Screw-in bone fixation system

Abstract

The bone fixation system includes a first anchor, a second anchor, and a third anchor. The first anchor is configured to be inserted into a first target location in a bone. The first anchor includes a first head and a first shaft extending from the first head and configured to couple the first anchor to the first target location. The first head defines a head bore extending through the first head along a head bore axis. The first shaft defines a shaft bore extending through the first shaft along a shaft bore axis. The second anchor is sized to extend through and out of the head bore to couple to the second target location in the bone. The third anchor is sized to extend through and out of the shaft bore to a third target location in the bone.

Description

Technical Field

[0001] The present disclosure relates to bone fixation systems, assemblies, and related surgical methods and procedures for using the same.

Background Art

[0002] Various fixation devices for the reduction of bone or bone fragments are well known. For example, external bone fixation devices or external fixators are used to reduce fractures of long bones within the human body. Internal bone fixation devices such as bone plates are also commonly used to reduce fractures.

[0003] Many fixation devices are attached to underlying bone using bone anchors that can include screws, pins, nails, etc. For example, conventional bone plates include screw holes that receive bone screws drilled into the underlying bone on opposite sides of the fracture site to join bone segments together. Unfortunately, attachment of the bone fixation device to the underlying bone can be problematic, for example, if the screw becomes disengaged from the bone during normal anatomical function.

[0004] The foregoing discussion of the background is intended solely to assist the reader. It is not intended to limit the technological innovations described herein. Accordingly, the foregoing discussion should not be construed as indicating that any particular element of a conventional system is not suitable for use with the technological innovations described herein, nor is it intended to indicate that any element is essential to the practice of the technological innovations described herein.

Summary of the Invention

Means for Solving the Problems

[0005] Fractures are one of the most common orthopedic trauma procedures. In particular, fractures of the distal radius are part of the most common fractures treated. Distal radius fractures are generally treated based on their severity. Less complex fractures can often be stabilized after hardening using a cast and can be further stabilized using pins. Comminuted fractures can utilize open reduction internal fixation (ORIF) plating, including bone plates and fixation screws. However, ORIF plating may result in soft tissue irritation and other undesirable outcomes due to the protrusion and position of the plating on the outer surface of the bone.

[0006] Improved bone fixation systems and insertion methods are desirable for treating fractures that are too complex to address via pin, wire, and / or cast fixation and that may result in tissue irritation or other medical complications, without the accompanying additional metal products protruding from the bone and that may be too small for plating and other fixation components.

[0007] Aspects of the present disclosure provide a bone fixation system. The bone fixation system includes a first anchor, a second anchor, and a third anchor. The first anchor is configured to be inserted into a first target position within the bone. The first anchor includes a first head and a first shaft extending from the first head and configured to connect the first anchor to the first target position. The first head defines a head bore extending through the first head along a head bore axis. The first shaft defines a shaft bore extending through the first shaft along a shaft bore axis. The second anchor is sized to extend through the head bore and out of the head bore to connect to a second target position within the bone. The third anchor is sized to extend through the shaft bore and out of the shaft bore to a third target position within the bone.

[0008] Another aspect of the present disclosure provides a bone anchor. The bone anchor is configured to be disposed within the distal radius. The bone anchor includes a head and a shaft. The head defines a head bore that extends through the head along a head bore axis. The shaft extends from the head and is configured to couple the bone anchor to a target location within the distal radius. The shaft defines a shaft bore that extends through the shaft along a shaft bore axis.

[0009] Another aspect of the present disclosure provides a method of securing a bone fixation system to a first bone segment of the distal radius and a second bone segment of the distal radius. The method includes inserting a first anchor into a first target location within the distal radius, the first anchor including a first head and a first shaft extending from the first head, the first head defining a head bore that extends through the first head along a head bore axis and the first shaft defining a shaft bore that extends through the first shaft along a shaft bore axis; inserting a second anchor through the head bore and out of the head bore to couple to a second target location of the distal radius; and inserting a third anchor through the shaft bore and out of the shaft bore and into a third target location within the distal radius.

[0010] This summary is provided to introduce a series of concepts in a simplified form that are further described in the Detailed Description section below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Further, the claimed subject matter is not limited by any limitations that solve any or all of the disadvantages described in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing summary and the following detailed description of exemplary embodiments of the present application will be better understood when read in conjunction with the accompanying drawings. For the purpose of exemplifying the present application, exemplary embodiments of the present disclosure are shown in the drawings. However, it should be understood that the present application is not limited to the exact arrangements and means shown.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0012] The specific terms used herein are for convenience only and are not limiting. The terms "top", "bottom", "distal", "proximal", "leading", "trailing", "inner", "outer", "above", "below", "axial", "transverse", "circumferential", and "radial" indicate directions in the referenced drawings. The term "substantially" means a significant degree or majority of the specified thing, but is not necessarily intended to be complete. All ranges disclosed herein include the recited endpoints and can be combined independently (e.g., a range of "2 grams to 10 grams" includes the endpoints 2 grams and 10 grams, as well as all intermediate values). The terms include the words listed above, their derivatives, and words having similar meanings.

[0013] Referring now to FIG. 1, the fixation system 100 can be configured as a bone fixation system according to an example, including a first bone anchor 200. The first bone anchor 200 includes a head 202 and a shaft 204 extending from the head 202 along a central longitudinal axis L1 (e.g., a shaft axis or a central axis). The first bone anchor 200 can include at least one head bore 216 extending through the head 202 and at least one shaft bore 205 extending through the shaft 204. Thus, the bone fixation system 100 can include at least one auxiliary head anchor 300 configured to be inserted into bone through at least one head bore 216. The bone fixation system 100 can further include at least one auxiliary shaft anchor 400 configured to be inserted into bone through at least one shaft bore 205. In this regard, both the at least one auxiliary head anchor 300 and the at least one auxiliary shaft anchor 400 are received by the first bone anchor 200. Unless otherwise specifically indicated, the fixation system 100 and its components, including the bone anchors, can be manufactured from any suitable biocompatible material known in the art, including but not limited to titanium alloys (such as titanium, TAN), stainless steel, reinforced plastics, allograft bone, and the like.

[0014] Referring now to FIGS. 2-6, the first bone anchor 200 includes a head 202 (e.g., a first head) and a shaft 204 (e.g., a first shaft). The shaft 204 extends longitudinally from the head 202 along a central shaft axis L1. The shaft 204 defines a proximal end or upper end 204a and a distal end or lower end 204b, respectively, that face each other in the longitudinal direction. The head 202 is located at the proximal end 204a of the shaft 204. As used herein, the terms "proximal" or "proximal end" refer to the end closer to the medical professional during a medical procedure than the distal end, and the terms "distal" or "distal end" refer to the end farther from the medical professional during a medical procedure than the proximal end. Further, the term "proximal direction" refers to the direction extending toward the medical professional during a medical procedure, while the term "distal direction" refers to the direction extending away from the medical professional during a medical procedure.

[0015] The shaft 204 includes threads 206 that extend radially outward from the shaft 204 at the positions of the proximal end 204a and the distal end 204b and at positions therebetween. The threads 206 are configured to engage the underlying bone, and thus, the shaft 204 can be threaded throughout. Alternatively, the shaft 204 may include a portion without threads. For example, the shaft portion 204 located in the direction of the distal end 204b can be threaded, and the shaft portion 204 located in the direction of the upper end 204a may not be threaded. As illustrated in FIG. 4, the threads 206 define a substantially constant outer diameter OD1 along the shaft 204 from the proximal end 204a to the distal end 204b. Alternatively, the outer diameter OD1 of the threads 206 may increase in the direction from the distal end 204b toward the proximal end 204a. Thus, the threads 206 disposed at the proximal end 204a can define a larger outer diameter than the outer diameter of the threads 206 disposed at the distal end 204b. It will be appreciated that the first bone anchor 200 can be provided as a set screw. Alternatively, the first bone anchor 200 can be provided as a compression screw, nail, rivet, or pin, if desired, with a smooth or ribbed shaft.

[0016] As illustrated in FIG. 4, the thread 206 defines a substantially constant outer diameter OD1 along the shaft 204 from the proximal end 204a to the distal end 204b. Alternatively, the outer diameter OD1 of the thread 206 may increase in a direction from the distal end 204b towards the proximal end 204a. Thus, the thread 206 disposed at the proximal end 204a can define an outer diameter larger than the outer diameter of the thread 206 disposed at the distal end 204b. It will be appreciated that the first bone anchor 200 can be provided as a set screw.

[0017] Referring to FIGS. 4, 5A and 5B, the shaft 204 defines at least one shaft bore 205 that extends through the shaft 204 from one position on the outer surface 207 of the shaft 204 to another position on the outer surface 207. The shaft bore 205 is located between the proximal end 204a and the distal end 204b of the shaft 204. The shaft bore 205 can extend about a shaft bore axis S1 and have a substantially cylindrical shape. As illustrated, the shaft bore axis S1 is substantially perpendicular to the central axis L1 of the shaft 204. Alternatively, the shaft bore axis S1 can extend at an angle that is not perpendicular to the central axis L1, if desired. It will be appreciated that the shaft 204 may alternatively define more than one shaft bore (see FIG. 13).

[0018] The shaft bore 205 can be surrounded by the shaft 204 along a plane perpendicular to the shaft bore axis S1. The shaft bore 205 is configured to internally accommodate at least one auxiliary shaft anchor 400 (for example, a third bone anchor). The shaft bore 205 can include helical threads that continuously extend spirally around the inner surface within the bore 205. Alternatively, the shaft bore 205 may be partially threaded or unthreaded for internally accommodating the third bone anchor 400. The shaft bore 205 can have a substantially circular cross-sectional dimension (for example, diameter). In an aspect, the diameter of the shaft bore 205 is smaller than the cross-sectional dimension (for example, diameter) of the head bore 216.

[0019] The shaft bore 205 can include a first portion 209 that extends from a first position on the outer surface 207 to a second portion 211. The second portion 211 extends from the first portion 209 to a second position on the outer surface 207. The first portion 209 can define a substantially conical shape that tapers in the direction of the second portion 111. Thus, the cross-sectional dimension of the first portion 209 at the outer surface 207 is larger than the cross-sectional dimension of the first portion 209 at a position spaced from the outer surface 207 to the second portion 211. When the auxiliary shaft anchor 400 is inserted into the shaft bore 205, the head 402 of the auxiliary shaft anchor 400 can abut the first portion 209. In some examples, the first portion 209 may not be threaded. In other examples, the first portion 209 can be threaded, such that the first portion 209 and the head 402 of the auxiliary shaft anchor 400 are threadedly engaged with each other. In an aspect, the head 402 of the auxiliary shaft anchor 400 can be fully nested within the first portion 209 of the shaft bore 205. Thus, no portion of the head 402 extends out of the first portion 209 and along the shaft axis S1. However, it should be understood that a portion of the head 402 can alternatively extend out of the outer surface 207 of the shaft. The second portion 211 can define a substantially cylindrical shape that is configured to receive the shaft 404 of the auxiliary shaft anchor 400.

[0020] Referring to FIG. 2, the head 202 includes an annular body 210 that defines a radially inner surface 212, an opposing radially outer surface 214, a proximal or upper end 202a, and a distal or lower end 202b. The annular body 210 can define the shape of a segment of a cone. For example, the outer surface 214 of the head 202 can be tapered radially outward in a direction from the distal end 202b to the proximal end 202a. The proximal end 202b has a cross-sectional dimension (e.g., diameter) smaller than the cross-sectional dimension (e.g., diameter) of the proximal end 202a. In an alternative embodiment, the annular body 210 can define the shape of a segment of a sphere that has a larger cross-sectional dimension at a position between the proximal end 202a and the distal end 202b. Thus, the outer surface 214 can be spherical or, if not, convex. In other alternative embodiments, the head 202 can be considered to be any other suitable alternative shape if desired.

[0021] The distal end 202b of the head 202 is placed adjacent to the proximal end 204a of the shaft 204. Alternatively, the distal end 202b of the head 202 may be spaced apart from the proximal end 204a of the shaft 204 by a neck (not shown). This neck can include a threaded region and / or a non-threaded region.

[0022] The head 202 includes helical threads 218 that extend radially outward from the head 202 at the positions of the proximal end 202a and the distal end 202b and at positions therebetween. The threads 218 are configured to engage the underlying bone, and thus the entire head 202 can be threaded. Alternatively, the head 202 may not be threaded and / or may be partially threaded. For example, the portion of the head 202 located in the direction of the distal end 202b can be threaded, and the portion of the head 202 located in the direction of the proximal end 202a may not be threaded.

[0023] The outer surface 214 of the head 202 extends concentrically around the central head axis C1 and can define a frustum. The central head axis C1 extends in a direction perpendicular to the proximal end 202a and the distal end 202b of the head 202. In an aspect, the cross-sectional dimensions of the outer surface 214 may increase in the direction from the distal end 202b to the proximal end 202a of the head 202. Alternatively, the head 202 can include any desired suitable shape, such as a segment of a sphere, that has a larger diameter or cross-sectional dimension at a position between the proximal end 202a and the distal end 202b than at either the proximal end 202a or the distal end 202b.

[0024] The head 202 may also include a slot 220 located at the proximal end 202a. The slot 220 extends from the edge of the head 202 that defines the proximal end 202a in the direction of the distal end 202b. The slot 220 is configured to receive the instrument therein to prevent the first bone anchor 200 from rotating during insertion of the assembly and / or fixation system 100 into the bone 90. The head 202 can include one or more slots 220 as desired.

[0025] The inner surface 212 of the head 202 defines at least one head bore 216 extending from the annular body 210 along the central bore axis H1 (see FIG. 4). The central bore axis H1 extends at an angular offset with respect to the central axis L1 such that the shaft 204 does not interfere with the bore 216. In an aspect, the head bore axis H1 extends in the same plane as the shaft bore axis S1. In an aspect, the head bore axis H1 can intersect the shaft bore axis S1 at a location outside the bone anchor 200. The head 202 includes a plurality of helical threads 219 on the head bore 216 that extend in a radially inward direction from the radially inner surface 212 of the annular body 210. In an aspect, the head bore 216 may be threadless or partially threaded. The central bore axis H1 of the head bore 216 intersects the central axis L1 of the shaft 204 so as to define an acute angle α. The angle α can be between 0° and 90°. In an aspect, the angle α can be between approximately 20° and 70°. In another aspect, the angle α can be between approximately 40° and 50°. In yet another aspect, the angle α can be approximately 45°. One or more slots 220 may form part of the head bore 216. It will be appreciated that the head 202 may alternatively define more than one head bore (see FIGS. 13 and 14).

[0026] The inner surface 212 of the head 202 can further define a hexagonal structure, or a structure of any alternative shape, that can be engaged by a screwdriver device that rotates the head 202 when the first bone anchor 200 is fixed to the bone.

[0027] The central head axis C1 of the head 202 and the central axis L1 of the shaft 204 are substantially coaxial. Both the central head axis C1 and the axis L1 are angularly offset from the central bore axis H1 of the bore 216. Alternatively, the central head axis C1 may be coaxial with the central bore axis H1 such that both the central head axis C1 and the central bore axis H1 are angularly offset from the central axis L1 of the shaft 204. For example, referring to FIG. 7, the shaft 204 of the first bone anchor 200 may be angularly offset with respect to one or both of the central head axis C1 and the central bore axis H1. Further, the central bore axis H1 can be parallel to or coincide with the central head axis C1. Alternatively, the central head axis C1 and the central bore axis H1 may be angularly offset from each other.

[0028] With reference to FIGS. 8-9, the auxiliary head anchor 300 (e.g., the second bone anchor) will now be described. As specifically noted above, the second bone anchor 300 can include a head 302 and a shaft 304 extending from the head 302 along an individual central shaft axis L2. The shaft 304 can be longer than, shorter than, or substantially the same as the longitudinal length of the shaft 204 of the first bone anchor 200. The shaft 304 defines a proximal or upper end 304a and a distal or lower end 304b that are longitudinally opposed to each other, respectively. The head 302 extends from the proximal end 304a of the shaft 304. The auxiliary head anchor 300 can include at least one helical thread 306 extending radially outward from the shaft 304. The helical thread 306 can extend outward from any position of the shaft 304, if desired. For example, in one example, the helical thread 306 can extend from the proximal end 304a to the distal end 304b. Thus, substantially the entire shaft 304 can be threaded. Alternatively, the helical thread can extend along any portion of the shaft 304 between the proximal end 304a and the distal end 304b. The distal end 304b can include cutting flutes or can be configured to be pressed into a pre-drilled hole. The helical thread 306 can be configured to threadedly engage with the underlying bone. The thread 306 defines a constant outer diameter OD2 over the entire exemplary proximal end 304a and distal end 304b. Alternatively, the outer diameter of the thread 36 can increase in the proximal direction from the distal end 304b to the proximal end 304a with respect to the shaft 204 of the first bone anchor 200, as described above. The outer diameter OD2 can be larger than, smaller than, or substantially the same as the outer diameter OD1. The thread 306 can define the same pitch or a different pitch than the thread 206 of the first bone anchor 200.

[0029] The head 302 includes an annular body 310 that defines a radially inner surface 312, an opposing radially outer surface 314, a proximal or upper end 302a, and a distal or lower end 302b. The outer surface 314 can define a frustoconical shape that extends concentrically about the axis C2 and has an outer diameter OD3 or a cross-sectional dimension that increases in the direction from the distal end 302b to the proximal end 302a of the head 302, as illustrated. Alternatively, the head 302 can be considered to be any suitable alternative shape desired, such as a segment of a sphere, as illustrated, having a larger cross-sectional dimension (e.g., diameter) at a position between the proximal end 302a and the distal end 302b than at either the proximal end 302a or the distal end 302b. In the illustrated embodiment, the central axis C2 is parallel to and coincides with or is collinear with the longitudinal axis L2 of the shaft 304, but it should be understood that the central axis C2 can be angularly offset from the longitudinal axis L2 if desired.

[0030] The distal end 302b of the head 302 is connected to the proximal end 304a of the shaft 304 either directly or indirectly, as illustrated, via a non-threaded neck 315 of the type described above, to the first bone anchor 200. The head 302 includes a helical thread 318 that extends radially outwardly from the outer surface 314 of the annular body 310. It will be understood that the second bone anchor 300 can be provided as a set screw, as illustrated. Alternatively, the second bone anchor 300 can be a compression screw, nail, rivet, or pin, as desired, provided as a pin having a smooth or ribbed shaft.

[0031] The head 302 further defines a central axis D2, which is defined by a proximal end 302a and a distal end 302b. In particular, the central axis D2 extends in a direction perpendicular to the proximal end 302a and the distal end 302b. The central axis C2 of the head 302 extends parallel to the direction extending between the proximal end 302a and the distal end 302b in the illustrated embodiment. Thus, in the illustrated embodiment, the axes C2 and D2 coincide or are aligned, and thus extend parallel to, coincide with, or are aligned with the longitudinal axis L2. It will be appreciated that the proximal end 302a and the distal end 302b may be geometrically configured such that the axes C2 and D2 are angularly offset from each other.

[0032] The threads 318 of the head 302 define an outer diameter OD3 that increases in the direction from the distal end 302b of the head 302 to the proximal end 302a of the head 302. Thus, the outer diameter of the threads 318 is larger at the proximal end 302a than at the distal end 302b. The inner diameter of the threads 219 of the head bore 216 of the first bone anchor 200 can define a cross-sectional dimension (e.g., inner diameter) that increases in the direction from the distal end to the proximal end of the bore 216. Thus, the threads 318 of the head 302 of the second anchor member 300 are configured to mate with the threads 219 of the head bore 216 of the first anchor member 200. It will be appreciated that the cross-sectional dimensions (e.g., diameters) of the threads 219 and 318 can be constant throughout the corresponding proximal and distal ends.

[0033] The auxiliary shaft anchor 400 will be described here with reference to FIGS. 10-11. The third bone anchor 400 includes a head 402 and a shaft 404 extending from the head 402 along an individual central axis L3. The shaft 404 can be longer, shorter, or substantially the same as the longitudinal length of the shaft 204 of the first bone anchor 200 or the shaft 304 of the second bone anchor 300. The shaft 404 defines a proximal or upper end 404a and a distal or lower end 404b that face each other in the longitudinal direction, respectively. The third bone anchor 400 includes a head 402 extending from the proximal end 404a of the shaft 404. The third bone anchor can include an embodiment that is substantially similar to the embodiment of the second bone anchor 300.

[0034] The helical threads 406 extend radially outward from the shaft 404 at the positions of the proximal end 404a and the distal end 404b and the positions therebetween, configured to engage the underlying bone. Accordingly, substantially the entire length of the shaft 404 can be threaded. The threads 406 define a constant outer diameter OD4 over the entire proximal end 404a and distal end 404b as illustrated, but the threads 406 can alternatively increase in the manner described above from the distal end 404b to the proximal end 404a with respect to the shaft 204 of the first bone anchor 200. The outer diameter OD4 can be larger, smaller, or substantially the same as the outer diameter OD1 of the shaft 204 of the first bone anchor 200 or the outer diameter OD2 of the shaft 304 of the second bone anchor 300. The threads 406 can define the same pitch or a different pitch as the threads 206 of the first bone anchor 200 and the threads 306 of the second bone anchor 300. In an embodiment, the outer diameter OD1 of the first bone anchor 200 is less than approximately 4.0 mm, the outer diameter OD2 of the second bone anchor 300 is less than approximately 3.0 mm, and the outer diameter OD4 of the third bone anchor 400 is less than approximately 2.0 mm. In an embodiment, the outer diameter OD4 of the third bone anchor 400 is between approximately 1.0 mm and 2.0 mm.

[0035] The head 402 includes an annular body 410 that defines a radially inner surface 412, an opposing radially outer surface 414, a proximal or upper end 402a, and a distal or lower end 402b. The outer surface 414 can define a frustoconical shape that extends concentrically about the axis C3 and has an outer diameter OD5 or a cross-sectional dimension that increases in the direction from the distal end 402b to the proximal end 402a of the head 402, as illustrated. Alternatively, the head 402 can be considered to be of any suitable alternative shape, such as a segment of a sphere, as illustrated, having a larger cross-sectional dimension (e.g., diameter) at a position between the proximal end 402a and the distal end 402b than at either one of the proximal end 402a and the distal end 402b. In the illustrated embodiment, the central axis C3 is parallel to and coincides with or is collinear with the longitudinal axis L3 of the shaft 404, but it should be understood that the central axis C3 can be angularly offset from the longitudinal axis L3 if desired. In an aspect, the head 402 can include a configuration that is substantially similar to the configuration of the head 302 of the second bone anchor 300.

[0036] The distal end 402b of the head 402 is connected to the proximal end 404a of the shaft 404, either directly or indirectly, as illustrated, via a threadless neck 415 of the type described above, relative to the first bone anchor 200. The head 402 includes a helical thread 418 that extends radially outwardly from the outer surface 414 of the annular body 410. The helical thread 418 is configured to threadedly engage corresponding threads of the shaft bore 205. It will be understood that the third bone anchor 400 can be provided as a set screw, as illustrated. Alternatively, the third bone anchor 400 can be a compression screw, nail, rivet, or pin, if desired, provided as a pin having a smooth or ribbed shaft.

[0037] The head 402 further defines a central axis D3, which is defined by a proximal end 402a and a distal end 402b. In particular, the central axis D3 extends in a direction perpendicular to the proximal end 402a and the distal end 402b. The central axis C3 of the head 402 extends parallel to the direction extending between the proximal end 402a and the distal end 402b in the illustrated embodiment. Thus, in the illustrated embodiment, the axes C3 and D3 coincide or are aligned in a row, and thus extend parallel to, coincide with, or are aligned in a row with the longitudinal axis L3. It will be appreciated that the proximal end 402a and the distal end 402b may be geometrically configured such that the axes C3 and D3 are angularly offset from each other.

[0038] The threads 418 of the head 402 define an outer diameter OD5 that increases in the direction from the distal end 402b of the head 402 to the proximal end 402a of the head 402. Thus, the outer diameter of the threads 418 is larger at the proximal end 402a than at the distal end 402b. The inner diameter of the threads 219 of the head bore 216 of the first bone anchor 200 can define a cross-sectional dimension (e.g., inner diameter) that increases in the direction from the distal end to the proximal end of the bore 216. Thus, the threads 318 of the head 302 of the second anchor member 300 are configured to mate with the threads 219 of the head bore 216 of the first anchor member 200. It will be appreciated that the cross-sectional dimensions (e.g., diameters) of the threads 219 and 318 can be constant throughout the corresponding proximal and distal ends.

[0039] The Anchor-in-Anchor fixation system 100 can be assembled by inserting a first bone anchor 200, a second bone anchor 300, and a third bone anchor 400 into a target region of bone. In particular, the head bore 216 of the first bone anchor 200 is configured to receive the second bone anchor 300, and the shaft bore 205 of the first bone anchor 200 is configured to receive the third bone anchor 400. During use, the surgeon forms an incision to access the target region of the underlying bone 90. Next, the first bone anchor 200 is, for example, screwed in such that the threads 206 of the shaft 204 engage and attach the first bone anchor 200 to at least one of the underlying bone segments 90a, 90b, and 90c and is pushed into the underlying bone 90. The first bone anchor 200 is inserted to a sufficient depth below segments such as bone segments 90a and 90c. The bone anchor 200 is rotated until the axis H1 of the head bore 216 and the axis S1 of the shaft bore 205 are aligned in a row at the desired fixation positions of the bone segments 90a, 90b, and 90c. Once the first bone anchor 200 is secured to the underlying bone, the second bone anchor 300 and the third bone anchor 400 are inserted into the underlying bone 90. The second bone anchor 300 is inserted through the head 202 of the first bone anchor 200. The second bone anchor 300 can be inserted into the underlying bone 90 from the same incision that receives the first bone anchor 200 or, if desired, from a second incision. The third bone anchor 400 can be inserted through the shaft 204 of the first bone anchor 200. The third bone anchor 400 can be inserted into the underlying bone 90 from the second incision or from the same incision that receives the first bone anchor 200. The bone anchors 200, 300, and 400 can be self-tapping and can thus include cutting flutes, or the bores can be pre-drilled into the bone 90 prior to inserting the anchors 200, 300, and 400 into the bone 90.

[0040] In one aspect, the first bone anchor 200 is inserted from the first fractured bone segment 90a and tightened to the third fractured bone segment 90c. The underlying bone 90 can be, if desired, a long bone such as the distal radius, or other long bones such as, for example, the femur, humorous, tibia or ulna. The second bone anchor 300 is inserted from the first fractured bone segment 90a and tightened to the second fractured bone segment 90b. The third bone anchor 400 is inserted from the third fractured bone segment 90c and tightened to the second fractured bone segment 90b. For example, the first bone anchor 200 can be tightened within the shaft or intramedullary portion of the patient's distal radius, while the second bone anchor 300 and the third bone anchor 400 can be tightened to the head portion of the fractured patient's radius. In this regard, the anchor-in-anchor fixation system 100 can be used to fix a radial fracture. It will be appreciated that the fixation system 100 and surgical method using this system can be applicable to other surgical procedures for connecting one or more bones or bone fragments.

[0041] FIG. 12 illustrates an exploded perspective view of an anchor-in-anchor fixation system 100 according to an aspect of the present disclosure. The other diameter OD2 of the thread 306 of the second bone anchor 300 is smaller than the inner diameter of the head bore 216 of the first bone anchor 200, such that the shaft 304 can be linearly pushed in from the head bore 216. Alternatively, the outer diameter OD2 can be sized such that when the second bone anchor 300 rotates therein, the thread 306 can engage the thread 219 of the head bore 216. The thread 318 on the outside of the head 302 of the second bone anchor 300 is configured to fit with the thread 219 of the head bore 216. The shaft 304 of the second bone anchor 300 can be pushed in from the head bore 216 of the first bone anchor 200 until either the distal end 304b of the shaft 304 engages the underlying bone 90 or the thread 318 engages and is fixed to the thread 219 of the head bore 216.

[0042] In an aspect, another diameter OD4 of the thread 406 of the third bone anchor 400 is smaller than the inner diameter of the shaft bore 205 of the first bone anchor 200, such that the shaft 404 can be linearly pushed into the shaft bore 205. Alternatively, the shaft bore 205 may be threaded, such that the outer diameter OD4 is sized such that when the third bone anchor 400 rotates therein, the thread 406 engages the thread of the shaft bore 205. The thread 418 outside the head 402 of the third bone anchor 400 is configured to mate with the thread of the shaft bore 205. The shaft 404 of the third bone anchor 400 can be pushed into the shaft bore 205 of the first bone anchor 200 until the distal end 404b of the shaft 404 engages the underlying bone 90 or until the thread 418 engages or is fixed to the thread and / or inner surface of the shaft bore 20⑤ For example, only a portion of the shaft 404 of the third bone anchor 400 may extend from the shaft bore 205 such that the head portion 402 is spaced apart from the first bone anchor 100 and pushed into the shaft bore 205 of the first bone anchor 200 (see, e.g., FIG. 1).

[0043] The third bone anchor 400 may be aligned in a row with the shaft bore 205 of the first bone anchor 200 using a navigation system or a fiducial array system. The navigation system may include a fiducial array operably attached to the fixation system 100. The navigation system can provide spatial reference information to a surgeon performing a surgical procedure to implant the fixation system 100. The navigation system can position spatial reference points to determine the positioning of the third bone anchor 400 relative to the first bone anchor 200 and / or the patient's body structure. The navigation system is known and used in the art and can be configured to cooperate with various fiducial array systems. The navigation system can also receive information related to magnetic resonance imaging (MRI), computed tomography (CT), ultrasound imaging, or other image datasets of the underlying bone 90. The navigation system can provide real-time information that enables the surgeon to accurately align the third bone anchor 400 with the first bone anchor 200 and the target location within the patient.

[0044] While inserting the fixation system 100, the first bone anchor 200 and the second bone anchor 300 can be rotated relative to each other so that the shaft 304 of the second bone anchor 300 advances longitudinally into the bone 90, and at the same speed as the advancement of the shaft 304 into the bone 90, the head 302 can be advanced longitudinally into the head 202 of the first bone anchor 200, and thus, the first bone anchor 200 and the second bone anchor 300 are locked to each other. In this regard, the second bone anchor 300 can be attached to the first bone anchor 200 without the first bone anchor 200 compressing the underlying bone 90. Alternatively, the head 302 of the second bone anchor 300 may not have threads, or may be partially threaded, and the inner surface of the head bore 216 may not have threads, or may be partially threaded, such that when the head 302 of the second bone anchor 300 engages the head 202 of the first bone anchor, the first bone anchor 200 compresses the underlying bone 90. The radially inner surface 312 of the head 302 can be engaged by driving a device that pushes the second bone anchor through the head bore 216 and into the underlying bone 90. In an aspect, when the second bone anchor 300 is inserted from the head bore 216, an instrument can be used to grip and / or fix the first bone anchor 200 and prevent rotation of the first bone anchor 200.

[0045] In an aspect, the second bone anchor 300 engages the underlying bone 90 before engaging the threads 318 of the second bone anchor with the threads 219 of the first bone anchor 200. Once the first bone anchor 200 and the second bone anchor 300 are fully fitted, at least a portion of the head 302 of the second bone anchor 300 is nested within the head 202 of the first bone anchor 200. In an aspect, the head 302 is fully nested within the head 202 such that the distal end 202a of the first bone anchor 200 is positioned distally relative to the distal end 302a of the second bone anchor 300.

[0046] After the first bone anchor 200 and the second bone anchor 300 are inserted into the underlying bone 90, the third bone anchor 400 can be inserted through the shaft bore 205 of the first bone anchor 200 and tightened against the underlying bone 90 as described above. The first bone anchor 200, the second bone anchor 300, and the third bone anchor 400 can each be arranged in a row in the same plane. The third bone anchor 400 can provide additional stability to the fixation system 100. For example, if the third bone anchor 400 is inserted through the shaft bore 205 and is angularly offset from the shaft 204 of the first bone anchor 200, the first bone anchor 200 and the second bone anchor 300 can be substantially prevented from moving distally away from their respective intended target positions within the underlying bone 90. In an aspect, the third bone anchor 400 can be substantially perpendicular to the shaft 204 of the first bone anchor 200. Alternatively, the third bone anchor 400 can be angularly offset from the shaft 204 of the first bone anchor 200 at an angle less than 90 degrees.

[0047] The anchor-in-anchor fixation system 100 can be used to treat simple fractures, comminuted fractures, and even more complex fractures. The anchor-in-anchor fixation system 100 can be applied within the bone surface of the underlying bone 90, thus restoring and stabilizing the body structure and thereby causing bone healing while generally eliminating the protrusions associated with plating.

[0048] Figures 13 and 14 illustrate a perspective view and a top view of an alternative aspect of the anchor-in-anchor fixation system 100 according to an aspect of the present disclosure. Alternatively or additionally, the fixation system 100 can include a plurality (e.g., more than one) of head bores and a plurality of shaft bores. The fixation system 100 includes bone anchors 200', a plurality of head anchors 300', 300'', and 300''', and a plurality of shaft anchors 400' and 400''. Each of the head anchors 300', 300'', and 300''' can be inserted from an individual head bore of the bone anchor 200' substantially in the same manner as the second bone anchor 300 is inserted from the head bore 216 of the first bone anchor 200 as described above. The head anchors 300', 300'', and 300''' can have substantially similar cross-sectional dimensions (e.g., diameter). Alternatively, the head anchors 300', 300'', and 300''' can have substantially similar cross-sections and / or can have different cross-sectional dimensions from each other. The individual heads of the individual head anchors 300', 300'', and 300''' can each be either fully nested or partially nested within the head of the bone anchor 200'. Each of the head anchors 300', 300'', and 300''' can be spaced apart from each other around the head 200'.

[0049] Shaft anchors 400' and 400'' may each be inserted from the respective shaft bores of bone anchor 200' substantially in the same manner as third bone anchor 400 is inserted from the shaft bore 205 of first bone anchor 200. Shaft anchors 400' and 400'' may each extend through bone anchor 200' substantially parallel to each other. Alternatively, shaft anchor 400' may be angularly offset from shaft anchor 400'' when each of shaft anchors 400' and 400'' is positioned within the shaft. As illustrated, bone anchor 200' includes three head bores and two shaft bores. It will be understood that bone anchor 200' may include more or fewer head bores and shaft bores configured to accommodate individual head anchors and shaft anchors.

[0050] The anchor-in-anchor fixation system 100 can be used with various instruments for inserting, positioning, and aligning the system 100 within the bone. For example, for performing a medical procedure, a targeting device, probe, locator, sensor, magnetic field generator, guide wire, hook removal device, or other instrument / component can be used with the system 100. The anchor-in-anchor fixation system 100 can be used for long bone applications, artificial shoulder joints, spinal applications, and can be used for stand-alone fixation where the bone anchor directly secures the underlying bone segment, or can include one or more auxiliary fixation devices such as bone plates, pins, screws, implants, and spacers. It should be noted that none of the anchor-in-anchor systems described herein are intended to be limited to any particular treatment and / or use, unless specifically stated otherwise.

[0051] It will be understood that the foregoing description provides examples of the disclosed system and method. However, it is contemplated that other implementations of the present disclosure may differ in detail from the foregoing examples. All references to the present disclosure or its embodiments are intended to refer to the particular embodiments being discussed at that time and are not intended to suggest any limitation as to the scope of the present disclosure more generally. All statements of distinction and negation with respect to specific features are intended to indicate a lack of preference for those features, but are not intended to exclude such features entirely from the scope of the present disclosure, absent a contrary indication.

[0052] 〔Embodiments〕 (1) A bone anchor configured to be fixed to bone, a head, a shaft extending along a shaft axis from the head and configured to be pressed into bone, and comprising the bone anchor defining a shaft bore extending along a shaft bore axis that is angularly offset with respect to the shaft axis through the shaft, bone anchor. (2) The bone anchor according to Embodiment 1, wherein the head defines a head bore extending through the head along a head bore axis. (3) The bone anchor according to Embodiment 2, wherein the head bore axis and the shaft bore axis intersect each other. (4) The bone anchor according to Embodiment 2, wherein the shaft axis and the head bore axis define an angle in the range of approximately 40° to approximately 50°. (5) The bone anchor according to Embodiment 2, wherein the shaft bore has a cross-sectional dimension smaller than the cross-sectional dimension of the head bore.

[0053] (6) The bone anchor according to Embodiment 1, wherein the shaft axis and the shaft bore axis are substantially perpendicular to each other. (7) A bone fixation system configured to be fixed to bone, the bone anchor according to Embodiment 1, and An auxiliary shaft anchor sized to extend through the shaft bore of the bone anchor and configured to be pressed into bone, A bone fixation system comprising the same. (8) The head of the bone anchor defines a head bore that extends through the head along the head bore axis, and the bone fixation system, An auxiliary head anchor sized to extend through the head bore and configured to be pressed into bone, The bone fixation system according to embodiment 7, further comprising the same. (9) The bone fixation system according to embodiment 8, wherein the head bore axis is angularly offset with respect to the shaft axis of the bone anchor. (10) The bone fixation system according to embodiment 8, wherein the head bore is threaded.

[0054] (11) The bone fixation system according to embodiment 7, wherein the auxiliary shaft anchor includes an auxiliary shaft, and at least one of the shaft of the bone anchor and the auxiliary shaft is threaded. (12) The bone fixation system according to embodiment 7, wherein the shaft bore is threaded. (13) The bone fixation system according to embodiment 12, wherein the auxiliary shaft anchor includes an auxiliary shaft head, and the auxiliary shaft head is configured to be screwed into the shaft bore in a threaded manner. (14) The bone fixation system according to embodiment 8, including an auxiliary head, wherein the auxiliary head anchor is configured to be disposed at least partially within the head of the bone anchor. (15) The bone fixation system according to embodiment 7, wherein an outer surface of the head of the bone anchor is tapered radially outward in a direction from the shaft to an upper end of the head.

[0055] (16) A method of fixing a bone fixation system to a first bone segment of the distal radius and a second bone segment of the distal radius, Inserting a bone anchor into a first target position within the distal radius, the bone anchor including a head and a shaft extending along a shaft axis from the head, the shaft defining a shaft bore extending through the shaft along a shaft bore axis Inserting an auxiliary shaft anchor through the shaft bore so as to connect to a second target position within the distal radius A method comprising the steps above (17) The head defines a head bore extending through the head along a head bore axis, and the method further includes Inserting an auxiliary head anchor through the head bore to a third target position within the distal radius, the method according to embodiment 16 (18) Adjusting the bone anchor such that the head bore defines a trajectory for inserting the auxiliary head anchor into at least one of the first bone segment and the second bone segment The method according to embodiment 17, further comprising the step above (19) Adjusting the bone anchor such that the shaft bore defines a trajectory for inserting the auxiliary shaft anchor into at least one of the first bone segment and the second bone segment The method according to embodiment 16, further comprising the step above (20) The method according to embodiment 16, wherein the shaft of the bone anchor and the shaft of the auxiliary shaft anchor are substantially perpendicular to each other

Claims

1. A bone fixation system configured to be fixed to a bone, comprising a bone anchor, the bone anchor including a head defining a threaded head bore extending through the head along a head bore axis, and a shaft extending from the head along a shaft axis and configured to be driven into the bone, the shaft having threads on an outer surface thereof, the bone anchor defining a threaded shaft bore extending along a shaft bore axis that is angularly offset with respect to the shaft axis and passing through the shaft, an auxiliary shaft anchor inserted through the threaded shaft bore along the shaft bore axis and driven into the bone, the auxiliary shaft anchor having a threaded first head configured to threadedly engage the threaded shaft bore, and an auxiliary head anchor inserted through the threaded head bore along the head bore axis and sized to be driven into the bone, the auxiliary head anchor having a threaded second head configured to threadedly engage the threaded head bore, the bone fixation system comprising the above.

2. The bone fixation system according to claim 1, wherein the head bore axis and the shaft bore axis intersect each other.

3. The bone fixation system according to claim 1, wherein the shaft axis and the head bore axis define an angle in the range of 40° to 50°.

4. The bone fixation system according to claim 1, wherein the threaded shaft bore has a cross-sectional dimension smaller than the cross-sectional dimension of the threaded head bore.

5. The bone fixation system according to claim 1, wherein the shaft axis and the shaft bore axis are substantially perpendicular to each other.

6. The bone fixation system according to claim 1, wherein the head bore axis is angularly offset with respect to the shaft axis of the bone anchor.

7. The bone fixation system according to claim 1, wherein the auxiliary shaft anchor includes an auxiliary shaft having threads thereon.

8. The bone fixation system according to claim 1, wherein an outer surface of the head of the bone anchor is tapered radially outward in a direction from the shaft to an upper end of the head.

Images