Matrix implant

Abstract

An implant for fusing or fixating two bone segments is described.SOLUTION: The implant 10 can be used to fuse or fixate the sacroiliac joint. The implant can have a matrix structure, have a straight cross-sectional area, and have a curvature.SELECTED DRAWING: Figure 7D

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention generally relate to bone implants that can be used to fuse two bone segments together. [Background technology]

[0002] Many types of hardware are available for fixation of fractured bones and for fixation of bones that are to be fused (arthrodesed).

[0003] For example, the human pelvic girdle (see Figures 1 and 2) is composed of three large bones joined by three relatively immobile joints. One of these bones is called the sacrum, which lies at the base of the lumbar spine and connects to the L5 vertebra. The other two bones are commonly called "hip bones," technically the right and left iliacus. The sacrum connects to both hip bones at the sacroiliac joints (SI joints for brevity).

[0004] The SI joints play a role in the transmission of force from the spine to the lower extremities and vice versa. The SI joints have been described as the pain generator in up to 22% of low back pain patients.

[0005] Sacroiliac joint fusion is typically indicated as a surgical procedure (e.g., for degenerative pelvic sacroiliitis, inflammatory sacroiliitis, iatrogenic instability of the sacroiliac joint, sclerotic sacroiliitis, or traumatic fracture-dislocation of the pelvis) to relieve pain originating from the SI joint. Currently, screws with plates are used for sacroiliac fusion. At the same time, cartilage must be removed from the "synovial" portion of the SI joint. This requires a large incision to access the damaged, partially dislocated, dislocated, fractured, or degenerated joint. The large incision and removal of tissue causes significant trauma to the patient, resulting in pain and increased healing time after surgery.

[0006] Additionally, screw-type implants are prone to rotation and loosening, especially in joints exposed to torsional forces (SI joints). Excessive movement of the implant after implantation can result in failure of the implant to integrate and fuse with the bone, which can lead to the need to remove and replace the failed implant.

[0007] Therefore, it would be desirable to provide an implant for bone fusion or fixation that resists rotation, can be implanted using minimally invasive procedures, and / or can be used to rescue a failed implant. Summary of the Invention

[0008] FIELD OF THE INVENTION This invention relates generally to bone implants that can be used to fuse two bone segments together.

[0009] In some embodiments, an implant for SI joint fixation or fusion is provided. The implant can include an elongate body having a longitudinal axis and a linear cross-sectional shape transverse to the longitudinal axis. The elongate body has a proximal end and a distal end. The elongate body can include a plurality of apical posts aligned with the longitudinal axis and extending between the proximal and distal ends of the elongate body, a plurality of support posts extending from one apical post to the other to form a matrix structure, and a first guide pin receiver disposed along the longitudinal axis of the elongate body.

[0010] In some embodiments, the linear cross-sectional shape is triangular.

[0011] In some embodiments, the linear cross-section is rectangular or square in shape.

[0012] In some embodiments, the elongate body is curved along the longitudinal axis from the proximal end to the distal end of the elongate body, hi some embodiments, the elongate body has a curvature of between about 5 degrees and about 45 degrees.

[0013] In some embodiments, the elongate body has a curvature of between about 15 degrees and about 30 degrees.

[0014] In some embodiments, the guide pin receiver has a circular opening adapted to securely receive the guide pin.

[0015] In some embodiments, the elongate body is coated with a plasma spray of titanium.

[0016] In some embodiments, the elongate body is coated with hydroxyapatite.

[0017] In some embodiments, the elongate body is made of metal.

[0018] In some embodiments, the metal is titanium.

[0019] In some embodiments, the metal comprises a lattice structure.

[0020] In some embodiments, the lattice structure is cubic.

[0021] In some embodiments, the lattice structure is hexagonal.

[0022] In some embodiments, the lattice structure comprises a plurality of beams with diameters between about 100 microns and about 1000 microns.

[0023] In some embodiments, the elongate body is made of a ceramic material.

[0024] In some embodiments, the elongate body is made of a plastic material.

[0025] In some embodiments, the elongate body has a porous outer surface.

[0026] In some embodiments, all of the struts are covered with a porous surface.

[0027] In some embodiments, all of the struts are preferentially covered with a porous surface.

[0028] In some embodiments, the porous outer surface has a pore size of about 100 microns to about 1000 microns.

[0029] In some embodiments, the thickness of the apical and support posts is from about 1 mm to about 5 mm.

[0030] In some embodiments, the first guide pin receiver is located at the distal end of the elongate body.

[0031] In some embodiments, the first guide pin receiver is located at the proximal end of the elongate body.

[0032] In some embodiments, a first guide pin receiver is located at the distal end of the elongate body, and a second guide pin receiver is located at the proximal end of the body.

[0033] In some embodiments, the implant can further include a continuous cannula extending between the first guide pin receiver and the second guide pin receiver.

[0034] In some embodiments, a third guide pin receiver is located between the first guide pin receiver and the second guide pin receiver.

[0035] In some embodiments, a plurality of pin receivers are located between the first guide pin receiver and the second guide pin receiver.

[0036] In some embodiments, a modular implant for fixating or fusing an SI joint is provided. The modular implant includes a distal section including a frame coupled to a distal guide pin receiver and a plurality of linearly arranged lateral support struts, a proximal section including a frame coupled to a proximal guide pin receiver and a plurality of linearly arranged lateral support struts, and at least one repeating internal section. The at least one repeating internal section includes a plurality of apical struts joined together with angled support struts arranged diagonally between the apical struts, a plurality of linearly arranged lateral support struts at both the proximal and distal ends of the repeating internal section and arranged orthogonally to the apical struts, and an internal guide pin receiver secured to the support struts and aligned with both the distal and proximal guide pin receivers. At least one internal repeating portion is positioned between the distal and proximal portions such that the lateral support struts of the distal portion are aligned with the lateral support struts of the first set of internal repeating portions and the lateral support struts of the proximal portion are aligned with the lateral support struts of the second set of internal repeating portions.

[0037] In some embodiments, the angled support columns are arranged in an "X" configuration. In some embodiments, the angled support columns are arranged in a non-overlapping diagonal configuration.

[0038] In some embodiments, the apex posts and support posts are arranged and spaced to receive bone graft material from the outer surface toward the center of the implant.

[0039] In some embodiments, the transplant material is an autograft.

[0040] In some embodiments, the transplant material is an allograft.

[0041] In some embodiments, the graft material is a bone morphogenetic protein.

[0042] In some embodiments, the implant does not have struts extending from the outer surface towards the center of the implant, thereby forming cavities for receiving graft material and / or guide pins.

[0043] The novel features of the invention are set forth with particularity in the claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: [Brief explanation of the drawings]

[0044] [Figure 1] An anterior anatomical view of the human pelvic girdle with the sacrum and hip bones (right and left ilium). The sacrum is connected to both hip bones at the sacroiliac joints (SI joints for simplicity). [Figure 2] Posterior anatomical view of the human pelvic girdle with the sacrum and hip bones (right and left ilium). The sacrum is connected to both hip bones at the sacroiliac joints (SI joints for simplicity). [Figure 3] 1A-1C are various linear implant embodiments that can be used to fuse or fixate a joint or two bone segments. [Figure 4] 1A-1C are various linear implant embodiments that can be used to fuse or fixate a joint or two bone segments. [Figure 5] 1 illustrates an axial cross-sectional view of the SI joint with an implant for SI joint fixation using a lateral approach across the ilium, SI joint, and sacrum S1. [Figure 6] 1 illustrates an axial cross-sectional view of the SI joint with an implant for SI joint fixation using a posterolateral approach entering through the iliac spine posterior to the ilium, curving through the SI joint, and terminating at the ala of the sacrum. [Figure 7A] 1 illustrates various embodiments of an implant having a matrix structure formed from a plurality of struts. [Figure 7B] 1 illustrates various embodiments of an implant having a matrix structure formed from a plurality of struts. [Figure 7C] 1 illustrates various embodiments of an implant having a matrix structure formed from a plurality of struts. [Figure 7D] 1 illustrates various embodiments of an implant having a matrix structure with multiple pin receivers. [Figure 7E] 1 illustrates various embodiments of an implant having a matrix structure with multiple pin receivers. [Figure 7F] 1 illustrates various embodiments of an implant having a matrix structure with multiple pin receivers. [Figure 7G] 10 illustrates another embodiment of an implant having a matrix structure from various angles and cross sections. [Figure 7H] 10 illustrates another embodiment of an implant having a matrix structure from various angles and cross sections. [Figure 7I] 10 illustrates another embodiment of an implant having a matrix structure from various angles and cross sections. [Figure 8] 1 illustrates an embodiment of a fenestrated implant. [Figure 9A] 1 illustrates various cross-sectional shapes of implant microstructures, which are formed with shape-changing trabecular microstructures. [Figure 9B] 1 illustrates various cross-sectional shapes of implant microstructures, which are formed with shape-changing trabecular microstructures. [Figure 9C] 1 illustrates various cross-sectional shapes of implant microstructures, which are formed with shape-changing trabecular microstructures. [Figure 9D] 1 illustrates various cross-sectional shapes of implant microstructures, which are formed with shape-changing trabecular microstructures. [Figure 10A] 1 illustrates various alternative beam microstructures. [Figure 10B] 1 illustrates various alternative beam microstructures. [Figure 10C] 1 illustrates various alternative beam microstructures. [Figure 11A] 1 illustrates various sizes for the beams that form the implant microstructure. [Figure 11B] 1 illustrates various sizes for the beams that form the implant microstructure. [Figure 11C] 1 illustrates various sizes for the beams that form the implant microstructure. [Figure 11D] 1 illustrates various sizes for the beams that form the implant microstructure. [Figure 12] 1 illustrates an embodiment of a curved matrix implant. [Figure 13] 1 illustrates an embodiment of a modular matrix implant. DETAILED DESCRIPTION OF THE INVENTION

[0045] Figures 3 and 4 illustrate a linear implant 10 with a solid, elongated body 12 that can be used to fixate or fuse two bone segments. The implant 10 shown in Figure 3 is cylindrical and can optionally have threads along the outside of the implant body. As mentioned above, cylindrical, threaded implants can be subject to excessive rotation. One solution to this problem is the implant 10 in Figure 4, which has a non-cylindrical cross-sectional area. For example, as shown, the implant 10 can have a triangular cross-sectional area, although other linear cross-sectional profiles, including rectangular, hexagonal, etc., can also be used. A non-cylindrical implant does not need to have a strictly linear cross-sectional shape to resist rotation. A non-circular cross-sectional area will generally be sufficient. For example, a teardrop-shaped cross-sectional area or a cross-sectional area with at least one vertex can resist rotation. Other non-circular cross-sectional shapes that do not have a linear component, such as an oval cross-section, can also work.

[0046] Figure 5 illustrates insertion of the implant 10 of Figures 3 or 4 across the SI joint using a lateral approach, crossing the ilium, across the SI joint, and into the sacrum. Figure 6 illustrates insertion of the same implant across the SI joint using a posterolateral approach, entering from the iliac spine posterior to the ilium, curving through the SI joint, and terminating at the ala of the sacrum. Many of the implants described herein may be inserted across the SI joint in a similar manner.

[0047] Matrix Implant In some embodiments, it may be desirable to provide the implant with an open-frame structure that can be filled with bone graft material and / or biological aid, while providing sufficient strength to facilitate articulation or fusion of two bone segments without bending or failure of the implant.

[0048] One method for providing an open frame structure is to configure the elongated body 12 of the implant 10 using a matrix structure, as illustrated in Figures 7A-7C and 7G-7I. In some embodiments, each face or side of the elongated body 12 can be configured using a matrix structure. The implant 10 can have a linear overall cross-sectional shape transverse to a longitudinal axis extending through the length of the elongated body 12. Each corner or apex of the elongated body 12 is formed by an apex strut 14 extending between the proximal end 16 and the distal end 18 of the elongated body 12. An implant with a triangular overall cross-sectional shape will have three apex struts, while an implant with a square or rectangular overall cross-sectional shape will have four apex struts, etc. To form the face of the implant, the support struts 20 are arranged in various matrix configurations.

[0049] For example, Figure 7A illustrates one embodiment of a matrix structure in which support struts 20 extend diagonally between two apex struts 14 and cross one another in an "X" configuration so that the support struts 20 define triangular and square openings. Additional lateral support struts can also be added, extending between the two apex struts at right angles to both apex struts. The lateral support struts can be positioned between the support struts of the "X" and / or across the middle or intersection of the support struts of the "X."

[0050] 7B illustrates another embodiment of a matrix structure in which support struts 20 are arranged in a horizontal pattern with alternating diagonals. In this embodiment, all of the diagonal support struts on one side of the implant are angled in the same direction so that the diagonal support struts lie parallel to one another. The support struts 20 define triangular openings.

[0051] 7C further illustrates another embodiment of a matrix structure in which support posts 20 are arranged in an alternating diagonal, horizontal pattern. In this embodiment, the diagonal support posts are angled in an alternating pattern such that they are oriented approximately 90 degrees from each other to form a zigzag pattern. The support posts 20 define triangular openings.

[0052] Various matrix structures can provide different levels of resistance to the various forces to which the implant is exposed, including compressive, tensile, shear, bending, and torsional forces.

[0053] 8 illustrates an alternative using a matrix structure to provide openings. The implant 10 can have an elongate body 12 with fenestrations 22. As shown, the fenestrations 22 can be circular or can be of different sizes, e.g., in an alternating pattern of large and small fenestrations. The fenestrations 22 can alternatively be rectilinear, such as triangular, square, or rectangular, or curvilinear, such as elliptical, oval, or circular.

[0054] In some embodiments, the fenestrations 22 may be triangular, square, rectangular, or a combination thereof, and are arranged to form a matrix structure. In other words, the openings in Figures 7A-7B defined by the support posts 20 can be considered fenestrations 22.

[0055] The walls of the elongate body 12 can be flat, as described above, or formed from support struts 20 and / or fenestrations 22, as shown in Figures 7G-7I. Using flat walls to form the elongate body 12 can result in a hollow cavity with the same or similar cross-sectional shape as the overall implant. For example, an implant with a triangular overall cross-sectional shape can have a cavity with a triangular cross-sectional shape. The thickness of the walls and apical and support struts can be from about 1 mm to about 5 mm, or from about 1 mm to about 3 mm. Additionally, the distal ends of the walls can be tapered.

[0056] To facilitate the use of conventional guide pins with these implants, the distal end of the implant can include a distal guide pin receptacle 24 with an opening 26 sized and shaped to receive a guide pin, as shown in FIGS. 7A-8. For example, the opening 26 can be rounded to receive a typical guide pin. In some embodiments, the proximal end can additionally or alternatively have a proximal guide pin receptacle with an opening sized and shaped to receive a guide pin. In some embodiments, a continuous cannula can extend from the proximal guide pin receptacle to the distal guide pin receptacle. In some embodiments, multiple individual and co-linear guide pin receptacles can be present within the implant body between the proximal and distal guide pin receptacles.

[0057] For example, FIG. 7D illustrates another embodiment of a matrix structure similar to the embodiment shown in FIG. 7A with support posts 20 extending diagonally between the apical posts 14 in an "X" configuration. However, in this embodiment, the implant 10 has a proximal guide pin receiver 28 located at the proximal end of the implant, a distal guide pin receiver 24 located at the distal end of the implant, and multiple internal guide pin receivers 30 disposed along the longitudinal axis of the implant. The internal guide pin receivers 30 can be attached to the support posts 20 and / or the apical posts 14. As shown, the internal guide pin receivers 30 are attached at the intersection points of the "X"-shaped support posts 20. In addition to receiving guide pins, the internal guide pin receivers 30 can provide additional support and bracing to the matrix structure.

[0058] FIG. 7E illustrates another embodiment of a matrix structure similar to the embodiment shown in FIG. 7D. Both embodiments have "X"-shaped support columns 20 and multiple internal guide pin receptacles 30. However, this embodiment has additional support columns 20 extending laterally between the apex columns 14 at right angles. The lateral support columns can be positioned between the "X"-shaped support columns as shown or integrated into the "X"-shaped support columns. The lateral support columns can provide additional support and bracing to the matrix structure.

[0059] Figure 7F illustrates another embodiment of a matrix structure similar to the embodiment shown in Figure 7D. However, instead of having multiple guide pin receptacles, the implant 10 has a single guide pin receptacle 32 extending from the proximal end to the distal end of the implant. This guide pin receptacle 32 can be a tube or cannula that can be attached to the support post 20. In some embodiments, the tube or cannula can also have multiple fenestrations 34. In some embodiments, the fenestrations 34 can be positioned along the openings in the support post. The fenestrations 34 promote bone ingrowth and allow for the introduction of bone graft material through the implant, while the tube supports the support post 20.

[0060] 7G-7I illustrate another embodiment of a matrix structure similar to the embodiment shown in FIG. 7E. This embodiment has "X"-shaped support posts 20 and additional support posts 20 extending laterally between the apical posts 14 at right angles. One difference between this embodiment and the embodiment illustrated in FIG. 7E is that while the embodiment disclosed in FIG. 7E has generally circular support posts 20 and apical posts 14, the support posts 20 and apical posts 14 in this embodiment have generally straight cross-sectional shapes. In some embodiments, the apical posts 14 can be chamfered to remove sharp edges and apexes of the implant. Additionally, this embodiment can have a distal guide pin receptacle 24 and a proximal guide pin receptacle, but unlike some of the embodiments described above, it can lack an internal guide pin receptacle. Instead, the guide pins can be internally supported by the inherent cross-sectional shape of the apical posts and / or support posts. Any of the embodiments herein can have a cross-section that is straight, circular, or a combination of the two shapes. While tubular struts are sometimes welded together, the use of straight struts allows for fabrication of the matrix implant by laser cutting the wall structure. Laser-cut structures can be structurally stronger than welded structures, which is important for supporting large loads applied to the implant after implantation. The distal end 18 of the implant 10 can have one or more openings 29 that allow graft material to be injected distally through the implant after implantation. Additionally, any of the embodiments described herein can optionally have an internal guide pin receiver or omit the internal guide pin receiver. Figure 7H illustrates a cross-section through a transverse strut, and Figure 7I illustrates a cross-section through an "X"-shaped support strut.

[0061] Implants, including the apex and / or support struts of the matrix, as well as the beams that form the microstructure, can have a variety of shapes. For example, the beams and / or struts can have cross sections that are curved, straight, or a combination of the two, as illustrated in Figures 9A-9D. For example, the beams and / or struts can have a circular cross section as shown in Figure 9A, a curved cross section as shown in Figures 9B and 9C, or a square or rectangular cross section as shown in Figure 9D. It should be understood that the corners and edges of the beams and / or struts can be rounded, if desired.

[0062] Implants can be made of a variety of materials. For example, implants can be made of metals or alloys, such as titanium or steel, or non-metallic materials, such as ceramics or polymers. In some embodiments, the implant material can have a lattice microstructure formed from trabecular particles. For example, the lattice microstructure of the apical posts, support posts, and other parts of the implant can have a rough or smooth surface texture, depending on the surface treatment techniques used, such as polishing or application of a metal plasma spray, and the size and shape of the trabeculae that form the lattice microstructure. For example, Figures 10A-10C illustrate various trabecular microstructures that can form the trabecular microstructure. Figure 10A illustrates a cubic trabecular structure, Figure 10B illustrates a hexagonal trabecular structure, and Figure 10C illustrates an octagonal trabecular structure. Other trabecular structures include tetragonal, rhombohedral, orthorhombic, monoclinic, and triclinic trabeculae. Figures 11A-11D illustrate that the trabeculae can have a variety of sizes. For example, Figures 11A-11D illustrate beams with diameters of about 100 microns, about 200 microns, about 350 microns, about 500 microns, and about 1000 microns. In other embodiments, the size of the beams can vary from 50 microns to 5000 microns.

[0063] Matrix implants can be manufactured using a variety of techniques. For example, matrix implants can be 3D printed using rapid prototyping techniques, including additive manufacturing, as described in U.S. Patent Publication No. 2010 / 0161061, which is incorporated by reference in its entirety for all purposes. 3D printed matrix implants can be made of metal, polymer, or ceramic materials. For example, metal powders (e.g., titanium powder) may be fused together to form the implant structure. Other techniques include cutting fenestrations or openings, using, for example, a laser to form apical and support posts, or using electrical discharge machining (EDM) to create the matrix or fenestrations.

[0064] 3D printing allows the porosity of the implant to be controlled. For example, the implant can have a volume porosity of about 30 percent to about 70 percent, with an average pore size of 100 microns to 1000 microns. The porosity can be mostly interconnected, mostly disconnected, or a mixture of interconnected and disconnected porosity. In some embodiments, the porosity can be located throughout the implant material, including the apical and support struts, and on all or some of the strut surfaces, including the inner and outer implant surfaces. For example, the fusion of trabecular particles to form the struts can result in a porous, semi-porous, or non-porous structure, depending on the degree of fusion between the trabecular particles. In other embodiments, the pores can be located in a porous coating that can be applied to the implant. For example, the porous coating can be applied using a titanium plasma spray process or a plasma spray process of another metal. The coating can be applied to the outer surface of the implant, the inner surface of the implant, or both the outer and inner surfaces of the implant. For example, a coating may be applied preferentially to the outer surface of a matrixed implant to provide bone ingrowth and overgrowth. The inner portion of the implant may be uncoated to maximize bone penetration within the implant. Furthermore, the coating may be applied preferentially from proximal to distal, or vice versa. The thickness of the porous coating may be from about 500 microns to about 1500 microns. In addition to or as an alternative to a porous metal coating, a hydroxyapatite coating may also be applied to the implant. In some embodiments, the porosity may vary along the length of the implant. In some embodiments, the thickness of the coating may vary along the length of the implant. In some embodiments, the thickness of the coating applied to the outer surface may differ from the thickness of the inner coating. For example, in some embodiments, the outer coating may be thicker than the inner coating.In other embodiments, the thickness of the inner and outer coatings may be the same.

[0065] 12, the apical post 14 can be curved from the proximal end to the distal end of the apical post 14, thereby resulting in a curved matrix implant 10 similar to the curved implant described in co-pending U.S. Provisional Application No. 62 / 052,318, filed September 18, 2014, and entitled "Implant for Bone Fixation or Fusion," which is incorporated herein by reference in its entirety for all purposes.

[0066] The length of the implant can vary from about 25 mm to about 95 mm. The matrix structure can be modular, as shown in FIG. 13, allowing the length of the implant to be varied by adding additional repeating subunits during implant design and / or fabrication. For example, a modular matrix implant 130 can have a distal end portion 132, a proximal end portion 134, and one or more repeating interior portions 136. The distal end portion 132 can have a distal guide pin receiver 138. The proximal end portion 134 can also have a proximal guide pin receiver 136, as in the embodiment described above. The repeating interior portion 136 can have an apical post 140 and a support post 142, as described above. For example, as shown, the support post 142 can have an "X" configuration and be located between two lateral support posts 144. The two lateral support struts 144 can be halves of perpendicular lateral support struts, such that when two repeating interior portions 136 are joined together, the two halves of the support struts fuse to form an overall lateral support strut. The proximal end portion 134 and the distal end portion 132 can have joints formed from halves of the lateral support struts 144 that can fuse with the halves of the lateral support struts 144 of the repeating interior portions 136. In some embodiments, the repeating interior portions 136 can have internal guide pin receivers 146.

[0067] In some embodiments, the length of the repeating interior portion 136 can be about 10 mm. In other embodiments, the length can be about 5 mm to about 25 mm. In some embodiments, the repeating interior portion 136 can have support struts forming halves of an "X," such that the repeating interior portion is arranged in an alternating pattern to form "X"-shaped support struts. In some embodiments, the support struts are simply diagonal struts that extend across the length of the repeating interior portion.

[0068] Embedding method Methods for implanting the various implants described herein are described in U.S. Patent Application No. 2011 / 0087294, U.S. Patent No. 8,425,570, U.S. Patent No. 8,444,693, U.S. Patent No. 8,414,648, and U.S. Patent No. 8,470,004, and co-pending U.S. Provisional Patent Application No. 61 / 891,326, each of which is incorporated herein by reference in its entirety for all purposes. These methods are particularly suitable for use with linear implants.

[0069] The curved implant illustrated in Figure 12 may require modifications to the method of insertion protocol. Because the implant is curved, it may not be possible or desirable to attempt to drive or tap the implant into the bone along a straight path using a straight guide pin, straight drill, straight broach, etc. Instead, it may be desirable to create and shape a curved insertion path that matches the curvature of the implant.

[0070] For example, a tool used to create a curved insertion path can have a radius of curvature that matches the radius of curvature of the implant. For example, some or all of the tool and implant can have matching radii of curvature. The tool, which can include guide pins, tool guides, drill bits, broaches, impact hammers, etc., can be rotatably mounted with an arm of length equal to the radius of curvature. One end of the arm is attached to the pivot, and the other end of the arm is used to secure the tool and / or implant.

[0071] The rotating arms can be used to drive curved guide pins into the bone (ilium and sacrum) to create a curved path through the bone. A relatively short drill bit with an internal bore for receiving the guide pin can be placed on the curved guide pin to drill a curved pilot hole. In some embodiments, a drill bit can be secured to the end of the curved guide with the rotating arms and can be used to drill a curved pilot hole without inserting a curved guide pin.

[0072] For curved implants with a circular cross-section, the curved implant can be advanced onto a curved guide pin and into a curved insertion path formed by a curved pilot hole. In some embodiments, the curved implant is held by a pivoting arm and inserted into the curved insertion path without the aid of a guide pin by rotating the curved arm.

[0073] For straight implants, or more generally, non-circular implants, a curved pilot hole can be created using an appropriately shaped broach that matches the overall cross-sectional shape of the implant. If present, the curved or short broach can be advanced over a curved guide pin. Otherwise, the curved or short broach is held in a pivot arm and advanced through the pilot hole with rotation of the pivot arm. As the broach advances, it shapes the pilot hole to match the shape of the implant.

[0074] The curved implant can be advanced over the curved guide pin and into the curved insertion path defined by the curved pilot hole. In some embodiments, the curved implant is held by a pivoting arm and inserted into the curved insertion path without the aid of a guide pin by rotating the curved arm.

[0075] More generally, the implants described herein can be used to fuse any two bone segments (two bones forming a joint or two bones resulting from a fracture).

[0076] Terms such as "about" and "approximately" can mean within 5 percent, 10 percent, 15 percent, 20 percent, 25 percent, or 30 percent.

[0077] It will be understood that this disclosure is, in many respects, merely illustrative of numerous alternative device embodiments of the present invention. Changes in detail may be made, particularly with respect to the shape, size, materials, and arrangement of the various device components, without departing from the scope of various embodiments of the present invention. Those skilled in the art will appreciate that the illustrated embodiment and its description as a whole are merely illustrative of the invention. While several principles of the present invention have been demonstrated in the above-described exemplary embodiments, those skilled in the art will appreciate that modifications in structure, arrangement, size, elements, materials, and methods of use may be utilized in practicing the invention and otherwise specifically adapted to particular environmental and operational requirements without departing from the scope of the present invention. In addition, although certain features and elements have been described in connection with particular embodiments, those skilled in the art will appreciate that these features and elements may be combined with other embodiments disclosed herein.

[0078] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 62 / 052,379, filed September 18, 2014, which is incorporated herein by reference in its entirety for all purposes.

[0079] Incorporation by Reference All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

Claims

1. 1. An implant for fixating or fusing a SI joint, comprising: an elongate body having a longitudinal axis and a linear general cross-sectional shape transverse to said longitudinal axis, said elongate body having a proximal end having a proximal guide pin receptacle and a distal end having a distal guide pin receptacle, said elongate body comprising: a plurality of apex posts aligned with the longitudinal axis and extending between the proximal and distal ends of the elongate body; a plurality of support struts extending from one apex strut to another apex strut to form a matrix structure; an internal guide pin receiver secured to the support post and / or the apex post, positioned along the longitudinal axis of the elongate body, and aligned with both the distal guide pin receiver and the proximal guide pin receiver.

2. The implant of claim 1 , wherein the overall cross-sectional shape of the straight line is triangular.

3. The implant of claim 1 , wherein the overall cross-sectional shape of the straight line is rectangular or square.

4. The implant of claim 1 , wherein the elongate body is curved along the longitudinal axis from the proximal end to the distal end of the elongate body.

5. The implant of claim 1 , wherein the distal guide pin receiver has a circular opening adapted to securely receive a guide pin.

6. 10. The implant of claim 1, wherein the elongate body is coated with a plasma spray of titanium.

7. The implant of claim 1 , wherein the elongate body is coated with hydroxyapatite.

8. The implant of claim 1 , wherein the elongate body is made of metal.

9. The implant of claim 8, wherein the metal is titanium.

10. The implant of claim 8 , wherein the metal comprises a lattice structure.

11. The implant of claim 10, wherein the lattice structure is cubic.

12. 11. The implant of claim 10, wherein the lattice structure is hexagonal.

13. 11. The implant of claim 10, wherein the lattice structure comprises a plurality of beams with diameters of about 100 microns to about 1000 microns.

14. The implant of claim 1 , wherein the elongate body is made of a ceramic material.

15. The implant of claim 1 , wherein the elongate body is made of a plastic material.

16. The implant of claim 1 , wherein the elongate body has a porous outer surface.

17. 17. The implant of claim 16, wherein the porous outer surface has a pore size of about 100 microns to about 1000 microns.

18. 10. The implant of claim 1, wherein the apex struts and support struts have a thickness of about 1 mm to about 5 mm.

19. The implant of claim 1 , wherein a plurality of guide pin receptacles are located between the proximal guide pin receptacle and the distal guide pin receptacle.

20. 1. A modular implant for fixation or fusion of a SI joint, comprising: a distal portion comprising a frame coupled to a distal guide pin receiver and a plurality of linearly arranged lateral support struts; a proximal portion comprising a frame coupled to a proximal guide pin receiver and a plurality of linearly arranged lateral support struts; a plurality of top supports connected to one another by inclined support supports disposed diagonally between the top supports; a plurality of lateral support struts arranged perpendicular to the top strut, the lateral support struts being arranged in a linear fashion at both the proximal and distal ends of the repeating interior portion; at least one repeating internal portion secured to the support post and / or the apical post and comprising an internal guide pin receiver aligned with both the distal guide pin receiver and the proximal guide pin receiver; and at least one repeating internal portion positioned between the distal portion and the proximal portion such that the lateral support struts of the distal portion are aligned with the lateral support struts of a first set of the repeating internal portion and the lateral support struts of the proximal portion are aligned with the lateral support struts of a second set of the repeating internal portion.

21. 21. The modular implant of claim 20, wherein the angled support struts are arranged in an "X" configuration.

22. 21. The modular implant of claim 20, wherein the angled support struts are arranged in a non-overlapping diagonal configuration.

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