A cage to separate and support adjacent vertebrae in the spine that have undergone orthopedic spinal fusion procedures. The cage has first and second spacer members for insertion between adjacent vertebrae with a hinge located between the spacers. An advancing mechanism is located between the first and second spacer members that pivotally moves the first and second spacer members relative to each other at an angle which facilitates the insertion of the cage around the spinal cord. After insertion, the advancing mechanism is operable to position the first and second spacer members in the desired position between the two adjacent vertebrae.