Spinal Fusion Apparatus

Abstract

An interbody spinal fusion cage for posterior interbody fusion procedures includes a superior member and an inferior member connected to each other via a joint. The joint allows the interbody spinal fusion cage to achieve lordosis even if implanted non-orthogonal to the sagittal plane. For example, the joint can be a hinge oriented non-normal to a longitudinal axis of the interbody spinal fusion cage, a polyaxial ball joint, and/or a universal joint. Complementary locking mechanisms, such as locking teeth or a ratchet-and-pawl arrangement, can be provided near the posterior ends of the superior and inferior members in order to prohibit the posterior ends of the superior and inferior members from separating from each other in situ. Bone holes can be provided in the superior and inferior members.

1 - 20 . (canceled) 
     
     
         21 . An interbody spinal fusion cage, comprising:
 a superior member including an anterior end, a posterior end, and a superior bearing surface extending along an axis between the anterior end of the superior member and the posterior end of the superior member;   an inferior member including an anterior end, a posterior end, and an inferior bearing surface extending along an axis between the anterior end of the inferior member and the posterior end of the inferior member;   a joint connecting the superior member to the inferior member, wherein the joint permits seesaw motion between the superior member and the inferior member about a single axis of rotation that is oriented non-normal to the axis of the superior member and the axis of the inferior member, and prohibits relative translation between the superior member and the inferior member along the axis of the superior member and the axis of the inferior member;   a lock that, when engaged, prevents the seesaw motion between the superior member and the inferior member.   
     
     
         22 . The interbody spinal fusion cage according to  claim 21 , wherein the lock engages the joint to prevent the seesaw motion between the superior member and the inferior member. 
     
     
         23 . The interbody spinal fusion cage according to  claim 21 , wherein the lock engages at least one of the superior member and the inferior member to prevent the seesaw motion between the superior member and the inferior member. 
     
     
         24 . The interbody spinal fusion cage according to  claim 21 , wherein the lock, when engaged, fixes a distance between the posterior end of the superior member and the posterior end of the inferior member. 
     
     
         25 . A method of performing a transforaminal lumbar interbody fusion, comprising:
 inserting, via a posterior approach, an interbody spinal fusion cage between two vertebrae, the interbody spinal fusion cage comprising:
 a superior member including an anterior end, a posterior end, and a superior bearing surface extending along an axis between the anterior end of the superior member and the posterior end of the superior member; 
 an inferior member including an anterior end, a posterior end, and an inferior bearing surface extending along an axis between the anterior end of the inferior member and the posterior end of the inferior member; and 
 a joint connecting the superior member to the inferior member, 
 wherein the joint permits seesaw motion between the superior member and the inferior member about a single axis of rotation that is oriented non-normal to the axis of the superior member and the axis of the inferior member, and 
 wherein the joint prohibits relative translation between the superior member and the inferior member along the axis of the superior member and the axis of the inferior member; 
   rotating the superior member relative to the inferior member about the single axis of rotation of the hinge into a desired angular relationship; and   locking the interbody spinal fusion cage against the seesaw motion between the superior member and the inferior member once the superior member and the inferior member are in the desired angular relationship.   
     
     
         26 . The method according to  claim 25 , wherein the locking step comprises locking the interbody spinal fusion cage against the seesaw motion between the superior member and the inferior member in at least a rotational direction that would increase a distance between the posterior end of the superior member and the posterior end of the inferior member. 
     
     
         27 . The method according to  claim 25 , wherein the locking step comprises engaging a lock against the joint to prevent the seesaw motion between the superior member and the inferior member. 
     
     
         28 . The method according to  claim 25 , wherein the locking step comprises engaging a lock against at least one of the superior member and the inferior member to prevent the seesaw motion between the superior member and the inferior member.