Diskectomy instrument and method

Details Diskectomy instrument and method Diskectomy instrument and method

2003-01-16

2004-04-27

Robert, Eduardo C. (Department: 3732)

Surgery

Instruments

Orthopedic instrumentation

C606S170000

Reexamination Certificate

active

06726690

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for performing diskectomy and more particularly to an instrument for performing partial diskectomies utilizing minimally invasive surgical techniques and a method for using the instrument.
Referring to prior art
FIGS. 9 and 10
, the spine
120
, also known as the vertebral column or the spinal column, is a flexible column of vertebrae
100
(special types of bones) held together by muscles, ligaments and tendons. The spine
120
extends from the cranium (not shown) to the coccyx
126
, encasing a spinal cord
128
and forming the supporting axis of the body (not shown). The spinal cord
128
is a thick bundle of nerve tissue (nerves) that branch off to various areas of the body for the purposes of motor control, sensation, and the like. The spine
120
includes seven cervical vertebrae (not shown), twelve thoracic vertebrae (not shown), five lumbar vertebrae, L
I
-L
V
, five sacral vertebrae, S
I
-S
V
, and three coccyx vertebrae
126
. The sacral and coccyx vertebrae are each fused, thereby functioning as a single unit.
FIG. 10
shows the lumbar region
122
, the sacral region
124
and the coccyx
126
of the spine
120
and that the vertebrae
100
are stacked one upon another. The top portion
100
a
and bottom portion
100
b
of each vertebrae
100
is slightly concave. The opposing concave vertebral surfaces form the intervertebral space
121
in which an intervertebral disk (not shown) resides. Each of the intervertebral disks has a soft core referred to as a nucleus pulposus or nucleus (not shown).
In
FIG. 9
, directional arrow
101
a
is pointing in the posterior direction and directional arrow
101
b
is pointing in the anterior direction.
FIG. 9
shows that each vertebrae
100
includes a body
106
in the innermost portion, a spinal canal
108
and a spinous process
102
at the posterior-most end of the vertebra
100
. The vertebrae
100
are substantially similar in composition, but vary in size from the larger lumbar to the smallest coccyx vertebrae
126
. Each vertebrae
100
further includes two transverse processes
104
located on either side and a protective plate-like structure referred to as a lamina
110
. Nerves from the spinal cord
128
pass through the spinal canal
108
and foramina
111
to reach their respective destinations within the body.
The natural aging process can cause a deterioration of the intervertebral disks, and therefore, their intrinsic support strength and stability is diminished. Sudden movements may cause a disk to rupture or herniate. A herniation of the disk is primarily a problem when the nucleus pulposus protrudes or ruptures into the spinal canal
108
placing pressure on nerves which in turn causes spasms, tingling, numbness, and/or pain in one or more parts of the body, depending on the nerves involved. Further deterioration of the disk can cause the damaged disk to lose height and as bone spurs develop on the vertebrae
100
, result in a narrowing of the spinal canal
108
and foramen
111
, and thereby causes pressure on the nerves emanating from the spinal cord
128
.
Presently, there are several techniques, in addition to non-surgical treatments, for relieving the symptoms related to intervertebral disk deterioration. Surgical options include chemonucleolysis, laminectomy, diskectomy, microdiskectomy, and spinal fusion.
Chemonucleolysis is the injection of an enzyme, such as chymopapain, into the disk to dissolve the protruding nucleus pulposus. The enzyme is a protein-digesting enzyme and is used to dissolve the disk material. Since the enzyme is essentially a tissue-dissolving agent, it is indiscriminate in the protein-based matter it dissolves. Should the enzyme be injected into the wrong place, or if there is a breach in the disk capsule that would allow the solution to enter the spinal canal or to contact nerve tissue or the like, the resultant damage to nerve tissue could not be reversed. Even worse, about half of the patients who receive chemonucleolysis treatments experience increased back pain and muscle spasms immediately after the injection and more than half have incapacitating back pain for durations up to three months after such treatments.
A laminectomy is performed to decompress the spinal canal
108
by open surgical techniques under general anesthesia. In this procedure, the lamina
110
, (the bone that curves around and covers the spinal canal
108
as shown in FIG.
9
), and any disk tissue causing pressure on a nerve or the spinal canal
108
, are partially removed. This technique is highly invasive and traumatic to the body, and therefore requires an extended recovery time of about five weeks and a hospital stay of a few days. In addition to the trauma inflicted on the body from even a successful surgery, there are increased risks of future problems due to the removed portion of the lamina
110
which is no longer in place to support and protect the spinal canal
108
at the area where the surgery took place. Further, the vertebrae
100
may shift due to the lack of support in the structure. Thus, simply removing the disk and parts of the vertebral bone is a short-term, pain-relieving corrective action but not a long-term solution.
Diskectomy is a form of spinal surgery wherein part or all of an intervertebral disk is excised typically through open surgical techniques. Recently, less invasive techniques referred to as percutaneous diskectomy or microdiskectomy have been developed to reduce the surgical trauma to the patient. In microdiskectomy, a much smaller incision is made than in normal open surgeries. A small retractor, working channel or tube is inserted through the posterior muscles (not shown) to allow access to the damaged or herniated disk. Surgeons utilize special surgical instruments modified to work in such small openings such as curettes, osteotomes, reamers, probes, retractors, forceps, and the like to cut and remove part of the disk while monitoring their technique using a microscope, fluoroscope (real-time X-ray monitoring), and/or an endoscope (a miniature TV camera with associated viewing monitor). While this technique is much less invasive than conventional open surgeries, due to their design the instruments presently available tend to extend the length of time of the surgery and may cause possible damage to areas other than the herniated disk. For example, the curette is a spoon-shaped instrument with a sharp edge that is used mainly to scrape the nucleus pulposus matter (not shown) from the end plates of the vertebral bones. Since the blade is unprotected, there is potential for damage to the surrounding nerves and ligaments during insertion and during use. Further, due to the varying concavity of the vertebral space (or the concavity of the top and bottom portions
100
a,b
of the vertebral bones) it is often a time consuming procedure for the surgeon to repeatedly scrape at varying angles using the curette. Another instrument that is often used is the reamer (not shown) which is intended to remove the nucleus pulposus matter more quickly than a curette. The reamer is usually a cylindrically-shaped, drill-bit-like device with a flat tip and a plurality of sharp edges along its outer sides. The reamer is continuously turned inside the vertebral disk space
121
to scrape the nucleus pulposus matter from the vertebral bones; however, reamers often cause damage to adjacent vertebrae and may cause damage to nerves, blood vessels and/or ligaments while being inserted into the intervertebral space.
The removal of a significant amount of disk material or numerous surgeries often increases the instability of the spine
120
thereby necessitating spinal fusion surgery. In a fusion procedure, a damaged disk may be completely removed. Parts of a bone from another part of the body, such as the pelvis, are harvested, and the bone parts or grafts are subsequently placed between the adjacent vertebrae
100
so that the adjacent vertebrae
100
grow together in a solid mass. In the fusion surgery, whic

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