Disposable burr attachment

A burr attachment removably attached to an adapter rotary driven by a motor that includes a tube with a wire shaft supported therein and a wire coil (no spring rate) serving as a journal bearing rotary supporting the wire shaft and having each of the coils randomly touch the outer periphery surface of the wire shaft and the inner peripheral surface of the tube to enhance cooling and attenuate vibrations while allowing the burr attachment to be bent without kinking. The burr attachment includes a proximal end support and a distal end support that removably attaches to the adapter. The wire shaft is affixed to the proximal end support and rotates relative to the distal end support operatively connected to the adapter. Only the burr attached is removable and disposable while the adapter and motor are re-usable.

RELATED APPLICATIONS

This invention relates to the patent application concurrently filed and entitled SURGICAL DRILL WITH CURVED BURR ATTACHMENT AND METHOD filed by the same inventors and assigned to the same assignee and incorporated in its entirety herein bearing Ser. No. 12/387,838 filed on May 8, 2009.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

TECHNICAL FIELD

This invention relates to a surgical cutting instrument (Curved Burr Attachment) and particularly to a portable and disposable burr attachment capable of use with the Curved Burr Attachment. The burr attachment of this invention has the ability to utilize different sized ball cutters primarily used for cutting bone and being capable of changing the angle of the attachment to different angles to fit into minute curved portions of the anatomy, as for example, the middle ear, although this surgical drill can be utilized for other surgical procedures.

BACKGROUND OF THE INVENTION

This invention is particularly efficacious because it is disposable and bendable without kinking and is characterized as being easily fitted into and removable from the adapter of a Curved Burr Attachment and that it is cost effective. What is meant by disposable in the context of this patent application is that the attachment, namely, the burr and its supporting structure (burr attachment) are detachable from the drill motor and the adapter and can be discarded. In the prior art, for example, the burr and its extensions are made integral with the adapter (sometimes referred to as the clutch or clutching mechanism) so that in order to make the burr disposable, the adapter, being attached thereto, is, of necessity, also disposable. It is readily understood that this is a less desirable scenario because it is less cost effective.

A good example of the differences between a more cost effective disposable component and a less cost effective disposable component is a comparison with the present invention and the instruments disclosed in the US Publication No. 2005/0177168 invented by Brunett, et al and entitled HIGH SPEED SURGICAL CUTTING INSTRUMENT (which is incorporated in its entirety herein by reference). In the present invention the comparable medical instrument is comprised of a motor, an adapter and the Curved Burr Attachment which is essentially the same elements of the instrument disclosed in the Publication, although the terminology is different. The elements in the instrument disclosed in the Publication, supra, that compares to the Curved Burr Attachment is the wire and the cutter extending at the end of the wire and its support structure, the chuck mechanism and the motor. Since the wire/cutter and support mechanism also includes an integral chuck mechanism (comparable to the adapter of the present invention) that serves to connect to the motor, the disposable portion includes the wire/cutter and its support mechanism, as well as the clutch mechanism. In contrast, the present invention merely disposes the burr attachment of the Curved Burr Attachment instrument and hence, the remaining portion of the instrument, namely, the adapter (the more expensive portions of the tool), are re-usable. What the industry needs and desires is a tool, of this type, which is extremely small, (ball cutters range in 0.5 mm-2 mm) which includes a disposable burr that is substantially inexpensive and hence, cost effective.

In addition to the ability to bend the burr attachment at-will and the burr attachment being disposable in a cost effective manner, the particular manner in which lubrication is applied to the burr is unique. In the present invention the wire-shaft of the burr is surrounded by a coil wire that extends to approximately from the proximate end to the distal end of the wire-shaft and is oriented in such a manner that the helix formed by the coil wire is in a upward direction so that by placing grease at the distal end, the rotation of the wire-shaft causes the grease to migrate from the distal end to the proximate end, namely, in the upward direction.

In addition to the lubrication feature and the bending without the kinking feature of the present invention, the coil wire which is fixed and non-rotatable, also serves another function, i.e. it dissipates heat. This is accomplished by judiciously locating the coil wire between the inner wall of the support sleeve or tube of the burr attachment and the wire-shaft such that the outer and inner edges of each coil touches both the side of the inner wall of the support sleeve and the outer periphery of the wire-shaft, respectively. This serves to conduct the heat away from the wire-shaft and from internally of the support sleeve. Distributing the heat dissipation load in this manner reduces the heat or slows down the heat at the cutter resulting in additional time that the Curved Burr Attachment can be in continuous use in a medical procedure. As one in this technology knows the heat generated by the cutter can adversely affect nerves and other portions of the anatomy. Further this arrangement attenuates vibrations created by the rotation of the wire shaft.

Another function of the coil wire is that it permits the bending of the burr attachment without causing kinking. In accordance with this invention, the burr attachment t may be bent at the factory and, at the option of the surgeon; it may be bent at-will.

SUMMARY OF THE INVENTION

An object of this invention is to provide an improved disposable burr attachment.

A feature of this invention is to provide a coil wire mounted in a support tube that surrounds the wire-shaft of the burr attachment such that it prevents kinking when the burr attachment is bent and it serves to provide heat transfer from the wire shaft to the inner diameter of the support tube surrounding the coil wire and provides a means for migrating grease from the distal end of the support tube upwardly toward the proximal end for lubricating the wire-shaft. This arrangement also attenuates vibrations created by the rotation of the coil wire.

Another feature of this invention is the inclusion of the proximal end support and the distal end support mounted on the end of the tube support that includes judicious dimensions that allow the attachment and the detachment of the burr attachment from the surgical instrument that provide means for rotating the wire shaft and locating the cutter in an exact and predetermined position.

Another feature of this invention is that it is designed to be disposable after a single use and is capable of use with a surgical drill that rotates at 80,000 revolutions per minute or higher.

The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

It will be noted that in the description of the elements of this invention as shown in each of the FIGS. in this patent application may be out of proportion with respect to the overall picture of the inventive unit. As for example, some of the elements are shown in a small size and some of the elements are shown in an enlarged size. The purpose, obviously, is to more clearly define the invention and better describe the function of each of the elements. It is to be understood by those skilled in this art that the drawings are not manufacturing drawings, but are drawings used to illustrate the invention and to teach the concept and the workings thereof. Moreover, while the burr attachment of this invention is disclosed as being capable of use in a particular adapter, it is to be understood that other adapters can be used without departing from the scope of this invention and that this invention, amongst other things, teaches the concept of making the burr attachment, per se, disposable and bendable without incurring kinks.

As best seen inFIGS. 1 and 2, this invention is capable of use with a high speed (80,000 RPM-90,000 RPM) surgical instrument that is particularly efficacious for operating on small bones as for example, those found in the ear, nose and throat area, although not restricted thereto and generally illustrated as reference numeral10comprising a motor12(shown in phantom), an adapter14and the burr attachment16with the capability of being bent as shown in phantom and the burr attachment being disposable as will be described in detail herein below. While the particular motor used to rotate the drilling burr is of no moment, the X-Max® series or the E-Max® series, pneumatic and electric motors, respectively, are contemplated for use with this invention and are commercially available from the assignee of this invention, namely, The Anspach Effort, Inc of Palm Beach Gardens, Fla. 33410.

The adapter14, while not a part of this invention, is described in the aforementioned patent application bearing Ser. No. 12/387,838 and for further details reference should be made to this document. Suffice it to say that the adapter is removably coupled to the motor and the burr attachment is removably coupled to the adapter for imparting rotary motion to the cutter that is attached to the wire shaft of the burr attachment.

The invention is best described by referring to all of the Figs wherein the medical instrument sometimes referred to as the Curved Burr Attachment generally indicated by reference numeral10comprising the motor12(shown in phantom, the adapter14and the burr attachment16, which is the subject matter of this invention. The burr attachment16is removably coupled to the adapter14as described in the aforementioned application bearing Ser. No. 12/387,838 and comprises a tube support18, a wire shaft20and cutter22, a distal end support24, a proximal end support26(seeFIGS. 2 & 3), coil wire30, and nose cap28. The cutter22may be a spherical ball with a diamond coating or with cut-in flutes. These devices are well known and for this particular medical instrument these cutters are particularly small, say from 0.5 mm to 2 mm.

All the elements of the burr attachment are made from a surgical steel or other suitable material where the hardness and tensile strength of the wire shaft26and attached cutter22, the tube18, proximal end support26, distal end support24and nose cap28are higher than the hardness and tensile strength of the coil wire30. (Unlike a spring, the coil wire30does not exhibit any spring-like characteristics and has no spring rate) These parameters are selected to assure that the burr attachment is sufficiently rigid to support the high rotational speed, yet the wire coil30is sufficiently malleable so that the burr attachment can be hand bent without incurring any kinking.

As alluded to in the above paragraphs, the burr attachment16is disposable. Hence, this invention assures that the burr attachment16is both easily inserted into and easily removed from the adapter. To this end the distal end support24and proximal end support26are judiciously dimensioned. As best seen inFIGS. 3,3A3B,4A,4B and4C, the proximal end support26includes a generally cylindrical shaped main body34, an annular groove36disposed intermediate the ends thereof, a tip portion38, a flat portion44formed on the periphery of the main body34and adjacent to the tip portion38, large diameter recess40formed on one end remote from the tip portion38and a smaller diameter bore42extending axially from the large diameter recess40. Preferably the tip portion38is asymmetrically shaped so that the tip is formed in a shape of an ellipse as shown inFIG. 4C. The larger diameter recess40serves to receive the proximal end of the distal end support24as will be described in more detail herein below. The smaller diameter bore42serves to receive the proximal end of the wire shaft20which is united to the proximal end support26, say, by swaging, shrink fitting or the like. In this particular embodiment, the holes51serve to receive a tool (not shown) used to swage the main body34to wire shaft20to form an integral unit so that the wire shaft20rotates with the proximal end support26for powering the cutter22. The annular groove36serves to cooperate with the adapter such that it couples the burr attachment so that the proximal end support26and wire shaft20are rotated. The pertinent dimensions of the proximal end support26are as follows in inches:

The distal end support24, as best seen inFIGS. 3,3A and3B, comprises generally cylindrical main body56including a larger diameter portion58, a smaller diameter portion60, a flat portion62formed on the periphery of the main body56intermediate the ends thereof a slot64formed on the periphery of the main body56adjacent to a flat portion62formed on the periphery of the main body56, a larger diameter recess61, a smaller diameter bore63and a grip portion66formed on the end of the main body56remote from the smaller diameter portion60. The slot64cooperates with the adapter such that it locates the cutter relative to the tip of the adapter and the distal end support is held fixed relative to the adapter. The grip portion66in this embodiment is formed by axially spaced annular ribs but other known configurations, like knurling, can be employed. The pertinent dimensions of the distal end support24are substantially as follows in inches:n =0.785; p =0.276; r =0.150; s =0.550; t =0.0725 and q =0.026

As noted inFIG. 2the peripheral end support26is fitted into the distal end support24such that the smaller diameter60fits into the slot40and the proximal end of the tube support18and coil wire30fits into the larger diameter recess61, which define a seat65therefore. The diameter of the bore63(0.026) is larger than the diameter of the of the wire shaft20(0.020) such that it is capable of freely rotate therein and since the wire shaft20is locked into the peripheral end support26it will rotate when the adapter rotates the peripheral end support26. The wire shaft20and cutter22are shown inFIG. 7.

As noted fromFIG. 2Athe coil wire30is mounted in. the seat80defined by the proximal end of the nose cap28and the seat65defined by the proximal end of the recess61and is held in place between these seats. When the coil wire30is installed into the tube18each end thereof bears against the spring seat65and the spring seat80formed when the nose cap28is inserted, such that the nose cap28will hold the coil wire30in place. This assures that coil wire30, surrounding the rotating wire shaft20, remains fixed. Hence, when the wire shaft is rotating, randomly, each of the coils of the coil wire will touch the inner surface of the tube18and outer periphery of the coil wire30. An enlarged view of the coil wire is shown inFIG. 5where the substantial value of h=2.240. A view of the tube support18is disclosed inFIGS. 6 and 6Awhere the substantial values of k=2.650 and m=0.042.

It will also be noted and in accordance with this invention that the helix orientation of the coils of coil wire30are in a direction as seen inFIG. 2Bare from right to left or looking from the right hand end ofFIG. 2Bthey are in a clockwise direction. The direction of the helix serves to flow grease in the upward direction toward the proximal end. Because of the orientation of the coils, grease inserted at the distal end of the burr attachment unit in a clearance between the wire shaft20and inner diameter of the nose cap22into the tube18so that when the wire shaft20rotates this motion forces the grease toward the proximal end of the burr attachment which lubricates the entire the wire shaft20.

It will also be noted and in accordance with this invention, as evidenced inFIG. 2B, that the peripheral top and bottom surfaces82and84of each coil of coil wire30touch, by a point contact, the inner diameter surface86of tube support18and the outer surface88of wire shaft20and this connection serves to minimize the heat transfer through the coil wire30and tube18. This minimizing of the heat transfer of wire shaft20serves to keep the outer tube18cooler than it would otherwise be without this feature. The importance of maintaining the outer surface of tube18cooler by virtue of this heat transfer feature of this invention results in enhancing the operational time of the Curved Burr Attachment. In addition, because of the location of the coil wire30, namely, by the touching of the wire shaft20and of the inner surface of tube18, vibration generated by the rotating wire shaft20of the Curved Burr Attachment is attenuated.

It will be appreciated that in certain operations, particularly affecting the ear, the surgeon may have to re-adjust the angle of the burr attachment. Since the coil wire30is mounted between tube28and wire shaft20, the surgeon can bend the burr attachment to any desired angle to suit the particular operation being performed. Because of this design, the burr attachment16will not kink and will leave a smooth bend and yet the tube and wire shaft will provide sufficient rigidity to perform the rotation in a precise manner.

In some of the embodiments of this invention the diameter of cutter22is smaller than the diameter of the wire shaft20which could under certain circumstances cause a problem, as for example, in the insertion and removal of the burr attachment16. To solve this problem the distal end support24includes the annular groove100formed on the smaller diameter portion60. And a dimple or indent102is formed on the larger diameter portion34adjacent to the larger bore portion40of the proximal end support26, obviating the possibility of the cutter22and wire shaft20from inadvertently falling out. Obviously, the dimple or indent102is formed after the proximal end support26and the distal end support24are assembled in the assembled burr attachment16.

Although this invention has been shown and described with respect to detailed embodiments thereof, it will be appreciated and understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the disclosed invention.