Methods for repairing damaged intervertebral discs

Abstract

Apparatus and methods for treating an intervertebral disc by ablation of disc tissue. A method of the invention includes positioning at least one active electrode within the intervertebral disc, and applying at least a first high frequency voltage between the active electrode(s) and one or more return electrode(s), wherein the volume of the nucleus pulposus is decreased, pressure exerted by the nucleus pulposus on the annulus fibrosus is reduced, and discogenic pain of a patient is alleviated. In other embodiments, a curved or steerable probe is guided to a specific target site within a disc to be treated, and the disc tissue at the target site is ablated by application of at least a first high frequency voltage between the active electrode(s) and one or more return electrode(s). A method of making an electrosurgical probe is also disclosed.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]The present inventionThis application is a REISSUE application of U.S. patent application Ser. No. 09 / 676,194, filed Sep. 28, 2000. U.S. patent application Ser. No. 09 / 676,194, filed Sep. 28, 2000, now U.S. Pat. No. 6,602,248claims priority from U.S. Provisional Application No. 60 / 224,107, filed Aug. 9, 2000, <?delete-start id="DEL-S-00002" date="20080318" ?>and from PCT<?delete-end id="DEL-S-00002" ?> <?insert-start id="INS-S-00002" date="20080318" ?>and is also a continuation-in-part application of International Application No. PCT / US00 / 13706, filed May 17, 2000, <?delete-start id="DEL-S-00003" date="20080318" ?>and<?delete-end id="DEL-S-00003" ?> <?insert-start id="INS-S-00004" date="20080318" ?>which claims priority from U.S. patent application Ser. No. 09 / 316,472, filed May 21, 1999, <?insert-start id="INS-S-00005" date="20080318" ?>now U.S. Pat. No. 6,624,650, which is a continuation...

AI Technical Summary

Benefits of technology

The present invention provides systems, methods, and apparatus for selectively applying electrical energy to structures within a patient's body, such as the intervertebral disc. The invention allows for debulking, ablation, resection, aspiration, and hemostasis of tissue in open and endoscopic spine surgery. The invention includes an electrosurgical probe with a flexible and curved shaft that can be guided to specific target sites within the disc. The high frequency voltage applied through the probe can debulk the nucleus pulposus and reduce the pressure on the annulus fibrosus, reducing pain and alleviating symptoms. The invention also provides a conductive fluid to facilitate the procedure and ensure sufficient conductive fluid for plasma formation and conductive current. Overall, the invention provides a safe and effective method for treating degenerative intervertebral discs and herniations.

Problems solved by technology

The major causes of persistent, often disabling, back pain are disruption of the disc annulus, chronic inflammation of the disc, contained and non-contained herniation, and relative instability of the vertebral bodies surrounding a given disc, such as the instability that often occurs due to a stretching of the interspinous tissue surrounding the vertebrae.

This results in a weakening of the shock absorption properties of the disc and a narrowing of the nerve openings in the sides of the spine which may pinch these nerves.

This disc degeneration can eventually cause back and leg pain.

A weakening of the annulus fibrosus can cause the disc to bulge, e.g., a contained herniation, and the mere proximity of the nucleus pulposus or the damaged annulus to a nerve can cause direct pressure against the nerve, resulting in pain and sensory and motor deficit.

In some cases, the disc tissue is irreparably damaged, thereby necessitating removal of a portion of the disc or the entire disc to eliminate the source of inflammation and pressure.

In addition, the risk of instability from ligament and bone removal is generally lower in endoscopic procedures than with open procedures.

Unfortunately, these mechanical instruments greatly lengthen and increase the complexity of the procedure.

In addition, these instruments might sever blood vessels within this tissue, usually causing profuse bleeding that obstructs the surgeon's view of the target site.

In addition to the above problems with mechanical instruments, there are serious concerns because these instruments are not precise, and it is often difficult, during the procedure, to differentiate between the target disc tissue, and other structures within the spine, such as bone, cartilage, ligaments, nerves and non-target tissue.

Unfortunately, lasers are both expensive and somewhat tedious to use in these procedures.

Another disadvantage with lasers is the difficulty in judging the depth of tissue ablation.

Monopolar devices, however, suffer from the disadvantage that the electric current will flow through undefined paths in the patient's body, thereby increasing the risk of undesirable electrical stimulation to portions of the patient's body.

This current, however, may inadvertently flow along body paths having less impedance than the defined electrical path, which will substantially increase the current flowing through these paths, possibly causing damage to or destroying surrounding tissue or neighboring peripheral nerves.

Other disadvantages of conventional RF devices, particularly monopolar devices, is nerve stimulation and interference with nerve monitoring equipment in the operating room.

In addition, these devices typically operate by creating a voltage difference between the active electrode and the target tissue, causing an electrical arc to form across the physical gap between the electrode and tissue.

At the point of contact of the electric arcs with tissue, rapid tissue heating occurs due to high current density between the electrode and tissue.

Thus, the tissue is parted along the pathway of evaporated cellular fluid, inducing undesirable collateral tissue damage in regions surrounding the target tissue site.

This collateral tissue damage often causes indiscriminate destruction of tissue, resulting in the loss of the proper function of the tissue.

In addition, the device does not remove any tissue directly, but rather depends on destroying a zone of tissue and allowing the body to eventually remove the destroyed tissue.

Such disc defects include annular fissures, fragmentation of the nucleus pulposus, and contained herniation.

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