Open intervertebral spacer

open separators provided with cameras, implant devices and procedures are presented. Spacers (500) may include a body (the 505) having a wall (506¿) defining a chamber (530¿) and an opening (531¿) in communication with the chamber (530¿). In one embodiment, the wall includes a pair of arms (the 520, 521¿) that face each other and form a mouth (525¿) in the chamber (530¿). Preferably, one arm (the 520) is truncated relative to the other, forming a channel (526). In one aspect, the body (the 505) is a bone dowel comprising a block offset from the aspect diaphysis of a long bone. Devices (800) include coupling means for coupling a spacer and occlusion means separator pair blocking an opening defined in the spacer. In some embodiments, the occluder (820) includes a plate (821) extendable from the housing (805). In a specific embodiment, the plate (821) defines a groove (822) that WILL disposed about a fastener (830) attached to the housing (805) so that the plate (821) slidable relative to the housing (805) .