Interbody spinal fusion device

Abstract

A spinal fusion implant device ( 10 ), and method of use, for promotes device for promoting a spinal fusion between neighboring vertebrae. The spinal fusion device may be located within the intervertebral disc space and includes a pair of plate member ( 12, 14 ) that preferably have flat support plates ( 18, 36 ) for contacting and resting against the softer, central cancellous bone portion of respective endplates of adjacent vertebrae. The support plates have a front template portion ( 27, 44 ) that is substantially orthogonal to the flat support plate and is bent in a direction to communicate with the anterior surface of the hard cortical endplate the respective vertebrae. The flat support plates are provided with a central channel ( 56 ) in which a support strut ( 55 ) may be placed. The support is configured to vary the distance between the support plates such that the height of the apparatus proximate the anterior end is greater than the height of the device at the posterior end whereby the natural lordosis of the spine is maintained after the apparatus is installed. The support strut may be selected from a set of support struts of predetermined height and angle, to alter the vertical distance between the support plates to customize the apparatus to fit a given patient. Channels formed ( 66, 67 ), on either side of the support strut, are filled with bone graft material and contact the endplates of the vertebrae through large openings ( 25, 26, 43, 45 ) in the flat support plates to facilitate fusion.

What is claimed is:  
     
         1 . An interbody spinal fusion device for facilitating fusion between adjacent vertebrae of a human spine, the interbody spinal fusion device comprising: 
 a pair of bone-engaging plate members adapted to engage respective ones of the vertebrae, and to be accommodated therebetween, for maintaining the respective vertebrae in a predetermined spaced apart relationship, the interbody fusion device having an anterior end distal from a posterior end, the bone-engaging plate members each having;    a support plate configured to communicate intimately with an endplate of an associated one of the adjacent vertebrae, the support plate having an outer surface that contacts the associated vertebra and an inner surface directed toward the other of the adjacent vertebrae, the support plate having apertures therethrough and at least one longitudinal support plate portion extending substantially through the support plate from the anterior end thereof to the posterior end thereof, and    a generally curved template having a first template surface extending outward substantially orthogonal with respect to the horizontal plane of the support plate in the direction of the outer surface of the support plate, the first template surface facing in the posterior direction and arranged for communicating with a substantially lateral anterior cortical surface portion of the associated vertebra, the template further having an anterior surface; and    a support strut interposed between respective inner surfaces of the bone-engaging plate members, said support strut being arrange to extend substantially parallel to the longitudinal support plate portion, the support strut being adapted to maintain the bone-engaging plate members apart in a predetermined spatial relationship wherein a distance between the respective inner surfaces proximate the anterior end is greater that the distance proximate the posterior end, whereby a substantially natural lordosis of the human spine is maintained.    
     
     
         2 . The interbody spinal fusion device of  claim 1  wherein the support plate is generally flat.  
     
     
         3 . The interbody spinal fusion device of  claim 1  wherein the support plate is adapted to follow generally the contour of the endplate of the vertebra with which it communicates.  
     
     
         4 . The interbody spinal fusion device of claims  1  and  2  wherein the support plate comprises three longitudinal members that define two large apertures through the support plate.  
     
     
         5 . The interbody spinal fusion device of  claim 4  wherein the longitudinal members terminate in a generally curved section at the posterior end, and terminate with the template at the anterior end.  
     
     
         6 . The interbody spinal fusion device of  claim 1  wherein the anterior surface of at least one template is provided with at least three apertures for accommodating fasteners.  
     
     
         7 . The interbody spinal fusion device of  claim 7  wherein the apertures are configured to determine the angle of penetration of the fasteners into each vertebra.  
     
     
         8 . The interbody spinal fusion device of claims  6  and  7  wherein the fasteners are orthopedic bone screws.  
     
     
         9 . The interbody spinal fusion device of  claim 1  wherein the support plate further includes at least two tabs that are integrally formed, and coplanar, with the anterior surface of the template, and extend in the direction of the inner surface of the support plate.  
     
     
         10 . The interbody spinal fusion device of  claim 9  wherein the support plate is provided with two adjacent tabs for guiding the support strut between the bone-engaging plate members during placement.  
     
     
         11 . The interbody spinal fusion device of  claim 10  wherein said two adjacent tabs define an opening having a width approximately equal to the width of the support strut.  
     
     
         12 . The interbody spinal fusion device of  claim 1  wherein at least one of the support plates includes a protuberance on the inner surface of the longitudinal member proximate the posterior end to preclude over-insertion of the support strut in the posterior direction.  
     
     
         13 . The interbody spinal fusion device of  claim 1  further including bone graft material packed into channels formed on either side of the support strut and extending between the support plates, the bone graft material communicating with the vertebrae through the openings in the support plates.  
     
     
         14 . The interbody spinal fusion device of  claim 1  wherein there is further provided an end cap proximate the anterior end.  
     
     
         15 . The interbody spinal fusion device of  claim 1  wherein the support strut is wedge-shaped.