Bone fixation and fusion device

Abstract

Disclosed is a bone fusion cage that contains bone graft and is implanted between bones in a skeletal system. The cage bears structural loads that are transmitted through the bones of the skeletal system and at least partially shields the contained bone graft from the structural loads. The cage is configured to provide a secondary load to the bone graft independent of the structural load to promote fusion of the bone graft to adjacent bones.

1 - 6 . (canceled) 
     
     
         7 . A method of using a fusion implant to reconstruct a defective portion within a spinal segment of a subject, the spinal segment comprising a superior vertebral bone, an inferior vertebral bone and an intervening intervertebral disc space, and the defective portion extending from an inferior aspect of the superior vertebral bone to a superior aspect of the inferior vertebral bone and disrupting transmission of a vertical load along a longitudinal axis of the spinal segment, the method comprising:
 coupling an implant placement assembly to a proximal side wall of the fusion implant, the fusion implant comprising: (i) an upper abutment member configured to abut the inferior aspect of the superior vertebral and comprising a least one feature that is configured to increase fixation of the fusion implant onto bone, (ii) a lower abutment member configured to abut the superior surface of the inferior vertebral, the lower abutment member positioned a first distance from the upper abutment surface; (iii) a distal side wall positioned opposite the proximal wall, the distal side wall and the proximal side wall being separated by a second distance when measured along a second axis; (iv) an internal cavity positioned at least partially between the proximal side wall and the distal side wall; and (v) a load member that is movable relative to the proximal side wall and configured to transition from a first position to a second position at least partially within the internal cavity;   placing a bone forming material within the internal cavity of the fusion implant;   positioning the fusion implant at least partially within the defective portion, such that the upper abutment member of the fusion implant abuts the inferior aspect of the superior vertebral bone and the lower abutment member of the fusion implant abuts the superior aspect of the inferior vertebral bone, the positioning causing at least a portion of the vertical load to be transmitted through the fusion implant; and   using a displacement instrument to transition the load member from the first position to the second position;   wherein the transitioning the load member from the first position to the second position causes at least: (i) a decrease of a distance between the load member and the distal side wall along the direction of the second axis while the first distance and the second distance remain unchanged, and (ii) the load member to apply a compressive force onto the bone forming material contained in the internal cavity.   
     
     
         8 . The method of  claim 7 , further comprising disengaging the displacement instrument from the fusion implant after the transitioning the load member from the first position to the second position has been completed. 
     
     
         9 . The method of  claim 8 , wherein after the disengaging the displacement instrument has been completed, the load member is retained at a distance from the distal side wall, as measured along the direction of the second axis, which is reduced relative to a distance from the side wall when in the load member was in the first position. 
     
     
         10 . The method of  claim 7 , wherein the compressive force applied by the load member comprises a load component extending along a direction that is non-parallel to the longitudinal axis of the spinal segment. 
     
     
         11 . The method of  claim 7 , wherein the compressive force applied by the load member comprises a vertical load component, the vertical load component extending along a direction which is at least approximately parallel to the longitudinal axis of the spinal segment. 
     
     
         12 . The method of  claim 7 , wherein the placing the bone forming material within the internal cavity of the fusion implant occurs prior to the positioning the fusion implant at least partially within the defective portion. 
     
     
         13 . The method of  claim 7 , wherein the placing the bone forming material within the internal cavity of the fusion implant occurs while the implant placement assembly is coupled to the proximal side wall of the fusion implant. 
     
     
         14 . The method of  claim 7 , wherein the placing the bone forming material within the internal cavity of the fusion implant occurs subsequent to completion of the positioning the fusion implant at least partially within the defective portion. 
     
     
         15 . The method of  claim 7 , wherein implant attachment assembly further comprises the displacement instrument. 
     
     
         16 . The method of  claim 7 , wherein the using the displacement instrument to transition the load member from the first position to the second position comprises using the displacement instrument to transition while the implant placement assembly is coupled to the fusion implant. 
     
     
         17 . The method of  claim 7 , wherein the positioning the fusion implant at least partially within the defective portion comprises positioning the fusion implant such that the load member does not bear at least a portion of the vertical load transmitted from the superior vertebral bone to the inferior vertebral bone and through the fusion implant. 
     
     
         18 . The method of  claim 7 , wherein the fusion implant further comprises a coupling member providing a biasing force on the load member towards the second position of the load member, and wherein the using the displacement instrument to transition the load member from the first position to the second position comprises at least using the biasing force. 
     
     
         19 . The method of  claim 7 , wherein the fusion implant further comprises a mechanism configured to bias the load member towards the second position. 
     
     
         20 . The method of  claim 7 , further comprising preloading the load member with a biasing force, the biasing force urging transition of the load member from the first position to the second position. 
     
     
         21 . The method of  claim 7 , wherein:
 the fusion implant comprises a non-expandable device; and   the second distance comprises a fixed distance.   
     
     
         22 . A method of using a fusion implant to reconstruct a defective portion within a spinal segment of a subject, the spinal segment comprising a superior vertebral bone, an inferior vertebral bone and an intervening intervertebral disc space, wherein the defective portion extends from an inferior aspect of the superior vertebral bone to a superior aspect of the inferior vertebral bone and disrupts transmission of a vertical load along a longitudinal axis of the spinal segment, the method comprising:
 coupling an implant placement assembly to the fusion implant, the fusion implant comprising: (i) an upper abutment member configured to abut the inferior aspect of the superior vertebral and comprising a least one feature configured to increase fixation of the upper abutment member onto bone, (ii) a lower abutment member configured to abut the superior surface of the inferior vertebral and positioned a first distance from the upper abutment surface; (iii) a distal side wall positioned opposite a proximal side wall, the distal side wall and the proximal side wall being separated by a second distance when measured along a second axis; (iv) an internal cavity positioned at least partially between the proximal side wall and the distal side wall; and (v) a load member configured to transition from a first position to a second position at least partially within the internal cavity;   inserting a bone forming material within the internal cavity of the fusion implant;   positioning the fusion implant at least partially within the defective portion, such that the upper abutment member of the fusion implant abuts the inferior aspect of the superior vertebral bone and the lower abutment member of the fusion implant abuts the superior aspect of the inferior vertebral bone, the positioning causing at least a portion of the vertical load to be transmitted through the fusion implant; and   using at least the displacement instrument, transitioning the load member from the first position to the second position while the implant placement assembly is coupled to the fusion implant;   wherein the act of transitioning the load member from the first position to the second position: (i) decreases a distance between the load member and the distal side wall of the fusion implant along the second axis while the first distance and the second distance remain unchanged, and (ii) causes the load member to apply a compressive force onto the bone forming material contained in the internal cavity.   
     
     
         23 . The method of  claim 22 , further comprising disengaging the displacement instrument from the fusion implant after the transitioning the load member from the first position to the second position has been performed. 
     
     
         24 . The method of  claim 23 , wherein after the disengaging the displacement instrument is performed, the load member is retained at a lesser distance from the distal side wall, as measured along the direction of the second axis, than the distance of the load member from the distal side when the load member in the first position. 
     
     
         25 . The method of  claim 22 , wherein the compressive force applied by the load member comprises an at least partly transverse load component, the at least partly transverse load component extending along a direction that is non-parallel to the longitudinal axis of the spinal segment. 
     
     
         26 . The method of  claim 22 , wherein the compressive force applied by the load member comprises a vertical load component, the vertical load component extending along the direction of the longitudinal axis of the spinal segment. 
     
     
         27 . The method of  claim 22 , wherein the inserting the bone forming material within the internal cavity of the fusion implant is performed prior to the positioning the fusion implant at least partially within the defective portion. 
     
     
         28 . The method of  claim 22 , wherein the inserting the bone forming material within the internal cavity of the fusion implant is performed while the implant placement assembly is coupled to the fusion implant. 
     
     
         29 . The method of  claim 22 , wherein the inserting the bone forming material within the internal cavity of the fusion implant is performed subsequent to the positioning the fusion implant at least partially within the defective portion. 
     
     
         30 . The method of  claim 22 , wherein the positioning the fusion implant at least partially within the defective portion comprises positioning the fusion implant such that the load member does not bear that portion of the vertical load transmitted from the superior vertebral bone to the inferior vertebral bone and through the fusion implant. 
     
     
         31 . The method of  claim 22 , wherein the fusion implant further comprises a mechanism configured to cause biasing of the load member towards the second position. 
     
     
         32 . The method of  claim 31 , further comprising preloading the load member with a biasing force, the biasing force easing transition of the load member from the first position to the second position. 
     
     
         33 . The method of  claim 22 , wherein the load member comprises a curvilinear configuration, and wherein the transition of the load member from the first position to the second position comprises utilizing at least a portion of the curvilinear configuration. 
     
     
         34 . The method of  claim 22 , wherein the transitioning the load member from the first position to the second position comprises causing the load member to apply a centripetal force onto the bone forming material, the centripetal force being at least partially directed towards a vertical axis of the spinal segment. 
     
     
         35 . The method of  claim 22 , wherein:
 the fusion implant comprises a non-expandable, rectangular body having the proximal side wall, the distal side wall, a first side wall connecting the proximal side wall and the distal side wall, and a second side wall opposing the first side wall; and   the positioning the fusion implant at least partially within the defective portion, such that the upper abutment member of the fusion implant abuts the inferior aspect of the superior vertebral bone and the lower abutment member of the fusion implant abuts the superior aspect of the inferior vertebral bone comprises maintaining a relationship between the first sidewall and second sidewall at least during said positioning.   
     
     
         36 . The method of  claim 22 , wherein the load member is configured to move relative to each of the proximal side wall, the distal side wall, the first side wall and the second side wall, and wherein the transitioning the load member from the first position to the second position comprises causing said movement relative to each of the proximal side wall, the distal side wall, the first side wall and the second side wall.