A spinal fusion implant includes a leading end, an opposite trailing end, an upper portion extending between the leading and trailing ends, a lower portion extending between the leading and trailing ends, and opposed first and second side portions extending between the leading and trailing ends. The upper portion includes at least two rails extending between the leading and trailing ends, the at least two rails including a first rail and a second rail spaced apart from one another, the first rail of the upper portion including a bone-contacting surface being at least partially smoothened. The lower portion includes at least two rails extending between the leading and trailing ends, the at least two rails including a first rail and a second rail spaced apart from one another, the first rail of the lower portion including a bone-contacting surface being at least partially smoothened.
