A spinal fusion implant assembly for spacing vertebrae and method of using the implant are provided. The implant includes two components each having a vertebral contact surface, a pair of side portions, and an end plate. The two components are complementary such that when placed together they form a whole. Each of the sides has a high point and a low point, such that a sloped edge of each side is defined between the high point and the low point, and the slope of the first sides is complementary to the slope of the second sides. The device also includes a translation mechanism for providing relative motion between the components.