Push-in interbody spinal fusion implants for use with self-locking screws

Abstract

An apparatus including an interbody spinal fusion implant having a leading end, a trailing end, and a length therebetween, and opposed upper and lower portions adapted to contact each of the adjacent vertebral bodies. Each of the upper and lower portions having at least one opening adapted to communicate with one each of the adjacent vertebral bodies and to communicate with one another to permit for the growth of bone from vertebral body to adjacent vertebral body through the implant. Each of the upper and lower portions has at least one screw hole passing therethrough proximate the trailing end. The apparatus further includes bone screws adapted for placement through the screw holes of the upper and lower portions and into each of the adjacent vertebral bodies adjacent the disc space to be fused and into which the implant is adapted to be positioned. At least one lock may be used to prevent the bone screws from backing out of the vertebral bodies and implant.

What is claimed is: 
     
         1 . An apparatus comprising:
 an interbody spinal fusion implant for surgical implantation at least in part within a disc space between two adjacent vertebral bodies in a segment of a human spine, said implant comprising an interior, a leading end for entry into the spine, a trailing end opposite said leading end, and a length therebetween, and upper and lower portions for contacting each of the adjacent vertebral bodies when positioned therein, said upper and lower portions having a maximum height therebetween, said upper and lower portions being at least in part non-arcuate, each of said upper and lower portions having at least one opening adapted to communicate with one of the adjacent vertebral bodies, said openings in said upper and lower portions being in communication with one another and adapted to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant, said implant including at least two vertebral body penetrating member receiving holes, each of said vertebral body penetrating member receiving holes having a central longitudinal axis passing through said trailing end and said interior of said implant;   vertebral body penetrating members adapted for placement through said vertebral body penetrating member receiving holes and into each of the adjacent vertebral bodies adjacent the disc space to be fused; and   a locking element adapted to be engaged to said trailing end of said implant to prevent movement of said vertebral body penetrating members in a direction opposite to the direction of insertion of said vertebral body penetrating members into said vertebral body penetrating member receiving holes, said locking element having an enlarged portion and a threaded shaft extending therefrom to threadably engage a portion of said trailing end of said implant.   
     
     
         2 . The apparatus of  claim 1 , wherein said implant further comprises a hollow interior for holding bone growth promoting material, said hollow interior being in communication with said at least one opening in each of said upper and lower portions. 
     
     
         3 . The apparatus of  claim 1 , wherein said vertebral body penetrating member receiving holes are opposed and divergently angled to one another. 
     
     
         4 . The apparatus of  claim 1 , wherein said vertebral body penetrating members are at least in part made of a resorbable material. 
     
     
         5 . The apparatus of  claim 1 , wherein said upper and lower portions are parallel to one another. 
     
     
         6 . The apparatus of  claim 1 , wherein said upper and lower portions are convergent to one another. 
     
     
         7 . The apparatus of  claim 1 , wherein said upper and lower portions are generally planar surfaces. 
     
     
         8 . The apparatus of  claim 1 , wherein each of said upper and lower portions have at least one bone engaging projection thereon. 
     
     
         9 . The apparatus of  claim 8 , wherein said projection is at least one of a fin and a ridge. 
     
     
         10 . The apparatus of  claim 1 , wherein said implant is at least in part bioabsorbable. 
     
     
         11 . The apparatus of  claim 1 , wherein said implant comprises a plastic material. 
     
     
         12 . The apparatus of  claim 1 , in combination with a chemical substance to inhibit scar formation. 
     
     
         13 . The apparatus of  claim 1 , in combination with a fusion promoting substance. 
     
     
         14 . The apparatus of  claim 13 , wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and genetic materials coding for the production of bone. 
     
     
         15 . The apparatus of  claim 1 , wherein said vertebral body penetrating members have a mid-longitudinal axis and a maximum dimension transverse to the mid-longitudinal axis, said locking element having a mid-longitudinal axis and a trailing end, said enlarged portion having a maximum dimension transverse to the mid-longitudinal axis of said locking element that is greater than the maximum transverse dimension of one of said vertebral body penetrating members. 
     
     
         16 . The apparatus of  claim 1 , wherein said locking element has a trailing end opposite said threaded shaft, said vertebral body penetrating members each having a mid-longitudinal axis and a trailing end having a head with a side, said enlarged portion of said locking element being adapted to contact a majority of said head of at least one of said vertebral body penetrating members. 
     
     
         17 . The apparatus of  claim 1 , wherein each of said at least two vertebral body penetrating member receiving holes has a seat at a depth along the central longitudinal axis that prevents a head of said vertebral body penetrating member from projecting beyond said trailing end of said implant when said head of said vertebral body penetrating member is in contact with said seat. 
     
     
         18 . A method for locking at least one bone screw to a spinal implant, the method comprising the steps of:
 inserting the spinal implant into a portion of a human spine, the implant including a leading end, a trailing end, and a mid-longitudinal axis through the leading and trailing ends;   inserting the bone screw into the trailing end of the implant, the bone screw having a trailing end and a central longitudinal axis;   locking the bone screw to the trailing end of the implant by rotating a locking element into a portion of the trailing end of the implant so that a portion of the locking element intersects the central longitudinal axis of the bone screw.   
     
     
         19 . The method of  claim 18 , wherein the step of inserting the bone screw includes inserting at least a second bone screw into the trailing end of the implant, and the step of locking includes locking at least two bone screws to the implant. 
     
     
         20 . The method of  claim 18 , further comprising engaging the locking element to the implant prior to the step of inserting the bone screw.