Abstract:
A surgical drilling instrument with a Curved Burr Attachment having an adapter removably coupled to a drill motor and a burr attachment coupled to said adapter. The burr attachment includes a tube with a wire shaft supported therein and a coil wire surrounding said wire shaft and having each of the coils touch the outer periphery surface of the wire shaft and the inner peripheral surface of said tube to enhance cooling of said outer periphery of said tube from the heat generated by said wire shaft and attenuate vibrations while allowing said burr attachment to be bent without kinking. The burr attachment includes a proximal end support and a distal end support formed on the end of said burr attachment wherein the wire shaft is affixed to said proximal end support and rotates relative to said distal end support and includes detents formed on each of the supports for engaging balls in said adapter so as to be operatively connected thereto when the burr attachment is aligned in said adapter to couple the burr attachment to said adapter for rotary motion of said wire shaft and locating the cutter of said burr attachment to a precise location relative to the end of the adapter. The burr attachment being disposable and the adapter being re-usable.

Description:
RELATED APPLICATIONS 
     This invention relates to U.S. patent application Ser. No. 12/387,828, entitled BURR ATTACHMENT filed May 8, 2009, by the same inventors and assigned to the same assignee. 
     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 with 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. For example, this invention can be utilized in surgical procedures such as otological surgery, cochleostomies, removal of acoustic neuroma tumors, removal of the scutum in a tympanoplasty, cochlear implant, ossicular chain reconstruction, drainage of petrous apex cyst, amstoidectomies, amongst others. 
     BACKGROUND OF THE INVENTION 
     This invention is particularly efficacious because it provides a good feel to the surgeon (user friendly), it provides significant visibility of the surgical sight, the attachment is bendable at-will without kinking to afford easy access to the target, enhances visibility, it is rigid and avoids any distortions and wobbling of the cutter, it operates at a high speed (RPM), say, 80,000 to 90,000 RPM, it provides heat dissipation, a unique lubrication technique and it is disposable. It is paramount that a medical instrument or component that is disposable should be 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 is disposable. 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 both 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. Obviously, every portion of the tool may be disposable, but this is impractical to do because of the cost and obviously, the drill motor is a capital investment and has many uses. 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. 
     This type of medical instrument, because of its size and speed that is required to perform certain medical procedures, under normal operational circumstances, it is limited to the amount of time it can be placed in continuous use. Under medical practices, it is well known that the surgeon in most instances typically perform a surgical procedure under a minute. This invention provides at least 2 minutes of continuous operation where the heat generated at the cutter will not adversely affect the nerves and other parts of the patient&#39;s anatomy. 
     This invention constitutes an improvement over the surgical instrument that is disclosed in U.S. Pat. No. 4,811,736 granted to Griggs et al on Mar. 14, 1989 and entitled SURGICAL DRILL AND BUR FOR USE THEREWITH and also being incorporated herein in its entirety by reference. This invention, like the structure disclosed in the &#39;736 patent, supra, is intended to be utilized in performing, amongst other types of surgery, otological surgery. While the surgical drill of the &#39;736 patent, supra, may be highly viable, it is limited in the potential available rotational or cutting speed, particularly, because it utilizes a plastic sleeve (journal) bearing. According to the patentee of the Publication, supra, the operational speed of the structure disclosed in the &#39;736 patent, supra, is “less than 20,000 RPM.” The present invention is intended for use where the RPM is typically in the 80,000 range. Furthermore, like the differences between the structure disclosed in the Publication, supra, the present invention is completely different from the structure in the &#39;736 patent, supra, and affords features that are not taught in this reference patent. 
     The aforementioned Publication, supra, is worthy of mention because, in addition to the features disclosed therein, the present invention includes features, that are unobvious and novel, and that constitute an improvement there over. As mentioned above, the Publication, supra, describes a cutting tool that is intended for surgical use for the same types of surgical procedures that are intended for use by the present invention. As disclosed therein the medical instrument describes structure that includes a cutting instrument assembly having a support tube, an inner wire assembly (bur), a cutting tip, a coupling chuck within a housing and a motor (not shown) for rotating the cutting tip. The present invention, while using different names, provides a motor, an adapter and the burr with a cutting tip, which is terminology that applies to both structures, albeit, that the present invention is designed differently than what is disclosed in the Publication, supra, The features of the present invention are, namely, without limitations, the Curved Burr Attachment which is disposable, it provides an enhanced thermal effectiveness, includes a lubrication delivery system and is bendable at-will by the operator without adverse effects. What this means is that the attachment may be bent in a normal or customary acceptable curvature at the factory, while also providing to the operator the option of changing the bend or angle of the attachment at-will while still maintaining the rigidity and structural integrity of the assembly. The present invention also provides to the user a medical instrument that is capable of being utilized a significant length of time to perform a particular operation because of the heat dissipation. And the Curved Burr Attachment is the only portion of the medical instrument that is disposable. This latter feature is an important distinction over the prior because no other component has to be disposed other than the disposable Curved Burr Attachment. Obviously. This makes the unit cost effective and leaves the more costly capital expenditures, the adapter, to be re-used. Hence, these features just described and that are afforded by the present invention are in addition to the features described in the Publication, supra, namely, high-speed operation with minimal impact of user visibility, minimized heat-build-up, and improved stiffness. 
     The following is an explanation to show and support the fact that the specific differences between the disposable portions of the present invention and the ones described in the Publication, supra. Referring to the Publication, supra, itself, it states that “The coupling chuck is secured to the proximal section of the inner wire assembly. To this end, the coupling chuck is adapted for coupling to a drive mechanism of a drill.” In comparison with the present invention, in the present invention the “coupling chuck” is referred to as an “adapter” and the wire assembly is referred to as “burr”. What is significant is that in the structure of the Publication the coupling chuck and wire assembly are united and form an integral unit and are un-separable after assembly. This means that for it to be disposable this entire unit would have to be disposed. In the present invention, the adapter and burr and its attendant hardware are separate items and the burr is removable from the adapter such that it is the only portion of the inventive surgical instrument that is disposable, resulting in a cost effective device. Obviously, in the present invention the adapter is re-usable for future use, as will be described in detail in the description to follow. 
     In addition to the aforementioned features of the present invention, namely, the ability to bend the burr at-will, and the burr 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 proximal 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 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. 
     Another function of the coil wire is that it permits the bending of the burr without causing kinking. In accordance with this invention, the burr attachment of the Curved Burr Attachment is bent at the factory and may be, at the option of the surgeon, bent at-will. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide an improved high speed surgical drill with a disposable and bendable burr attachment. 
     Another object of this invention is to provide an improved high speed surgical drill characterized by being high-speed operation with minimal impact of user visibility, minimized heat-build-up, lubrication technique, enhanced time in use during medical procedure, and improved stiffness characteristics. 
     A feature of this invention is to provide a coil wire that wraps around the wire-shaft of the burr such that it prevents kinking when the Curved 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. 
     Another feature of this invention is the inclusion of key slots for both the rotating and non-rotating portions of the Curved Burr Attachment that complement keys formed on the rotating and non-rotating portion of the Curved Burr Attachment instrument for accepting the burr attachment. 
     Another feature of this invention is to provide mechanism for locking the burr attachment in place when inserted into the adapter and orienting it so that the cutting member is in the exact proper position. 
     Another feature of this invention is that the adapter is re-usable. 
     The coil wire is seated and placed in position by an upper and lower seat formed in the members attached to the tube support member. 
     The burr attachment of the Curved Burr Attachment instrument is intended to be bent in the optimum position at the factory with the option of being capable of being further bent at the will of the surgeon and the bent can be made without the incidence of kinking. 
     The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view in elevation and phantom illustrating the present invention of the burr attachment attached to the adapter and illustrating the various positions that the instrument can be bent into; 
         FIG. 2  is a sectional view of the invention depicted in  FIG. 1  and including in a phantom view the motor attached to the adapter for rotating the burr attachment of this invention; 
         FIG. 3  is an exploded view of the adapter of the Curved Burr Attachment instrument depicted in  FIG. 1 ; 
         FIG. 4  is a perspective view of the burr attachment for the Curved Burr Attachment instrument of this invention; 
         FIG. 4A  is a fragmentary enlarged view in perspective illustrating an elevation of the burr attachment depicted in  FIG. 4 ; 
         FIG. 4B  is a fragmentary enlarged view in perspective illustrating a plan view of the burr attachment depicted in  FIG. 4A ; 
         FIG. 5  is an exploded view in perspective illustrating the disposable and bendable burr attachment and the adapter combination of the Curved Burr Attachment instrument; 
         FIG. 5A  is a sectional view of the burr attachment depicted in  FIG. 5 ; 
         FIG. 5B  is an enlarged fragmentary view of the tube, wire shaft and coil wire depicted in  FIG. 5 ; 
         FIG. 6  is a perspective view of the burr attachment proximal end of this invention; 
         FIG. 6A  is a sectional view of the burr attachment proximal end depicted in  FIG. 6 ; 
         FIG. 6B  is a side elevation view of the burr attachment proximal end depicted in  FIG. 6 ; 
         FIG. 6C  is an end view taken along lines  6 C- 6 C of the adapter depicted in  FIG. 2  illustrating the entrance to the passageway into the adapter for admitting the burr attachment proximal end depicted in  FIG. 6B ; 
         FIG. 7  is a view in elevation illustrating the coil wire of this invention; 
         FIG. 8  is a view in perspective illustrating the tube support structure for the burr attachment; 
         FIG. 8A  is a sectional view of the tube depicted in  FIG. 8 ; 
         FIG. 9  is a perspective view of the distal end support of the burr attachment of this invention; 
         FIG. 9A  is a side view in elevation illustrating the distal end support depicted in  FIG. 9 ; 
         FIG. 9B  is a sectional view of the distal end support depicted in  FIG. 9 ; 
         FIG. 9C  is an end view of the tip at the distal end of the adapter taken along lines  9 C- 9 C depicted in  FIGS. 2 and 3 ; 
         FIG. 10  is a view in elevation illustrating the burr cutter and shaft for use with this invention; and 
         FIG. 11  is a fragmentary view illustrating another embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As best seen in  FIGS. 1 and 2 , this invention is a high speed (80,000 RPM-90,000 RPM) surgical instrument 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 numeral  10  comprising a motor  12  (shown in phantom), an adapter  14  and the burr attachment  16  with 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 adapter  14  of this invention is best seen in  FIGS. 2 and 3  comprising the main housing  18 , the detent spring cover  20 , O-ring  22 , spring ring  24 , wave washer  26 , bearing  28 , ball retainer  30 , spring  32 , spindle  34 , bearing  36 , O-seal  38 , bushing and motor coupling  40 , pin  42 , retaining ring  44 , ball  46  and ball  48  ( FIG. 3 ). The motor  12  serves to power the Curved Burr Attachment instrument by providing rotary movement to the burr cutter which is essentially a spherical ball that is diamond coated or fluted and well known in this technology. Attached to the motor by a suitable and well known chuck (not shown and available from The Anspach Effort, Inc., supra) is the adapter  14  and connected to the spindle  34  for rotating the same. Spindle  34  is supported in the main housing  18  by the bearing  36  and bearing  28 . Sandwiched between the inner surface of the main housing is sleeve/cam  52  having bevel edge  54  formed on the inner diameter thereof. Spring  32  disposed between shoulder  56  and the proximal end  58  of the sleeve/cam  52  biases the sleeve/cam  52  toward the distal end so that the sleeve/cam  52  engages the balls  48 . Balls  48  fit into a circular hole and engage the cam surface  60  of the sleeve/cam  52  at a judicious location at the proximal end of the burr attachment  16 . When the balls  48  are in engagement, the balls are forced against the peripheral surface of the proximal which serves to rotate the cutter wire shaft  70  and burr cutter  50  as will be described in further detail herein below. O-seal  38  mounted at the proximal end at the juncture between the bushing motor coupling  40  and main housing  18  and O-seal mounted in the distal end of the main housing  18  serve to assure that the inside of the adapter  14  remains clean and free from foreign matter. 
     Also nested in the main housing  18  is ball  46  biased radially inward by the spring ring  6  to engage detent  68  formed on the distal end support of the burr attachment  16 . This serves to define the position of the burr cutter  50  relative to the Curve Burr Attachment instrument when the burr attachment  16  is inserted into the adapter  14 . In other words, the relative position of the cutter  50  will be determined by the position of the ball  46  when in its detent  68 , which will be described in further detail herein below. 
     The disposable burr attachment  16  of the Curved Burr Attachment instrument will be described next and reference should be made to  FIGS. 4 through 10 . As noted from these Figs., the burr attachment  16  comprises the wire shaft  70 , and attached cutter  50 , the tube  80  defining the outer support for the burr attachment  16 , and proximal end support  82 , distal end support  72 , coil wire  86  and nose cap  108 . 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 shaft  70  and attached cutter, the tube  80 , proximal end support  82 , distal end support  72  and nose cap  85  are higher than the hardness and tensile strength of the coil wire  86 . (Unlike a spring the coil wire does not exhibit any spring-like characteristics) These parameters are selected to assure that the burr attachment is sufficiently rigid to support the high rotational speed, yet sufficiently malleable to be hand bent without incurring any kinking. 
     As alluded to in the above paragraphs, the burr attachment  16 , and only the burr attachment  16 , is disposable. Hence, this invention assures that the burr attachment  16  is both easily inserted into the adapter and easily removed. To this end, the operator must be able to easily put the end of the burr attachment  16  into the passageway or central bore  83  with the burr attachment  16  being oriented so that the coupling between the adapter and the burr attachment are mated (ball  48  fits into annular groove  81 ) and that the burr attachment  16  aligns with the adapter (ball  46  fits into detent  68 ) so that when the burr attachment  16  is locked into place the cutter  50  is in its exact position relative to the distal end of adapter  14  to assure that the instrument is exacting and precise for use by the surgeon. As noted in  FIGS. 4A ,  4 B,  6 A,  6 B and  6 C, the distal end support  82  is comprised of a main generally cylindrical body  90  with an annular groove  57  formed intermediate the ends thereof, a generally tapered end  92  and a flat portion  94  formed on the peripheral surface of the main body  90 . The tapered end  92  is not symmetrical but rather is asymmetrical and tapered to match the inlet opening  96  formed at the entrance  87  of the central bore  83 . Hence, the shapes of the entrance and the tip of the proximal end support  82  serve as a key and key slot such that the proximal end support  82  can fit into the central bore  83  in only one position. Internally of the proximal end support  82  includes a central passage or partial bore  100  and a wider diameter partial bore  102 , The smaller bore  100  receives the end of the wire shaft  70  which is suitably fitted to form an integral unit, say by shrink fitting, swaging or the like, so that in operation the proximal end support  82  and wire shaft  70  rotate together as a unit. The distal end support  72  and the proximal end support  82  are joined together through the reduced diameter portion  123  formed on the end of distal end support  72  that fits into the larger diameter slot  102  formed on the proximal end support  82  and these elements are dimensioned to allow the proximal end support  82  and wire shaft  70  to rotate while the distal end support  72  remains fixed, as will be described in more detail herein below. 
     It is important and in accordance with this invention that the distal support end  72 , as best seen in  FIGS. 9 ,  9 A and  9 B, is properly oriented when inserted into the adapter  14 , so that the wire shaft  70  and cutter  50  (representing all the different sizes used by this medical instrument) are always in the exact same position relative to the distal end of adapter  14 . To this end, the main body  120  of the distal support end  72  is generally cylindrical in shape and includes a large diameter portion  125 , a smaller diameter portion  123 . The smaller diameter  123  portion fits into the end of the proximal end support  82  as was discussed above. Each unit is oriented relative to each other so that the flat portion  94  lies in the same plane as the flat portion  124  formed on the inner periphery of the nose cap  85  of adapter  14 . Groove  126  formed adjacent to the flat portion  124  serves to receive ball  46  which, in turn, serves to position the cutter  50  relative to the end of the nose cap  108 . The foreward portion of the main body  120  includes a serrated or grooved portion  128  that serves as a grip for the surgeon to remove the burr attachment from the adapter. Obviously, any type of grip, such as a knurl, can be used without departing from the scope of this invention. 
     Coil wire  86  fits between the spring seat  104  and the seat  106  formed on the proximal end  110  of the nose cap  85 . When the coil wire  86  is installed into the tube  80  each end thereof bears against the coil wire seat  104  and the coil wire seat  106  and the insertion of the nose cap  108  is dimensioned so that it holds coil wire  86  in place. This assures that coil wire  86 , surrounding the rotating wire shaft  70 , remains fixed. It will be noted that coil wire  86  is tightly wound and essentially serves as a journal bearing for the wire shaft  70 . 
     It will also be noted and in accordance with this invention that the helix orientation of the coils of coil wire  86  are in a direction that looking at  FIG. 2  are from left to right or looking at the bottom they 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, the grease inserted at the distal end of the unit in the clearance between the wire shaft  70  and inner diameter of the nose cap  108  into the tube  80  lubricates the entire the wire shaft  70 . 
     It will also be noted and in accordance with this invention, as evidenced in  FIG. 5B , that the peripheral top and bottom surfaces  112  and  114  of each coil wire  86  touch, by a point contact, the inner diameter surface  116  of tube  80  and the outer surface  118  of wire shaft  70  and this connection serves to minimize the heat transfer through the coil wire  86  and tube  80 . This minimizing of the heat transfer of shaft  70  serves to keep the outer tube  80  cooler than it would otherwise be without this feature. It wilt be obvious to the skilled artisan that the wire shaft  70  is notably supported by the coil wire  86  and that for rotation to be effective that is a minimal space between the wire shaft  70  and coil wire  86  where lubricant can be placed. Hence the point contact of the coils of the coil wire  86  is random that occurs as the shaft rotates around 80,000 to 90,000 rpm. The importance of maintaining the outer surface of tube  80  cooler by virtue of this heat transfer feature of this invention the operational time of the Curved Burr Attachment is enhanced. In addition, because of the coil wire  86  location, namely, by the touching of the wire shaft  70  and of the inner surface of tube  80 , vibration of the Curved Burr Attachment is minimized. 
     In operation of the medical instrument, when the adapter is coupled to a motor, the surgeon will insert the burr attachment into the adapter by orienting the proximal end support  82  so that the flat portion  94  aligns with the secanted portion  122  formed in the opening  120  of the adapter  14 . Obviously the surgeon may have to rotate the burr attachment  16  until the flat portion  94  which serves as the key aligns with the secanted portion  122  defining a key slot formed at the entrance of the adapter  16 . Once aligned, the surgeon merely pushes the burr attachment  16  into the adapter  14  where the tapered asymmetrical end  92  fits into the key slot  96  formed at the entrance of the central bore  83 . In order to permit the burr attachment  16  to reach the end of the adapter and into its operating position, the cam  52  must detach from the balls  48  which would initially be in the contact position shown in  FIG. 2 . This invention has a unique design for accomplishing this task. As one skilled in this art appreciates, there are ball locking mechanism available in the prior art, as for example, key chains and others, which include both a ball and detent. However, in all these designs, an actuator must be engaged to allow the positioning of the cam to become detached from the ball. In accordance with this invention, no external actuation mechanism is utilized and the locking feature merely requires the insertion of the burr attachment  16 , which obviously is a very simple, uncomplicated operation. To this end, the movement of the burr attachment  16  into the adapter  14  causes shoulder  126  and the balls  48  resting in the slot  57  of the proximal end support  82  to bear against the end surface of sleeve like cam  52  which, in turn, forces the cam  52  rearward against the force of the spring  32 . This movement causes spring  32  to compress. The spring rate of spring  32  is selected such that the cam  52  will move rearward until the spring compresses a sufficient distance which creates a force on the spring so that its value reaches a point where the force of the spring will now drive the cam toward the distal direction and back to its original position. As is evident from the drawing ( FIG. 2 ) the proximal end support  82  reaches its maximum position and the shoulder  126  bears against the shoulder  128  formed internally of spindle  34 . At this juncture the force of spring  32 , as noted above, urges the cam  52  toward the distal end so that the bevel portion  60  drives the balls  48  radially inwardly to fit into the aligned annular groove  57 . (Hole  51  serves to receive a tool to swage the proximal end support to the wire shaft  70  of the burr attachment). This connection couples the spindle to the proximal end support  82  as well as the wire shaft  70  which is connected thereto so as to impart rotary motion thereto. Obviously, the motor  12  being suitably attached to the adapter to drive the spindle  34  and the adapter  14 , in turn, will drive the cutter  50  to now rotate at the desired rotational speed, say 80,000 RPM and become ready for the surgeon to perform the medical procedure. It will be appreciated that the cutter  50 , as described above, is in the precise operating position because the ball  46  of the adapter  14  aligns with the slot  126  formed in the distal end support  72 . 
     The removal of the burr attachment is a simple operation where the surgeon merely pulls on the grip  128  and pulls the burr attachment  16  outward to remove the same. The balls  48  in this instance are moved toward the distal end of the burr attachment  16  into the space formed at the distal end of cam  52 . Since the balls  48  have room to move radially outward, the proximal end support  82  of the burr attachment  16  can proceed toward the distal end. The other ball  46  is spring loaded radially inward and the movement merely forces this ball  46  radially outward, allowing the burr attachment  16  to progress out of the adapter  14 . Obviously, the consequence of this design is that the removal of the burr attachment  16  is simple and at this point the burr attachment  16  may be discarded, leaving the adapter for future use. 
     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 wire  86  is mounted between the tube  80  and wire shaft  70 , the surgeon can bend the burr attachment to any desired angle to suit the particular operation being performed. Because of this design, the burr attachment  16  will 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. 
       FIG. 11  discloses another embodiment and is identical to the burr attachment  16  save for inserting a double coil wire to replace coil wire  86  (like reference numerals represent like parts in all the embodiments). Obviously, the larger coil wire  132  that is located where the bend occurs, serves to strengthen the burr attachment  16 , and the rigidity and the bending thereof. As seen in  FIG. 11  a smaller coil wire  130  surrounds the wire-shaft (not shown) and fits against the inner surface of the tube  80  and extends a portion into the burr attachment  16 . The larger coil wire  132  whose helix is oriented in the same direction as the smaller coil wire  130 , continues the remaining distance so that the coil wires when assembled are held in a place, similarly to the design of the other embodiment. It will be noted, as in the case of the other embodiment, the orientation of the helix allows the lubrication of the wire-shaft in the same manner as in the previous embodiment, namely, merely by placing grease or the like at the entrance of the burr attachment  16 , the rotation of the wire shaft will cause the lubricant to migrate upwardly into the burr attachment  16  to lubricate the entire wire shaft. 
     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.