US20220249131A1 - Fastening devices, systems, and methods - Google Patents

Abstract

A method of preventing bone blowout may include forming a hole in a bone, the hole having a bone hole diameter, and inserting a bone fastener into the hole. The bone fastener may include a shaft having a minor diameter and a helical thread. The helical thread may be disposed about the shaft and may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The minor diameter of the shaft may not be greater than 5% larger the bone hole diameter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/147,640 filed on Feb. 9, 2021, entitled “FASTENING DEVICES, SYSTEMS, AND METHODS”. The foregoing document is hereby incorporated by reference in its entirety.
TECHNICAL FIELD
• The present disclosure relates to fastening devices, systems, and methods. More specifically, the present disclosure relates to fastening devices with improved thread designs and fastening systems/methods utilizing fastening devices with improved thread designs.
BACKGROUND
• Surgical procedures involving fasteners implanted within bone and other tissues can become lose over time due to multi-axial forces and off-axis loading scenarios that may be applied to the fastener during the healing process. Traditional fastener thread designs may not provide sufficient fastener fixation to overcome these multi-axial forces and off-axis loading scenarios.
• Accordingly, fasteners with improved thread designs for increasing bone fixation and load sharing between a bone/fastener interface experiencing multi-axial and off-loading conditions would be desirable.
SUMMARY
• The various fastening devices, systems, and methods of the present disclosure have been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available fastening devices, systems, and methods. In some embodiments, the fastening devices, systems, and methods of the present disclosure may provide improved bone fixation and load sharing between a bone/fastener interface under multi-axial and off-loading conditions.
• In some embodiments, a pedicle bone fastener may include a shaft and a helical thread. The shaft may have a proximal end, a distal end, a longitudinal axis, and a minor diameter. The helical thread may be disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft. The helical thread may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft, and the minor diameter of the shaft may be constant.
• In some embodiments, the attachment feature may be coupled to the proximal end of the shaft and configured to be secured to an implement.
• In some embodiments, the attachment feature may include a polyaxial head having a first semi-spherical surface.
• In some embodiments, the implement may include a discrete tulip having a second semi-spherical surface configured to engage the first semi-spherical surface of the polyaxial head to secure the discrete tulip to the polyaxial head at any of a variety of relative orientations.
• In some embodiments, the discrete tulip may include at least one opening and a locking member configured to secure a rod received through the at least one opening to the discrete tulip.
• In some embodiments, the attachment feature may include an integrated tulip having at least one opening configured to receive at least a part of the implement therethrough.
• In some embodiments, the implement may include a rod receivable through the at least one opening of the integrated tulip and the integrated tulip may include a locking member configured to secure the rod to the integrated tulip.
• In some embodiments, a method of preventing bone blowout may include forming a hole in a bone, the hole having a bone hole diameter, and inserting a bone fastener into the hole. The bone fastener may include a shaft and a helical thread. The shaft may have a proximal end, a distal end, a longitudinal axis, and a minor diameter. The helical thread may be disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft. The helical thread may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft. The second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft, and the minor diameter of the shaft may not be greater than 5% larger the bone hole diameter.
• In some embodiments, the minor diameter of the shaft may be greater than the bone hole diameter.
• In some embodiments, the minor diameter of the shaft may be equal to the bone hole diameter.
• In some embodiments, the minor diameter of the shaft may be less than the bone hole diameter.
• In some embodiments, the minor diameter of the shaft may be at least 0.1 mm less than the bone hole diameter.
• In some embodiments, the minor diameter of the shaft may be at least 0.2 mm less than the bone hole diameter.
• In some embodiments, the minor diameter of the shaft may be constant.
• In some embodiments, a bone fastener may include a shaft and a helical thread. The shaft may have a proximal end, a distal end, a longitudinal axis, and a minor diameter. The helical thread may be disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft and defining a major diameter of the bone fastener. The helical thread may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft. The second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft, and a ratio of the major diameter to the minor diameter may be less than 1.50.
• In some embodiments, the ratio of the major diameter to the minor diameter may be less than 1.25.
• In some embodiments, the ratio of the major diameter to the minor diameter may be less than 1.10.
• In some embodiments, the ratio of the major diameter to the minor diameter may be less than 1.05.
• In some embodiments, at least a portion of the shaft may be configured to be received with an intramedullary canal of a bone.
• In some embodiments, the bone fastener may also include an attachment feature at the proximal end of the shaft configured to be adjustably secured to an implement.
• These and other features and advantages of the present disclosure will become more fully apparent from the following description and appended claims or may be learned by the practice of the devices, systems, and methods set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
• Exemplary embodiments of the present disclosure will become more fully apparent from the following description taken in conjunction with the accompanying drawings. Understanding that these drawings depict only exemplary embodiments and are, therefore, not to be considered limiting of the scope of the present disclosure, the exemplary embodiments of the present disclosure will be described with additional specificity and detail through use of the accompanying drawings in which:
• FIG. 1A illustrates a front perspective view of a fastener, according to an embodiment of the present disclosure;FIG. 1B illustrates a rear perspective view of the fastener ofFIG. 1A;
• FIG. 1C illustrates a side view of the fastener ofFIG. 1A;FIG. 1D illustrates a cross-sectional side view of the fastener ofFIG. 1A taken along the line A-A shown inFIG. 1C;
• FIG. 2A illustrates a front perspective view of a fastener, according to another embodiment of the present disclosure;FIG. 2B illustrates a rear perspective view of the fastener ofFIG. 2A;FIG. 2C illustrates a side view of the fastener ofFIG. 2A;FIG. 2D illustrates a cross-sectional side view of the fastener ofFIG. 2A taken along the line B-B shown inFIG. 2C;
• FIG. 3 illustrates a partial cross-sectional side view of a fastener comprising crescent-shaped threading;
• FIG. 4A illustrates a front perspective view of a fastener, according to another embodiment of the present disclosure;FIG. 4B illustrates a rear perspective view of the fastener ofFIG. 4A;FIG. 4C illustrates a side view of the fastener ofFIG. 4A;FIG. 4D illustrates a cross-sectional side view of the fastener ofFIG. 4A taken along the line D-D shown inFIG. 4C;
• FIG. 5A illustrates a front perspective view of a fastener, according to another embodiment of the present disclosure;FIG. 5B illustrates a rear perspective view of the fastener ofFIG. 5A;FIG. 5C illustrates a side view of the fastener ofFIG. 5A;FIG. 5D illustrates a cross-sectional side view of the fastener ofFIG. 5A taken along the line E-E shown inFIG. 5C;
• FIG. 6A illustrates a front perspective view of a fastener, according to another embodiment of the present disclosure;FIG. 6B illustrates a rear perspective view of the fastener ofFIG. 6A;FIG. 6C illustrates a side view of the fastener ofFIG. 6A;FIG. 6D illustrates a cross-sectional side view of the fastener ofFIG. 6A taken along the line F-F shown inFIG. 6C;
• FIG. 7A illustrates a front perspective view of a fastener, according to another embodiment of the present disclosure;FIG. 7B illustrates a rear perspective view of the fastener ofFIG. 7A;FIG. 7C illustrates a side view of the fastener ofFIG. 7A;FIG. 7D illustrates a cross-sectional side view of the fastener ofFIG. 7A taken along the line G-G shown inFIG. 7C;
• FIG. 8A illustrates a front perspective view of a fastener, according to another embodiment of the present disclosure;FIG. 8B illustrates a rear perspective view of the fastener ofFIG. 8A;
• FIG. 9A illustrates an exploded view of a pedicle fastener stabilization system, according to an embodiment of the present disclosure;FIG. 9B illustrates the pedicle fastener stabilization system ofFIG. 9A assembled together with a spinal stabilization rod;FIG. 9C illustrates a top perspective view of the discrete tulip shown inFIG. 9A;FIG. 9D illustrates a bottom perspective view of the discrete tulip;FIG. 9E illustrates a side view of the discrete tulip;FIG. 9F illustrates a cross-sectional side view of the discrete tulip taken along the line H-H shown inFIG. 9E;
• FIG. 10A illustrates a top view of a vertebral body with the pedicle fastener stabilization system ofFIG. 9A inserted into pedicles of the vertebral body;FIG. 10B illustrates a cross-sectional side view ofFIG. 10A;
• FIG. 11A illustrates a front perspective view of a threaded stem, according to an embodiment of the present disclosure;FIG. 11B illustrates a rear perspective view of the threaded stem ofFIG. 11A;FIG. 11C illustrates a side view of the fastener ofFIG. 11A;FIG. 11D illustrates a cross-sectional side view of the fastener ofFIG. 11A taken along the line I-I shown inFIG. 11C;
• FIG. 12A illustrates a front perspective view of a threaded stem, according to another embodiment of the present disclosure;FIG. 12B illustrates a rear perspective view of the threaded stem ofFIG. 12A;FIG. 12C illustrates a side view of the fastener ofFIG. 12A;FIG. 12D illustrates a cross-sectional side view of the fastener ofFIG. 12A taken along the line J-J shown inFIG. 12C;FIG. 12E illustrates a perspective side view of the threaded stem ofFIG. 12A coupled to an implant;FIG. 12F illustrates a system comprising the threaded stem ofFIG. 12A;
• FIG. 13A illustrates a front perspective view of a threaded stem, according to another embodiment of the present disclosure;FIG. 13B illustrates a rear perspective view of the threaded stem ofFIG. 13A;FIG. 13C illustrates a side view of the fastener ofFIG. 13A;FIG. 13D illustrates a cross-sectional side view of the fastener ofFIG. 13A taken along the line K-K shown inFIG. 13C;
• FIG. 14A illustrates a front perspective view of a threaded stem, according to another embodiment of the present disclosure;FIG. 14B illustrates a rear perspective view of the threaded stem ofFIG. 14A;FIG. 14C illustrates a side view of the fastener ofFIG. 14A;FIG. 14D illustrates a cross-sectional side view of the fastener ofFIG. 14A taken along the line L-L shown inFIG. 14C;FIG. 14E illustrates a front perspective view of a radial head component, according to an embodiment of the present disclosure;FIG. 14F illustrates a rear perspective view of the radial head component ofFIG. 14E;FIG. 14G illustrates a side view of the radial head component ofFIG. 14E;FIG. 14H illustrates a bottom view of the radial head component ofFIG. 14E; andFIG. 14I illustrates an assembly comprising the threaded stem ofFIG. 14A and the radial head component ofFIG. 14E.
• It is to be understood that the drawings are for purposes of illustrating the concepts of the present disclosure and may not be drawn to scale. Furthermore, the drawings illustrate exemplary embodiments and do not represent limitations to the scope of the present disclosure.
DETAILED DESCRIPTION
• Exemplary embodiments of the present disclosure will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present disclosure, as generally described and illustrated in the drawings, could be arranged, and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the implants, systems, and methods, as represented in the drawings, is not intended to limit the scope of the present disclosure but is merely representative of exemplary embodiments of the present disclosure.
• The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
• The following disclosure presents various fasteners for utilization in bone and other tissues as implantable devices (e.g., orthopedic implants, spine implants, etc.) for the purpose of streamlining the present disclosure. However, it will be understood that the various fasteners and helical threading concepts presented herein can be utilized in any medium beyond bones/tissues and/or for any application beyond surgical procedures.
• Example applications/procedures that may utilize any of the fasteners described or contemplated herein, in any configuration and with any of the features described herein, may include, but are not limited to: spine procedures (e.g., SI fusion, facet fixation, etc.), extremity procedures, reconstruction procedures, trauma procedures, sports related procedures, bone fixation procedures, bone fusion procedures, joint arthroplasty procedures, veterinary procedures, procedures involving osteoporotic or compromised bone, etc.
• Moreover, fastener types that may utilize any of the thread designs, morphology, and/or features described herein may include, but are not limited to pedicle fasteners, cervical fasteners, threaded stems, threaded intramedullary canal stems, cortical fasteners, soft tissue fasteners, long fasteners, cannulated fasteners, joint stems, revision fasteners, compression fasteners (e.g., hip compression fasteners, etc.), veterinary fasteners, etc.
• FIGS. 1A-1D illustrate various views of afastener100, implantable bone anchor, or bone screw, according to one embodiment of the present disclosure. Specifically,FIG. 1A is a front perspective view of thefastener100,FIG. 1B is a rear perspective view of thefastener100,FIG. 1C is a side view of thefastener100, andFIG. 1D is a cross-sectional side view of thefastener100 taken along the line A-A inFIG. 1C.
• In general, thefastener100 may include ashaft105 having aproximal end101, adistal end102, and alongitudinal axis103. Thefastener100 may also include ahead104 located at theproximal end101 of theshaft105, atorque connection interface106 formed in/on the head104 (in either a male/female configuration), and a self-tappingfeature107 formed in thedistal end102 of theshaft105.
• In some embodiments, thefastener100 may include a firsthelical thread110 disposed about theshaft105, and a secondhelical thread120 disposed about theshaft105 adjacent the firsthelical thread110.
• In some embodiments, thefastener100 may include a “dual start” or “dual lead” thread configuration comprising the firsthelical thread110 and the secondhelical thread120.
• In some embodiments, a depth of the firsthelical thread110 and/or the secondhelical thread120 with respect to theshaft105 may define a major diameter vs. a minor diameter of theshaft105 alone.
• In some embodiments, a major diameter and/or a minor diameter of thefastener100 may be constant or substantially constant along the entire length of the fastener, or along a majority of the length of the fastener. In these embodiments, a constant minor diameter may help avoid blowout of narrow/delicate bones (e.g., a pedicle) when inserting a fastener into a bone. In some embodiments, a pilot hole may first be drilled into a narrow/delicate bone and then a fastener having a similar minor diameter in comparison to the diameter of the pilot hole may be chosen to avoid blowout when inserting the fastener into the bone, as will be discussed in more detail below.
• In some embodiments, a depth of the firsthelical thread110 and/or the secondhelical thread120 with respect to theshaft105 may vary along a length of theshaft105 to define one or more major diameters of thefastener100 and/or one or more regions along thefastener100 may comprise a one or more continuously variable major diameters.
• In some embodiments, a thickness of theshaft105 may vary along a length of theshaft105 to define one or more minor diameters of thefastener100, and/or one or more regions along thefastener100 may comprise one or more continuously variable minor diameters. In some embodiments, a thickness/height/width/length/pitch/shape, etc., of the firsthelical thread110 and/or the second helical thread120 (or any additional helical thread) may vary along a length of theshaft105. For example, a thickness/height/width/length/pitch/shape, etc., of the firsthelical thread110 and/or the secondhelical thread120 may be greater towards the tip of the fastener and thinner towards the head of the fastener (or vice versa) in either a discrete or continuously variable fashion, etc.
• In some embodiments, the major and/or minor diameters may increase toward a proximal end or head of a fastener in order to increase bone compaction as the fastener is terminally inserted into the bone/tissue.
• In some embodiments, a pitch of the firsthelical thread110 and/or the secondhelical thread120 may vary along a length of thefastener100.
• In some embodiments, thefastener100 may include a plurality of helical threads disposed about theshaft105. However, it will also be understood that any of the fasteners disclosed or contemplated herein may include a single helical thread disposed about the shaft of the fastener. Moreover, thefastener100 may comprise a nested plurality of helical threads having different lengths (not shown). As one non-limiting example, thefastener100 may include a firsthelical thread110 that is longer than a secondhelical thread120, such that thefastener100 comprises dual threading along a first portion of theshaft105 and single threading along a second portion of theshaft105.
• In some embodiments, the plurality of helical threads may include three helical threads (not shown) comprising a “triple start” or “triple lead” thread configuration (not shown).
• In some embodiments, the plurality of helical threads may include four helical threads (not shown) comprising a “quadruple start” or “quadruple lead” thread configuration (not shown).
• In some embodiments, the plurality of helical threads may include more than four helical threads (not shown).
• In some embodiments, thefastener100 may include first threading with any of the shapes disclosed herein oriented toward one of the proximal end and the distal end of thefastener100, with the first threading located proximate the distal end of thefastener100, as well as second threading with any of the shapes disclosed herein oriented toward the other one of the proximal end and the distal end of thefastener100, with the second threading located proximate the head of the fastener100 (not shown).
• In some embodiments, thefastener100 may include multiple threading (e.g., dual helical threading, etc.) with any of the shapes disclosed herein located proximate one of the proximal end and the distal end of thefastener100, as well as single threading with any of the shapes disclosed herein with the second threading located proximate the other of the proximal end and the distal end of the fastener100 (not shown).
• In some embodiments, the firsthelical thread110 may include a plurality of first concave undercutsurfaces131 and a plurality of first convex undercut surfaces141.
• In some embodiments, the secondhelical thread120 may include a plurality of second concave undercutsurfaces132 and a plurality of second convex undercut surfaces142.
• In some embodiments, when thefastener100 is viewed in section along a plane that intersects thelongitudinal axis103 of the shaft105 (seeFIG. 1D), the plurality of first concave undercutsurfaces131 and the plurality of second convex undercutsurfaces142 may be oriented toward (i.e., point toward) theproximal end101 of theshaft105.
• In some embodiments, the plurality of first convex undercutsurfaces141 and the plurality of second concave undercutsurfaces132 may be oriented toward (i.e., point toward) thedistal end102 of theshaft105.
• In some embodiments, at least one of the plurality of first concave undercutsurfaces131, the plurality of first convex undercutsurfaces141, the plurality of second concave undercutsurfaces132, and the plurality of second convex undercutsurfaces142 may comprise at least one substantially flat surface.
• In some embodiments, when thefastener100 is viewed in section along a plane intersecting thelongitudinal axis103 of theshaft105, the firsthelical thread110 may comprise a plurality of first bent shapes (comprising at least one surface that is angled relative to thelongitudinal axis103 of theshaft105 and/or at least one undercut surface) with a plurality of firstintermediate portions151 that are oriented toward (i.e., point toward) thedistal end102 of theshaft105. This may be referred to as “standard” threading, having a “standard” orientation.
• In some embodiments, when thefastener100 is viewed in section along a plane intersecting thelongitudinal axis103 of theshaft105, the secondhelical thread120 may comprise a plurality of second bent shapes (comprising at least one surface that is angled relative to thelongitudinal axis103 of theshaft105 and/or at least one undercut surface) with a plurality of secondintermediate portions152 that are oriented toward (i.e., point toward) theproximal end101 of theshaft105. This may be referred to as “inverted” threading, having an “inverted” orientation.
• In some embodiments, one or more helical threads may morph/transition between a standard orientation and an inverted orientation along a shaft of a fastener.
• In some embodiments, at least one of the plurality of first concave undercutsurfaces131, the plurality of first convex undercutsurfaces141, the plurality of second concave undercutsurfaces132, and the plurality of second convex undercutsurfaces142 may comprise at least one curved surface.
• As shown inFIG. 1D, the proximally-oriented and distally-oriented surfaces of the first helical thread110 (i.e., the first concave undercutsurfaces131 and the first convex undercutsurfaces141 in thefastener100 ofFIG. 1D) may not have mirror symmetry relative to each other about any plane perpendicular to thelongitudinal axis103 of thefastener100. Rather, the first concave undercutsurfaces131 and the first convex undercutsurfaces141 may be generally parallel to each other. The same may be true for the secondhelical thread120, in which the second concave undercutsurfaces132 and the second convex undercutsurfaces142 may not have mirror symmetry relative to each other but may be generally parallel to each other.
• Conversely, as also shown inFIG. 1D, the proximally-oriented surfaces of the firsthelical thread110 may have mirror symmetry relative to the distally-oriented surfaces of the secondhelical thread120. Specifically, the first concave undercutsurfaces131 may have mirror symmetry relative to the second convex undercutsurfaces142 about aplane170 that bisects the space between them and lies perpendicular to thelongitudinal axis103.
• Similarly, the distally-oriented surfaces of the firsthelical thread110 may have mirror symmetry relative to the proximally-oriented surfaces of the secondhelical thread120. Specifically, the second concave undercutsurfaces132 may have mirror symmetry relative to the first convex undercutsurfaces141 about aplane172 that bisects the space between them and lies perpendicular to thelongitudinal axis103.
• This mirror symmetry may be present along most of the length of the firsthelical thread110 and the secondhelical thread120, with symmetry across different planes arranged between adjacent turns of the firsthelical thread110 and the secondhelical thread120 along the length of thelongitudinal axis103. Such mirror symmetry may help more effectively capture bone between the firsthelical thread110 and the secondhelical thread120 and may also facilitate manufacture of thefastener100.
• In some embodiments, when thefastener100 is viewed in section along a plane intersecting thelongitudinal axis103 of theshaft105, the firsthelical thread110 may include at least one partial crescent shape that is oriented toward (i.e., points toward) thedistal end102 of theshaft105 and/or theproximal end101 of theshaft105.FIG. 3 illustrates a partial cross-sectional view of afastener300 comprising crescent shapes, as one non-limiting example of such an embodiment.
• In some embodiments (not shown), when thefastener100 is viewed in section along a plane intersecting thelongitudinal axis103 of theshaft105, the firsthelical thread110 may include at least one partial crescent shape that is oriented toward (i.e., points toward) thedistal end102 of theshaft105, and the secondhelical thread120 may include at least one partial crescent shape that is oriented toward (i.e., points toward) theproximal end101 of theshaft105.
• In some embodiments (not shown), the firsthelical thread110 may include a first plurality of partial crescent shapes that are oriented toward (i.e., point toward) thedistal end102 of theshaft105, and the secondhelical thread120 may include a second plurality of partial crescent shapes that are oriented toward (i.e., point toward) theproximal end101 of theshaft105.
• In some embodiments (not shown), the first plurality of partial crescent shapes and the second plurality of partial crescent shapes may be arranged in alternating succession along theshaft105 of thefastener100.
• In some embodiments, the firsthelical thread110 may be bisected by theline123 shown inFIG. 3 with each crescent shape including a plurality of firstundercut surfaces111, a plurality of secondundercut surfaces112, a plurality of thirdundercut surfaces113, and a plurality of fourthopen surfaces114 similar to the helical threading shown inFIG. 1D, except with curved surfaces in place of flat surfaces.
• In some embodiments, the plurality of firstundercut surfaces111 and the plurality of secondundercut surfaces112 may comprise concave curved surfaces. However, it will be understood that portions of the plurality of firstundercut surfaces111 and/or portions of the plurality of secondundercut surfaces112 may also comprise convex curved surfaces and/or flat surfaces (not shown inFIG. 3).
• In some embodiments, the plurality of thirdundercut surfaces113 and the plurality of fourthopen surfaces114 may comprise convex curved surfaces. However, it will be understood that portions of the plurality of thirdundercut surfaces113 and the plurality of fourthopen surfaces114 may also comprise concave curved surfaces and/or flat surfaces (not shown inFIG. 3).
• In some embodiments, the plurality of thirdundercut surfaces113 and the plurality of fourthopen surfaces114 may be replaced by a ramped surface (such as that utilized in a standard buttress thread design) without any undercuts (not shown inFIG. 3). Likewise, any of the other thread designs disclosed herein may utilize a ramped or buttress thread design on at least one side of the helical thread.
• In some embodiments, a fastener may have only standard threads or only inverted threads. The type of threads that are desired may depend on the type and/or magnitude of loads to be applied to the fastener. For example, a screw loaded axially away from the bone in which it is implanted may advantageously have a standard thread, while a screw loaded axially toward the bone in which it is implanted may advantageously have an inverted thread. A screw that may experience multi-axial loading and/or off-loading conditions may advantageously include at least one standard thread and at least one inverted thread in order to increase bone fixation and load sharing between a bone/fastener interface during multi-axial and off-loading conditions to reduce high bone strain and distribute multi-axial forces applied to the bone in a load-sharing, rather than load-bearing, configuration. Shear loads and/or bending moments may also be optimally resisted with any chosen combination of threading, threading morphology, and/or threading variations contemplated herein to optimally resist shear loads, bending moments, multi-axial loading, off-loading conditions, etc.
• In some embodiments, fasteners with standard threads may be used in conjunction with fasteners with inverted threads in order to accommodate different loading patterns.
• In some embodiments, a single fastener may have both standard and inverted threads, like thefastener100. Such a combination of threads may help thefastener100 remain in place with unknown and/or varying loading patterns.
• In some embodiments, the geometry of the threading of a fastener (with standard and/or inverted threads) may be varied to suit the fastener for a particular loading scheme. For example, the number of threads, the number of thread starts, the pitch of the threading, the lead(s) of the threading, the shape(s) of the threading, any dimension(s) associated with the threading (e.g., any length(s)/width(s)/height(s), etc., associated with the threading), the major diameter(s), the minor diameter(s), any angulation/angles associated with any surfaces of the threading, the “handedness” of the threading (e.g., right-handed vs. left-handed), etc., may be varied accordingly to suit any specific medium of installation, loading pattern, desired radial loading force, pull-out strength, application, procedure, etc., that may be involved.
• In some embodiments, the material(s) of any portion of a fastener described herein may include, but are not limited to metals (e.g., titanium, cobalt, stainless steel, etc.), metal alloys, plastics, polymers, PEEK, UHMWPE, composites, additive particles, textured surfaces, biologics, biomaterials, bone, etc.
• In some embodiments, any of the fasteners described herein may include additional features such as: self-tapping features, locking features (e.g., locking threading formed on a portion of the fastener, such as threading located on or near a head of the fastener), cannulation, any style of fastener head (or no fastener head at all), any style of torque connection interface (or no torque connection interface at all), etc.
• In some embodiments, a tap (not shown) may be utilized to pre-form threading in a bone according to any threading shape that is disclosed or contemplated herein. In this manner, taps with any suitable shape may be utilized in conjunction with any fastener described or contemplated herein to match or substantially match the threading geometry of a given fastener.
• In some embodiments, a minor diameter of the fastener may be selected to match, or substantially match, a diameter of a pilot hole that is formed in a bone to avoid bone blowout when the fastener is inserted into the pilot hole, as will be discussed in more detail below.
• Additionally, or alternatively thereto, the type of threads and/or thread geometry may be varied based on the type of bone in which the fastener is to be anchored. For example, fasteners anchored in osteoporotic bone may fare better with standard or inverted threads, or when the pitch, major diameter, and/or minor diameter are increased or decreased, or when the angulation of thread surfaces is adjusted, etc.
• In some embodiments, a surgical kit may include multiple fasteners with any of the different fasteners and thread options described or contemplated herein. The surgeon may select the appropriate fastener(s) from the kit based on the particular loads to be applied and/or the quality of bone in which the fastener(s) are to be anchored.
• Continuing withFIG. 1D, in some embodiments the firsthelical thread110 may include a plurality of firstundercut surfaces111, a plurality of secondundercut surfaces112, a plurality of thirdundercut surfaces113, and a plurality of fourthopen surfaces114.
• In some embodiments, the secondhelical thread120 may include a plurality of fifthundercut surfaces125, a plurality of sixthundercut surfaces126, a plurality of seventhundercut surfaces127, and a plurality of eighthopen surfaces128.
• In some embodiments one or more of the plurality of firstundercut surfaces111, the plurality of secondundercut surfaces112, the plurality of thirdundercut surfaces113, the plurality of fourthopen surfaces114, the plurality of fifthundercut surfaces125, the plurality of sixthundercut surfaces126, the plurality of seventhundercut surfaces127, and the plurality of eighthopen surfaces128 may comprise at least one flat or substantially flat surface.
• In some embodiments, the plurality of firstundercut surfaces111, the plurality of thirdundercut surfaces113, the plurality of sixthundercut surfaces126, and the plurality of eighthopen surfaces128 may be angled towards thedistal end102 of theshaft105.
• In some embodiments, the plurality of secondundercut surfaces112, the plurality of fourthopen surfaces114, the plurality of fifthundercut surfaces125, and the plurality of seventhundercut surfaces127 may be angled towards theproximal end101 of theshaft105.
• In some embodiments, when thefastener100 is viewed in section along a plane that intersects thelongitudinal axis103 of the shaft105 (as shown inFIG. 1D), the firsthelical thread110 may include at least one chevron shape that is oriented toward (i.e., points toward) thedistal end102 of theshaft105. Likewise, the secondhelical thread120 may also include at least one chevron shape that is oriented toward (i.e., points toward) theproximal end101 of theshaft105.
• In some embodiments, when thefastener100 is viewed in section along a plane that intersects thelongitudinal axis103 of the shaft105 (as shown inFIG. 1D), the firsthelical thread110 may include a first plurality of chevron shapes that are oriented toward (i.e., point toward) thedistal end102 of theshaft105. Likewise, the secondhelical thread120 may include a second plurality of chevron shapes that are oriented toward (i.e., point toward) theproximal end101 of theshaft105.
• In some embodiments, the first plurality of chevron shapes and the second plurality of chevron shapes may be arranged in alternating succession along theshaft105 of thefastener100, (e.g., seeFIG. 1D).
• In some embodiments, a plurality of first interlockingspaces161 and a plurality of second interlockingspaces162 may be formed between the firsthelical thread110 and the secondhelical thread120 along theshaft105 of thefastener100.
• In some embodiments, the plurality of first interlockingspaces161 may be formed intermediate the first concave undercutsurfaces131 and the second concave undercut surfaces132.
• In some embodiments, the plurality of second interlockingspaces162 may be formed intermediate the first convex undercutsurfaces141 and the second convex undercut surfaces142.
• In some embodiments, the plurality of first interlockingspaces161 may be larger in size than the plurality of second interlocking spaces.
• In some embodiments, the plurality of first interlockingspaces161 and the plurality of second interlockingspaces162 may be shaped and/or configured to interlock with bone/other tissues received therein to increase fixation of thefastener100 within the bone/other tissues and provide additional resistance against multi-axial forces that may be applied to thefastener100 and/or the bone/other tissues.
• In some embodiments, the plurality of secondundercut surfaces112 and the plurality of sixthundercut surfaces126 may be angled toward each other to trap bone/other tissues within the plurality of first interlockingspaces161 in order to increase fixation and resistance against multi-axial forces.
• In some embodiments, the plurality of thirdundercut surfaces113 and the plurality of seventhundercut surfaces127 may be angled toward each other to trap bone/other tissues within the plurality of second interlockingspaces162 in order to increase fixation and resistance against multi-axial forces.
• In some embodiments, the plurality of firstundercut surfaces111 and the plurality of fifthundercut surfaces125 may each form an angle α with respect to thelongitudinal axis103 of theshaft105, as shown inFIG. 1D.
• In some embodiments, the angle α may be greater than 90 degrees.
• In some embodiments, the plurality of secondundercut surfaces112 and the plurality of sixthundercut surfaces126 may each form an angle β with respect to thelongitudinal axis103 of theshaft105.
• In some embodiments, the angle β may be less than 90 degrees.
• In some embodiments, the plurality of thirdundercut surfaces113 and the plurality of seventhundercut surfaces127 may each form an angle θ with respect to thelongitudinal axis103 of theshaft105.
• In some embodiments, the angle θ may be approximately 90 degrees.
• In some embodiments, the angle θ may be greater than 90 degrees.
• It will be understood that thefastener100 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. Moreover, it will also be understood that thefastener100 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIGS. 2A-2D illustrate various views of a polyaxial screw, pedicle bone fastener, orfastener200, according to another embodiment of the present disclosure. Specifically,FIG. 2A is a front perspective view of thefastener200,FIG. 2B is a rear perspective view of thefastener200,FIG. 2C is a side view of thefastener200, andFIG. 2D is a cross-sectional side view of thefastener200 taken along the line B-B inFIG. 2C. Thefastener200 may include ashaft205 having aproximal end201, adistal end202, and alongitudinal axis203. Thefastener200 may also include apolyaxial head204 having a firstsemi-spherical surface221 located at theproximal end201 of theshaft205, atorque connection interface206 formed in/on thepolyaxial head204, and a self-tappingfeature207 formed in thedistal end202 of theshaft205. In some embodiments, thefastener200 may include a firsthelical thread210 disposed about theshaft205, and a secondhelical thread220 disposed about theshaft205 adjacent the firsthelical thread210. In these embodiments, thefastener200 may comprise a “dual start” or “dual lead” thread configuration. However, it will also be understood that thefastener200 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. Moreover, it will also be understood that thefastener200 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIGS. 4A-4D illustrate various views of a polyaxial screw, pedicle bone fastener, orfastener400, according to another embodiment of the present disclosure. Specifically,FIG. 4A is a front perspective view of thefastener400,FIG. 4B is a rear perspective view of thefastener400,FIG. 4C is a side view of thefastener400, andFIG. 4D is a cross-sectional side view of thefastener400 taken along the line D-D inFIG. 4C. Thefastener400 may include ashaft405 having aproximal end401, adistal end402, and alongitudinal axis403. Thefastener400 may also include apolyaxial head404 having a firstsemi-spherical surface421 located at theproximal end401 of theshaft405, atorque connection interface406 formed in/on thepolyaxial head404, and a self-tappingfeature407 formed in thedistal end402 of theshaft405. In some embodiments, thefastener400 may include a singlehelical thread410 disposed about theshaft405, as shown inFIG. 4D. In some embodiments, thefastener400 may comprise a “single start” or “single lead” thread configuration having a standard orientation, as shown inFIG. 4D. However, it will also be understood that thefastener400 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. Moreover, it will also be understood that thefastener400 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIGS. 5A-5D illustrate various views of a polyaxial screw, pedicle bone fastener, orfastener500, according to another embodiment of the present disclosure. Specifically,FIG. 5A is a front perspective view of thefastener500,FIG. 5B is a rear perspective view of thefastener500,FIG. 5C is a side view of thefastener500, andFIG. 5D is a cross-sectional side view of thefastener500 taken along the line E-E inFIG. 5C. Thefastener500 may include ashaft505 having aproximal end501, adistal end502, and alongitudinal axis503. Thefastener500 may also include apolyaxial head504 having a firstsemi-spherical surface521 located at theproximal end501 of theshaft505, atorque connection interface506 formed in/on thepolyaxial head504, and a self-tappingfeature507 formed in thedistal end502 of theshaft505. In some embodiments, thefastener500 may include a singlehelical thread510 disposed about theshaft505, as shown inFIG. 5D. In some embodiments, thefastener500 may comprise a “single start” or “single lead” thread configuration having an inverted orientation, as shown inFIG. 5D. However, it will also be understood that thefastener500 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. Moreover, it will also be understood that thefastener500 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIGS. 6A-6D illustrate various views of a polyaxial screw, pedicle bone fastener, orfastener600, according to another embodiment of the present disclosure. Specifically,FIG. 6A is a front perspective view of thefastener600,FIG. 6B is a rear perspective view of thefastener600,FIG. 6C is a side view of thefastener600, andFIG. 6D is a cross-sectional side view of thefastener600 taken along the line F-F inFIG. 6C. Thefastener600 may include ashaft605 having aproximal end601, adistal end602, and alongitudinal axis603. Thefastener600 may also include apolyaxial head604 having a firstsemi-spherical surface621 located at theproximal end601 of theshaft605, atorque connection interface606 formed in/on thepolyaxial head604, and a self-tappingfeature607 formed in thedistal end602 of theshaft605. In some embodiments, thefastener600 may include a firsthelical thread610 disposed about theshaft605, and a secondhelical thread620 disposed about theshaft605 adjacent the firsthelical thread610. In these embodiments, thefastener600 may comprise a “dual start” or “dual lead” thread configuration. In some embodiments, a dual start thread configuration may allow quicker insertion of thefastener600 into bone/other tissues by requiring fewer rotations of thefastener600 during insertion. In some embodiments, the firsthelical thread610 and the secondhelical thread620 may each comprise “standard” threading having a “standard” orientation, as shown inFIG. 6D. However, it will also be understood that thefastener600 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. Moreover, it will also be understood that thefastener600 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIGS. 7A-7D illustrate various views of a polyaxial screw, pedicle bone fastener, orfastener700, according to another embodiment of the present disclosure. Specifically,FIG. 7A is a front perspective view of thefastener700,FIG. 7B is a rear perspective view of thefastener700,FIG. 7C is a side view of thefastener700, andFIG. 7D is a cross-sectional side view of thefastener700 taken along the line G-G inFIG. 7C. Thefastener700 may include ashaft705 having aproximal end701, adistal end702, and alongitudinal axis703. Thefastener700 may also include apolyaxial head704 having a firstsemi-spherical surface721 located at theproximal end701 of theshaft705, atorque connection interface706 formed in/on thepolyaxial head704, and a self-tappingfeature707 formed in thedistal end702 of theshaft705. In some embodiments, thefastener700 may include a firsthelical thread710 disposed about theshaft705, and a secondhelical thread720 disposed about theshaft705 adjacent the firsthelical thread710. In these embodiments, thefastener700 may comprise a “dual start” or “dual lead” thread configuration. This dual start thread configuration may allow quicker insertion of thefastener700 into bone/tissue by requiring fewer rotations of thefastener700 during insertion. In some embodiments, the firsthelical thread710 and the secondhelical thread720 may each comprise “inverted” threading having an “inverted” orientation, as shown inFIG. 7D. However, it will be understood that thefastener700 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. Moreover, it will also be understood that thefastener700 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIGS. 8A and 8B illustrate various views of a pedicle bone fastener orfastener800, according to another embodiment of the present disclosure. Specifically,FIG. 8A is a front perspective view of thefastener800, andFIG. 8B is a rear perspective view of thefastener800.
• Thefastener800 may generally include ashaft805 having aproximal end801, adistal end802, ahelical thread810, and self-tappingfeature807. Thefastener800 may also include an integrated attachment feature, such as anintegrated tulip840 located at theproximal end801 of theshaft805, and atorque connection interface806 within theintegrated tulip840.
• In some embodiments, at least a portion of a minor diameter of theshaft805 and/or a major diameter of thehelical thread810 may be constant to help prevent bone blowout during insertion of the bone fastener, as will be discussed below in more detail.
• Thefastener800 may also include ahelical thread810 disposed about theshaft805. In some embodiments, thehelical thread810 may comprise standard threading. In some embodiments, thehelical thread810 may comprise inverted threading. However, it will be understood that thefastener800 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments thehelical thread810 may comprise a first helical thread with standard or inverted threading comprising a first concave undercut surface, and thefastener800 may also include a second helical thread (not shown) with standard or inverted threading adjacent the first helical thread comprising a second concave undercut surface, forming a “dual start” thread configuration. Moreover, it will also be understood that thefastener800 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• In some embodiments, theintegrated tulip840 may include at least oneopening843 formed through one or more sides of theintegrated tulip840.
• In some embodiments, theintegrated tulip840 may include two openings formed through opposing sides of theintegrated tulip840.
• In some embodiments, the at least oneopening843 may be configured to receive at least a part of a spinal stabilization implement therethrough.
• In some embodiments, the spinal stabilization implement may comprise a spinal stabilization rod or rod (e.g., seerod930 shown inFIG. 9B).
• In some embodiments, theintegrated tulip840 may be configured to adjustably secure at least a part of the spinal stabilization implement to theintegrated tulip840 through the at least oneopening843.
• In some embodiments, theintegrated tulip840 may include a locking member opening855 configured to receive a locking member therein (e.g., see lockingmember950 shown inFIG. 9A).
• In some embodiments, the locking member may be configured to secure at least a part of the spinal stabilization rod received through the at least oneopening843 of theintegrated tulip840.
• FIGS. 9A-9F illustrate various views of a pedicle fastener stabilization system, according to an embodiment of the present disclosure. Specifically,FIG. 9A illustrates an exploded view of the pedicle fastener stabilization system,FIG. 9B shows the pedicle fastener stabilization system ofFIG. 9A assembled together (including a spinal stabilization rod),FIG. 9C illustrates a top perspective view of a discrete tulip ortulip940 of the pedicle fastener stabilization system shown inFIG. 9A,FIG. 9D illustrates a bottom perspective view of thetulip940,FIG. 9E illustrates a side view of thetulip940, andFIG. 9F illustrates a cross-sectional side view of thetulip940 taken along the line H-H shown inFIG. 9E.
• As shown inFIG. 9A, the pedicle fastener stabilization system may generally include a pedicle bone fastener orfastener900, thetulip940, and the lockingmember950. In some embodiments, the pedicle fastener stabilization system may also include a spinal stabilization rod orrod930 that may be securable to the tulip940 (seeFIG. 9B).
• Thefastener900 may generally include ashaft905 having aproximal end901, adistal end902, and alongitudinal axis903. Thefastener900 may also include ahelical thread910 disposed about theshaft905 along thelongitudinal axis903 between the proximal anddistal ends901,902 of theshaft905. Thefastener900 may also include an integrated attachment feature located at theproximal end901 of theshaft905, such as apolyaxial head904 having a firstsemi-spherical surface921. Thefastener900 may additionally include atorque connection interface906 formed in/on thepolyaxial head904 and a self-tappingfeature907 formed in thedistal end902 of theshaft905.
• In some embodiments, thehelical thread910 may comprise standard threading. In some embodiments, thehelical thread910 may comprise inverted threading. However, it will be understood that thefastener900 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments thehelical thread910 may comprise a first helical thread with standard or inverted threading comprising a first concave undercut surface, and thefastener900 may also include a second helical thread (not shown) with standard or inverted threading adjacent the first helical thread comprising a second concave undercut surface, forming a “dual start” thread configuration. Moreover, it will also be understood that thefastener900 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• In some embodiments, thepolyaxial head904 at the proximal end of theshaft905 may be configured to be polyaxially-adjustably secured to a spinal stabilization implement.
• In some embodiments, the spinal stabilization implement may comprise thetulip940.
• In some embodiments, thetulip940 may include a secondsemi-spherical surface922 that may be configured to engage the firstsemi-spherical surface921 of thepolyaxial head904 to polyaxially-adjustably secure thetulip940 to thepolyaxial head904 at any of a variety of relative orientations.
• In some embodiments, thetulip940 may include at least oneopening943 formed through one or more sides of thetulip940.
• In some embodiments, thetulip940 may include two openings formed through opposing sides of thetulip940.
• In some embodiments, the at least oneopening943 may be configured to receive at least a part of a spinal stabilization rod orrod930 therethrough, as shown inFIG. 9B.
• In some embodiments, thetulip940 may also include a locking member opening955 configured to receive the lockingmember950 therein.
• In some embodiments, thetulip940 may be configured to adjustably secure at least a part of therod930 to thetulip940 by tightening the lockingmember950 to compress therod930 between thetulip940 and the lockingmember950, as shown inFIG. 9B.
• Thefastener900 may comprise any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a vertebra, or within any other bone/tissue. Moreover, it will also be understood that thefastener900 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• FIG. 10A illustrates a top view of avertebral body980 with the pedicle fastener stabilization system ofFIG. 9A inserted into thepedicles982 of thevertebral body980, andFIG. 10B illustrates a cross-sectional side view of thevertebral body980 ofFIG. 10A.
• In some embodiments, a method of implanting a polyaxial bone fastener assembly (e.g., such as the pedicle fastener stabilization system shown inFIGS. 9A-10B, or the bone fastener assembly shown inFIGS. 12A-12F, etc.) may generally include: (1) inserting a bone fastener into a bone, (2) adjusting an orientation of an implement to a selected orientation relative to an attachment feature of the bone fastener, and (3) attaching the implement to the attachment feature at the selected orientation.
• In some embodiments, the bone fastener may include a shaft, a helical thread, and the attachment feature.
• In some embodiments, the shaft may include a proximal end, a distal end, a longitudinal axis, and the helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft.
• In some embodiments, at least a portion of a minor diameter and/or a major diameter of the shaft/helical thread(s) may be constant to help prevent bone blowout during insertion of the bone fastener, as will be discussed below in more detail.
• In some embodiments, the helical thread may include a first undercut surface and a second undercut surface.
• In some embodiments, the first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. However, it will be understood that the bone fastener may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments the bone fastener may comprise a first helical thread with standard or inverted threading, as well as a second helical thread with standard or inverted threading adjacent the first helical thread in a “dual start” thread configuration, etc.
• In some embodiments, the attachment feature may be disposed at the proximal end of the shaft and configured to be adjustably secured to the implement.
• In some embodiments, the attachment feature may be configured to be polyaxially-adjustably secured to the implement.
• In some embodiments, the attachment feature may be coupled to the bone fastener or to the shaft of the bone fastener.
• In some embodiments, adjusting the orientation of the implement to the selected orientation relative to the attachment feature may comprise polyaxially adjusting the orientation of the implement to a selected relative orientation, of a plurality of polyaxially-differentiated potential relative orientations, relative to the attachment feature.
• In some embodiments, the attachment feature may be integrally formed with the bone fastener or the shaft of the bone fastener.
• In some embodiments, the attachment feature may include a polyaxial head having a first semi-spherical surface and the implement may include a discrete tulip having a second semi-spherical surface configured to engage the first semi-spherical surface of the polyaxial head to polyaxially-adjustably secure the discrete tulip to the polyaxial head at any of a variety of relative orientations. For example, the second semi-spherical surface of the discrete tulip may be polyaxially adjusted to a selected orientation (of a plurality of polyaxially-differentiated potential relative orientations) relative to the first semi-spherical surface of the polyaxial head, and the discrete tulip may then be attached to the polyaxial head at the selected relative orientation.
• In some embodiments, the discrete tulip may comprise at least one opening and a locking member configured to secure a rod received through the at least one opening to the discrete tulip at the selected relative orientation.
• In some embodiments, the attachment feature may include a polyaxial head having a first semi-spherical surface, and the implement may include a radial head component having a second semi-spherical surface configured to engage the first semi-spherical surface and permit polyaxial articulation of the radial head component with respect to the polyaxial head, as will be discussed in more detail below with respect toFIGS. 12A-12F. However, in some embodiments the attachment feature may include a head that may rigidly couple with a radial head component, as will be discussed in more detail below with respect toFIGS. 14A-14I.
• In some embodiments, the method may also include drilling a pilot hole (not shown) into the bone and inserting the shaft of the bone fastener into the pilot hole.
• In some embodiments, the method may also include tapping (not shown) one or more bone threads in the bone to form one or more tapped bone threads about the pilot hole and inserting the helical thread(s) into the one or more tapped bone threads.
• Bone blowout can occur when a bone fastener is inserted into a bone and generates a sufficient outwardly directed radial force on the bone to cause bone blowout due to the size/morphology of the bone fastener and/or the size/morphology of the bone hole receiving the bone fastener.
• In some embodiments, a method of preventing bone blowout may generally include forming a hole in a bone (not shown), the hole having a bone hole diameter, and inserting a bone fastener into the hole having a minor diameter that is not greater than 5% larger the bone hole diameter. In this manner, an outwardly directed radial force applied to the bone by the minor diameter of the fastener may be reduced to prevent bone blowout.
• In some embodiments, the shaft may include a proximal end, a distal end, and a longitudinal axis with at least one helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft.
• In some embodiments, at least a portion of the minor diameter of the shaft may be constant to help prevent bone blowout during insertion of the bone fastener. For example, a main portion of a bone fastener may exclude a pointed tip portion of the bone fastener (e.g., see themain portion986 and thepointed tip portion984 of thefastener900 inFIG. 10B, as one non-limiting example). Moreover, in some embodiments, a main portion of a bone fastener may exclude a proximal portion of the bone fastener that may or may not be fully inserted into the bone (e.g., see theproximal portion988 of thefastener900 inFIG. 10B, as one non-limiting example). Thus, in some embodiments a minor diameter of a main portion of a bone fastener may be constant (e.g., see theminor diameter960 of the main portion of thefastener900 inFIG. 10B which is constant, as one non-limiting example).
• In some embodiments, at least a portion of the major diameter of a fastener may also be constant to help prevent bone blowout from the threading of the bone fastener during insertion (e.g., see themajor diameter965 of the main portion of thefastener900 inFIG. 10B which is constant, as one non-limiting example).
• In some embodiments, the helical thread may include a first undercut surface and a second undercut surface.
• In some embodiments, the first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. However, it will be understood that the bone fastener may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments the bone fastener may comprise a first helical thread with standard or inverted threading, as well as a second helical thread with standard or inverted threading adjacent the first helical thread in a “dual start” thread configuration, etc.
• In some embodiments, the minor diameter of at least a main portion of the shaft may be greater than the bone hole diameter. For example, the minor diameter of at least a main portion of the shaft may be greater than the bone hole diameter, but not greater than 5% larger the bone hole diameter.
• In some embodiments, the minor diameter of at least a main portion of the shaft may not be greater than the bone hole diameter.
• In some embodiments, the minor diameter of at least a main portion of the shaft may be equal to the bone hole diameter.
• In some embodiments, the minor diameter of at least a main portion of the shaft may be less than the bone hole diameter.
• In some embodiments, the minor diameter of the main portion of the shaft may be between 0 mm and 0.1 mm less than the bone hole diameter.
• In some embodiments, the minor diameter of the main portion of the shaft may be at least 0.1 mm less than the bone hole diameter.
• In some embodiments, the minor diameter of the main portion of the shaft may be between 0.1 mm and 0.2 mm less than the bone hole diameter.
• In some embodiments, the minor diameter of the main portion of the shaft may be at least 0.2 mm less than the bone hole diameter.
• However, it will be understood that at least a portion of the minor diameter of the shaft may any size that is less than, equal to, or greater than the bone hole diameter.
• In these embodiments, the unique morphology of the thread designs disclosed herein allow for “over-drilling” a given bone hole to create a bone hole diameter that is equal to or greater than the minor diameter of at least a main portion of the shaft, while maintaining good bone purchase and loading characteristics provided by the unique morphology of the thread designs disclosed herein. In this manner, an over-drilled bone hole in combination with a smaller minor diameter and the unique morphology of the thread designs disclosed herein can achieve a lower radial outward load force that is placed on the bone by the minor diameter of the shaft in order to prevent bone blowout. This is in contrast to typical procedures that “under-drill” bone holes and rely on bone compaction by fasteners with larger minor diameters than the bone hole diameter in order to achieve sufficient bone purchase. However, this will result in higher radial outward load forces placed on the bone by the larger minor diameter of the shaft, thus increasing the risk of bone blowout.
• In some embodiments, the method may also include tapping (not shown) one or more bone threads in the bone to form one or more tapped bone threads about the hole in the bone, and then inserting the helical thread(s) into the one or more tapped bone threads to further reduce an outwardly directed radial force applied to the bone by the helical thread(s) as the bone fastener is inserted into the bone.
• FIGS. 11A-11D illustrate various views of a threaded stem, bone fastener, orfastener1100, according to another embodiment of the present disclosure. Specifically,FIG. 11A is a front perspective view of thefastener1100,FIG. 11B is a rear perspective view of thefastener1100,FIG. 11C is a side view of thefastener1100, andFIG. 11D is a cross-sectional side view of thefastener1100 taken along the line I-I shown inFIG. 11C.
• Thefastener1100 may generally include ashaft1105 having aproximal end1101, adistal end1102, alongitudinal axis1103, ahelical thread1110 disposed about theshaft1105 along thelongitudinal axis1103, ahead1104, and atorque connection interface1106 formed in/on thehead1104.
• In some embodiments, thefastener1100 may include thehelical thread1110 disposed about theshaft1105 in a “single start” or “single lead” thread configuration having standard or inverted threading.
• In some embodiments, thehelical thread1110 may include a first undercut surface, a second undercut surface, a third undercut surface, and a fourth open surface.
• In some embodiments, the first undercut surface and the third undercut surface may be angled towards one of theproximal end1101 and thedistal end1102 of theshaft1105, and the second undercut surface and the fourth open surface may be angled towards the other one of theproximal end1101 and thedistal end1102 of theshaft1105.
• However, it will be understood that thefastener1100 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments thehelical thread1110 may comprise a first helical thread with standard or inverted threading, and thefastener1100 may also include a second helical thread (not shown) with standard or inverted threading adjacent the first helical thread, forming a “dual start” thread configuration, etc. Moreover, it will also be understood that thefastener1100 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• In some embodiments, at least a portion of thefastener1100 may be sized, shaped, and configured for use within an intramedullary canal (IMC) of a bone. For example, in some embodiments thefastener1100 may be sized, shaped, and configured for use within an IMC as a transfemoral stem (or transfemoral stem abutment), a humeral stem, a tibial stem, etc. However, it will also be understood that thefastener1100 may be sized, shaped, and configured for use within any IMC of any bone, and/or for any other suitable procedure or application outside of an IMC of a bone.
• In some embodiments, thefastener1100 may include aminor diameter1160 and amajor diameter1165, as shown inFIG. 11D.
• In some embodiments, a ratio of themajor diameter1165 to theminor diameter1160 may be less than 1.50.
• In some embodiments, a ratio of themajor diameter1165 to theminor diameter1160 may be less than 1.25.
• In some embodiments, a ratio of themajor diameter1165 to theminor diameter1160 may be less than 1.10.
• In some embodiments, a ratio of themajor diameter1165 to theminor diameter1160 may be less than 1.05.
• In some embodiments, at least a portion of theminor diameter1160 of theshaft1105 may be constant to help prevent bone blowout during insertion of thefastener1100.
• In some embodiments, at least a portion of themajor diameter1165 of theshaft1105 may be constant to help prevent bone blowout during insertion of thefastener1100.
• FIGS. 12A-12F illustrate various views of a threaded stem, bone fastener, orfastener1200, according to another embodiment of the present disclosure. Specifically,FIG. 12A is a front perspective view of thefastener1200,FIG. 12B is a rear perspective view of thefastener1200,FIG. 12C is a side view of thefastener1200,FIG. 12D is a cross-sectional side view of thefastener1200 taken along the line J-J shown inFIG. 12C,FIG. 12E is a perspective side view of thefastener1200 coupled to aradial head component1220, andFIG. 12F shows a system/kit1250 including thefastener1200.
• Thefastener1200 may generally include ashaft1205 having aproximal end1201, adistal end1202, alongitudinal axis1203, ahelical thread1210, apolyaxial head1204, atorque connection interface1206 formed in/on thepolyaxial head1204, and one or more self-tappingfeatures1207.
• In some embodiments, thefastener1200 may include thehelical thread1210 disposed about theshaft1205 in a “single start” or “single lead” thread configuration having a standard or inverted orientation.
• In some embodiments, thehelical thread1210 may include a first undercut surface and a second undercut surface.
• In some embodiments, the first undercut surface may be angled toward one of theproximal end1201 and thedistal end1202 of theshaft1205, and the second undercut surface may be angled toward the other one of theproximal end1201 and thedistal end1202 of theshaft1205.
• In some embodiments, thehelical thread1210 may include a first undercut surface, a second undercut surface, a third undercut surface, and a fourth open surface.
• In some embodiments, the first undercut surface and the third undercut surface may be angled towards one of theproximal end1201 and thedistal end1202 of theshaft1205, and the second undercut surface and the fourth open surface may be angled towards the other one of theproximal end1201 and thedistal end1202 of theshaft1205.
• However, it will be understood that thefastener1200 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments thehelical thread1210 may comprise a first helical thread with standard or inverted threading, and thefastener1200 may also include a second helical thread (not shown) with standard or inverted threading adjacent the first helical thread, forming a “dual start” thread configuration, etc. Moreover, it will also be understood that thefastener1200 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• In some embodiments, at least a portion of thefastener1200 may be sized, shaped, and configured for use within an IMC of a bone. For example, in some embodiments thefastener1200 may be sized, shaped, and configured for use within an IMC of a radial bone as a threaded radial stem, etc. However, it will also be understood that thefastener1200 may be sized, shaped, and configured for use within any IMC of any bone, and/or for any other suitable procedure or application outside of an IMC of a bone.
• In some embodiments, thefastener1200 may include aminor diameter1260 and amajor diameter1265, as shown inFIG. 12D.
• In some embodiments, a ratio of themajor diameter1265 to theminor diameter1260 may be less than 1.50.
• In some embodiments, a ratio of themajor diameter1265 to theminor diameter1260 may be less than 1.25.
• In some embodiments, a ratio of themajor diameter1265 to theminor diameter1260 may be less than 1.10.
• In some embodiments, a ratio of themajor diameter1265 to theminor diameter1260 may be less than 1.05.
• In some embodiments, at least a portion of theminor diameter1260 of theshaft1205 may be constant to help prevent bone blowout during insertion of thefastener1200.
• In some embodiments, at least a portion of themajor diameter1265 of theshaft1205 may be constant to help prevent bone blowout during insertion of thefastener1200.
• In some embodiments, an attachment feature may be located at theproximal end1201 of theshaft1205 and configured to be adjustably secured to an implement, such as theradial head component1220 or a glenoid component (not shown), etc.
• In some embodiments, the attachment feature may comprise apolyaxial head1204 that may be coupled to, or integrally formed with, theproximal end1201 of theshaft1205.
• In some embodiments, thepolyaxial head1204 may include a firstsemi-spherical surface1221.
• In some embodiments, the radial head component1220 (or a glenoid component, etc.) may be coupled to thepolyaxial head1204 of thefastener1200 for utilization in a radial head arthroplasty procedure, a glenoid procedure, etc.
• In some embodiments, theradial head component1220 may include a secondsemi-spherical surface1222 configured to engage the firstsemi-spherical surface1221 and permit polyaxial articulation of theradial head component1220 with respect to thepolyaxial head1204.
• In some embodiments, theradial head component1220 may include aconcave articulation surface1224 configured to receive a convex articulation surface (not shown) to form a prosthetic joint.
• In some embodiments, a system/kit1250 may comprise one ormore drill bits1230 of varying sizes to form pilot holes of varying size in a radial bone (not shown). The system/kit1250 may also comprise one ormore fasteners1200 of varying size, one or moreradial head components1220 of varying size, and one ormore couplers1240 for coupling aradial head component1220 to afastener1200, etc.
• FIGS. 13A-13D illustrate various views of a threaded stem, bone fastener, orfastener1300, according to another embodiment of the present disclosure. Specifically,FIG. 13A is a front perspective view of thefastener1300,FIG. 13B is a rear perspective view of thefastener1300,FIG. 13C is a side view of thefastener1300, andFIG. 13D is a cross-sectional side view of thefastener1300 taken along the line K-K shown inFIG. 13C.
• Thefastener1300 may generally include ashaft1305 having aproximal end1301, adistal end1302, alongitudinal axis1303, ahelical thread1310 disposed about theshaft1305 along thelongitudinal axis1303, ahead1304, and atorque connection interface1306 formed in/on thehead1304.
• In some embodiments, thefastener1300 may include thehelical thread1310 disposed about theshaft1305 in a “single start” or “single lead” thread configuration having standard or inverted threading.
• In some embodiments, thehelical thread1310 may include a first undercut surface and a second undercut surface.
• In some embodiments, the first undercut surface may be angled toward one of theproximal end1301 and thedistal end1302 of theshaft1305, and the second undercut surface may be angled toward the other one of theproximal end1301 and thedistal end1302 of theshaft1305.
• In some embodiments, thehelical thread1310 may include a first undercut surface, a second undercut surface, a third undercut surface, and a fourth open surface.
• In some embodiments, the first undercut surface and the third undercut surface may be angled towards one of theproximal end1301 and thedistal end1302 of theshaft1305, and the second undercut surface and the fourth open surface may be angled towards the other one of theproximal end1301 and thedistal end1302 of theshaft1305.
• However, it will be understood that thefastener1300 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments thehelical thread1310 may comprise a first helical thread with standard or inverted threading, and thefastener1300 may also include a second helical thread (not shown) with standard or inverted threading adjacent the first helical thread, forming a “dual start” thread configuration, etc. Moreover, it will also be understood that thefastener1300 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• In some embodiments, at least a portion of thefastener1300 may be sized, shaped, and configured for use within an intramedullary canal (IMC) of a bone. For example, in some embodiments thefastener1300 may be sized, shaped, and configured for use within an IMC as a transfemoral stem (or transfemoral stem abutment), a humeral stem, a tibial stem, etc. However, it will also be understood that thefastener1300 may be sized, shaped, and configured for use within any IMC of any bone, and/or for any other suitable procedure or application outside of an IMC of a bone.
• In some embodiments, thefastener1300 may include apin hole1391 formed through theshaft1305 of thefastener1300. Thepin hole1391 may be configured to receive ananti-rotation pin1390 therethrough. In this manner, theanti-rotation pin1390 may prevent thefastener1300 from rotating and/or loosening once thefastener1300 has been implanted within a bone.
• In some embodiments, thefastener1300 may be utilized in a limb salvage procedure to prevent amputation and/or mitigate the need for additional amputation.
• In some embodiments, thefastener1300 may include anattachment feature1395 that may be configured to removably couple with an implement, such as a prosthetic component (not shown). For example, thefastener1300 may be inserted within an intramedullary canal of a long bone (e.g., a femur, a humerus, etc.). Once thefastener1300 has achieved sufficient osseointegration within the long bone, another prosthetic component such as an abutment (not shown), etc., may be removably coupled to thefastener1300 via theattachment feature1395 and may extend outside the skin of the patient to connect with a prosthetic limb (e.g., a prosthetic arm, leg, foot, etc., not shown), as one non-limiting example.
• In some embodiments, thefastener1300 may include aminor diameter1360 and amajor diameter1365, as shown inFIG. 13D.
• In some embodiments, a ratio of themajor diameter1365 to theminor diameter1360 may be less than 1.50.
• In some embodiments, a ratio of themajor diameter1365 to theminor diameter1360 may be less than 1.25.
• In some embodiments, a ratio of themajor diameter1365 to theminor diameter1360 may be less than 1.10.
• In some embodiments, a ratio of themajor diameter1365 to theminor diameter1360 may be less than 1.05.
• In some embodiments, at least a portion of theminor diameter1360 of theshaft1305 may be constant to help prevent bone blowout during insertion of thefastener1300.
• In some embodiments, at least a portion of themajor diameter1365 of theshaft1305 may be constant to help prevent bone blowout during insertion of thefastener1300.
• FIGS. 14A-14F illustrate various views of a threaded stem, bone fastener, orfastener1400, according to another embodiment of the present disclosure. Specifically,FIG. 14A is a front perspective view of thefastener1400,FIG. 14B is a rear perspective view of thefastener1400,FIG. 14C is a side view of thefastener1400,FIG. 14D is a cross-sectional side view of thefastener1400 taken along the line L-L shown inFIG. 14C.FIG. 14E is a front perspective view of aradial head component1420 that may be utilized with thefastener1400,FIG. 14F is a rear perspective view of theradial head component1420,FIG. 14G is a side view of theradial head component1420,FIG. 14H is a bottom view of theradial head component1420, andFIG. 14I is a side view of an assembly comprising theradial head component1420 and thefastener1400.
• Thefastener1400 may generally include ashaft1405 having aproximal end1401, adistal end1402, alongitudinal axis1403, ahelical thread1410, an attachment feature orhead1404, atorque connection interface1406 formed in/on thehead1404, and one or more self-tapping features1407.
• In some embodiments, thefastener1400 may include thehelical thread1410 disposed about theshaft1405 in a “single start” or “single lead” thread configuration having a standard or inverted orientation.
• In some embodiments, thehelical thread1410 may include a first undercut surface and a second undercut surface.
• In some embodiments, the first undercut surface may be angled toward one of theproximal end1401 and thedistal end1402 of theshaft1405, and the second undercut surface may be angled toward the other one of theproximal end1401 and thedistal end1402 of theshaft1405.
• In some embodiments, thehelical thread1410 may include a first undercut surface, a second undercut surface, a third undercut surface, and a fourth open surface.
• In some embodiments, the first undercut surface and the third undercut surface may be angled towards one of theproximal end1401 and thedistal end1402 of theshaft1405, and the second undercut surface and the fourth open surface may be angled towards the other one of theproximal end1401 and thedistal end1402 of theshaft1405.
• However, it will be understood that thefastener1400 may include any thread configuration, feature, or morphology described or contemplated herein to achieve optimal fixation within a given bone/tissue. For example, in some embodiments thehelical thread1410 may comprise a first helical thread with standard or inverted threading, and thefastener1400 may also include a second helical thread (not shown) with standard or inverted threading adjacent the first helical thread, forming a “dual start” thread configuration, etc. Moreover, it will also be understood that thefastener1400 may be utilized in conjunction with (or within) any system, method, or instrumentation described or contemplated herein.
• In some embodiments, at least a portion of thefastener1400 may be sized, shaped, and configured for use within an IMC of a bone. For example, in some embodiments thefastener1400 may be sized, shaped, and configured for use within an IMC of a radial bone as a threaded radial stem, etc. However, it will also be understood that thefastener1400 may be sized, shaped, and configured for use within any IMC of any bone, and/or for any other suitable procedure or application outside of an IMC of a bone.
• In some embodiments, thefastener1400 may include a minor diameter1460 and amajor diameter1465, as shown inFIG. 14D.
• In some embodiments, a ratio of themajor diameter1465 to the minor diameter1460 may be less than 1.50.
• In some embodiments, a ratio of themajor diameter1465 to the minor diameter1460 may be less than 1.25.
• In some embodiments, a ratio of themajor diameter1465 to the minor diameter1460 may be less than 1.10.
• In some embodiments, a ratio of themajor diameter1465 to the minor diameter1460 may be less than 1.05.
• In some embodiments, at least a portion of the minor diameter1460 of theshaft1405 may be constant to help prevent bone blowout during insertion of thefastener1400.
• In some embodiments, at least a portion of themajor diameter1465 of theshaft1405 may be constant to help prevent bone blowout during insertion of thefastener1400.
• In some embodiments, the attachment feature, orhead1404, may be located at theproximal end1401 of theshaft1405 and configured to be adjustably secured to an implement, such as theradial head component1420 or a glenoid component (not shown), etc.
• In some embodiments, thehead1404 that may be coupled to, or integrally formed with, theproximal end1401 of theshaft1405.
• In some embodiments, thehead1404 may include aneck portion1412 and aprojection portion1414.
• In some embodiments, theprojection portion1414 may comprise a disc shape.
• In some embodiments, theprojection portion1414 may also comprise one or morebeveled surfaces1416.
• In some embodiments, the radial head component1420 (or a glenoid component, etc.) may be coupled to thehead1404 of thefastener1400 for utilization in a radial head arthroplasty procedure, a glenoid procedure, etc., as shown inFIG. 14I.
• In some embodiments, theradial head component1420 may include aconcave articulation surface1424 that may be configured to receive a convex articulation surface (not shown) to form a prosthetic joint.
• In some embodiments, theradial head component1420 may include anattachment feature1430.
• In some embodiments, theattachment feature1430 may include awindow1432 that may be sized and shaped to receive thehead1404 andneck portion1412 of thefastener1400 therein, as shown inFIG. 14I.
• In some embodiments, theattachment feature1430 may also include one or moreset screw holes1436 configured to receive one or more set screws (not shown) to removably couple theradial head component1420 to thefastener1400.
• Any of the fasteners described or contemplated herein may be configured for removal and replacement during a revision procedure by simply unscrewing and removing the fastener from the bone/tissue in which the fastener resides. Moreover, the fasteners described herein may advantageously be removed from bone without removing any appreciable amount of bone during the removal process to preserve the bone. In this manner, implants may be mechanically integrated with the bone, while not being cemented to the bone or integrated via bony ingrowth, in order to provide an instant and removable connection between an implant and a bone. Accordingly, revision procedures utilizing the fasteners described herein can result in less trauma to the bone and improved patient outcomes. However, it will also be understood that any of the fasteners described or contemplated herein may also be utilized with cement, as desired.
• Any procedures/methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified.
• Reference throughout this specification to “an embodiment” or “the embodiment” means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment.
• Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the present disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any embodiment requires more features than those expressly recited in that embodiment. Rather, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment.
• Recitation of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. § 112(f). It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles set forth herein.
• The phrases “connected to,” “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be functionally coupled to each other even though they are not in direct contact with each other. The term “coupled” can include components that are coupled to each other via integral formation, as well as components that are removably and/or non-removably coupled with each other. The term “abutting” refers to items that may be in direct physical contact with each other, although the items may not necessarily be attached together. The phrase “fluid communication” refers to two or more features that are connected such that a fluid within one feature is able to pass into another feature. Moreover, as defined herein the term “substantially” means within +/−20% of a target value, measurement, or desired characteristic.
• While specific embodiments and applications of the present disclosure have been illustrated and described, it is to be understood that the scope of this disclosure is not limited to the precise configuration and components disclosed herein. Various modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the devices, systems, and methods disclosed herein.

Claims (20)

What is claimed is:

1. A pedicle bone fastener comprising:

a shaft comprising:

a proximal end;

a distal end;

a longitudinal axis; and

a minor diameter;

a helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft, the helical thread comprising:

a first undercut surface; and

a second undercut surface, wherein:

the first undercut surface is angled toward one of the proximal end and the distal end of the shaft;

the second undercut surface is angled toward the other one of the proximal end and the distal end of the shaft; and

the minor diameter of the shaft is constant.

2. The pedicle bone fastener ofclaim 1, further comprising:

an attachment feature coupled to the proximal end of the shaft and configured to be secured to an implement.

3. The pedicle bone fastener ofclaim 2, wherein the attachment feature comprises a polyaxial head having a first semi-spherical surface.

4. The pedicle bone fastener ofclaim 3, wherein the implement comprises a discrete tulip having a second semi-spherical surface configured to engage the first semi-spherical surface of the polyaxial head to secure the discrete tulip to the polyaxial head at any of a variety of relative orientations.

5. The pedicle bone fastener ofclaim 4, wherein the discrete tulip further comprises:

at least one opening; and

a locking member configured to secure a rod received through the at least one opening to the discrete tulip.

6. The pedicle bone fastener ofclaim 2, wherein the attachment feature comprises an integrated tulip having at least one opening configured to receive at least a part of the implement therethrough.

7. The pedicle bone fastener ofclaim 6, wherein the implement comprises a rod receivable through the at least one opening of the integrated tulip, and wherein the integrated tulip comprises a locking member configured to secure the rod to the integrated tulip.

8. A method of preventing bone blowout comprising:

forming a hole in a bone, the hole having a bone hole diameter; and

inserting a bone fastener into the hole, the bone fastener comprising:

a shaft comprising:

a proximal end;

a distal end;

a longitudinal axis; and

a minor diameter; and

a helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft, the helical thread comprising:

a first undercut surface; and

a second undercut surface, wherein:

the first undercut surface is angled toward one of the proximal end and the distal end of the shaft;

the second undercut surface is angled toward the other one of the proximal end and the distal end of the shaft; and

the minor diameter of a main portion of the shaft is not greater than the bone hole diameter to reduce a radial outward load force imparted on the bone and prevent bone blowout.

9. The method ofclaim 8, wherein the minor diameter of the main portion of the shaft is equal to the bone hole diameter.

10. The method ofclaim 8, wherein the minor diameter of the main portion of the shaft is less than the bone hole diameter.

11. The method ofclaim 10, wherein the minor diameter of the main portion of the shaft is between 0 mm and 0.1 mm less than the bone hole diameter.

12. The method ofclaim 10, wherein the minor diameter of the main portion of the shaft is at least 0.1 mm less than the bone hole diameter.

13. The method ofclaim 10, wherein the minor diameter of the main portion of the shaft is at least 0.2 mm less than the bone hole diameter.

14. The method ofclaim 8, wherein the minor diameter of the main portion of the shaft is constant.

15. A bone fastener comprising:

a shaft comprising:

a proximal end;

a distal end;

a longitudinal axis; and

a minor diameter;

a helical thread disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft and defining a major diameter of the bone fastener, the helical thread comprising:

a first undercut surface; and

a second undercut surface, wherein:

the first undercut surface is angled toward one of the proximal end and the distal end of the shaft; and

the second undercut surface is angled toward the other one of the proximal end and the distal end of the shaft; and

a ratio of the major diameter to the minor diameter is less than 1.50.

16. The bone fastener ofclaim 15, wherein the ratio of the major diameter to the minor diameter is less than 1.25.

17. The bone fastener ofclaim 15, wherein the ratio of the major diameter to the minor diameter is less than 1.10.

18. The bone fastener ofclaim 15, wherein the ratio of the major diameter to the minor diameter is less than 1.05.

19. The bone fastener ofclaim 15, wherein at least a portion of the bone fastener is configured to be received with an intramedullary canal of a bone.

20. The bone fastener ofclaim 19, further comprising an attachment feature at the proximal end of the shaft configured to be adjustably secured to an implement.

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