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Method and apparatus for the treatment of the intervertebral disc annulus

Method and apparatus for the treatment of the intervertebral disc annulus description/claims

This application is a continuation-in-part of U.S. patent application Ser. No. 10/352,981 filed Jan. 29, 2003 and a continuation-in-part of U.S. patent application Ser. No. 10/327,106 filed Dec. 24, 2002, each of which are continuations-in-part of U.S. patent application Ser. No. 10/133,339 filed Apr. 29, 2002, which is a continuation-in-part of U.S. patent application Ser. No. 09/947,078, filed Sep. 5, 2001, now U.S. Pat. No. 6,592,695, issued Jul. 15, 2003, which is a continuation of U.S. patent application Ser. No. 09/484,706, filed Jan. 18, 2000, which claims the benefit of U.S. Provisional Application No. 60/160,710, filed Oct. 20, 1999. This application also claims, through application Ser. No. 10/133,339 the benefit of U.S. Provisional Application No. 60/309,105, filed Jul. 31, 2001. This application is also related to, and claims the benefit of, U.S. patent application Ser. No. 10/075,615, filed on Feb. 15, 2002. All are incorporated herein by reference in their entirety.

The invention generally relates to methods and devices for the closure, sealing, repair and/or reconstruction of an intervertebral disc annulus, and accompanying delivery devices and tools, and their methods of use. The repair can be of an aperture in the disc wall, or a weakened or thin portion. The term “aperture” refers to a hole in the annulus that is a result of a surgical incision or dissection into the intervertebral disc annulus, or the consequence of a naturally occurring tear (rent). The invention generally relates to surgical devices and methods for the treatment of intervertebral disc wall repair or reconstruction. The invention further relates to an annular repair device, or stent, for annular disc repair. These stents can be of natural or synthetic materials. The effects of said reconstruction is restoration of disc wall integrity, which may reduce the failure rate (3-21%) of a common surgical procedure (disc fragment removal or discectomy), or advantageously provide a barrier to intradiscal material migration.

The spinal column is formed from a number of bony vertebrae, which in their normal state are separated from each other by intervertebral discs. These discs are comprised of the annulus fibrosus, and the nucleus pulposus, both of which are soft tissue. The intervertebral disc acts in the spine as a crucial stabilizer, and as a mechanism for force distribution between adjacent vertebral bodies. Without a competent disc, collapse of the intervertebral disc may occur, contributing to abnormal joint mechanics and premature development of degenerative and/or arthritic changes.

The normal intervertebral disc has an outer ligamentous ring called the annulus surrounding the nucleus pulposus. The annulus binds the adjacent vertebrae together and is constituted of collagen fibers that are attached to the vertebrae and cross each other so that half of the individual fibers will tighten as the vertebrae are rotated in either direction, thus resisting twisting or torsional motion. The nucleus pulposus is constituted of soft tissue, having about 85% water content, which moves about during bending from front to back and from side to side.

The aging process contributes to gradual changes in the intervertebral discs. The annulus loses much of its flexibility and resilience, becoming more dense and solid in composition. The aging annulus may also be marked by the appearance or propagation of cracks or fissures in the annular wall. Similarly, the nucleus desiccates, increasing viscosity and thus losing its fluidity. In combination, these features of the aged intervertebral discs result in less dynamic stress distribution because of the more viscous nucleus pulposus, and less ability to withstand localized stresses by the annulus fibrosus due to its desiccation, loss of flexibility and the presence of fissures. Fissures can also occur due to disease or other pathological conditions. Occasionally fissures may form rents through the annular wall. In these instances, the nucleus pulposus is urged outwardly from the subannular space through a rent, often into the spinal column. Extruded nucleus pulposus can, and often does, mechanically press on the spinal cord or spinal nerve rootlet. This painful condition is clinically referred to as a ruptured or herniated disc.

In the event of annulus rupture, the subannular nucleus pulposus migrates along the path of least resistance forcing the fissure to open further, allowing migration of the nucleus pulposus through the wall of the disc, with resultant nerve compression and leakage of chemicals of inflammation into the space around the adjacent nerve roots supplying the extremities, bladder, bowel and genitalia. The usual effect of nerve compression and inflammation is intolerable back or neck pain, radiating into the extremities, with accompanying numbness, weakness, and in late stages, paralysis and muscle atrophy, and/or bladder and bowel incontinence. Additionally, injury, disease or other degenerative disorders may cause one or more of the intervertebral discs to shrink, collapse, deteriorate or become displaced, herniated, or otherwise damaged and compromised.

Surgical repairs or replacements of displaced or herniated discs are attempted approximately 390,000 times in the USA each year. Historically, there has been no known way to repair or reconstruct the annulus. Instead, surgical procedures to date are designed to relieve symptoms by removing unwanted disc fragments and relieving nerve compression. While results are currently acceptable, they are not optimal. Various authors report 3.1-21% recurrent disc herniation, representing a failure of the primary procedure and requiring re-operation for the same condition. An estimated 10% recurrence rate results in 39,000 re-operations in the United States each year.

An additional method of relieving the symptoms is thermal annuloplasty, involving the heating of sub-annular zones in the non-herniated painful disc, seeking pain relief, but making no claim of reconstruction of the ruptured, discontinuous annulus wall.

Some have also suggested that the repair of a damaged intervertebral disc might include the augmentation of the nucleus pulposus, and various efforts at nucleus pulposus replacement have been reported. The present invention is directed at the repair of the annulus, whether or not a nuclear augmentation is also warranted.

In addition, there has been experimentation in animals to assess various surgical incisions with and without the direct surgical repair of the annulus. These studies were performed on otherwise healthy animals and involved no removal or augmentation of nucleus pulposus. The authors of these experiments conclude that direct repair of the annulus does not influence the healing of the disc.

The present inventors have found, advantageously and contrary to accepted practice, that the annulus tissue may be sutured and that annular healing may be facilitated by reapproximation, reinforcement, and/or support of annular tissue. Methods and devices for carrying out annular repair and/or reconstruction are a subject of the present invention.

The present inventions provide methods and related devices for reconstruction of the disc wall in cases of displaced, herniated, thinned, ruptured, or otherwise damaged or infirm intervertebral discs. In accordance with the invention, a method is disclosed for intervertebral disc reconstruction for treating a disc having an aperture, weakened or thin portion in the wall of the annulus fibrosis of the intervertebral disc. Repair, reconstruction, sealing, occluding an aperture, weakened or thin portion in the wall of the annulus may prevent or avoid migration of intradiscal material from the subannular space.

The method of the invention includes, in one embodiment, the steps of providing a first delivery tool having a proximal end and a distal end, the distal end carrying a treatment device; providing at least one second delivery tool having a proximal end and a distal end, the distal end carrying a fixation element; introducing the distal end of the first delivery tool at least partially into subannular intervertebral disc space; deploying said treatment device; introducing the distal end of said at least one second delivery tool at lest partially into subannular intervertebral disc space; and deploying at least one fixation device into, or through, the wall of an annulus to hold said treatment device at least partially within the subannular intervertebral disc space; and removing the delivery tools.

A fixation device useful for intervertebral disc reconstruction for treating a disc having an aperture, weakened, or thin portion in the wall of the annulus fibrosis of said intervertebral disc, said device, in one embodiment comprises at least one anchor portion and at least one band.

A treatment device, according to one embodiment, comprises a mesh patch that radially expands in the subannular space.

The invention also comprises delivery tools for delivering fixation devices and treatment devices, as well as kits comprising devices and tools.

The objects and various advantages of the invention will be apparent from the description which follows. In general, the implantable medical treatment devices are placed, positioned, and subsequently affixed in the annulus to reduce re-extrusion of the nucleus or other intradiscal material through an aperture by: establishing a barrier or otherwise closing or partially closing the aperture; and/or helping to restore the natural integrity of the wall of the annulus; and/or promoting healing of the annulus. Increased integrity and faster and/or more thorough healing of the aperture may reduce future recurrence of herniation of the disc nucleus, or intradiscal material, from the intervertebral disc, and the recurrence of resulting back pain. In addition, it is believed that the repair of the annular tissue could promote enhanced biomechanics and reduce the possibility of intervertebral disc height collapse and segmental instability, thus possibly avoiding back pain after a surgical procedure.

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