Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-04-28
2001-08-21
Seidel, Richard K (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06277094
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to percutaneous dilators and more particularly to an apparatus and method for dilating the ligamentum flava and other soft tissue by the alternating insertion of expandable tubes.
2. Description of the Related Art
Electrical stimulation of electrically excitable tissue such as the brain and/or nerve tissue of the spinal cord or peripheral nerve is an increasingly popular technique for treatment of pain or treatment of neural disorders. For example, medical leads having electrode contacts have been implanted near the spinal cord of the human body to provide pain relief for chronic intractable pain. A current technique for implanting a medical lead into the epidural space of the spinal column is a laminotomy which is a highly invasive technique requiring the cutting of the skin, tissue, ligamentum flava, and bone surrounding the epidural space. A more desirable and less invasive technique is to percutaneously implant a medical lead in the epidural space. This technique involves piercing a needle through the skin and tissue to the targeted area, thereby creating an access hole for the insertion of the medical lead. It is often desirable to implant larger leads which are more stable when implanted in the epidural space and provide better nerve fiber coverage for more effective pain reduction. An example of such leads are paddle leads as disclosed in U.S. Pat. No. 5,417,719. These larger leads, however, require a larger access hole and presently, these leads have been implanted by a laminotomy. A more efficient and equally effective method of increasing the access hole to the targeted area is through the use of dilators or similar expansion tubes. By using a dilator, the surrounding skin and tissue is expanded, thereby enlarging the access hole without doing a laminotomy. A related patent includes U.S. Pat. No. 5,183,464 which describes an expandable dilator for forming and enlarging percutaneous penetrations into hollow body organs, tissues or cavities. This patent, however, requires several components to effect expansion including, for example, a pair of coaxial cylinders, an outer sheath, and an inner rod. This patent also does not provide for the anchoring of the dilator at the targeted penetration area. Other background patents include U.S. Pat. No. 5,320,611 which describes an expandable cannula, and U.S. Pat. No. 4,738,666 which describes an expandable catheter. These patents are incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention overcomes the aforementioned disadvantages of the prior art. Accordingly, an object of the present invention is to provide for the implantation of larger diameter lead bodies percutaneously through the dilation of the small opening formed in the skin, ligamentum flava, or other soft tissue.
The present invention provides an apparatus and method for dilating the ligamentum flava and other soft tissue from a small puncture opening having a small diameter to a larger workable diameter wherethrough larger medical lead bodies, surgical instruments or medication can pass. The apparatus works by progressively dilating the opening from the skin to the targeted tissue. The dilation is accomplished by the alternating insertion of dilators and progressively larger diameter tubes.
In use, a needle is percutaneously inserted into the ligamentum flava or targeted cavity. An expandable tube or dilator is then inserted inside the lumen of the needle. The dilator includes a slit extending longitudinally across the length of the dilator and a plurality of slits at the distal end of the dilator to permit the expansion of the dilator. The needle is removed leaving the dilator in place at the targeted area. A larger diameter slotted or solid tube is then inserted inside the dilator effecting the expansion of the dilator which, in turn, expands the surrounding skin and tissue creating a larger access hole. The dilator is then removed leaving the larger diameter tube in place for the introduction of larger leads, such as paddle type leads, or surgical instruments. If desirable, an even larger opening can be made by simply repeating the previous steps using a slightly larger diameter dilator and a larger slotted or solid tube. This process may be repeated until the tube with the desired diameter is in position at the targeted insertion area.
As preferred and detailed below, the dilator includes an offset guide channel for receiving a guide wire which is drilled into the bone adjacent to the targeted area. The guide wire serves to anchor the dilator in the desired position. A second dilator having a slotted lumen and a guide cam extending along the length of the second dilator is inserted into the opening of the dilator with the offset guide channel. Through the alternating insertion of these dilators, the access hole can be enlarged while maintaining a fixed position of the dilator relative to the targeted area.
The full range of objects, aspects and advantages of the invention are only appreciated by a full reading of this specification and a full understanding of the invention. Therefore, to complete this specification, a detailed description of the invention and the preferred embodiments follow, after a brief description of the drawings.
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Banner & Witcoff Ltd
Medtronic Inc.
Seidel Richard K
Sirmons Kevin
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