Patent ID: 7137997

Claim:
An intervertebral fusion cage for implantation in a treated area of an intervertebral space between vertebral bodies of a spine, wherein said fusion cage comprises: a spacer body comprising an inferior surface and a superior surface, wherein the inferior and superior surfaces each have a contact area capable of engaging with anatomy in the treated area, and wherein said inferior and superior surfaces define a through-hole extending through the spacer body; a sidewall disposed between the inferior surface and the superior surface of the spacer body, wherein the sidewall defines at least a portion of an outer perimeter of the spacer, wherein the outer perimeter has a generally arcuate posterior side and an anterior side formed from a combination of convex and concave curves; a first window having a first area formed in said sidewall, wherein the first window extends from a first side of said spacer body to a second side along a first window axis, thereby forming a second window having a second area in the second side, wherein the first and second windows are capable of permitting confirmation that the vertebral bodies in the treated area are fusing together, and wherein when viewing the spacer body along the first window axis the first window area is about 20 percent or more of the visible area of the first side when viewed from the first window axis; a first leading edge comprising a chamfer along a portion of a lateral side for insertion of the spacer into the treated area using a posterior approach, wherein the first leading edge is substantially free of protrusions; and a second leading edge comprising a chamfer along a portion of an anterior side, wherein the second leading edge is substantially free of protrusions and is configured to slide against an anterior lip of an end plate of a vertebral body in the treated area and guide the spacer into position as it is being inserted, and wherein a portion of the anterior side is configured to act as a fulcrum to facilitate pivoting and translation during insertion.