Surgery – Instruments – Orthopedic instrumentation
Patent
1996-11-06
1998-08-04
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
408227, 408229, A61B 1716
Patent
active
057886997
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a drill section of a medical drill rod including a Kirschner wires, bone routers, bone drills or the like equipped with a shaft and drill section.
In various medical applications it is necessary to make a hole in a bone. For this purpose it is customary to equip diverse tools with drill sections, which serve to produce a hole of this kind.
For example, the use of a drill section as mentioned above in combination with a so-called Kirschner wire is known. Kirschner wires--also known as bone-transfixion wires--are employed particularly in cases of wire extension in association with an external fixation device. Wire extension is a method of adjusting displaced ends of a fracture by overcoming the opposed pulling force of a muscle. The extension is achieved by loading with variable weights steel wires, namely so-called Kirschner wires, that have been drilled through the bone and arranged in a frame so that tension is maintained.
However, bone drills are also of special importance when routing tools are used to produce openings and cavities in bone, in particular during the creation of spaces for implantation. The reason is that care must be taken to define precisely the implantation space to be created in the bone. For this purpose it is customary first to drill a pilot hole with a separate drill. Then the bone router is centered in the pilot hole and used for further excavation.
Conventional drill sections, most of which employ a conical drill tip, have the disadvantage that during drilling at a speed of 1200 to 2000 rpm the bone is heated, reaching temperatures up to 120.degree. in the drilling region. Such temperatures cause deterioration and destruction, in particular charring, of the bone or bony tissue in the region of the drilled hole.
SUMMARY OF THE PRESENT INVENTION
It is the object of the present invention to create a drill section with which a hole can be made in a bone with no deterioration of the remainder of the bone or the remaining bony tissue.
This object is achieved by a drill section proximate to the drill tip which is flattened diametrically relative to the central axis (15) of the drill section.
One characteristic of the drill section essential to the invention is the diametrically flattened drill section. Experiments have shown that with such a configuration of the drill section, especially when the diametric flattening extends into the drill tip so that the latter forms a section shaped like part of a cone, even when the drill rotates at speeds of 1200 to 2000 rpm the temperature at the drill tip is maximally about 50.degree.-60.degree. C. As a result charring and the associated deterioration of the bone during the creation of a hole are effectively prevented.
For removal of the chips of bone it is particularly significant that the one flat side, which defines the cutting edge, extends in the region of the central axis of the shaft, whereas the opposite flat side is spaced slightly apart from the central axis of the shaft.
To achieve minimal temperatures at the drill tip, the latter preferably tapers at an angle of at most about 55.degree.-65.degree., in particular about 60.degree.. If this angle is outside this range on either side, either the drill section becomes less efficient or higher temperatures are produced at the drill tip.
It is also advantageous regarding the reduction of temperature at the drill tip for the surface of the drill tip to be polished smooth.
The proximal end of the shaft of a Kirschner wire or the like provided with a drill section of the stated kind comprises a surface or a section with triangular or polygonal cross section, so that it transmits torque when attached to a drilling machine or a hand lever or the like.
It is particularly advantageous when the drill section in accordance with the invention is combined with a routing tool, in particular a cartilage or bone router. As described above, to create implantation spaces it is customary first to drill pilot holes, in which the routing tools are then ce
REFERENCES:
patent: 385088 (1888-06-01), Benzie
patent: 2981127 (1961-04-01), Ransom
patent: 4341206 (1982-07-01), Perrett et al.
patent: 4373518 (1983-02-01), Kaiser et al.
Bobst Frank
Griss Peter
Buiz Michael
Endocare AG
Reip David O.
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