Method and Spacer Device for Spanning a Space Formed upon Removal of an Intervertebral Disc

Abstract

An intervertebral spacer is designed particularly for patients who are not candidates for total disc replacement. The spacer maintains disc height and prevents subsidence with a large vertebral body contacting surface area while substantially reducing recovery time by eliminating the need for bridging bone. The intervertebral spacer or fusion spacer includes a rigid spacer body sized and shaped to fit within an intervertebral space between two vertebral bodies. In one embodiment, the spacer body has two opposed metallic vertebral contacting surfaces, at least one fin extending from each of the vertebral contacting surfaces and configured to be positioned within slots cut into the two vertebral bodies. Holes, if present, cover less than 40 percent of the entire vertebral body contacting surfaces to provide increased bone ongrowth surfaces and to prevent subsidence.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]The present application claims priority from U.S. Provisional Patent Application No. 60 / 981,665 filed Oct. 22, 2007, entitled “Method and Spacer Device for Spanning a Space Formed Upon Removal of an Intervertebral Disc,” the full disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to medical devices and methods. More specifically, the invention relates to intervertebral spacers and methods of spanning a space formed upon removal of an intervertebral disc.[0003]Back pain takes an enormous toll on the health and productivity of people around the world. According to the American Academy of Orthopedic Surgeons, approximately 80 percent of Americans will experience back pain at some time in their life. In the year 2000, approximately 26 million visits were made to physicians' offices due to back problems in the United States. On any one day, it is estimated that 5% of the work...

AI Technical Summary

Benefits of technology

[0014]Embodiments of the present invention provide a rigid intervertebral space

Problems solved by technology

Back pain takes an enormous toll on the health and productivity of people around the world.

One common cause of back pain is injury, degeneration and / or dysfunction of one or more intervertebral discs.

Discs often become damaged due to wear and tear or acute injury.

Degeneration or other damage to a disc may cause a loss of “disc height,” meaning that the natural space between two vertebrae decreases.

Decreased disc height may cause a disc to bulge, facet loads to increase, two vertebrae to rub together in an unnatural way and / or increased pressure on certain parts of the vertebrae and / or nerve roots, thus causing pain.

In general, chronic and acute damage to intervertebral discs is a common source of back related pain and loss of mobility.

When one or more damaged intervertebral discs cause a patient pain and discomfort, surgery is often required.

However, PEEK is a material that does not allow bone to attach.

Another problem associated with the typical fusion procedure is the subsidence of the cage into the vertebral body.

However, the large amount of open space means that the load on each segment of the cage is significantly higher than if the cage surface area was larger.

This results in the cage subsiding or sinking into the bone over time causing the disc space to collapse.

In addition, the hard cortical bone on the outer surface of the vertebral body that transfers load to the interbody cage or spacer is often scraped, punctured or otherwise damaged to provide blood to the interbody bone graft to facilitate bone growth.

This damage to the bone used to promote bone growth can also lead to subsidence.

However, InFUSE™ adds significantly to the cost of a typical fusion surgery.

Additionally, even with the bone graft and InFUSE™ bone may fail to grow completely between the two vertebrae or the cage may subside into the vertebrae such that the fusion fails to achieve its purpose of maintaining disc height and preventing motion.

Although existing disc prostheses provide advantages over traditional treatment methods, many patients are not candidates for an artificial disc due to facet degeneration, instability, poor bone strength, previous surgery, multi-level disease, and pain sources that are non-discogenic.

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