Expandable spinal fusion cage and associated instrumentation

Abstract

An expandable spinal implant comprising a cage body including at least two movable branches having first end portions that are interconnected to one another and second end portions that are movable relative to one another. The movable branches include a first shell portion having a first pair of longitudinal edges and defining a first hollow region therebetween, and a second shell portion having a second pair of longitudinal edges and defining a second hollow region therebetween, with the first and second hollow regions cooperating to define at least a portion of a hollow interior of the cage body. An expansion member co-acts with the first and second shell portions to transition the cage body to an expanded configuration as the expansion member is axially displaced along said first and second pairs of longitudinal edges. In one embodiment, at least one of the shell portions defines a plurality of retention elements positioned at select axial locations along a corresponding one of the longitudinal edges, with the expansion member engaged with one or more of the retention elements to retain the expansion member at a select axial position to maintain the implant in the expanded configuration.

1 .- 37 . (canceled) 
     
     
         38 . A surgical method, comprising:
 providing an expandable spinal implant comprising a cage body having a hollow inner chamber, the spinal implant having a length extending along a longitudinal axis and defining an outer cross section having a first transverse dimension defined by a first pair of oppositely facing surfaces extending substantially entirely along the length and a second transverse dimension defined by a second pair of oppositely facing surfaces extending between the first pair of oppositely facing surfaces, the second transverse dimension sized greater than the first transverse dimension;   inserting the spinal implant into an intervertebral space with the first transverse dimension generally aligned along a height of the intervertebral space;   orienting the spinal implant within the intervertebral space to generally align the second transverse dimension along the height of the intervertebral space; and   expanding the spinal implant along at least the second transverse dimension.   
     
     
         39 . The method of  claim 38 , wherein the orienting comprises rotating the expandable spinal implant 90 degrees about the longitudinal axis. 
     
     
         40 . The method of  claim 38 , wherein the expanding occurs subsequent to the orienting. 
     
     
         41 . The method of  claim 38 , further comprising:
 reorienting the spinal implant within the intervertebral space to generally realign the first transverse dimension along the height of the intervertebral space; and   removing the spinal implant from the intervertebral space.   
     
     
         42 . The method of  claim 41 , wherein the reorienting is accomplished without collapsing the spinal implant along the second transverse dimension. 
     
     
         43 . The method of  claim 41 , further comprising reinserting the spinal implant into the intervertebral space with the first transverse dimension generally aligned along the height of the intervertebral space and reorienting the spinal implant within the intervertebral space to generally align the second transverse dimension along the height of the intervertebral space. 
     
     
         44 . The method of  claim 38 , wherein the second pair of oppositely facing surfaces comprises a pair of opposite arcuate surfaces and the first pair of oppositely facing surfaces comprises a pair of opposite generally planar surfaces extending between the pair of arcuate surfaces; and
 wherein a distance between the pair of planar surfaces defines the first transverse dimension and a distance between the pair of arcuate surfaces defines the second transverse dimension.   
     
     
         45 . The method of  claim 38 ,
 further comprising positioning a bone growth promoting material within the inner chamber.   
     
     
         46 . The method of  claim 45 , wherein the positioning of the bone growth promoting material within the inner chamber occurs prior to the inserting. 
     
     
         47 . The method of  claim 44 , wherein the pair of arcuate surfaces comprise convex outer surfaces; and
 wherein the generally planar surfaces each extending from one of the convex outer surfaces to the opposite convex outer surface.   
     
     
         48 . The method of  claim 38 , wherein the second pair of opposite surfaces comprise a pair of opposite arcuate surfaces that each define external threads. 
     
     
         49 . The method of  claim 38 , wherein the second pair of oppositely facing surfaces comprise a pair of opposite arcuate surfaces; and
 wherein the first pair of oppositely facing surfaces comprises a pair of truncated side portions arranged generally opposite one another and peripherally interrupting and extending between the pair of opposite arcuate surfaces.   
     
     
         50 . The method of  claim 49 , wherein the pair of opposite arcuate surfaces each define external threads. 
     
     
         51 . The method of  claim 49 , wherein the pair of truncated side portions are defined by a pair of opposite generally planar surfaces extending between the pair of opposite arcuate surfaces. 
     
     
         52 . The method of  claim 38 , wherein the cage body includes at least two movable branches each having first end portions that are interconnected to one another and opposite second end portions that are movable relative to one another, the movable branches including inner surfaces cooperating with one another to define the hollow inner chamber of the cage body, the cage body including:
 a first shell portion having a first pair of longitudinal edges and defining a first hollow region between the first pair of longitudinal edges;   a second shell portion having a second pair of longitudinal edges and defining a second hollow region between the second pair of longitudinal edges, the first hollow region of the first shell portion cooperating with the second hollow region of the second shell portion to define at least a portion of the hollow inner chamber of the cage body; and   further comprising providing an expansion member and slidably engaging the expansion member simultaneously along the first and second pairs of longitudinal edges of the first and second shell portions which results in the expanding of the spinal implant along the second transverse dimension as the expansion member is axially displaced between opposing ones of the first and second pairs of longitudinal edges.   
     
     
         53 . The method of  claim 52 , wherein the first and second pairs of longitudinal edges are arranged transversely opposite one another with the first pair of longitudinal edges extending generally along a first plane and the second pair of longitudinal edges extending generally along a second plane. 
     
     
         54 . The method of  claim 52 , wherein at least one of the longitudinal edges of the first and second shell portions defines one or more retention elements positioned at select axial locations, the expansion member engaged with at least one of said retention elements to retain the expansion member at a select axial position between the first and second shell portions and to maintain said cage body in a transversely expanded configuration. 
     
     
         55 . The method of  claim 52 , wherein the second pair of oppositely facing surfaces comprise a pair of opposite arcuate surfaces, and the first pair of oppositely facing surfaces comprises a pair of truncated side portions arranged generally opposite one another and peripherally interrupting and extending between the pair of opposite arcuate surfaces; and
 wherein each of the at least two movable branches defines one of the outer arcuate surfaces and a portion of each of the truncated side portions.   
     
     
         56 . The method of  claim 55 , wherein the truncated side portions comprise substantially planar outer surfaces extending between the pair of opposite arcuate surfaces. 
     
     
         57 . The method of  claim 52 , wherein each of the first and second shell portions has a substantially semi-cylindrical shape; and
 wherein the first and second shell portions cooperate with one another to provide the cage body with a substantially cylindrical configuration with the hollow regions of the first and second shell portions defining at least a portion of the hollow inner chamber of the cage body.