Patent ID: 12256945

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

The following description includes disclosure of rotatable surgical burs (also referred to below as the surgical burs). Cutting edges and trailing edges, as disclosed below. The surgical burs may include one or more of a plurality of external geometries, such as a ball, a cylindrical, an oval, or other generally known shape, such as the Midas Rex® surgical burs sold by Medtronic, Inc. having a place of business in Minneapolis, MN Surgical burs, including those disclosed herein, may be driven by high speed drills, such as the Midas Rex® Legend EHS Stylus High-Speed Surgical Drill which may be appropriate for a wide range of surgeries, including spine, neurology, and ear-nose-throat (ENT) procedures. The drills may drive the burs at appropriate and selectable speeds, such as about 200 to 75,000 rotations per minute (rpm), including about 7,000 to 70,000 rpms.

Example embodiments will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. For example, although a human patient is illustrated as a subject, it is under stood that a subject may be any appropriate subject. Further, the subject may include inanimate and non-living subjects. Non-living subjects may include solid working materials such as a objects formed of wood, ceramics, metal, etc. Certain tissues, such as bone tissue, may be rigid and may be shaped with a cutting tool. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

FIG.1shows a surgical dissection cutter assembly10incorporating a dissection tool20in use on a patient30at a surgical access site32. The patient30is illustrated as undergoing a neurological operation. Access to a brain or other neurological structures of the patient30often requires delicate dissection of bone (e.g. a skull) and other tissues.FIG.1is provided for example purposes only; the surgical burs disclosed herein may be used in different tools and/or cutter assemblies and may be used for other procedures and/or operations. The dissection cutter assembly10includes a dissection tool driver40, which is being utilized to dissect a portion of bone and adjacent tissue of the patient30in the surgical access site32. The tool driver may include the Midas Rex® Legend EHS Stylus High-Speed Surgical Drill, as noted above, or other appropriate driver.

FIG.2is a perspective view of the surgical dissection cutter assembly10. The dissection tool driver40includes a motor housing42connected to a connector44, the connector may include a hose or cable assembly. The connector44supplies external power and control for a motor included within the motor housing42. The dissection tool driver40further includes an attachment housing46that connects to the dissection tool20. A dissection tool distal end includes a surgical bur64. A dissection tool proximal end may include a driver connection54. The driver connection54may engage a connection within the attachment housing46to receive rotary power from the motor within the motor housing42.

Although the following described dissection tools, for example surgical burs, are disclosed and illustrated in the drawings as having a particular number of flutes, rake surfaces per flute, rake angles per flute, clearance surfaces per flute, lands, axial relief surfaces, clearance surfaces, etc., the surgical burs may have other quantities of each of these items.

FIG.3shows a side and perspective view of the dissection tool20. The dissection tool20may be used as part of the dissection assembly10ofFIG.1. The dissection tool20includes a shaft62and the surgical bur64. The surgical bur64has a design that may generally be referred to as a “match head”, “neuro”, or “matchstick” design and includes a body66. The body66has two convex lands68and two flutes70. Each of the flutes70is located between the lands68and has a corresponding chip space72. The lands68are convex-shaped and/or rounded and may be in respective 180° locations about a longitudinal axis78of the dissection tool20, the shaft62, and/or the surgical bur64. The surgical bur64is rotated about the longitudinal axis78. The flutes70may also be in respective 180° locations about the longitudinal axis78. Each of the flutes70has one or more rake surfaces on or at a cutting edge76. A clearance surface73, which may be a flat or concave surface, may also correspond to the cutting edge76. The clearance surfaces73are formed relative to the flutes70, and may be on both proximal and distal portions of the flutes70, near respective bur proximal end64aand bur distal end64b.

With additional reference toFIGS.4and5, the surgical bur64further includes the cutting edge76. The cutting edge76is spaced a distance82from a center or central axis78of the bur64. Generally, the cutting edge76axially extends from and is spaced the distance82from the center axis78. Further, the cutting edge76is generally set on an edge of the flute70. The cutting edge76is a leading edge while cutting the bur64rotates in the direction of arrow80around the central point or axis78. The cutting edge76offset the distance82generally places the cutting edge76at a maximum distance from the center point78of the bur64. That is the cutting edge76is generally at a most exterior point or distance from the center78as the cutting edge76is cutting into a material, as discussed further herein. A rig surface84extends from the cutting edge towards a distal tip86at the bur distal end64b, through which the central axis78may extend. The distal tip86may be a terminal distal tip of the dissection tool20.

A trailing edge90of the bur64can be formed at an edge of the curved land68and generally adjacent to the flute70of the bur64. The trailing edge90is generally an edge of the curved land68that follows the cutting edge76as the bur64rotates in the direction of arrow80. The trailing edge90may be at a distance94from the center axis78. The distance82of the cutting edge76from the central axis78and the distance94of the trailing edge90from the central axis78may be substantially the same or identical. With continuing reference toFIG.4, the leading edge76and the trailing edge90may generally lie on a circle96having a radius that is substantially equivalent to or defined by the distances82and94from the center78. Thus, the cutting edge76may not extend beyond the circle96or the trailing edge90. Both the cutting edge76and the trailing edge90may extend only to the circle96. Moreover, the cutting edge and the trailing edge may be include more than one of each, as discussed herein. A third distance95of a surface forming the convex land68may be less than either of the first distance82or the second distance94. Further, the clearance area73of the flutes, as discussed herein, may have a fourth distance73afrom the center78that is less than the first, second or third distance.

As further illustrated inFIG.4, two flutes may be included with the surgical bur64. A second flute70amay include a second leading or cutting edge76aand a second trailing edge90a. Thus, the bur64may include two flutes70,70awith equivalent two cutting edges76,76aand two trailing edges90,90a. The second cutting edge76aand second trailing edge90amay also be formed on the circle96centered on the central axis78of the bur64.

The bur64may include any selected geometry for forming a dissection of a selected structure. For example, the flute may define an arc97that is about 5 degrees (°) to about 35°. The curved land68may also define an arc99, which may also be the arcuate distance from the trailing edge90,90ato a cutting edge76,76athat is about 175° to about 145°. The arcs97,99, however, may be formed with the bur64to be any selected arcuate angle. The distances82,94of the cutting edges76,76aand the trailing edge90,90a, however, may all generally be equivalent.

Turning reference toFIGS.6-8, a surgical bur164is illustrated. The surgical bur164can be used as the dissection tool20in the assembly10in the manner similar to the surgical bur64, as discussed above. The surgical bur164can also include various features and portions similar to the surgical bur64, as discussed above. Accordingly, this portion will not be described in substantial detail and have similar reference numerals as those noted above increased by 100.

The surgical bur164may include a central axis178that extends through a shaft162of the surgical bur164. The surgical bur164includes a body166. The surgical bur164can include a flute170with a cutting edge176. Further, a trailing edge190can be formed on the body166and follow the cutting edge176as the surgical bur164rotates in a direction of arrow180. Further, a chip collection area172can be defined in the flute170. A convex land168is formed between the cutting edge176and the trailing edge190.

The surgical bur164may differ from the surgical bur64in that the surgical bur164includes three cutting edges176,176aand176b. Accordingly, the surgical bur164can also include three flutes170,170aand170b. Further, the surgical bur can include three trailing edges190,190aand190b.

Similar to the surgical bur64, the surgical bur164can define or have a circle196that defines an outer perimeter or edge of the surgical bur164. Accordingly, the cutting edge176may be formed at a distance182from the central axis178. The trailing edge190can be formed at a distance194from the central axis178. The distance182may be substantially equal or equivalent to the distance194. Therefore, the cutting edge176and the trailing edge190can both be positioned on the circle196. Additionally, the surgical bur may include a distal tip186that is generally on the axis178and other features that are similar to the surgical bur164. Also, the convex land168may have a surface that is a third distance195from the center axis178that is less than either of the first distance182or the second distance194.

The surgical bur164, therefore, includes three flutes170,170a,170bwhile the surgical bur64includes two flutes. On the bur164, the arcuate distance of the flutes170,170a,170band the arcuate distance from a trailing edge to the next cutting edge176,176a,176bmay be selected to be any appropriate distance. The arcuate distances between the various portions may be smaller than on the bur64given that there are a greater number of flutes on the bur164.

It is further understood that a surgical bur, according to the various embodiments, can include any appropriate number of flutes. Regardless, the cutting edge and trailing edge may both be generally on a circle that defines an outer extent of the surgical bur. Therefore, the distance from the central axis to the cutting edge and trailing edge may generally be substantially equivalent or identical, as discussed above. Further, it is understood that the surgical bur may be formed in any appropriate shape such as including a ball shape, a cylindrical shape, or other appropriate shape. The surgical bur, according to various embodiments, can therefore be used to form a dissection or resection of an appropriate portion of a subject, such as the patient30as illustrated inFIG.1and discussed further herein.

Turning reference toFIGS.9A and9B, the surgical bur64is illustrated relative to a bone structure or mass210. The surgical bur64includes the cutting edge76and the cutting edge76a, as discussed above. The surgical bur64can move or bore axially generally along the axis78of the dissection tool20. Accordingly, as illustrated inFIGS.9A and9B, the surgical bur64can move along the axis78and generally directly out of the plane of the page. An additional movement of the surgical bur64can be to cut radially or generally away from the central axis78, such as in the direction of arrow212. As the surgical bur is moved in the direction of arrow212into the bone mass210, a channel or trough214may be formed. In forming the channel214, the cutting edge76can form one or more bone chips218from the bone mass210. The bone chips218can be moved into the flute70of the surgical bur64. In moving into the flute70of the surgical bur64, the bone chip218can be moved out of the cutting path of the surgical bur64, which generally in the direction of arrow212.

The surgical bur64, in cutting the bone210, is rotating in the direction of arrow80, as discussed above. Further, the bur64is moved in the direction of arrow212to form the channel214in the bone210. Therefore, the cutting edge76, moving in the direction of arrow80, cuts the bone chip218and then continues to rotate in the direction of arrow80and generally away from a front wall or cutting area220of the channel214. The cutting edge76in forming the bone chip218, therefore, moves the bone chip218towards the already formed portion of the channel214.

As illustrated inFIG.9B, the cutting edge76, after forming the bone chip218, is passing into or through the formed portion of the channel214and the trailing edge90trailing as the cutting edge76is engaging the front or forming wall220of the channel214. As discussed above, the trailing edge90can include the distance94from the central axis78that is substantially equivalent or equal to the distance82of the cutting edge76from the central axis78. Therefore, the trailing edge90can engage the wall220at substantially the same distance from the central axis78as the cutting edge76and the forthcoming second cutting edge76a. This an guide and or stabilize the bur64, as discussed further herein, during cutting with the cutting edge76a.

The cutting edge76aincludes a distance82awhich is substantially identical to the distance82from the central axis78. Therefore, the cutting edge76a, prior to cutting the wall220, is generally at substantially the same position as the trailing edge90. Because the radius or distance from the central axis78to the wall220is substantially identical for the trailing edge90and the second cutting edge76a, there is no jump or jerking of the bur64prior to the second cutting edge76ainitiating a cut and formation of the bone chip218. Therefore, the trailing edge90can form or act as a stabilizing edge or surface relative to the wall220of the channel214prior to the second cutting edge76acutting the wall220. Similarly, the second trailing edge90acan act as a stabilizing surface or edge relative to the cutting edge76prior to the cutting edge76cutting the forward wall220of the channel214.

The bur64can rotate by the motor generally at a selected rotational rate, such as about 700 to about 75,000 rpm. As an example, the bur64may rotate at about 7,000 rpm. Therefore, the engaging of the cutting edges76and76aon the forward wall220and the stabilizing by the trailing edges services90,90a, can substantially stabilize the bur64as the bur64forms the channel214.

Returning reference toFIG.9A, the bur64is stabilized during radial cutting, for example when the cutting edge76forms the bone chip218to cut or dissect the bone210. The bur64may experience reduced vibrational and forces and chatter during radial cutting. In one example, the bur64can experience a reduction of vibration by at least about 40%, including a reduction of about 20-40%, including about 42%. Vibration forces may be measured with an accelerator and reported in g-forces using units such as meters/second2.

During operation, the stabilization may occur by the bur64rotating within the channel, the cutting edge76moves away from the front wall220of the channel214. As the cutting edge76moves away from the front wall220, the trailing edge90can engage the wall220prior to the next cutting edge76a. Due to the rotational speed of the bur64, the elapsed time between the cutting edge leaving the wall220and the trailing edge90engaging the wall may be very short, such as on the order of micro-seconds.

The trailing edge90, however, engages the wall220prior to the second cutting edge76abeginning the cut of the front wall and formation of the bone chip218. Therefore, as the cutting edge76abegins to cut the front wall220of the channel214, the bur64may be substantially stabilized relative to the front wall220. This is at least because the trailing edge90is the same or substantially the same distance from the center78as the cutting edge76a.

Further, the trailing edge90can continue to ride along the wall220to stabilize the bur64as the bur64rotates in the direction of arrow80and the cutting edge76acuts and forms bone chips along the wall220. Therefore, the trailing edge may act as a guide that stabilizes the bur64. The trailing edge90stabilizes the bur64as following cutting edge, for example the cutting edge76a, follows the trailing edge90as illustrated inFIG.9B. This assists in stability of the bur64during cutting the channel214.

The contact of the trailing edge90with the front wall substantially simultaneously with the cutting edge76aor immediately prior to may reduce chatter or vibration of the bur64while cutting or dissecting. This can reduce user fatigue during use of the assembly10including the bur64. This can also increase precision of the dissection when using the bur64due to reduced vibration and chatter. Thus, a user may be able to cut longer without a break to decrease time needed for a procedure and to increase precision of a cut. Accordingly, the bur64may also decrease a chance of a mic-cut. It is further understood, as discussed above, that the trailing edge and cutting edge may be any appropriate combination of edges and need not specifically be the ones referred to by reference number above.

In cutting the channel214, various surgical procedures may occur. For example, a bur hole may be formed in a scalp, as illustrated inFIG.1. The bur hole may be used to allow access to the brain dura and brain tissue for various procedures, such as placement of a deep-brain simulation probe, a resection of a tumor, and the like. Further, other procedures may include forming a hole in other cranial tissues, forming a depression or removal of tissue and other bone matter, including long bones and vertebrae, and other appropriate procedures. Regardless of the specific procedure, however, the bur64may cut the channel214and the bone210without substantial vibration due to the positioning of the trailing edge90at substantially the same radial position relative to the central axis78as the cutting edge76a.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Moreover, the design and structure of a surgical bur may be altered from the specific examples provide above, but include a trailing edge that has a distance from a center equal to or substantially equal to a following, such as an immediately following cutting edge. This may allow a substantially smooth and jitter or jump free dissection of tissue, including boney tissue.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.