 , wherein the expansion device includes a plurality of flexible joints that permit relative movement of the shells after being embedded in the vertebral endplates.  
   
   
       31 . A method of inserting a total artificial expansible disc, comprising the steps of: 
 inserting, into a space defined by vertebral endplates, at least two pairs of substantially parallel shells, that move in multiple directions defined by at least two axes;    expanding the pairs of shells in multiple directions; and    permitting the vertebral endplates to move relative to one another, when a core is disposed between the pairs of shells.    
   
   
       32 . A method according to  claim 31  which further includes the step of expanding the pairs of shells along an axis substantially defined by the dorsal and ventral portions of the body.  
   
   
       33 . A method according to  claim 32  which further includes the step of expanding the pairs of shells along an axis substantially defined by the rostral and caudal portions of the body.  
   
   
       34 . A method according to  claim 33  which further includes the step of expanding the pairs of shells along an axis substantially defined by the left and right portions of the body.  
   
   
       35 . A method according to  claim 31  wherein the inserting step is performed from the posterior portion of the body.  
   
   
       36 . A method according to  claim 35  wherein the inserting step is performed in the lumbar portion of the spine.  
   
   
       37 . A method according to  claim 35  wherein the inserting step is performed in the thoracic portion of the spine.  
   
   
       38 . A method according to  claim 35  wherein the inserting step is performed in the cervical portion of the spine.  
   
   
       39 . A medical instrument for performing a total discectomy, comprising: 
 a pituitary rongeur, that is hand operated;    a light emitting device, for illuminating a region at the end of the pituitary rongeur; and    an imaging device, for imaging the illuminated region at the end of the pituitary rongeur.    
   
   
       40 . An instrument according to  claim 39  which further includes a monitor coupled to the imaging device.  
   
   
       41 . A medical instrument for rotating a control member; comprising: 
 a rotatable member, disposed at the end of the instrument;    a light emitting device, disposed in the vicinity of the rotatable member for illuminating the control member;    a drive mechanism, for imparting rotational movement to the rotatable member, the drive mechanism including an input member having an axis of rotation and a transfer device for communicating the rotation of the input member to the rotatable member; and    an imaging device for imaging the illuminated region.    
   
   
       42 . An instrument according to  claim 41  wherein the drive mechanism imparts rotational motion from the input member to the rotatable member using a plurality of miter gears.  
   
   
       43 . An instrument according to  claim 42  wherein the control member includes a screw head.