Intervertebral disc implants and tooling

Abstract

A kit for preparing an intervertebral disc space for receiving an implant (100) includes a plurality of trials (152) having different sizes. Each trial (152) includes a body (154) insertible into an intervertebral disc space, the body (154) having a leading end (162), a trailing end (164), a top surface (156) and a bottom surface (160), the top surface of the body having a first groove (176) formed therein. Each implant also includes a flange (166) secured to the trailing end (164) of the body (154), the flange (166) having a first channel (180) aligned with the first groove (176), wherein each of the different sized trials has a different flange thickness. The flange thickness controls advancement of a cutting tool such as a chisel (192) into the first groove at the top surface of the trial body, which controls the depth of the cut into vertebral bone.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60 / 846,196 filed Sep. 21, 2006, the disclosure of which is hereby incorporated herein by reference.[0002]The present application is related to U.S. patent application Ser. No. 11 / 439,808, filed May 24, 2006, which claims the benefit of U.S. Provisional Patent Application No. 60 / 790,415, filed Apr. 7, 2006, which claims the benefit of U.S. Provisional Patent Application No. 60 / 721,053, filed Sep. 27, 2005, which claims the benefit of U.S. Provisional Patent Application No. 60 / 701,306, filed Jul. 21, 2005, which claims the benefit of U.S. Provisional Patent Application No. 60 / 685,295, filed May 27, 2005, the disclosures of which are hereby incorporated by reference herein.[0003]The present application also relates to U.S. Pat. No. 6,908,484, entitled “Cervical Disc. Replacement” and filed on Mar. 6, 2003; U.S. Pat. No. 6,994,728, entitled “Cerv...

AI Technical Summary

Benefits of technology

[0019]The top element of the implant preferably includes a first bone engaging surface having a protrusion and a second articulating surface. The top element desirably includes a posterior end, an anterior end and an opening at the anterior end that is adapted to receive a prong or post of an insertion instrument. The top element desirably includes opposing lateral sides that extend between the posterior end and the anterior end of the top element. In certain preferred embodiments, the intervertebral disc implant may be at least partially coated with an osteoconductive material to facilitate long-term fixation to endplates of vertebral bodies.

[0021]The protrusions on the top element preferably include teeth 122, which desirably have sloping surfaces. Each of the sloping surfaces preferably has a low point nearer to the posterior end of the top element and a high point nearer to the anterior end of the top element. The sloping surfaces preferably facilitate insertion of the posterior end of the top element into a disc space while making it more difficult for the top element to be removed or discharged from the disc space in a posterior to anterior direction.

[0025]When the top element is assembled with the bottom element, the opposing articulating surfaces are adapted to engage one another. When the top and bottom elements are assembled together, the projection on the top element is offset from the two projections on the bottom element. In prior art devices, it has been observed that stacking two implants in successive disc spaces may result in cracking of vertebral bone between the implants because the apexes on the teeth of the two implants are in alignment. The present invention seeks to avoid this cracking problem by offsetting the projection on the top element from the projections on the bottom element. Although the present invention is not limited by any particular theory of operation, it is believed that providing projections that are offset from one another enables two or more intervertebral disc implants to be inserted into two or more successive disc spaces, while minimizing the likelihood of cracking the vertebral bodies between the disc spaces.

[0028]In certain preferred embodiments, the top surface of the body desirably tapers toward the bottom surface of the body between the trailing end and the leading end of the body. In other words, the leading end of the body has a taper which facilitates insertion into a disc space.

Problems solved by technology

This degeneration of this critical disc material, from the hydrated, elastomeric material that supports the separation and flexibility of the vertebral bones, to a flattened and inflexible state, has profound effects on the mobility (instability and limited ranges of appropriate motion) of the segment, and can cause significant pain to the individual suffering from the condition.

Unfortunately, until the advent of spine arthroplasty devices, the only methods known to surgeons to maintain the necessary disc height necessitated the immobilization of the segment.

Either way, however, it is clear that a progressive fusion of a long sequence of vertebrae is undesirable from the perspective of the patient's quality of life as well as from the perspective of pushing a patient to undergo multiple operative procedures.

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