Banana cage

Abstract

A banana shaped intevertebral fusion cage having a domed profile, an internal planar wall defining first and second graft chambers, asymmetrically disposed leading and trailing insertion, and an anterior wall recess.

Description

[0001]This application is a reissue of U.S. Pat. No. 7,500,991.BACKGROUND OF THE INVENTION[0002]The leading cause of lower back pain arises from rupture or degeneration of lumbar intervertebral discs. Pain in the lower extremities is caused by the compression of spinal nerve roots by a bulging disc, while lower back pain is caused by collapse of the disc and by the adverse effects of articulation weight through a damaged, unstable vertebral joint. One proposed method of managing these problems is to remove the problematic disc and replace it with a porous device that restores disc height and allows for bone growth therethrough for the fusion of the adjacent vertebrae. These devices are commonly called “fusion devices”.[0003]U.S. Pat. No. 4,743,256 (“Brantigan”) discloses an improved surgical method for eliminating spinal back pain caused by ruptured or degenerated vertebral discs by spanning the disc space between adjacent vertebrae with rigid fusion devices, or “cages”, having surf...

AI Technical Summary

Benefits of technology

[0019]The present inventors have appreciated that, although the Frey cage may be useful for supporting the middle portion of the disc space, it may be more desirable for a fusion cage to be adapted to support the anterior portion of the disc space. When a device is so positioned, the surgeon using a posterior or posterolateral approach is provided with additional room posterior to the device in which to place graft materials such as autograft. In addition, when the device is so positioned within the anterior third portion of the disc space, the resulting cantilever action upon the vertebral bodies forces a more natural lordotic relation between the vertebral bodies, and also reduces the stresses distributed through the implant.

[0021]Therefore, the device of the present invention provides for enhanced filling of the disc space with graft material when compared to these prior art devices.

Problems solved by technology

The leading cause of lower back pain arises from rupture or degeneration of lumbar intervertebral discs.

Because there is only a single support, the cage is susceptible to rocking about this single support.

Accordingly, this symmetric hole placement does not provide the surgeon with any intra-operative flexibility to adjust for differences in patient anatomy or approach.

Lastly, although Frey discloses that the upper and lower bearing surfaces can have grooves therein, Frey does not disclose that the upper and lower bearing surfaces can have teeth thereon.

The Kim cage has a single insertion hole, and so does not provide for surgeon flexibility as discussed above.

In addition, it has only a single middle strut, thereby raising the possibility of tilting in the medial-lateral direction.

Lastly, the requirement that it have a constant polygonal cross-section precludes the possibility of doming.

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