Open intervertebral spacer

Open chambered spacers, implanting tools and methods are provided. The spacers 500 ' include a body 505 ' having a wall 506 ' which defines a chamber 530 ' and an opening 531 ' in communication with the chamber 530 '. In one embodiment the wall 506 ' includes a pair of arms 520', 521 ' facing one another and forming a mouth 525 ' to the chamber 530 '. Preferably, one of the arms 520 ' is truncated relative to the other, forming a channel 526 . In one aspect the body 505 ' is a bone dowel comprising an off-center plug from the diaphysis of a long bone. The tools 800 include spacer engaging means for engaging a spacer and occlusion means for blocking an opening defined in the spacer. In some embodiments, the occlusion means 820 includes a plate 821 extendable from the housing 805 . In one specific embodiment the plate 821 defines a groove 822 which is disposed around a fastener 830 attached to the housing 805 so that the plate 821 is slideable relative to the housing 805.