WO2025212935A1 - Hybrid bur and methods of using same to remove hard tissue - Google Patents

Abstract

Disclosed herein are components, systems, and methods to remove hard tissue from a surgical site within a body through an incision in the body. A surgical bur includes a body having a tip with multiple working surfaces. The tip (354) includes an abrasive surface (330) and a fluted portion (340). The abrasive surface and the fluted portions have different tissue removal rates when brought into rotating contact with hard tissue. A method of use includes removing a first section of hard tissue with the fluted portion and removing a second section of hard tissue with the abrasive surface without removing the tip from the body.

Description

HYBRID BUR AND METHODS OF USING SAME TO REMOVE HARD TISSUE CROSS-REFERENCE TO RELATED APPLICATION [0001] This patent application claims priority of U.S. Patent Application No. 63/575,467, filed on April 5, 2024, the entire disclosure of which is hereby incorporated by reference herein for all purposes. BACKGROUND [0002] This disclosure relates to rotary tissue removal tools and more particularly to surgical burs with cutting portions and abrasive surfaces that remove hard tissue upon contact with the hard tissue while the surgical bur is rotating. [0003] Rotary tissue removal tools are used to remove tissue during surgical procedures. Surgical burs are a known tissue removal tool that includes a shaft that is coupled to a driver that rotates the surgical bur about an axis. The shaft supports a working end that includes features that remove tissue upon rotational contact with the tissue. The shaft is typically long and narrow to facilitate entry of the working end into a body (e.g., through an incision, with or without the assistance of a cannula) and to a surgical site where the tissue to be removed is located. [0004] Known surgical burs include different types of working ends, which provide different tissue removal rates. For example, a working end may include cutting flutes (alternating flutes and cutting edges arranged radially about the central axis of the surgical bur). Other working ends of surgical burs may include an abrasive working surface (typically a substrate coated with a plurality of abrasive particles). [0005] Cutting flutes typically provide faster/more aggressive tissue removal compared to an abrasive surface. Abrasive surfaces, on the other hand, typically provide finer control over which tissue is removed and the amount of tissue that is removed. During a surgical procedure, different surgical burs with different abrasive working surfaces of varying roughness may be used throughout the procedure. [0006] For example, a first surgical bur with a rougher working surface may be used to remove a first section of hard tissue. When approaching sensitive tissue/anatomical structures, the first surgical bur may be removed from the surgical site and replaced with a second surgical bur that has a smoother working surface that is used to remove a second section of hard tissue. The smoother working surface results in the second section of hard tissue being removed more slowly so as to better protect the sensitive tissue/anatomical structures. [0007] Removal of a surgical bur with one type of working end from the surgical site and insertion of another surgical bur with a different type of working end increases the procedures complexity and time necessary for completion. Thus, even in view of conventional techniques and equipment, a need exists for devices that advantageously provide multiple options for tissue removal without the need to remove and insert multiple tools. BRIEF SUMMARY [0008] This disclosure relates to a surgical bur used to remove tissue (e.g., hard tissue) from a surgical site within a body. The surgical bur may be inserted into the body through an incision (with or without the assistance of a cannula forming a stable passage through the incision), and a tip of the surgical bur may be advanced to the surgical site. [0009] The tip includes at least two different working surfaces that provide different rates of tissue removal upon contact with tissue. The different working surfaces may include an abrasive surface formed by a plurality of particles with an average particle size. Additionally, the working surfaces may include a fluted portion including a plurality of cutting edges each separated by grooves. The different working surfaces provide a tip capable of different rates of tissue removal while maintaining a constant rotational speed of the surgical bur (e.g., provided by a driver or other source of rotation). [0010] Some embodiments described herein relate to a surgical bur including an elongate body. The elongate body includes an abrasive surface comprising particles, and further includes a fluted portion that is discrete from the abrasive surface. The fluted portion includes a plurality flutes extending into the elongate body and a plurality of cutting edges each positioned between adjacent ones of the plurality of flutes. [0011] The elongate body includes a proximal end and a distal end spaced from the proximal end along a central axis. The elongate body further includes a tip and a shaft. The tip extends away from the shaft distally and includes both the abrasive surface and the fluted portion. The shaft extends away from the tip and toward the proximal end. One of the abrasive surface and the fluted portion is positioned closer to the distal end and the other of the abrasive surface and the fluted portion is positioned closer to the proximal end. [0012] The different working surfaces being carried by the tip of the surgical bur enables a user of the surgical bur to remove sections of tissue with the different working surfaces without removing one tool from the surgical site and replacing it with another tool. [0013] This disclosure further relates to methods of removing tissue. Some embodiments described herein include a method of removing tissue that includes first and second sections of hard tissue. The method includes rotating an elongate body of a surgical bur about an axis. The elongate body includes an abrasive surface and a fluted portion. The fluted portion includes a plurality of flutes that extend into the elongate body and a plurality of cutting edges positioned between adjacent ones of the flutes. The first section of hard tissue is removed with the fluted portion while rotating the elongate body about the axis. According to the method, the second section of hard tissue is removed with the abrasive surface while rotating the elongate body about the axis. [0014] Some surgical methods include removing the first section of hard tissue at a first removal rate, and removing the second section of hard tissue at a second removal rate while maintaining a constant rotation rate of the elongate body about the axis. The abrasive surfaces and the fluted portion have different cutting power, which results in different removal rates while maintaining a constant rotational speed of the surgical bur. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0015] In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not necessarily intended to convey any information regarding the actual shape of the particular elements and may have been solely selected for ease of recognition in the drawings. The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments. [0016] Figure 1 is an isometric view of a surgical bur in use during a surgical procedure. [0017] Figure 2 is an elevation view of a surgical bur with a cylindrical tip. [0018] Figure 3 is an isometric view of a surgical bur with a tapered cylindrical tip. [0019] Figure 4 is an elevation view of a surgical bur with a spherical tip. [0020] Figure 5 is an isometric view of another surgical bur with a spherical tip. [0021] Figure 6 is an isometric view of a surgical bur with an ovoid tip. [0022] Figure 7 is an isometric view of another surgical bur with an ovoid tip. [0023] Figure 8 is an isometric view of a surgical bur with a conical tip. [0024] Figure 9 is an isometric view of another surgical bur with a conical tip. [0025] Figure 10 is an isometric view of a surgical bur with an inverted conical tip. [0026] Figure 11 an isometric view of another surgical bur with an inverted conical tip. [0027] Figure 12 is an isometric view of the surgical bur illustrated in Figure 1 in use during a surgical procedure, with a fluted portion of the surgical bur adjacent a first section of hard tissue. [0028] Figure 13 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 12, with the fluted portion of the surgical bur removing the first section of hard tissue. [0029] Figure 14 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 13, with an abrasive surface of the surgical bur adjacent a second section of hard tissue. [0030] Figure 15 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 14, with the abrasive surface of the surgical bur removing the second section of hard tissue. [0031] Figure 16 is an isometric view of the surgical bur illustrated in Figure 1 in use during a surgical procedure, with a fluted portion of the surgical bur adjacent a first section of hard tissue. [0032] Figure 17 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 16, with the fluted portion of the surgical bur removing the first section of hard tissue. [0033] Figure 18 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 17, with an abrasive surface of the surgical bur adjacent a second section of hard tissue. [0034] Figure 19 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 18, with the abrasive surface of the surgical bur removing the second section of hard tissue. DETAILED DESCRIPTION [0035] As noted above, during a surgical procedure, a rotary tissue removal tool may be inserted through an opening (e.g., an incision) in a body to provide access to a surgical site within an interior portion of the body. [0036] It has now been found that the disclosed surgical bur with different tissue removal surfaces provides for multiple, synergistic advantages over conventional surgical burs. For example, the disclosed surgical bur remains within the body during removal of tissue with the different tissue removal surfaces. Thus, the surgical bur disclosed herein enables a user to remove different sections of tissue at the surgical site, at different removal rates, with surfaces of different roughness values or cutting power. This saves time otherwise needed to remove and replace one surgical bur with a first tissue removal surface with another surgical bur having a second tissue removal surface. [0037] Immediate availability of the different tissue removal surfaces within the surgical site at the same time provides the user with additional options/flexibility during a procedure. For example, one of the tissue removal surfaces may be better at controlling bleeding during tissue removal. In the event of a bleed, or when potential bleeding is anticipated, the user can switch to the preferred tissue removal surface as needed and then switch back to another tissue removal surface once bleeding is no longer an issue. The use of a surgical bur with multiple, different tissue treatment surfaces also reduces cleanup time and sterilization cost by reducing the number of instruments used during the procedure. [0038] In some embodiments the surgical bur includes an elongate body having multiple tissue removal surfaces/portions. The elongate body includes proximal and distal ends, opposite one another along an axis of elongation and/or a central axis. The multiple tissue removal surfaces/portions may be arranged (e.g., on a tip of the elongate body) such that one of the tissue removal surfaces/portions is closer to the distal end and another of the tissue removal surfaces/portions is closer to the proximal end. [0039] Some methods of use of the surgical bur include rotating the elongate body of the surgical bur about an axis (e.g., the axis of elongation and/or the central axis). While rotating the surgical bur, a first section of hard tissue is removed via contact of a fluted portion with the first section of hard tissue. A second section of hard tissue is removed via contact with an abrasive surface, also while rotating the surgical bur. The first and second sections of hard tissue are removed at different rates (e.g., while maintaining a constant rate of rotation of the elongate body about the axis). The elongate body may be rotated by a driver or other source of rotation. [0040] In some embodiments the method includes removing the first section of hard tissue to expose the second section of hard tissue. Thus, the method may include forming a cutout within hard tissue with the fluted portion and then continuing/expanding the cutout within the hard tissue with the abrasive surface. Other methods include removing separate first and second sections of hard tissue (e.g., within the same surgical site). Thus, the method may include moving the tip of the surgical bur from the first section of hard tissue to the second section of hard tissue between removal of the first and second sections of hard tissue (e.g., thereby forming separate cutouts within hard tissue within the body). [0041] Referring now to the drawings, and specifically to Figure 1, some surgical procedures (e.g., discectomies, laminotomies, laminectomies) involve the insertion of surgical instruments (e.g., rotary tissue removal tools such as a surgical bur 310 supported by a drill/driver 112) through an opening (e.g., an incision 114) of a body 116 to view and/or interact with an interior portion of the body 116 (e.g., at a surgical site 118). The opening may be maintained with a working tube, such as a cannula (not shown), that defines a passageway through the opening, into the interior portion of the body 116, and to the surgical site 118. A cannula holder (not shown) may be used to secure a position of the cannula (e.g., relative to a fixed reference point such as the incision 114 in the body 116 or an operating table upon which the body 116 is supported during the procedure). [0042] Referring to Figures 2 to 11, the surgical bur 310 may include a body 322 that is elongated (e.g., along an axis 324 that is parallel to a first direction D1). The body 322 may include a proximal end 326 and a distal end 328 spaced from (e.g., opposite) one another with respect to the first direction D1 such that the body 322 extends between the proximal end 326 and the distal end 328 (e.g., from the proximal end 326 to the distal end 328). [0043] The surgical bur 310 may include an abrasive surface 330 with a surface roughness. The surface roughness may be between 50 and 150 grit, for example between 60 and 120 grit. In terms of upper limits, the surface roughness may be less than 150 grit, e.g., less than 140 grit, less than 130 grit, less than 120 grit, less than 110 grit, less than 100 grit, less than 90 grit, or less than 80 grit. In terms of lower limits, the first surface roughness may be greater than 50 grit, e.g., greater than 60 grit, greater than 70 grit, greater than 80 grit, greater than 90 grit, greater than 100 grit, or greater than 110 grit. In terms of ranges, the first surface roughness may be between 50 grit and 150 grit, e.g., between 60 grit and 80 grit, between 80 grit and 100 grit, or between 100 grit and 120 grit. [0044] As shown in the illustrated embodiment, the abrasive surface 330 may be formed by particles 332 that have an average size. According to some embodiments, the body 322 includes a substrate 334 that is coated or embedded with the particles 332. The particles 332 may be secured to the substrate 334 using methods including but not limited to laser ablation, ion-beam assisted deposition, and radio-frequency plasma deposition. [0045] The particles 332 may include, but are not limited to, diamond particles (e.g., natural or synthetic diamond particles), diamond-like particles, metallic particles (e.g., steel), compounds (e.g., tungsten carbide), and other known abrasive particles used in rotary tissue cutting/removal tools. The particles 332 may be a material known for use in removing hard tissue upon rotatory contact with the particles. Hard tissue as described herein includes any tissue that is not “soft tissue.” For example, hard tissue includes, but is not limited to bone, enamel, dentin, cementum, and ossified tissue. [0046] The surgical bur 310 may include a fluted portion 340 with a surface roughness or cutting power that is different from that of the abrasive surface 330. As shown in the illustrated embodiment, the fluted portion 340 may include a plurality of cutting edges 342 and a plurality of flutes 344. The flutes 344 may be formed by spiral grooves that extend into the body 322 toward the axis 324. When the surgical bur 310 is rotating (e.g., about the axis 324), contacting hard tissue with the cutting edges 342 removes sections of the hard tissue (e.g., in the form of small particles/chips). [0047] The surface roughness/cutting power of the abrasive surface 330 and the fluted portion 340 may be different. For example, the abrasive surface 330 may be finer (i.e., less rough with a lower cutting power) than the fluted portion 340 (i.e., the fluted portion 340 may have a higher cutting power than the abrasive surface 330). [0048] The different working surfaces/portions of the surgical bur 310 may be arranged separate or discrete from one another (e.g., such that there is no overlap between adjacent ones of the different surfaces/portions) along the body 322. For example, one of the working surfaces/portions (e.g., the abrasive surface 330) may be positioned closer to the distal end 328 of the body 322 (e.g., forming a first portion or distal portion 350) and another of the abrasive surfaces (e.g., the fluted portion 340) may be positioned closer to the proximal end 326 of the body 322 (e.g., forming a second portion or proximal portion 352). [0049] The abrasive surface 330 may be finer (e.g., having a lower cutting power or tissue removal rate) and positioned closer to the distal end 328 than the fluted portion 340, which is coarser (e.g., having a higher cutting power or tissue removal rate) and positioned closer to the proximal end 326, as shown in Figures 2, 3, 7, 9, and 11. Alternatively, the abrasive surface 330 may be positioned closer to the proximal end 326, while the fluted portion 340 is positioned closer to the distal end 328, as shown in Figures 4, 5, 6, 8, and 10. The relative positions of the abrasive surface 330 and the fluted portion 340 are independent from the shape of the body 322, as described in greater detail below. Accordingly, embodiments of the disclosure include surgical burs 310 as shown in each of the illustrated embodiments, but with the positions of the abrasive surface 330 and the fluted portion 340 reversed. [0050] The body 322 of the surgical bur 310 may include a tip 354 and a shaft 356. As shown, the tip 354 may extend distally from the shaft 356 toward the distal end 328 and the shaft 356 may extend proximally away from the tip 354 toward the proximal end 326. The tip 354 may include the different working surfaces/portions (e.g., the abrasive surface 330 and the fluted portion 340). When the distal portion 350 includes the abrasive surface 330, the fluted portion 340 may be positioned between the shaft 356 and the distal end 328. Similarly, when the distal portion 350 includes the fluted portion 340, the abrasive surface 330 may be positioned between the shaft 356 and the distal end 328. [0051] The body 322 may define a body length J1 measured from the proximal end 326 to the distal end 328 along the first direction D1 (e.g., along the axis 324). The tip 354 may define a tip length J2 measured from the shaft 356 to the distal end 328 along the first direction D1, and the shaft 356 may define a shaft length J3 measured from the tip 354 to the proximal end 326 along the first direction D1. Typically, the shaft length J3 is longer than the tip length J2 to enable the tip 354 to be positioned through an incision and/or cannula to reach a surgical site. However, the surgical bur 310 is not limited to such relative lengths, and some embodiments include a greater tip length J2 than shaft length J3. The abrasive surface 330 may define a length J4, and the fluted portion 340 may define a length J5, each measured along the first direction D1. [0052] According to some embodiments, the length J4 of the abrasive surface 330 may be about equal (e.g., plus or minus less than five percent) to the length J5 of the fluted portion 340, as shown in Figures 3, 4, 5, and 10. Alternatively, the length J4 of the abrasive surface 330 may be different than (e.g., plus or minus greater than five percent) of the length J5 of the fluted portion 340. For example, the length J4 of the abrasive surface 330 may be greater than the length J5 of the fluted portion 340, as shown in Figures 6 and 9. The length J4 of the abrasive surface 330 may be less than the length J5 of the fluted portion 340, as shown in Figures 2, 7, 8, and 11. The relative lengths J4, J5 of the abrasive surface 330 and the fluted portion 340 are independent from the shape of the body 322, as described in greater detail below. Accordingly, embodiments of the disclosure include surgical burs 310 as shown in each of the illustrated embodiments, but with the relative lengths J4, J5 of the abrasive surface 330 and the fluted portion 340 reversed and/or equal to one another. [0053] The tip 354 may define an outer perimeter 358 within a longitudinal plane P that is parallel to the axis 324. As shown, the axis 324 may lie entirely within the longitudinal plane P, according to some embodiments. The surgical bur 310 may be symmetric about the longitudinal plane P. The surgical bur 310 may be radially symmetric about the axis 324. The outer perimeter 358 may define a length (e.g., the tip length J2) and a width K1 measured perpendicular to the length J2. Both the length J2 and the width K1 of the outer perimeter 358 may be measured within the longitudinal plane P. [0054] The abrasive surface 330 may define a width K2 having a first maximum dimension, and the fluted portion 340 may define a width K3 having a second maximum dimension. According to some embodiments, the second maximum dimension of the width K3 may be greater than the first maximum dimension of the width K2, as shown in Figures 7, 9, and 10. According to other embodiments, the second maximum dimension of the width K3 may be less than the first maximum dimension of the width K2, as shown in Figures 6 and 8. Alternatively, the second maximum dimension of the width K3 may be substantially equal to (e.g., plus or minus less than five percent) the first maximum dimension of the width K2, as shown in Figures 2, 3, 4, 5, and 11. [0055] According to some embodiments, the width K1 of the outer perimeter 358 may be tapered, decreasing along the length J2 of the tip 354 in a direction toward the distal end 328, as shown in Figures 3, 8, and 9. For example, the outer perimeter 358 may be substantially conical, or a tapered cylinder. The width K1 of the outer perimeter 358 may be an inversely tapered, increasing along the length J2 of the tip 354 in a direction toward the distal end 328, as shown in Figures 10 and 11. For example, the outer perimeter 358 may be an inverted cone or pear shaped. [0056] According to some embodiments, the width K1 of the outer perimeter 358 may be constant along all or a portion of the length J2 of the tip 354 in a direction toward the distal end 328, as shown in Figures 2 and 3. For example, the outer perimeter 358 may be substantially cylindrical. The outer perimeter 358 may include a double taper (e.g., increasing to a maximum along the length J2 of the tip 354 in a direction toward the distal end 328 and then decreasing from the maximum along the length J2 of the tip 354 along the direction toward the distal end 328), as shown in Figures 4, 5, 6, and 7. For example, the outer perimeter 358 may be substantially spherical or ovoidal. [0057] Other shapes of the outer perimeter 358 are included in embodiments of the surgical bur 310. For example, combinations of one or more of the outer perimeters 358 above (e.g., a partial sphere and a partial cylinder) may cooperatively form the outer perimeter 358 of the surgical bur 310. [0058] According to some embodiments, the outer perimeter 358 may include a flat surface 360. As shown in Figures 2, 10, and 11, the flat surface 360 may form the distal end 328 of the body 322. One of the working surfaces/portions (e.g., the abrasive surface 330) may be positioned within the flat surface 360, as shown in Figure 11. For example, the particles 332 may be disposed only on the flat surface 360 and the cutting edges 342 and the flutes 344 may be disposed on a radial wall 362 that encircles the axis 324. The flat surface 360 may include some of the particles 332 of the abrasive surface 330, while a remainder of the particles 332 of the abrasive surface 330 are disposed on the radial wall 362. [0059] As described above, the specific combinations of outer perimeter 358, relative widths K2, K3, relative lengths J4, J5, and relative positions of the abrasive surface 330 and the fluted portion 340 may be independent from each other. Accordingly, embodiments of the disclosure include outer perimeters 358 as shown in each of the illustrated embodiments, but with the relative widths K2, K3, lengths J4, J5, positions, or any combination thereof of the abrasive surface 330 and the fluted portion 340 reversed or changed to match what is shown for other shapes of the outer perimeter 358. [0060] Although a number of embodiments of the surgical bur 310 have been shown and described as including the abrasive surface 330 and the fluted portion 340, some embodiments of the surgical bur 310 may include additional sections of abrasive and/or smooth, non-abrasive portions. For example, the tip 354 may include a non- abrasive surface 364 positioned between the abrasive surface 330 and the fluted portion 340, as shown in Figure 5. Thus, the non-abrasive surface 364 may be described as an intermediate portion. Embodiments of the surgical bur 310 with other sizes and positions of the non-abrasive surface 364 are included within the present disclosure. [0061] Referring to Figures 1 and 12 to 19, a method of removing tissue that includes a first section of hard tissue 200 and a second section of hard tissue 202 may include use of the surgical bur 310. According to some embodiments, the body 322 of the surgical bur 310 may be rotated (e.g., about the axis 324). Rotation of the body 322 may include attachment of the surgical bur 310 to the drill/driver 112 (as shown in Figure 1) or some other source of rotation. The method may include removing the first section of hard tissue 200 with one of the working surfaces/portions of the tip 354 (e.g., the fluted portion 340 as shown in Figures 13 and 17), wherein the removing is conducted by rotating the body 322 about the axis 324 and bringing the rotating fluted portion 340 into rotating contact with the first section of hard tissue 200. [0062] The method may further include removing the second section of hard tissue 202 with another of the working surfaces of the tip 354 (e.g., the abrasive surface 330 as shown in Figures 15 and 19). Similar to removal of the first section of hard tissue 200, removing the second section of hard tissue 202 is conducted by rotating the body 322 about the axis 324 and bringing the rotating abrasive surface 330 into rotating contact with the second section of hard tissue 202. [0063] According to the method, the first section of hard tissue 200 may be removed at a first removal rate, and the second section of hard tissue 202 may be removed at a second removal rate. The first and second removal rates may be different (e.g., with the abrasive surface 330 having a slower removal rate and the fluted portion 340 having a faster removal rate). The first and second removal rates may be independent from a rotational speed of the surgical bur 310. For example, the surgical bur 310 may be rotated at a constant speed while removing the first section of hard tissue 200 at the first removal rate, and removing the second section of hard tissue 202 at the second removal rate. [0064] The first section of hard tissue 200 and the second section of hard tissue 202 may be adjacent portions of the same bone (e.g., a vertebral body). According to some embodiments of the method, removing the first section of hard tissue 200 exposes the second section of hard tissue 202, as shown in Figures 12 to 15. During some surgical procedures, the first section of hard tissue 200 and the second section of hard tissue 202 may be separate portions of the same bone (e.g., a vertebral body) or different bones (e.g., adjacent vertebral bodies). Accordingly, the method may include moving the tip 354 (e.g., and the abrasive surface 330 and the fluted portion 340) from a first location that includes the first section of hard tissue 200 to a second location that includes the second section of hard tissue 202, as shown in Figures 16 to 19. [0065] As part of the method, the abrasive surface 330 and the fluted portion 340 may be moved through the incision 114 and into the body 116 before being advanced to a surgical site 118 that includes both the first section of hard tissue 200 and the second section of hard tissue 202. According to some embodiments of the method, the tip 354 (including the abrasive surface 330 and the fluted portion 340) remains within the body 116 (e.g., at the surgical site 118) until both the first section of hard tissue 200 and the second section of hard tissue 202 are removed. In other words, the tip 354 is not removed from the body 116 (e.g., is not withdrawn through the incision 114) until both the first section of hard tissue 200 and the second section of hard tissue 202 are removed. [0066] A cannula may be used as part of the method to maintain a rigid passageway through the incision 114 (e.g., formed by a lumen of the cannula). The method may include moving the abrasive surface 330 and the fluted portion 340 through the lumen of the cannula, and positioning the shaft 356 of the body 322 within the lumen. A portion of the shaft 356 may remain within the lumen until both the first and second sections of hard tissue 200, 202 are removed. [0067] The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments of and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art. The various embodiments described above can be combined to provide further embodiments. [0068] The methods described herein can be performed with variations. For example, many of the methods may include additional acts, omit some acts, and/or perform acts in a different order than as illustrated or described. [0069] As used herein, “greater than” and “less than” limits may also include the number associated therewith. Stated another way, “greater than” and “less than” may be interpreted as “greater than or equal to” and “less than or equal to.” It is contemplated that this language may be subsequently modified in the claims to include “or equal to.” For example, “greater than 50 percent” may be interpreted as, and subsequently modified in the claims as “greater than or equal to 50 percent.” [0070] In some embodiments, any or some of the components or steps disclosed herein may be considered optional. In some cases, the disclosed compositions may expressly exclude any or some of the aforementioned elements or steps in this description, e.g., via claim language. For example, claim language may be modified to recite that the disclosed surgical burs and/or methods, etc., do not utilize or comprise a flat surface that forms the distal end of the surgical bur. Such negative limitations are contemplated, and this text serves as support for negative limitations for components, steps, and/or features. [0071] These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims

CLAIMS 1. A surgical bur comprising: an elongate body comprising: an abrasive surface comprising particles; and a fluted portion having a plurality of flutes extending into the elongate body and a plurality of cutting edges each positioned between adjacent ones of the plurality of flutes, wherein the abrasive surface is discrete from the fluted portion.

2. The surgical bur of claim 1 wherein the elongate body comprises a proximal end and a distal end spaced from the proximal end along a central axis.

3. The surgical bur of claim 2 wherein one of the abrasive surface and the fluted portion is positioned closer to the distal end and the other of the abrasive surface and the fluted portion is positioned closer to the proximal end.

4. The surgical bur of claim 3 wherein the abrasive surface is closer to the distal end than the fluted portion is from the distal end.

5. The surgical bur of claim 3 wherein the fluted portion is closer to the distal end than the abrasive surface is from the distal end.

6. The surgical bur of any one of claims 2 to 5 wherein the elongate body comprises: a tip comprising the abrasive surface and the fluted portion; and a shaft extending from the tip toward the proximal end.

7. The surgical bur of claim 6 wherein: the elongate body has a length measured from the proximal end to the distal end parallel to the central axis; the tip has an outer perimeter within a longitudinal plane that is parallel to the central axis; and the outer perimeter has a width measured within the longitudinal plane perpendicular to the central axis.

8. The surgical bur of claim 7 wherein the width decreases along the length toward the distal end.

9. The surgical bur of claim 8 wherein the tip has a substantially conical shape.

10. The surgical bur of claim 7 wherein the width increases along the length toward the distal end.

11. The surgical bur of claim 10 wherein the tip has a substantially inverted conical shape.

12. The surgical bur of claim 7 wherein the width remains constant along the length.

13. The surgical bur of claim 12 wherein the tip has a substantially cylindrical shape.

14. The surgical bur of claim 7 wherein the width increases to a maximum and then decreases along the length toward the distal end.

15. The surgical bur of claim 14 wherein the tip has a substantially spherical shape.

16. The surgical bur of claim 14 wherein the tip has a substantially ovoidal shape.

17. The surgical bur of claim 7 wherein the width decreases to a minimum and then increases along the length toward the distal end.

18. The surgical bur of claim 17 wherein the tip has a dog bone shape.

19. The surgical bur of any one of claims 7 to 18 wherein the tip is symmetric about the longitudinal plane.

20. The surgical bur of any one of claims 7 to 19 wherein the tip is radially symmetric about the central axis.

21. The surgical bur of any one of claims 7 to 20 wherein the abrasive surface has a first maximum width, the fluted portion has a second maximum width, and the second maximum width is greater than the first maximum width.

22. The surgical bur of any one of claims 7 to 20 wherein the abrasive surface has a first maximum width, the fluted portion has a second maximum width, and the first maximum width is greater than the second maximum width.

23. The surgical bur of any one of claims 7 to 20 wherein the abrasive surface has a first maximum width, the fluted portion has a second maximum width, and the first maximum width is substantially equal to the second maximum width.

24. The surgical bur of any one of claims 7 to 23 wherein the abrasive surface has a first length measured along the central axis, the fluted portion has a second length measured along the central axis, and the first length is substantially equal to the second length.

25. The surgical bur of any one of claims 7 to 23 wherein the abrasive surface has a first length measured along the central axis, the fluted portion has a second length measured along the central axis, and the first length is less than the second length.

26. The surgical bur of any one of claims 7 to 23 wherein the abrasive surface has a first length measured along the central axis, the fluted portion has a second length measured along the central axis, and the first length is greater than the second length.

27. The surgical bur of any one of claims 24 to 26 wherein the shaft defines a third length measured along the central axis, and the third length is greater than both the first length and the second length.

28. The surgical bur of claim 27 wherein the third length is greater than both the first length and the second length combined.

29. The surgical bur of any one of claims 2 to 6 wherein the abrasive surface includes a flat surface that is intersected by the central axis and that forms the distal end, and the particles of the abrasive surface are disposed on the flat surface.

30. The surgical bur of any one of claims 1 to 29 wherein the elongate body includes an intermediate surface positioned between the abrasive surface and the fluted portion, the intermediate surface being relatively flat and devoid of abrasive particles.

31. The surgical bur of any one of claims 1 to 30 wherein the particles of the abrasive surface include diamond particles.

32. The surgical bur of any one of claims 1 to 31 wherein the abrasive surface has a roughness ranging from 60 to 120 grit.

33. A method of removing tissue comprising first and second sections of hard tissue, the method comprising: rotating an elongate body comprising an abrasive surface and a fluted portion about an axis, the fluted portion including a plurality of flutes extending into the elongate body and a plurality of cutting edges each positioned between adjacent ones of the plurality of flutes; removing the first section of hard tissue with the abrasive surface, wherein the removing is conducted by rotating the elongate body about the axis; and removing the second section of hard tissue with the fluted portion, wherein the removing is conducted by rotating the elongate body about the axis.

34. The method of claim 33, further comprising: removing the first section of hard tissue at a first removal rate; removing the second section of hard tissue at a second removal rate; and maintaining a constant rotation rate of the elongate body about the axis while removing both the first and second sections of hard tissue.

35. The method of any one of claims 33 and 34 wherein removing the first section of hard tissue exposes the second section of hard tissue.

36. The method of any one of claims 33 and 34, further comprising: moving the abrasive surface and the fluted portion from the first section of hard tissue to the second section of hard tissue.

37. The method of any one of claims 32 to 36, further comprising: moving the abrasive surface and the fluted portion through an incision in a body and to a surgical site including both the first section of hard tissue and the second section of hard tissue.

38. The method of claim 37 wherein the abrasive surface and the fluted portion both remain within the surgical site and are not removed from the body until both the first and second sections of hard tissue are removed.

39. The method of any one of claims 32 to 38, further comprising: moving the abrasive surface and the fluted portion through a lumen of a cannula; and positioning a shaft of the elongate body within the lumen.

40. The method of claim 39, further comprising: maintaining the shaft within the lumen until both the first and second sections of hard tissue are removed.

41. The method of claim 40 wherein the fluted portion is positioned closer to the shaft than the abrasive surface is from the shaft.

42. The method of any one of claims 32 to 41 wherein the abrasive surface has a surface roughness of between 60 and 120 grit.