Patent ID: 8795373

Claim:
A spinal fusion device comprising: a single piece U-shaped load bearing device configured to fit between two adjacent vertebrae, the load bearing device having one or more openings to allow access to surgically prepare the end plates of the two adjacent vertebrae after insertion of the load bearing device between the two adjacent vertebrae; a stress shielded, separate retention device configured to prevent migration of the load bearing device, wherein the height of the retention device is less than the load bearing device, wherein the retention device does not contact the end plates of the vertebrae; one or more fasteners coupled to the stress shielded, separate retention device to compress the two adjacent vertebrae to the load bearing device wherein the one or more fasteners do not pass through the load bearing device; and wherein the spinal fusion device has a shape that is zero-profile anteriorly; and further comprising an anti-backout mechanism coupled to the retention device, wherein the anti-backout mechanism comprises a locking plate and said locking plate comprises at least two opposing protrusions that extend outward from the plate and are positioned over the ends of the one or more fasteners and prevent the one or more fasteners from backing out, and further wherein the locking plate is located within a recess in the retention device and wherein a portion of the recess has a first depth and a portion of the recess has a second depth and wherein the second depth is deeper than the first depth and the locking plate has a locked position and an unlocked position, wherein, in the unlocked position, the locking plate is disposed within the first depth of the recess and in the locked position, the locking plate is disposed within the second depth of the recess.