US Patent 8066709 Distractor with opening

An apparatus and method for placing adjacent vertebrae at a fixed distance and angular relationship relative to each other, fixing said vertebrae in said position by use of a milling block engaging each of said adjacent vertebrae and then using a milling means, the depth, length and excursion of which from side to side are controlled by said apparatus to machine out a defined thickness of bone and a space of defined length, height, width and shape in preparation for receiving an interbody spinal implant or graft of known size and configuration are disclosed.