Surgery – Instruments – Cutting – puncturing or piercing
Patent
1998-08-31
2000-05-30
Buiz, Michael
Surgery
Instruments
Cutting, puncturing or piercing
A61B 1732
Patent
active
060686421
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to flexible cutting tools and to surgical drilling and other cutting procedures using such tools.
BACKGROUND OF THE INVENTION
Modern surgical techniques often require holes or channels to be cut into bone, teeth or soft tissue, for various reasons. Holes may be drilled in bone to receive screws, sutures or bone anchors enabling anchorage of implants or reattachment of ligaments or tendons. Ordinarily, surgical drills can be employed which utilize a motor (often an air motor) and a drill bit of the desired length and diameter. However, because of the proximity of other tissue or prosthetic materials, it often becomes difficult to appropriately orient a surgical drill and drill bit so that the desired bore can be formed in tissue. Dental drills are available, of course, but have generally very short bit lengths.
U.S. Pat. No. 5,330,468 (Burkhart) proposes a drill mechanism for arthroscopic surgery in which a rotating pin of nitinol is caused to emerge from a gently bent aiming tube, drill through a thickness of bone, and then be received in an appropriately positioned receiving tube. The device itself is somewhat bulky. Another device using nitinol pins or probes is shown in U.S. Pat. No. 4,926,860 (Stice et al.). Here, a needle or other probe of nitinol may be received in a curved cannula to deliver the end of the probe to the desired location. The probe is then advanced through the cannula and exits from the cannula end in a straight orientation.
If a nitinol pin, as shown in the previously mentioned U.S. Pat. No. 5,330,468, is bent through a sharp angle and rotated at high speed, the pin becomes work hardened at the area of the bend due to its constant flexing during rotation. The superelastic characteristic of the pin in that area is reduced, and the pin can readily break. Nitinol wire drills in which a nitinol pin is rapidly rotated in a sharp bend, hence, have not become commercially successful.
SUMMARY OF THE INVENTION
We have found that an appropriate flexible cutting instrument can be obtained through the use of an elongated, flexible cutting element having a longitudinal axis about which the cutting element may be rotated, the cutting element comprising a cable or bundle of parallel cables each comprising an outer layer of helically wound fibers. Cutting means is disposed at the distal end of the cutting element to perform a cutting function when the cutting element is rotated. The cables preferably are of metal and most preferably are of nitinol or other superelastic alloy. Cables of this type can withstand rapid rotation while proceeding about tight bends, without substantial work hardening. A single helically wound 1 cable can be employed, or a bundle of generally parallel cables can be used to obtain a larger diameter hole.
Because cables are far more flexible than solid pins of the same diameter, it would be expected that the distal free end (that is, the cutting end) of a cable or bundle of cables, being relatively unsupported, would tend to whip around in an uncontrolled fashion when rotated rapidly. That is, a trade-off to using a much more flexible superelastic alloy cable or cable bundle would be expected to be lack of control of its drilling end. We have found that the cutting end of a flexible cutting element that is formed as cable or bundle of cables and that is slidingly supported in a stationary tubular support from which the cutting end may protrude, when used as a drill, produces a bore that remains relatively straight and true as the cutting element is advanced, even though the length of the cutting element that protrudes from the tube is supported only by the tissue being drilled. As long as the stationary tubular support remains in close proximity to the tissue being drilled, the tissue itself appears to provide sufficient support and guidance to the otherwise unsupported cutting end to keep it in a substantially straight path.
As used herein, "tissue" refers to both soft tissue and to hard tissue such as bones and teeth.
Thus
REFERENCES:
patent: 5690660 (1997-11-01), Kauker et al.
patent: 5695513 (1997-12-01), Johnson et al.
Johnson Wesley D.
Peterson Francis C.
Stursa Bruce Wayne
Sutton Gregg S.
Buiz Michael
Cotterell Gregory F.
Orthopaedic Innovations, Inc.
Trinh Vikki
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