Instruments and methods for non-parallel disc space preparation

#The lateral access approach is frequently utilized to deliver interbody fusion cages to the lumbar spine. In comparison to conventional anterior or posterior approaches to the lumbar spine, the lateral approach is thought to minimize posterior and/or anterior tissue damage as well as reduce surgery time, associated blood loss, and infection risk.

#When multi-level access to the spine is provided through a single minimal access port, the insertion trajectory to the superior and inferior levels is not parallel to those levels. In addition, direct lateral access parallel to the L4/5 and L5/S1 levels is prevented by the presence of the iliac crest.

#Accordingly, the angled trajectory required for lateral access to these lower levels requires the cages to be implanted at a “malpositioned” angle that prevents balanced loading across the vertebral endplates and spine. See FIG. 1. This “malpositioned” access, associated endplate damage and device placement can initiate subsidence and spinal instability.

#FIG. 1 discloses a coronal view of a human spine in which a a conventional method of laterally implanting cages in the lower spine is used, producing malpositioned cages.

#FIG. 2a-c discloses various shavers of the present invention having a universal joint, wherein the shavers are presented in varying degrees of angulation.

#FIG. 2d-e discloses a universal jointed shaver of the present invention preparing an endplate in the lower spine through a port of the present invention.

#The present invention relates to flexible spreaders and shaver devices and methods for parallel preparation of an intervertebral disc space in the context of a non-parallel access trajectory. The flexible shavers utilize curved guide tubes to enable their placement, insertion, flexing, bending and/or pivoting in the disc space.

#In some embodiments, the flexible shaft can have a flexibility-imparting geometry that includes use of at least one of a) a spring (available from SS White of Piscataway, N.J.), b) a slotted tube (available from Necomed of Hicksville, Ohio), and c) a standard universal joint. Now referring to FIGS. 2a -e, in some embodiments, the flexible shaver 11 of this embodiment also includes a proximal handle 15, an intermediate shaft 19 comprising a universal joint 20, and a distal shaver head 23.

#Therefore, now referring to FIGS. 2a-e, there is provided a flexible shaver 11 for preparing a vertebral endplate, comprising: