Methods and apparatus for treating disc herniation and preventing the extrusion of interbody bone graft
Methods and apparatus for treating disc herniation provide a conformable device which assumes a first shape associated with insertion and a second shape or expanded shape to occlude the defect which typically follows partial discectomy. The device may take different forms according to the invention, including patches size to cover the defect or plugs adapted to fill the defect. In a preferred embodiment, however, the device is a gel or other liquid or semi-liquid which solidifies to occlude the defect from within the body of the disc itself. In another preferred embodiment, a mesh screen is collapsed into an elongated form for the purposes of insertion, thereby minimizing the size of the requisite incision while avoiding delicate surrounding nerves. Such a configuration also permits the use of instrumentation to install the device, including, for example, a hollow tube or sheath adapted to hold the collapsed screen, and a push rod to expel the collapsed device out of the sheath for use in occluding the disc defect. A device according to the invention may further include one or more anchors to assist in permanently affixing the device with respect to the defect.
1. A device for at least partially preventing intervertebral disc material from exiting a defect in an anulus fibrosus of an intervertebral disc disposed between a first vertebra and a second vertebra, the device comprising:
a flexible element having a distal end, a proximal end and a connecting portion extending between the distal end and the proximal end; and
an anchor for fixedly attaching the proximal end of the flexible element to the first vertebra;
wherein the flexible element is sized and configured so as to be positionable within the nucleus of the intervertebral disc so that the distal end of the flexible element flexingly engages, but is not fixedly attached to, the second vertebra adjacent the intervertebral disc; and
wherein the proximal end of the flexible element is engaged with the anchor and is configured to engage only the first vertebra adjacent the intervertebral disc, and the connecting portion is configured to extend from the first vertebra through the nucleus to the second vertebra so as to at least partially prevent intervertebral disc material from exiting the defect in the anulus fibrosus of the intervertebral disc.
2. A device according to claim 1 wherein the distal end of the flexible element extends substantially parallel to the proximal end of the flexible element.
3. The device according to claim 1 wherein the flexible element is adapted to engage load bearing vertebral body endplate tissue.
4. The device according to claim 1 wherein the distal end of the flexible element and the proximal end of the flexible element are each adapted to present a surface in conformity with an endplate of an adjacent vertebral body.
5. The device according to claim 1 wherein the flexible element has top and bottom edges and first and second side edges, wherein said top and bottom edges are dimensioned to contact the endplates of adjacent vertebral bodies at maximum distraction.
6. A device according to claim 1 wherein the flexible element is of sufficient rigidity to not be extrudable through an anulus defect.
7. The device according to claim 1 wherein the flexible element has a width in a lateral direction and a height in an inferior-superior direction, wherein the height exceeds the distance between an inferior vertebral body and a superior vertebral body when compressed.
8. A device according to claim 1 wherein the flexible element is made from a shape memory material.
9. A device according to claim 1 wherein the flexible element is configured to allow movement between the first vertebra and second vertebra.
10. A device according to claim 1 wherein the flexible element is configured to flex under compression of the intervertebral disc.
11. A device according to claim 1 wherein the flexible element and anchor are configured to be inserted into the intervertebral disc so that the flexible element and the anchor are disposed within the intervertebral disc.