Apparatus and method for performing spinal surgery

Abstract

A cutting guide for use in spinal surgery includes a sidewall defining an internal cavity. A chisel guide, for use with the cutting guide, includes a first block member to be inserted into the internal cavity of the cutting guide to position the first block member adjacent the vertebral body. The chisel guide also includes a second block member connected to the first block member. An apparatus for creating a cavity in a-vertebral body endplate and in an intervertebral disc may be a compressor or a distractor having at least one cutting implement thereon. A tensioner determines a proper elongation distance in a prosthesis implanted in a vertebral body.

Description

BACKGROUND OF THE INVENTION [0001] This invention relates to the field of spinal surgery. More specifically, this invention relates to apparatuses for creating cavities in vertebral bodies and in intervertebral discs located between the vertebral bodies. This invention also relates to methods for creating such cavities. Once the cavities are created with the apparatuses and according to the methods of the present invention, an intervertebral prosthetic device, designed to replace a damaged intervertebral disc, can be implanted in the cavities. Moreover, the implanted device may be used in vertebral body fusion or in reconstruction of mobile discs through spinal arthroplasty (i.e., disc replacement). [0002] The human spine is a flexible structure comprised of twenty-five vertebrae. Intervertebral discs separate and cushion adjacent vertebrae. The intervertebral discs act as shock absorbers and allow bending between the vertebrae. [0003] An intervertebral disc comprises two major comp...

AI Technical Summary

Benefits of technology

"The patent describes various apparatuses and methods for creating cavities in a vertebral body and intervertebral disc for replacing a damaged intervertebral disc. The apparatuses include a cutting guide with a sidewall that defines an internal cavity, a chisel guide with a first and second block member, and a reamer with a cutting member. The methods involve using the cutting guide to position the cutting member adjacent the vertebral body, using the chisel guide to remove bone from the vertebral body, and using the reamer to collect bone fragments. The apparatuses and methods provide improved tools for creating cavities in the spine."

Problems solved by technology

Individuals with damaged or degenerated discs often experience significant pain.

The pain results, in part, from instability in the intervertebral joint due to a loss of hydrostatic pressure in the nucleus pulposus, which leads to a loss of disc height and altered loading of the annulus fibrosis.

Although spinal fusion may alleviate pain associated with degenerative disk disease, it also results in loss of motion at the fused vertebral joint.

Lack of motion at the fused site puts abnormal loads on the adjacent discs above and below the fusion.

This additional pressure may cause the adjacent discs to degenerate and produce pain, thereby recreating the problem which originally existed.

Existing prosthetic devices have met with limited success in reproducing the biomechanics of a natural disc.

Although the hinged disc allows forward bending between adjacent vertebrae, the hinged disc does not allow axial compression or lateral flexion.

Nor does it allow axial rotation of the vertebral column at the site of the implant.

Therefore, the Hedman et al. device lacks many of the biomechanics of a natural disc.

Likewise, the prosthetic disc device disclosed in U.S. Pat. No. 4,309,777 to Patil does not replicate natural motion between adjacent discs.

Thus, the Patil device does not enable natural flexion of the spine in any direction.

In addition, the highly constrained motion of the Patil device can lead to high device / tissue interface stresses and implant loosening.

Other synthetic devices use plastic or elastomeric components which, over a lifetime, produce debris from wear and possible unknown side effects.

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