Abstract: Cutters for disrupting tissue include a cutter body and replaceable cutter blades. The cutter blades may be placed in one of three positions (sheathed for transport, unsheathed for use, and sufficiently exposed for blade exchange) by the relative movement of a cutter sheath with respect to the engagement zone between the cutter blade and the cutter body. The relative movement of the cutter sheath may be limited to an operational range to preclude inadvertent exposure of the cutter blade to prevent unintended disengagement from the cutter body. Various sheath limiters are disclosed that selectively limit movement of the cutter sheath to an operational range or allow extraordinary movement to allow blade exchange. In some instances other intermediate stops may be used to further limit the relative motion. The relative motion could be imparted by the movement of a cutter rod (rather than the movement of the cutter sheath) and thus limited by a rod limiter.

Abstract: Cutter blades made of shape memory materials. Rotation of a cutter blade as part of a cutter assembly within an intervertebral disc space cuts the material present there for removal from the intervertebral disc space. Cutter blades with different attributes (such as throw length, cutter blade angle, type and location of blade edges) are adapted to achieve different objectives within the intervertebral disc space. The use of a hollow ground to enhance the cutting action of a blade edge is described in connection with the creation of cutter blades. A variety of thin cutter blades are described which may be used in the interior of a thin intervertebral disc (having a reduced distance between the endplates of the adjacent vertebral bodies).