Surgery – Instruments – Light application
Reexamination Certificate
2001-04-10
2004-01-06
Shay, David M. (Department: 3739)
Surgery
Instruments
Light application
C606S013000, C606S016000, C606S018000, C606S041000, C606S046000, C607S088000, C607S089000, C607S901000, C607S100000, C607S101000
Reexamination Certificate
active
06673063
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a treatment for injured or degenerated intervertebral discs. Specifically, the present invention is a method and apparatus for strengthening an injured or degenerated intervertebral disc and relieving pain. The treatment may allow a spine surgeon to avoid a discectomy and removal of the nucleus pulposus during laminectomy operations and may reduce postoperative discogenic pain.
As shown in
FIG. 1
, each intervertebral disc
10
is a cushionlike pad with top and bottom endplates adjoining the bone surfaces on each adjacent vertebral body
20
. As shown in
FIG. 2
, each disc has an inner sphere, the nucleus pulposus
30
, which acts as a cushion for compressive stress. Around the nucleus pulposus is an outer collar of approximately 12 concentric rings, the annulus fibrosis
40
, which limits the expansion of the nucleus pulposus when the spine is compressed. The rings of the annulus fibrosis also bind the successive vertebrae together, resist torsion of the spine, and assist the nucleus pulposus in absorbing compressive forces.
The grains of collagen fibers in adjacent rings of the annulus fibrosis
40
run in different directions so that the grains cross like an X. This arrangement of the collagen layers allows the spine to withstand twisting, shear forces.
FIG. 2
shows an exemplary injury to an intervertebral disc. A herniated or prolapsed disc is commonly called a “slipped disc.” Severe or sudden trauma to the spine or nontraumatic pathology such as degenerative spine disease may cause a bulge, rupture, degeneration, or other area of injury (“injury”)
50
in one or more intervertebral discs. The annulus fibrosis
40
is thinnest posteriorly in the general direction of the spinous process
60
, so the nucleus pulposus
30
usually herniates in that direction. The injury usually proceeds posterolaterally instead of directly posteriorly because the posterior longitudinal ligament strengthens the annulus fibrosis at the posterior sagittal midline of the annulus. The terms “posterior” and “posteriorly” mean the general posterior and posterolateral aspects of the disc as distinguished from the anterior aspects of the disc. The posterior aspect of the annulus fibrosis is also the location of vulnerable nerve tissues, including but not limited to the cauda equina
70
and spinal nerve roots
80
.
A posterior injury of the nucleus pulposus often impinges on the spinal nerve roots
80
exiting the spinal canal
90
. The resulting pressure on these nerve roots often leads to pain and/or numbness in the lower extremities. Injured intervertebral discs are treated with bed rest, physical therapy, modified activities, and painkillers over time. If these treatments are ineffective, the injured and usually protruding disc is often surgically removed.
Current treatments offer only limited success in avoiding surgical removal of injured intervertebral discs that do not heal themselves over time. A few treatments are adopted for use on an intervertebral disc from broad methods to shrink collagen in various other parts of the body. Several treatments attempt to reduce discogenic pain.
Several exemplary prior art references disclose using heat to shrink collagen. U.S. Pat. Nos. 5,374,265 and 5,484,432 to Sand (the “Sand references”) are directed to methods for shrinking collagen with an infrared laser. The collagen shrinkage in the Sand references is generally accomplished in an ophthalmological context. Laser light that is optimally absorbed by collagen tissue is applied to a corneal stoma resulting in collagen shrinkage and reshaping of the cornea for vision correction. Although the Sand method generally applies to shrinkage of collagen, it only contemplates applying relatively small amounts of energy to delicate eye tissue. No provision is made for protecting vulnerable tissue near collagen in other parts of the body. The amount of energy needed to shrink collagen in synovial joints or the spine is greater than the amount needed for eye tissue and may damage vulnerable tissue near the collagen being treated.
U.S. Pat. Nos. 5,458,596 and 5,569,242 to Lax et al. (the “Lax references”) are directed to broad methods and apparatuses for controlled contraction of soft tissue. The Lax references disclose the application of radio frequency energy through an electrode to tissue containing collagen. Such an application of energy as envisioned by the Lax references to an intervertebral disc would damage vulnerable tissues near the application site. The Lax references do not disclose the use of energy other than radio frequency. The shape of the Lax electrode is not designed for use on the spine. Also, because the Lax electrode is a general applicator, it does not protect vulnerable tissues during application of energy and therefore would not be suitable for applications involving the spine.
U.S. Pat. No. 5,954,716 to Sharkey et al. (the “Sharkey '716 reference”) is directed to a method and device for modifying the length of a ligament. In the Sharkey '716 reference, radio frequency energy is applied to one ligament in a set of opposing ligaments. Only radio frequency energy is disclosed. The radio frequency energy shrinks one ligament, restoring equal length and a balance of function to the set of opposing ligaments. Although the Sharkey '716 treatment uses radio frequency energy to shrink a ligament, it would not work on an intervertebral disc because an intervertebral disc is surrounded by vulnerable tissues. Because intervertebral discs lie close to the spinal canal and spinal nerve roots, application without thermal protection of radio frequency energy suitable for shrinking a ligament might harm vulnerable nerve tissues.
Heating an intervertebral disc for relief of discogenic pain is disclosed in U.S. Pat. Nos. 5,433,739 and 5,571,147 to Sluijter et al. (the “Sluijter references”). In the Sluijter references, probes are inserted into an intervertebral disc by puncturing the annulus fibrosis. Radio frequency or direct current energy is delivered through probes to heat the nucleus pulposus of a disc to approximately 60° C. to 70° C. The heat travels to the outer perimeter of the disc being treated so that the entire disc is heated. The applied heat relieves back pain by denervating fine nerve endings in the disc. Although the probes of the Sluijter references may relieve back pain, the Sluijter probes invade the disc and are not intended to shrink collagen or repair a bulging, ruptured, or injured intervertebral disc. Since the entire disc is heated to approximately 60° C. to 70° C., the heat may harm vulnerable tissues near the disc and have other thermally detrimental side effects. Some recent studies have shown that the amount of thermal energy provided to the posterior annulus by the IDET procedure is insufficient to cause either shrinkage/strengthening of the posterior annulus or ablation of the pain-sensing posterior annular nerve endings.
Several prior art references disclose methods for applying energy to the interior of an intervertebral disc by invading the disc with a needle or catheter. For example, U.S. Pat. No. 5,865,833 to Daikuzono is directed to a device for laser treatment. The Daikuzono device is for a discectomy procedure and for removal of intervertebral disc tissue, not to avoid a discectomy or to preserve disc tissue or ablate posterior annulus pain-sensing nerve endings. The Daikuzono method uses a hollow needle that is advanced into the center of an intervertebral disc, and then disc tissue is vaporized with laser energy and the vapor removed through the hollow needle. The hollow needle invasively punctures the disc.
U.S. Pat. Nos. 6,007,570, 6,073,051, 6,095,149, and 6,122,549 to Sharkey et al. (the “Sharkey references”) are directed to methods for treating an intervertebral disc and to devices with tip portions for performing various functions on a disc. Externally guidable catheters having one lumen or several lumina puncture the annulus fibrosis of an intervertebral disc and are inserted in
Expanding Concepts, LLC.
Oster Karen Dana
Shay David M.
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