An interbody spacer assembly includes a pair of end pieces spaced apart by a connector extending between them. The end pieces extend generally parallel to the end plates of adjoining vertebral bodies. Fasteners connect the end pieces to the vertebral bodies. Bone graft material or solid bone can be placed in the interior space defined by the end pieces and connector, which bone graft material or solid bone eventually fuses together and to the adjoining end plates through the end pieces. The spacer assembly has ratchets to connect the two end pieces. The ratchets near the fasteners are more closely spaced than the ratchets further from the fasteners, allowing the spacer assembly to more closely approximate the lordosis of the spine.