Vertebral cage

Abstract

Systems, methods and devices for spinal fusion are disclosed. In particular, certain disclosed embodiments are configured to permit the addition of lordosis to a spinal fusion cage after implantation through the use of various expansion mechanisms to spread arms of the spinal fusion cage. Disclosed embodiments may include the use of a threaded wedge to expand the arms, the use of a keel within a series of detents, the use of supplemental fixation screws, and the use of a rotating cam.

What is claimed is: 
     
         1 . A fusion cage, comprising:
 an elongate, threaded, cylindrical body having:
 a base portion defining a base opening configured to receive a spinal fixation screw therethrough, and 
 an expandable portion that includes first and second arms extending from and integrally and movably connected to the base portion such that the arms are spreadable from each other from an unexpanded position to an expanded position, the arms defining an inner space of the fusion cage, wherein the expandable portion defines an expandable portion opening aligned with the base opening to receive the fixation screw extending through both the base and expandable portion openings and into a vertebra in each of the unexpanded position, the expanded position, and during the spreading therebetween, and 
   an expansion member positioned within the inner space and associated with the arms such that movement of the expansion member within the inner space causes spreading of the arms from the unexpanded position to the expanded position.   
     
     
         2 . The fusion cage of  claim 1 , wherein the expandable portion opening and base opening are positioned such that an axis running through the expandable portion opening and base opening does not intersect the first arm or second arm when the body is in the unexpanded position, the expanded position, or during the spreading therebetween. 
     
     
         3 . The fusion cage of  claim 1 , wherein the expandable portion opening is defined between the first and second arms. 
     
     
         4 . The fusion cage of  claim 3 , wherein the first arm defines another expandable portion opening that is defined through the first arm. 
     
     
         5 . The fusion cage of  claim 1 , wherein the expandable portion opening is defined through the first arm. 
     
     
         6 . The fusion cage of  claim 1 , wherein:
 the base defines another base opening configured to receive another spinal fixation screw therethrough; and   the expandable portion defines another expandable portion opening aligned with the other base opening to receive the other fixation screw extending through both the other base opening and the other expandable portion opening and into a vertebra in each of the unexpanded position, the expanded position, and during the spreading therebetween.   
     
     
         7 . The fusion cage of  claim 6 , wherein the expandable portion openings are defined through the first and second arms. 
     
     
         8 . The fusion cage of  claim 6 , wherein the expandable portion openings are defined between the first and second arms. 
     
     
         9 . The fusion cage of  claim 6 , wherein one expandable portion opening is defined between the first and second arms and the other expandable portion opening is defined as not extending through an arm. 
     
     
         10 . The fusion cage of  claim 6 , wherein the base openings are disposed on opposite sides of the cylindrical body, and the expandable portions are disposed on the opposite sides of the cylindrical body such that the fixation screws are aligned to screw into opposing vertebra in a spinal column. 
     
     
         11 . The fusion cage of  claim 1 , wherein the expansion member is associated with the arms such that rotation of the expansion member causes spreading of the arms from the unexpanded position to the expanded position. 
     
     
         12 . The fusion cage of  claim 11 , wherein the expansion member comprises a cam disposed within the inner space such that the cam spreads the first and second arms responsive to the cam rotating a first amount. 
     
     
         13 . The fusion cage of  claim 12 , wherein the cam is disposed within the inner space in a first position, and wherein at least one detent is positioned within the inner space and configured to arrest the motion of the cam after the cam is rotated the first amount. 
     
     
         14 . The fusion cage of  claim 13 , wherein:
 a second detent is positioned within the inner space and configured to arrest the motion of the cam after the cam is rotated a second amount;   the second amount is greater than the first amount; and   when the cam is rotated the second amount, the first arm and second arm are spread further apart than when the cam is rotated the first amount.   
     
     
         15 . The fusion cage of  claim 11 , wherein:
 the expansion member comprises exterior threads; and   the first and second arms cooperatively define interior threads within the inner space that engage the threads of the expansion member such that rotation of the expansion member within the inner space moves the expansion member along the threads of the first and second arms, thereby causing the arms to spread from the unexpanded position to the expanded position.   
     
     
         16 . The fusion cage of  claim 1 , wherein the cylindrical body further comprises a tool engagement feature located at the base portion of the cylindrical body configured to allow driving of the cylindrical body in rotation to screw threaded body between opposing vertebra. 
     
     
         17 . The fusion cage of  claim 1 , wherein the expansion member comprises a slider and is associated with the arms such that movement of the expansion member along the arms causes spreading of the arms from the unexpanded position to the expanded position. 
     
     
         18 . A spinal fusion system, comprising:
 the fusion cage of  claim 1 ; and   the spinal fixation screw.   
     
     
         19 . The spinal fusion system of  claim 18 , wherein the expandable portion opening is defined through the first arm. 
     
     
         20 . The spinal fusion system of  claim 18 , wherein the expandable portion opening is defined between the first and second arms. 
     
     
         21 . A spinal fusion system, comprising:
 the fusion cage of  claim 7 ; and   the spinal fixation screws.