WO2025212909A1

WO2025212909A1 - Composite bur and methods of using same to remove hard tissue

Info

Publication number: WO2025212909A1
Application number: PCT/US2025/022986
Authority: WO
Inventors: Zachary Kemp; Michael GALLIZZI
Original assignee: Arthrex Inc
Current assignee: Arthrex Inc
Priority date: 2024-04-05
Filing date: 2025-04-03
Publication date: 2025-10-09
Anticipated expiration: 2026-10-05

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 abrasive surfaces. The tip includes a first abrasive surface (130) having a first surface roughness and a second abrasive surface (140) having a second surface roughness The surface roughness of the first and second abrasive surfaces corresponds to average particles sizes of the particles that form the first and second abrasive surfaces. A method of use includes removing a first section of hard tissue with one of the abrasive surfaces and removing a second section of hard tissue with another of the abrasive surfaces without removing the tip from the body.

Description

COMPOSITE 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. 63/575,339, 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 multiple 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 first and second abrasive surfaces, each formed by respective pluralities of particles with different average particles sizes. The different average particles sizes result in a tip with portions that have different surface roughness values, resulting in the tip being 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 a first abrasive surface and a second abrasive surface. The first abrasive surface is formed by first particles having a first average particle size and the second abrasive surface is formed by second particles having a second average particle size that is different from the first average particle size. The surgical bur includes an elongate body with a proximal end and a distal end. The proximal end is opposite the distal end along an axis about which the surgical bur rotates when in use. [0011] The first and second average particle sizes are different, and one of the first and second abrasive surfaces is closer to the distal end than the other of the first and second abrasive surfaces is from the distal end. This enables the user of the surgical bur to remove sections of tissue with the different abrasive surfaces without removing one tool from the surgical site and replacing it with another tool. [0012] 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 comprising a first abrasive surface and a second abrasive surface about an axis. The first section of hard tissue is removed with the first abrasive surface while rotating the elongate body about the axis. According to the method, the second section of hard tissue is removed with the second abrasive working surface while rotating the elongate body about the axis. [0013] 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 first and second abrasive surfaces have different roughness values, which results in different removal rates while maintaining a constant speed. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0014] 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. [0015] Figure 1 is an isometric view of a surgical bur in use during a surgical procedure. [0016] Figure 2 is a side elevation view of a surgical bur with a spherical tip. [0017] Figure 3 is an isometric view of another surgical bur with a spherical tip. [0018] Figure 4 is a side elevation view of another surgical bur with a spherical tip. [0019] Figure 5 is an isometric view of a surgical bur with an ovoid tip. [0020] Figure 6 is an isometric view of a surgical bur with a conical tip. [0021] Figure 7 is an isometric view of a surgical bur with an inverted conical tip. [0022] Figure 8 is an isometric view of a surgical bur with a cylindrical tip. [0023] Figure 9 is an isometric view of a surgical bur with a tapered cylindrical tip. [0024] Figure 10 is an isometric view of a surgical bur with a multi-shape tip. [0025] Figure 11 an isometric view of a surgical bur with a conical tip having a flat distal end. [0026] Figure 12 is an isometric view of a surgical bur with an inverted conical tip having a flat distal end. [0027] Figure 13 is an isometric view of a surgical bur with a dog bone tip. [0028] Figure 14 is an isometric view of a surgical bur with a tip including first, second, and third abrasive surfaces. [0029] Figure 15 is an isometric view of a surgical bur with a tip including a transition zone between first and second abrasive surfaces. [0030] Figure 16 is an isometric view of the surgical bur illustrated in Figure 1 in use during a surgical procedure, with a second abrasive surface of the surgical bur adjacent a first section of hard tissue. [0031] Figure 17 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 16, with the second abrasive surface of the surgical bur removing the first section of hard tissue. [0032] Figure 18 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 17, with a first abrasive surface of the surgical bur adjacent a second section of hard tissue. [0033] Figure 19 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 18, with the first abrasive surface of the surgical bur removing the second section of hard tissue. [0034] Figure 20 is an isometric view of the surgical bur illustrated in Figure 1 in use during a surgical procedure, with a second abrasive surface of the surgical bur adjacent a first section of hard tissue. [0035] Figure 21 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 20, with the second abrasive surface of the surgical bur removing the first section of hard tissue. [0036] Figure 22 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 21, with a first abrasive surface of the surgical bur adjacent a second section of hard tissue. [0037] Figure 23 is an isometric view of the surgical bur in use during the surgical procedure illustrated in Figure 22, with the first abrasive surface of the surgical bur removing the second section of hard tissue. DETAILED DESCRIPTION [0038] 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. [0039] 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. 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. [0040] 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. [0041] In some embodiments the surgical bur includes an elongate body having multiple (e.g., first and second) abrasive surfaces. Each of the multiple abrasive surfaces includes respective particles having a respective average particle size. The elongate body includes proximal and distal ends, opposite one another along an axis of elongation and/or a central axis. The multiple abrasive surfaces may be arranged (e.g., on a tip of the elongate body) such that one of the abrasive surfaces is closer to the distal end and another of the abrasive surfaces is closer to the proximal end. [0042] 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 the first abrasive surface with the first section of hard tissue, and a second section of hard tissue is removed via contact with the second abrasive surface. 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. [0043] 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 first abrasive surface and then continuing/expanding the cutout within the hard tissue with the second 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). [0044] 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 110 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). [0045] Referring to Figures 2 to 15, the surgical bur 110 may include a body 122 that is elongated (e.g., along an axis 124 that is parallel to a first direction D1). The body 122 may include a proximal end 126 and a distal end 128 spaced from (e.g., opposite) one another with respect to the first direction D1 such that the body 122 extends between the proximal end 126 and the distal end 128 (e.g., from the proximal end 126 to the distal end 128). [0046] The surgical bur 110 may include a first abrasive surface 130 with a first surface roughness. The first surface roughness may be between 50 and 150 grit, for example between 80 and 150 grit. In terms of upper limits, the first 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, or less than 90 grit. In terms of lower limits, the first surface roughness may be greater than 80 grit, e.g., greater than 90 grit, greater than 100 grit, greater than 110 grit, greater than 120 grit, greater than 130 grit, or greater than 140 grit. In terms of ranges, the first surface roughness may be between 50 grit and 150 grit, e.g., between 70 grit and 140 grit, between 80 grit and 130 grit, or between 100 grit and 120 grit. [0047] As shown in the illustrated embodiment, the first abrasive surface 130 may be formed by first particles 132 that have a first average size. According to some embodiments, the body 122 includes a substrate 134 that is coated or embedded with the first particles 132. The first particles 132 may be secured to the substrate 134 using methods including but not limited to laser ablation, ion-beam assisted deposition, and radio-frequency plasma deposition. [0048] The surgical bur 110 may include a second abrasive surface 140 with a second surface roughness. The second surface roughness may be between 50 and 150 grit, for example between 50 and 100 grit. In terms of upper limits, the second surface roughness may be less than 100 grit, e.g., less than 90 grit, less than 80 grit, less than 70 grit, or less than 60 grit. In terms of lower limits, the second surface roughness may be greater than 50 grit, e.g., greater than 60 grit, greater than 70 grit, greater than 80 grit, or greater than 90 grit. In terms of ranges, the second surface roughness may be between 50 grit and 150 grit, e.g., between 50 grit and 100 grit, between 55 grit and 90 grit, or between 60 grit and 80 grit. [0049] As shown in the illustrated embodiment, the second abrasive surface 140 may be formed by second particles 142 that have a first average size. According to some embodiments, a portion of the substrate 134 is coated or embedded with the second particles 142. The second particles 142 may be secured to the substrate 134 using methods including but not limited to laser ablation, ion-beam assisted deposition, and radio-frequency plasma deposition. [0050] The first particles 132, the second particles 142, or both the first particles 132 and the second particles 142 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 first particles 132 and the second particles 142 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. [0051] The first surface roughness and the second surface roughness may be different. For example, the first abrasive surface 130 may be finer (i.e., less rough) than the second abrasive surface 140 (i.e., the second abrasive surface 140 may be coarser than the first abrasive surface 130). According to some embodiments, the first average particle size may be less than the second average particle size. [0052] For some embodiments of the surgical bur 110, one of the abrasive surfaces (e.g., the first abrasive surface 130) may have an average particles size between 50 percent and 100 percent of another of the abrasive surfaces (e.g., the second abrasive surface 140). In terms of upper limits, the first average size may be less than 100 percent of the second average size, e.g., less than 90 percent, less than 80 percent, less than 70 percent, or less than 60 percent. In terms of lower limits, the first average size may be greater than 50 percent of the second average size, e.g., greater than 60 percent, greater than 70 percent, greater than 80 percent, or greater than 90 percent. In terms of ranges, the first average size may be between 50 percent and 100 percent of the second average size, e.g., between 60 percent and 90 percent, or between 70 percent and 80. [0053] The different abrasive surfaces of the surgical bur 110 may be arranged separate from one another (e.g., such that there is no overlap between adjacent ones of the different abrasive surfaces) along the body 122. For example, one of the abrasive surfaces (e.g., the first abrasive surface 130) may be positioned closer to the distal end 128 of the body 122 (e.g., forming a first portion or distal portion 150) and another of the abrasive surfaces (e.g., the second abrasive surface 140) may be positioned closer to the proximal end 126 of the body 122 (e.g., forming a second portion or proximal portion 152). [0054] The first abrasive surface 130 may be finer (e.g., less coarse, having a smaller average particles size, etc.) and positioned closer to the distal end 128 than the second abrasive surface 140, which is coarser (e.g., having a larger average particle size) and positioned closer to the proximal end 126, as shown in Figures 2, 3, 5, 6, 9, 10, 12, 13, 14, and 15. Alternatively, the first abrasive surface 130 may be finer and positioned closer to the proximal end 126, while the second abrasive surface 140 is coarser and positioned closer to the distal end 128, as shown in Figures 4, 7, and 8. The relative positions of the first and second abrasive surfaces 130, 140 are independent from the shape of the body 122, as described in greater detail below. Accordingly, embodiments of the disclosure include surgical burs 110 as shown in each of the illustrated embodiments, but with the positions of the first and second abrasive surfaces 130, 140 reversed. [0055] The body 122 of the surgical bur 110 may include a tip 154 and a shaft 156. As shown, the tip 154 may extend distally from the shaft 156 toward the distal end 128 and the shaft 156 may extend proximally away from the tip 154 toward the proximal end 126. The tip 154 may include the different abrasive surfaces (e.g., the first abrasive surface 130 and the second abrasive surface 140). When the distal portion 150 includes the first abrasive surface 130, the second abrasive surface 140 may be positioned between the shaft 156 and the distal end 128. Similarly, when the distal portion 150 includes the second abrasive surface 140, the first abrasive surface 130 may be positioned between the shaft 156 and the distal end 128. [0056] The body 122 may define a body length L1 measured from the proximal end 126 to the distal end 128 along the first direction D1 (e.g., along the axis 124). The tip 154 may define a tip length L2 measured from the shaft 156 to the distal end 128 along the first direction D1, and the shaft 156 may define a shaft length L3 measured from the tip 154 to the proximal end 126 along the first direction D1. Typically, the shaft length L3 is longer than the tip length L2 to enable the tip 154 to be positioned through an incision and/or cannula to reach a surgical site. However, the surgical bur 110 is not limited to such relative lengths, and some embodiments include a greater tip length L2 than shaft length L3. The first abrasive surface 130 may define a length L4, and the second abrasive surface 140 may define a length L5, each measured along the first direction D1. [0057] According to some embodiments, the length L4 of the first abrasive surface 130 may be about equal (e.g., plus or minus less than five percent) to the length L5 of the second abrasive surface 140, as shown in Figures 2, 3, 4, 5, 9, 10, 13, 14, and 15. Alternatively, the length L4 of the first abrasive surface 130 may be different than (e.g., plus or minus greater than five percent) of the length L5 of the second abrasive surface 140. For example, the length L4 of the first abrasive surface 130 may be greater than the length L5 of the second abrasive surface 140, as shown in Figures 6 and 8. The length L4 of the first abrasive surface 130 may also be less than the length L5 of the second abrasive surface 140, as shown in Figures 7, 11, and 12. The relative lengths L4, L5 of the first and second abrasive surfaces 130, 140 are independent from the shape of the body 122, as described in greater detail below. Accordingly, embodiments of the disclosure include surgical burs 110 as shown in each of the illustrated embodiments, but with the relative lengths L4, L5 of the first and second abrasive surfaces 130, 140 reversed and/or equal to one another. [0058] The tip 154 may define an outer perimeter 158 within a longitudinal plane P that is parallel to the axis 124. As shown, the axis 124 may lie entirely within the longitudinal plane P, according to some embodiments. The surgical bur 110 may be symmetric about the longitudinal plane P. The surgical bur 110 may be radially symmetric about the axis 124. The outer perimeter 158 may define a length (e.g., the tip length L2) and a width W1 measured perpendicular to length L2. Both the length L2 and width W1 of the outer perimeter 158 may be measured within the longitudinal plane P. [0059] The first abrasive surface 130 may define a width W2 having a first maximum dimension, and the second abrasive surface 140 may define a width W3 having a second maximum dimension. According to some embodiments, the second maximum dimension of the width W3 may be greater than the first maximum dimension of the width W2, as shown in Figures 6, 7, and 11. According to other embodiments, the second maximum dimension of the width W3 may be less than the first maximum dimension of the width W2, as shown in Figures 10 and 12. Alternatively, the second maximum dimension of the width W3 may be substantially equal to (e.g., plus or minus less than five percent) the first maximum dimension of the width W2, as shown in Figures 2, 3, 4, 5, 8, 9, 13, 14, and 15. [0060] According to some embodiments, the width W1 of the outer perimeter 158 may be tapered, decreasing along the length L2 of the tip 154 in a direction toward the distal end 128, as shown in Figures 6, 9, and 11. For example, the outer perimeter 158 may be substantially conical, or a tapered cylinder. The outer perimeter 158 may be an inversely tapered, increasing along the length L2 of the tip 154 in a direction toward the distal end 128, as shown in Figures 7 and 12. For example, the outer perimeter 158 may be an inverted cone or pear shaped. [0061] According to some embodiments, the width W1 of the outer perimeter 158 may be constant along all or a portion of the length L2 of the tip 154 in a direction toward the distal end 128, as shown in Figures 8, 9, 10, 14, and 15. For example, the outer perimeter 158 may be substantially cylindrical. The outer perimeter 158 may include a double taper (e.g., increasing to a maximum along the length L2 of the tip 154 in a direction toward the distal end 128 and then decreasing from the maximum along the length L2 of the tip 154 along the direction toward the distal end 128), as shown in Figures 2, 3, 4, and 5. For example, the outer perimeter 158 may be substantially spherical or ovoidal. [0062] The outer perimeter 158 may include an inverted double taper (e.g., decreasing to a minimum along the length L2 of the tip 154 in a direction toward the distal end 128 and then increasing from the minimum along the length L2 of the tip 154 along the direction toward the distal end 128), as shown in Figure 13. For example, the outer perimeter 158 may have a dog bone shape. Other shapes of the outer perimeter 158 are included in embodiments of the surgical bur 110. For example, mutli-shapes or combinations of one or more of the outer perimeters 158 above (e.g., a partial sphere and a partial cylinder as shown in Figure 10) may cooperatively form the outer perimeter 158 of the surgical bur 110. [0063] According to some embodiments, the outer perimeter 158 may include a flat surface 160. As shown in Figure 12, the flat surface 160 may form the distal end 128 of the body 122. One of the abrasive surfaces (e.g., the first abrasive surface 130, as shown) may be positioned within the flat surface 160. For example, the first particles 132 may be disposed on the flat surface 160 and the second particles 142 may be disposed on a radial wall 162 that encircles the axis 124. As shown in Figures 7, 8, and 11 the flat surface 160 may include some of the particles of one of the abrasive surfaces, while a remainder of the particles of the one abrasive surface are disposed on the radial wall 162. [0064] As described above, the specific combinations of outer perimeter 158, relative widths W2, W3 of the first and second abrasive surfaces 130, 140 relative lengths L4, L5 of the first and second abrasive surfaces 130, 140, and relative positions of the first and second abrasive surfaces 130, 140 may be independent from each other. Accordingly, embodiments of the disclosure include outer perimeters 158 as shown in each of the illustrated embodiments, but with the relative widths W2, W3, lengths L4, L5, positions, or any combination thereof of the first and second abrasive surfaces 130, 140 reversed or changed to match what is shown for other shapes of the outer perimeter 158. [0065] Although a number of embodiments of the surgical bur 110 have been shown and described as including the first abrasive surface 130 and the second abrasive surface 140, some embodiments of the surgical bur 110 may include additional sections of abrasive and/or smooth, non-abrasive portions. For example, the tip 154 may include a non-abrasive surface 164 positioned between the first abrasive surface 130 and the second abrasive surface 140, as shown in Figure 3. Thus, the non-abrasive surface 164 may be described as an intermediate portion. Embodiments of the surgical bur 110 with other sizes and positions of the non-abrasive surface 164 are included within the present disclosure. [0066] The surgical bur 110 may include an intermediate portion 166 (e.g., positioned between the distal portion 150 and the proximal portion 152. The intermediate portion 166 may include a third abrasive surface 168 (e.g., with a surface roughness between that of the first abrasive surface 130 and the second abrasive surface 140), as shown in Figure 14. According to some embodiments, the intermediate portion 166 may include a transition zone in which the surface roughness gradually changes along the tip length L2 (e.g., from the surface roughness of the first abrasive surface 130 to the surface roughness of the second abrasive surface 140), as shown in Figure 15. [0067] Referring to Figures 1 and 16 to 21, 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 110. According to some embodiments, the body 122 of the surgical bur 110 may be rotated (e.g., about the axis 124). Rotation of the body 122 may include attachment of the surgical bur 110 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 abrasive surfaces of the tip 154 (e.g., the second abrasive surface 140 as shown in Figures 17 and 21), wherein the removing is conducted by rotating the body 122 about the axis 124 and bringing the rotating second abrasive surface 140 into rotating contact with the first section of hard tissue 200. [0068] The method may further include removing the second section of hard tissue 202 with another of the abrasive surfaces of the tip 154 (e.g., the first abrasive surface 130 as shown in Figures 19 and 23). 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 122 about the axis 124 and bringing the rotating first abrasive surface 130 into rotating contact with the second section of hard tissue 202. [0069] 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 finer abrasive surface having a slower removal rate and the coarser abrasive surface having a faster removal rate). The first and second removal rates may be independent from a rotational speed of the surgical bur 110. For example, the surgical bur 110 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. [0070] 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 16 to 19. 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 154 (e.g., and the first and second abrasive surfaces 130, 140) 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 20 to 23. [0071] As part of the method, the first and second abrasive surfaces 130, 140 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 154 (including the first and second abrasive surfaces 130, 140) 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 154 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. [0072] 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 first and second abrasive surfaces 130, 140 through the lumen of the cannula, and positioning the shaft 156 of the body 122 within the lumen. A portion of the shaft 156 may remain within the lumen until both the first and second sections of hard tissue 200, 202 are removed. [0073] 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. [0074] 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. [0075] 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.” [0076] 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 particles with average particles sizes. Such negative limitations are contemplated, and this text serves as support for negative limitations for components, steps, and/or features. [0077] 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: a first abrasive surface comprising first particles having a first average particle size; and a second abrasive surface comprising second particles having a second average particle size, wherein the first average particle size is different than the second average particle size.

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 the first average particle size is less than the second average particle size, and the first abrasive surface is closer to the distal end than the second abrasive surface is from the distal end.

4. The surgical bur of claim 3 wherein the first average particle size is less than 80 percent of the second average particle size.

5. The surgical bur of claim 3 wherein the first abrasive surface has a roughness ranging from 100 to 120 grit and/or the second abrasive surface has a roughness ranging from 60 to 80 grit.

6. The surgical bur of claim 2 wherein the first average particle size is larger than the second average particle size, and the second abrasive surface is closer to the distal end than the first abrasive surface is from the distal end.

7. The surgical bur of claim 6 wherein the second average particle size is less than 80 percent of the first average particle size.

8. The surgical bur of claim 6 wherein the first abrasive surface has a roughness ranging from 60 to 80 grit and/or the second abrasive surface has a roughness ranging from 100 to 120 grit.

9. The surgical bur of any one of claims 2 to 8 wherein the elongate body comprises: a tip comprising the first abrasive surface and the second abrasive surface; and a shaft extending from the tip toward the proximal end of the elongate body.

10. The surgical bur of claim 9 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.

11. The surgical bur of claim 10 wherein the width decreases along the length toward the distal end.

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

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

14. The surgical bur of claim 13 wherein the tip has a substantially inverted conical shape.

15. The surgical bur of claim 10 wherein the width remains constant along the length.

16. The surgical bur of claim 15 wherein the tip has a substantially cylindrical shape.

17. The surgical bur of claim 10 wherein the width increases to a maximum and then decreases along the length toward the distal end.

18. The surgical bur of claim 17 wherein the tip has a substantially spherical shape.

19. The surgical bur of claim 17 wherein the tip has a substantially ovoidal shape.

20. The surgical bur of claim 10 wherein the width decreases to a minimum and then increases along the length toward the distal end.

21. The surgical bur of claim 20 wherein the tip has a dog bone shape.

22. The surgical bur of any one of claims 10 to 21 wherein the tip is symmetric about the longitudinal plane.

23. The surgical bur of any one of claims 10 to 22 wherein the tip is radially symmetric about the central axis.

24. The surgical bur of any one of claims 10 to 23 wherein the first abrasive surface has a first maximum width, the second abrasive surface has a second maximum width, and the second maximum width is greater than the first maximum width.

25. The surgical bur of any one of claims 10 to 23 wherein the first abrasive surface has a first maximum width, the second abrasive surface has a second maximum width, and the first maximum width is greater than the second maximum width.

26. The surgical bur of any one of claims 10 to 23 wherein the first abrasive surface has a first maximum width, the second abrasive surface has a second maximum width, and the first maximum width is substantially equal to the second maximum width.

27. The surgical bur of any one of claims 10 to 26 wherein the first abrasive surface has a first length measured along the central axis, the second abrasive surface has a second length measured along the central axis, and the first length is substantially equal to the second length.

28. The surgical bur of any one of claims 10 to 26 wherein the first abrasive surface defines a first length measured along the central axis, the second abrasive surface defines a second length measured along the central axis, and the first length is less than the second length.

29. The surgical bur of any one of claims 10 to 26 wherein the first abrasive surface defines a first length measured along the central axis, the second abrasive surface defines a second length measured along the central axis, and the first length is greater than the second length.

30. The surgical bur of any one of claims 27 to 29 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.

31. The surgical bur of claim 30 wherein the third length is greater than both the first length and the second length combined.

32. The surgical bur of any one of claims 2 to 9 wherein the first abrasive surface includes a flat surface that is intersected by the central axis and that forms the distal end, and the first particles are disposed on the flat surface.

33. The surgical bur of any one of claims 1 to 32 wherein the elongate body includes an intermediate portion positioned between the first abrasive surface and the second abrasive surface, and the intermediate portion has a surface that is relatively smooth.

34. The surgical bur of any one of claims 1 to 32 wherein the elongate body includes an intermediate portion positioned between the first abrasive surface and the second abrasive surface, and the intermediate portion includes a third abrasive surface that is smoother than one of the first abrasive surface and the second abrasive surface and rougher than the other of the first abrasive surface and the second abrasive surface.

35. The surgical bur of any one of claims 1 to 32 wherein the elongate body includes an intermediate portion positioned between the first abrasive surface and the second abrasive surface, and the intermediate portion includes a transition zone with a surface that has a varying roughness between the first abrasive surface and the second abrasive surface.

36. The surgical bur of any one of claims 1 to 35 wherein the first particles and the second particles include diamond particles.

37. A method of removing tissue comprising first and second sections of hard tissue, the method comprising: rotating an elongate body comprising a first abrasive surface and a second abrasive surface about an axis; removing the first section of hard tissue with the first 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 second abrasive surface.

38. The method of claim 37, 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.

39. The method of any one of claims 37 and 38 wherein the first abrasive surface is formed by a first plurality of particles having a first average size, the second abrasive surface is formed by a second plurality of particles having a second average size, and the first average size is different than the second average size.

40. The method of any one of claims 37 to 39 wherein removing the first section of hard tissue exposes the second section of hard tissue.

41. The method of any one of claims 37 to 39, further comprising: moving the first and second abrasive surfaces from the first section of hard tissue to the second section of hard tissue.

42. The method of any one of claims 37 to 41, further comprising: moving the first and second abrasive surfaces 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.

43. The method of claim 42 wherein the first and second abrasive surfaces remain within the surgical site and are not removed from the body until both the first and second sections of hard tissue are removed.

44. The method of any one of claims 37 to 43, further comprising: moving the first and second abrasive surfaces through a lumen of a cannula; and positioning a shaft of the elongate body within the lumen.

45. The method of claim 44, further comprising: maintaining the shaft within the lumen until both the first and second sections of hard tissue are removed.

46. The method of claim 45 wherein the second abrasive surface is positioned closer to the shaft than the first abrasive surface is from the shaft.

47. The method of any one of claims 37 to 46 wherein the first abrasive surface comprises first particles having a first average particle size and the second abrasive surface comprises second particles having a second average particle size, and wherein the first average particle size is less than the second average particle size.