Fenestrated implant

Abstract

To provide implants used in medical procedures such as bone fixation or fusion, specifically fenestrated implants used in bone fixation or fusion.SOLUTION: In some embodiments, an implant for bone fixation is provided. The implant can comprise an elongate body having a longitudinal axis and a rectilinear cross section transverse to the longitudinal axis, a plurality of faces, a plurality of apexes joining the plurality of faces, a central lumen extending along the longitudinal axis of the elongate body, and a plurality of holes with openings on the plurality of faces, wherein the holes are in fluid communication with the central lumen.SELECTED DRAWING: Figure 1B

Description

[Technical field]

[0001] This application relates generally to implants used in medical procedures such as bone fixation or fusion. More specifically, this application relates to fenestrated implants used in bone fixation or fusion. [Background technology]

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

[0003] For example, the human pelvic girdle is made up of three large bones connected by three relatively immovable joints. One of these bones is called the sacrum, and sits at the base of the lumbar spine. It connects to the L5 vertebra. The other two bones are commonly called the "hip bones," and technically the right ilium and left ilium. The sacrum connects to both hip bones at the sacroiliac joints, or SI joints for short.

[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 generators responsible for up to 22% of low back pain.

[0005] To relieve pain generated from the SI joint, sacroiliac joint fusion is typically indicated as a surgical treatment for, for example, degenerative sacroiliac pelvic malunion, inflammatory sacroiliac malunion, iatrogenic instability of the sacroiliac joint, sclerotic sacroiliac malunion, or traumatic fracture-dislocation. Currently, screws and screws with plates are used for sacroiliac fusion.

[0006] To promote bone growth into the implant as well as enhance integration of the implant with bone, pockets or channels are created in the implant that promote bone growth into the implant. However, the pockets or channels may weaken the structural integrity of the implant, which may be required to withstand large stresses. Therefore, it would be desirable to provide an implant with pockets or channels to promote bone growth while substantially maintaining the structural integrity of the implant. Summary of the Invention

[0007] This invention relates generally to implants used in medical procedures such as bone fixation or fusion. More specifically, this application relates to fenestrated implants used in bone fixation or fusion.

[0008] In some embodiments, an implant for bone fixation is provided that can include an elongate body having a longitudinal axis and a linear cross-section perpendicular to the longitudinal axis, a plurality of faces and a plurality of apexes connecting the faces, a central lumen extending along the longitudinal axis of the elongate body, and a plurality of holes having openings on the faces, the holes being in fluid communication with the central lumen.

[0009] In some embodiments, the holes are circular. In some embodiments, the holes are oval. In some embodiments, the holes are arranged in a single longitudinal row on each face. In some embodiments, the holes are arranged in multiple longitudinal rows on each face.

[0010] In some embodiments, the elongated body is covered with a biologic aid.

[0011] In some embodiments, the holes have a diameter approximately equal to the diameter of the central lumen, hi some embodiments, the holes have a diameter between about 0.2 and about 0.5 times the width of the face.

[0012] In some embodiments, an implant for bone fixation is provided that can include an elongate body having a longitudinal axis and a linear cross-section perpendicular to the longitudinal axis, a plurality of faces, a plurality of apices connecting the faces, a central lumen extending along the longitudinal axis of the elongate body, and a plurality of side pockets extending along a portion of each of the faces, the side pockets having a depth that does not extend into the central lumen.

[0013] In some embodiments, each of the multiple faces has only one side pocket. In some embodiments, each of the side pockets is centered on each of the faces. In some embodiments, the side pockets have a width that is about 0.2 to about 0.8 times the width of the face and a length that is about 0.5 to about 0.9 times the length of the face.

[0014] In some embodiments, the implant further comprises a plurality of holes within the side pockets, the holes being in fluid communication with the central lumen.

[0015] In some embodiments, an implant for bone fixation is provided that can include an elongate body having a longitudinal axis and a linear cross-section perpendicular to the longitudinal axis, a plurality of faces, a plurality of apices connecting the faces, and a central lumen extending along the longitudinal axis of the elongate body, each of the apices including a groove extending along a length of the apices.

[0016] In some embodiments, an implant for bone fixation is provided that can include an elongate body having a longitudinal axis and a linear cross-section perpendicular to the longitudinal axis, a plurality of faces, a plurality of apices connecting the faces, and a central lumen extending along the longitudinal axis of the elongate body, each of the apices including a plurality of pockets located at discrete points along a length of the apices.

[0017] In some embodiments, an implant for bone fixation is provided that can include an elongate body having a longitudinal axis, a distal end, a proximal end, and a linear cross-section perpendicular to the longitudinal axis, a plurality of faces, each face formed from a wall having a thickness of about 2 mm to about 3 mm, and a plurality of fenestrations disposed on each face.

[0018] In some embodiments, the distal end of the elongate body is formed into one or more cutting edges.

[0019] In some embodiments, the linear cross section has three sides. In some embodiments, the linear cross section has four sides.

[0020] In some embodiments, the fenestrations are located on a distal portion of the elongate body configured to be implanted within the patient's sacrum, while a proximal portion of the elongate body configured to be implanted within the ilium is devoid of fenestrations.

[0021] In some embodiments, the fenestrations are arranged in a staggered pattern.

[0022] In some embodiments, the implant further includes a cap at a proximal end of the elongate body, the cap having a hole sized to receive the guide pin.

[0023] In some embodiments, the elongated body has porous inner and outer surfaces. In some embodiments, the elongated body has roughened inner and outer surfaces. In some embodiments, the elongated body has plasma coated inner and outer surfaces. In some embodiments, the elongated body has inner and outer surfaces that are covered with a biological aid. In some embodiments, the biological aid is a bone morphogenic protein.

[0024] The novel features of the invention are set forth with particularity in the following 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. [Brief description of the drawings]

[0025] [Figure 1A] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1B] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1C] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1D] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1E] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1F] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1G] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1H] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1I] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1J] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1K] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1L] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1M] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1N] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1O] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1P] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1Q] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1R] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1S] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1T] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1U] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 1V] 1 illustrates various embodiments of implant structures with different fenestrations. [Figure 2A] FIG. 1 is a side cross-sectional view of the formation of a blanched hole in a bone according to one embodiment of the present invention. [Figure 2B] FIG. 1 is a side cross-sectional view of the formation of a blanched hole in a bone according to one embodiment of the present invention. [Figure 2C] FIG. 1 is a side cross-sectional view of the formation of a blanched hole in a bone according to one embodiment of the present invention. [Figure 2D] FIG. 1 is a side cross-sectional view of the formation of a blanched hole in a bone according to one embodiment of the present invention. [Figure 2E] 1 illustrates the assembly of a soft tissue protector system for placement over a guidewire. [Figure 2F] 1 illustrates the assembly of a soft tissue protector system for placement over a guidewire. [Diagram 3] A diagram of the anterior part of the human pelvic girdle, including the sacrum and hip bones (right ilium and left ilium), where the sacrum is connected to both hip bones at the sacroiliac joints (SI joints). [Figure 4]An anterior-posterior view of the human pelvic girdle, including the sacrum and hip bones (right ilium and left ilium), where the sacrum is connected to both hip bones at the sacroiliac joints (SI joints). [Diagram 5] 1 is a diagram of the anatomy shown in a previously implanted fluoroscopy. Implantation of three implant structures for SI joint fixation uses a lateral approach through the ilium, through the SI joint, and into the sacrum. [Figure 6] 1 is a diagram of the anatomy shown in an implanted fluoroscopy. Implantation of three implant structures for SI joint fixation uses a lateral approach through the ilium, through the SI joint, and into the sacrum. [Figure 7A] 1 is a diagram of the anatomy shown in an anterior view of the implant. Implantation of three implant structures for SI joint fixation uses a lateral approach through the ilium, through the SI joint, and into the sacrum. [Figure 7B] 1 is a diagram of the anatomy shown in craniocaudal cross section after implantation. Implantation of three implant structures for SI joint fixation uses a lateral approach through the ilium, through the SI joint, and into the sacrum. [Figure 8A] 1 illustrates another embodiment of an implant structure having fenestrations. [Figure 8B] 1 illustrates another embodiment of an implant structure having fenestrations. [Figure 9A] 1 illustrates yet another embodiment of an implant structure having fenestrations. [Figure 9B] 1 illustrates yet another embodiment of an implant structure having fenestrations. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Long, stemmed implant structures 20 such as that shown in FIG 1A allow for minimally invasive fixation of the SI joint (shown in anterior-posterior views in FIGS. 3 and 4, respectively). These implant structures 20 are effectively implanted through the use of a lateral surgical approach. The procedure is desirably assisted by conventional lateral and / or anterior-posterior (AP) visualization techniques (e.g., using an x-ray image intensifier (C-arm or fluoroscope) to generate a live video feed that is displayed on a television screen).

[0027] In some embodiments, the implant structure 20 can include pockets, passages, cavities, openings, fenestrations, channels, and / or recesses that allow bone graft materials to be incorporated into the implant structure. These bone graft materials can promote bone growth into and / or around the implant structure. The bone graft materials can reduce the time it takes for the implant structure to become stable and integrated into the bone. The bone graft material can be applied to and / or injected into the implant structure prior to implantation, or applied after implantation by injection of the bone graft material into a proximal cannula or other tube. In some embodiments, the surfaces of the implant structure 20 can be roughened or textured to promote bone growth and attachment of the bone graft material. The interior and / or exterior surfaces can be roughened or textured by mechanical means or spray coated with a material that is roughened.

[0028] The bone graft material may be in a liquid, gel, slurry, paste, powder or other form and may include a biologic aid that may promote and / or enhance bone ingrowth and tissue repair and / or reduce inflammation, infection and pain. For example, the biologic aid may include growth factors such as bone morphogenetic proteins (BMPs), e.g., hydroxyapatite, demineralized bone, morselized autograft or allograft bone in a liquid or slurry carrier, and drugs that reduce inflammation, infection or pain (painkillers, antibiotics and steroids). In some embodiments, the growth factors may be human recombinant growth factors, such as hr-BMP-2 and / or hr-BMP-7 or other human recombinant forms of BMPs. The carrier for the biologic aid may be a liquid or gel (saline or collagen gel). The biologic aid may be encapsulated or incorporated in a controlled release formulation so that the biologic aid is released to the patient over an extended period of time at the implant site. For example, a controlled release formulation may be configured to release biological aid over a period of days, weeks, or months, over the estimated time it will take for the implant site to heal. The amount of biological aid delivered to the implant structure can be controlled using a variety of techniques, including controlling or varying the amount of coating material applied to the implant and / or controlling or varying the amount of biological aid incorporated within the coating. Controlling the amount of biological aid delivered may be important, since excessive use of some biological aid may result in adverse effects (e.g., radicular pain).

[0029] In general, any pockets, passages, cavities, openings, fenestrations, channels, and / or recesses in an implant structure may weaken its structural strength, including, for example, bending strength and shear strength. The following example of an implant structure is a variation of the solid triangular implant structure 20 of FIG. 1A. It has a single central longitudinally oriented lumen or cannula for receiving a guide wire or guide pin. The relative bending strength and shear strength are compared to the cannulated but solid implant structure 20 of FIG. 1A. It can be assigned a bending strength of 1.00 and a shear strength of 1.00. The relative bending strength and shear strength can be improved or optimized for structural strength and bone grafting facilitation capabilities by varying the size, number, spacing, location, orientation, and shape of the pockets, passages, cavities, openings, fenestrations, channels, and / or recesses. Although the illustrated embodiment in this application shows a triangular implant structure, implant structures with different rectilinear shapes, such as a rectangle or square, can be used or substituted in place of the triangular implant structure.

[0030] 1B-1D illustrate an embodiment of a triangular implant structure 100 having a central lumen 101 and a series of holes 102 on each face 103 of the implant structure 100 that reach and provide access to the central lumen 101. The holes 102 can be centered on the face 103 and extend inwardly at an angle that is substantially perpendicular or orthogonal to the face 103 of the implant structure 100. In some embodiments, each of the apexes 104 can be chamfered or rounded. In some embodiments, the distal end 105 of the implant structure 100 can be tapered to facilitate embedding in bone. In some embodiments, the diameter of the holes 102 can be equal or substantially equal to the diameter of the central lumen 101. In other embodiments, the diameter of the holes 102 can be greater than or less than the diameter of the central lumen 101. 1B-1D has a relative bending strength of about 0.82 and a relative shear strength of about 0.66. In some embodiments, to inject or load bone graft material into the implant structure 100, the distal holes 106 of the central lumen 101 are blocked or sealed, so that the flow of bone graft material fills the central lumen 101 and exits the side holes 102.

[0031] In some embodiments, the holes 102 can have a diameter (D1) that is about 0.3 times the width (W1) of the surface 103 of the implant structure 100. In some embodiments, the holes 102 can have a diameter greater than about 0.3 times the width of the surface 103 of the implant structure 100. In some embodiments, the holes 102 can have a diameter less than about 0.3 times the width of the surface 103 of the implant structure 100. In some embodiments, the holes 102 can have a diameter between about 0.2 times and about 0.5 times the width of the surface 103 of the implant structure. In some embodiments, the holes 102 can be separated from adjacent holes 102 by a distance of about 2 / 3 times the hole diameter. The separation distance (S1) is measured by the distance between the perimeters of the holes 102. In some embodiments, the holes 102 can be separated from adjacent holes 102 by a distance less than about 2 / 3 times the hole diameter. In some embodiments, the holes 102 can be separated from adjacent holes 102 by a distance greater than about 2 / 3 times the hole diameter. In some embodiments, the holes 102 can be spaced apart from adjacent holes 102 by a distance of about 0.5 to about 2 times the diameter of the holes 102, or by a distance of about 0.5 to about 1 time the diameter of the holes 102. In some embodiments, the relative bending strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative bending strength can be about 0.5 to about 0.9. In some embodiments, the relative shear strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative shear strength can be about 0.5 to about 0.9.

[0032] 1E-1G illustrate another embodiment of an implant structure 110 having a central lumen 111 and a series of slots 112 on each face 113 of the implant structure 110 that reach into and provide access to the central lumen 111. The slots 112 are centered on the face 113 and extend inwardly at an angle that is substantially perpendicular or orthogonal to the face 113 of the implant structure 110. In some embodiments, each of the apices 114 can be chamfered or rounded. In some embodiments, the distal end 115 of the implant structure 110 can be tapered to facilitate embedding in bone. In some embodiments, the width of the slots can be equal or substantially equal to the diameter of the central lumen 111. In other embodiments, the width of the slots can be greater or less than the diameter of the central lumen 111. 1E-1G has a relative bending strength of about 0.82 and a relative shear strength of about 0.66. In some embodiments, to inject or load bone graft material into the implant structure 110, the distal hole 116 of the central lumen 111 is blocked or sealed, resulting in a flow of bone graft material filling and exiting the slot 112.

[0033] In some embodiments, the slot 112 can have a width (W3) that is about 0.3 times the width (W2) of the face 113 of the implant structure 110. In some embodiments, the slot 112 can have a width that is greater than about 0.3 times the width of the face 113 of the implant structure 110. In some embodiments, the slot 112 can have a width that is less than about 0.3 times the width of the face 113 of the implant structure 110. In some embodiments, the slot 112 can have a width that is about 0.2 to about 0.6 times the width of the face 113 of the implant structure 110. In some embodiments, the slot 112 can have a length (L3) that is about 0.15 times the length (L2) of the face 113. In some embodiments, the slot 112 can have a length that is less than about 0.15 times the length of the face 113. In some embodiments, the slot 112 can have a length that is greater than about 0.15 times the length of the face 113. In some embodiments, the slots 112 can have a length of about 0.1 to about 0.4 times, or about 0.1 to about 0.25 times, the length of the face 113. In some embodiments, the slots 112 are separated from adjacent slots 112 by a distance (S2) of about 2 / 3 of the width of the slots 112. In some embodiments, the slots 112 are separated from adjacent slots 112 by a distance greater than about 2 / 3 of the width of the slots 112. In some embodiments, the slots 112 are separated from adjacent slots 112 by a distance less than about 2 / 3 of the width of the slots 112. In some embodiments, the slots 112 can be separated from adjacent slots 112 by a distance of about 0.5 to 2 times, or about 0.5 to about 1 times, the width of the slots 112. In some embodiments, the relative bending strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative bending strength can be about 0.5 to about 0.9. In some embodiments, the relative shear strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9, hi some embodiments, the relative shear strength can be from about 0.5 to about 0.9.

[0034] 1H-1J illustrate another embodiment of an implant structure 120 having a central lumen 121 and a side pocket 122 on each face 123 of the implant structure 120. The side pocket 122 can be a depression, cavity, groove, or slot centered on the face 123 having a width, length, and depth. In some embodiments, the side pocket 122 is relatively shallow and does not extend to the central lumen 121. In some embodiments, each of the apexes 124 can be chamfered or rounded. In some embodiments, the distal end 125 of the implant structure 120 can be tapered to facilitate implantation into bone. In some embodiments, the implant structure 120 illustrated in FIGS. 1H-1J has a relative bending strength of about 0.77 and a relative shear strength of about 0.72. In some embodiments, to load the bone graft material onto the implant structure 120, bone graft material is applied to the side pockets 122 prior to implantation. In other embodiments, bone graft material is applied during implantation, as further described in U.S. Patent Application No. 61 / 609,043, entitled Tissue Expanders and Protectors, which is incorporated herein by reference in its entirety and may be applicable to other implants.

[0035] In some embodiments, the side pocket 122 can have a width (W4) that is about 0.5 times the width (W5) of the face 123 of the implant structure 120. In some embodiments, the side pocket 122 can have a width greater than about 0.5 times the width of the face 123 of the implant structure 120. In some embodiments, the side pocket 122 can have a width less than about 0.5 times the width of the face 123 of the implant structure 120. In some embodiments, the side pocket 122 can have a width between about 0.2 times and about 0.8 times the width of the face 123 of the implant structure 120. In some embodiments, the side pocket 122 can have a length (L4) that is about 0.75 times the length (L5) of the face 123. In some embodiments, the side pocket 122 can have a length less than about 0.75 times the length of the face 123. In some embodiments, the side pocket 122 can have a length greater than about 0.75 times the length of the face 123. In some embodiments, the side pocket 122 can have a length of about 0.5 to about 0.9 times the length of the face 123. In some embodiments, the side pocket 122 can have a depth of about 0.2 mm to about 5 mm, about 0.2 mm to about 2 mm, or about 0.2 to about 1 mm. In some embodiments, the side pocket 122 can have a depth of about 0.25 mm, about 0.5 mm, about 0.75 mm, about 1 mm, or about 2 mm. In some embodiments, the relative flexural strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative flexural strength can be about 0.5 to about 0.9. In some embodiments, the relative shear strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative shear strength can be about 0.5 to about 0.9.

[0036] 1K-1M illustrate another embodiment of an implant structure 130 having a central lumen 131, a side pocket 132 on each face 133 of the implant structure 130, and a number of holes 134 within the side pocket 132. The side pocket 132 of the embodiment illustrated in FIGS. 1K-1M can be the same as or similar to the side pocket 122 previously described and illustrated in FIGS. 1H-1J. Similarly, the holes 134 illustrated in FIGS. 1K-1M can be the same as or similar to the holes 102 previously described and illustrated in FIGS. 1B-1D. In some embodiments, as illustrated in FIGS. 1K-1M, the holes 134 have a diameter smaller than the diameter of the central lumen 131. In other embodiments, the holes 134 have a diameter equal to or larger than the diameter of the central lumen 131. In some embodiments, each of the apexes 135 can be chamfered or rounded. In some embodiments, the distal end 136 of the implant structure 130 can be tapered to facilitate implantation into the bone. In some embodiments, the implant structure 130 depicted in FIGS. 1K-1M has a relative bending strength of about 0.74 and a relative shear strength of about 0.62. In some embodiments, to load the implant structure 130 with bone graft material, the bone graft material is injected and / or painted into the side pockets 132 and holes 134 prior to implantation. In other embodiments, the bone graft material can be injected into the central lumen 131. The central lumen 131 can have a distal opening 137 that is closed or plugged so that the bone graft material fills the central lumen 131 and exits through the holes 134, which are in fluid communication with the central lumen 131. As the bone graft material exits through the holes 134, the bone graft material can cover and fill both the holes 134 and the side pockets 132. This injection process can occur prior to implantation, during implantation, or after implantation.

[0037] In some embodiments, the side pocket 132 shown in Figures 1K-1M has the same or similar dimensions as the side pocket 122 shown in Figures 1H-1J and described above. In some embodiments, the holes 134 can have a diameter (D2) that is about 0.4 times the width (W6) of the side pocket 132. In some embodiments, the holes 134 can have a diameter that is greater than or less than about 0.4 times the width of the side pocket 132. In some embodiments, the holes 134 can be spaced apart at a distance (S3) that is about 1.5 times the diameter of the holes 134. In some embodiments, the holes 134 can be spaced apart at a distance that is greater than or less than about 1.5 times the diameter of the holes 134. In some embodiments, the relative bending strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative bending strength can be between about 0.5 and about 0.9. In some embodiments, the relative shear strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9, hi some embodiments, the relative shear strength can be from about 0.5 to about 0.9.

[0038] 1N-1P illustrate another embodiment of an implant structure 140 having a central lumen 141 and multiple peripheral lumens 142 surrounding the central lumen 141. The peripheral lumens 142 can be oriented longitudinally and can be located between the central lumen 141 and each of the apices 143. As shown, the implant structure 140 is triangular in shape and has three apices 143 and three peripheral lumens 142 surrounding the central lumen 141. In some embodiments, both the central lumen 141 and the peripheral lumens 142 can extend the entire longitudinal length of the implant structure 140. In other embodiments, the peripheral lumen 142 does not extend the entire length of the implant structure 140. And instead, the peripheral lumen 142 terminates prior to the distal end 144 of the implant structure 140. Additionally, multiple side holes 145 can be included in the implant structure 140. Each of the peripheral lumens 142 can be intersected by a number of side holes 145. Each of the side holes 145 extends between two faces 146 of the implant structure with a side hole opening 147 on each of the two faces 146. The side holes 145 can extend transversely through the implant structure 140 at an angle of about 60 degrees from the surface of the faces 146. In some embodiments, each of the apexes 143 can be chamfered or rounded. In some embodiments, the distal end 144 of the implant structure 140 can be tapered to facilitate embedding in bone. In some embodiments, the implant structure 140 illustrated in FIGS. 1N-1P has a relative bending strength of about 0.63 and a relative shear strength of about 0.66. In some embodiments, bone graft material is injected into the peripheral lumen 142 to load the implant structure 140 with the bone graft material. The bone graft material fills the peripheral lumen and exits the side holes 145. Injection of the bone graft material can occur prior to, during, or after implantation. In some embodiments in which the peripheral lumen 142 extends throughout all of the implant structure 140, the distal end of the peripheral lumen 142 is blocked or plugged prior to injection of the bone graft material.

[0039] In some embodiments, the peripheral lumen 142 has a diameter (D3) that is about 0.2 times the width (W7) of the face 146 of the implant structure. In some embodiments, the peripheral lumen 142 has a diameter that is greater than or less than about 0.2 times the width of the face 146 of the implant structure. In some embodiments, the peripheral lumen 142 can have a smaller diameter than the central lumen 141. In other embodiments, the peripheral lumen 142 can have a diameter equal to or greater than the central lumen 141. In some embodiments, the side hole 145 has a diameter (D4) that is equal to or substantially equal to the diameter of the peripheral lumen 142. In other embodiments, the side hole 145 has a diameter smaller than or greater than the diameter of the peripheral lumen 142. In some embodiments, the relative flexural strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative flexural strength can be between about 0.5 and about 0.9. In some embodiments, the relative shear strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9, hi some embodiments, the relative shear strength can be from about 0.5 to about 0.9.

[0040] 1Q-1S illustrate another embodiment of an implant structure 150 having a central lumen 151. Each of the apices 152 can be chamfered or rounded. Also, the apices 152 can have a plurality of pockets or cavities 153 located at discrete points along the length of the apices 152. These pockets 153 extend from the apices 152 toward the central lumen 151 but do not reach the central lumen 151. In some embodiments, the pockets 153 are curved cutout shaped. They can be shaped to correspond to a portion of a cylinder. In some embodiments, the distal end 154 of the implant structure 140 can be tapered to facilitate embedding in bone. In some embodiments, the implant structure 150 illustrated in FIGS. 1Q-1S has a relative bending strength of about 0.89 and a relative shear strength of about 0.86. In some embodiments, the bone graft material is applied externally to the implant structure 150, either prior to or during implantation, to load the implant structure 150. In addition to receiving the bone graft material, the pockets 153 act to eliminate or reduce corner haloing effects.

[0041] In some embodiments, the pocket 153 can have a length (L6) or diameter of about 0.06 times the length (L7) of the apex 152. In some embodiments, the pocket 153 can have a length or diameter that is greater than or less than about 0.06 times the length of the apex 152. In some embodiments, the pocket 153 can be separated from an adjacent pocket 153 by a distance (S4) of about ⅔ of the pocket length or diameter. In some embodiments, the pocket 153 can be separated from an adjacent pocket 153 by a distance greater than or less than about ⅔ of the hole diameter. In some embodiments, the relative flexural strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative flexural strength can be from about 0.5 to about 0.95. In some embodiments, the relative shear strength can be at least about 0.5, about 0.6, about 0.7, about 0.8, or about 0.9. In some embodiments, the relative shear strength may be from about 0.5 to about 0.95.

[0042] 1T-1V illustrate another embodiment of an implant structure 160 having a central lumen 161. Each of the apices 162 has a groove 163 extending along the length of the apices 162. In some embodiments, the distal end 164 of the implant structure 160 can be tapered to facilitate implantation into bone. In some embodiments, the implant structure 160 illustrated in FIGS. 1T-1V has a relative bending strength of about 0.87 and a relative shear strength of about 0.88. In some embodiments, to load the implant structure 160 with bone graft material, the bone graft material is applied externally to the implant structure 160 either prior to or during implantation. In addition to receiving the bone graft material, the groove 163 also serves to eliminate or reduce the corner haloing effect.

[0043] In some embodiments, groove 163 can be a circular notch along apex 162 having a diameter (D5) of about 0.25 times the width of face 165 and an arc length of about 0.28 times the width of face 165. In some embodiments, groove 163 can have a diameter greater than or less than about 0.25 times the width of face 165. In some embodiments, groove 163 can have an arc length greater than or less than about 0.28 times the width of face 165.

[0044] In one embodiment of the lateral approach (see FIGS. 5, 6, and 7A / B), one or more implant structures 20 are introduced laterally through the ilium, SI joint, and into the sacrum. This path and resulting placement of the implant structures 20 is best shown in FIGS. 6 and 7A / B. In the illustrated embodiment, three implant structures 20 are so placed. Furthermore, in the illustrated embodiment, the implant structures 20 are rectilinear in cross section, in this case triangular. However, it should be appreciated that implant structures 20 of other cross sections may be used. Additionally, any of the implant structures disclosed above may be used in the implantation procedures herein.

[0045] Before attempting a lateral implantation procedure, the physician will identify the SI joint segment that is to be fixed or fused (arthrodesed) using, for example, the Fortin finger test, femoral thrust, FABER, Gaenslen test, compression, distraction, and diagnostic SI joint injections.

[0046] Assisted with the lateral, entrance, and exit C-arm views, and with the patient lying prone, the surgeon aligns (using lateral visualization) the greater sciatic notch and then the alae to provide the correct lateral position. Following blunt tissue separation down to the ilium, a 3 cm incision is first made with the posterior cortex of the sacral canal aligned. From the lateral view, a guide pin 38 (e.g., a Steinmann pin with a sleeve (not shown)) is inserted, resting on the ilium in a position that is inferior to the sacral end plate and just anterior to the sacral canal. In the exit view, the guide pin 38 should be parallel to the sacral end plate with a shallow angle anteriorly (e.g., 15 to 20 degrees from horizontal, as shown in Figure 7B). In the lateral view, the guide pin 38 should be posterior to the anterior wall of the sacrum. In the entrance view, the guide pin 38 should not disrupt the sacral foramen. This generally corresponds to the sequence illustrated in Figures 2A and 2B. A soft tissue protector (not shown) is desirably slid against the ilium to firmly resist the guide pin 38 before removing the guide pin sleeve (not shown).

[0047] A pilot hole 42 is drilled in the manner previously described over the guide pin 38 (and through the soft tissue protector), as shown in Figure 2C. The pilot hole 42 extends through the ilium, through the SI joint, and into the sacrum. The drill bit 40 is then removed.

[0048] A shaped broach 44 is tapped over the guide pin 38 (and through the soft tissue protector) into the pilot hole 42 to create a broached hole 48 with the desired profile for the implant structure 20. The broached hole 48 is triangular in the illustrated embodiment. This generally corresponds to the sequence illustrated in Figure 2D. The triangular profile of the broached hole 48 is also shown in Figure 5.

[0049] 2E and 2F illustrate an embodiment of an assembly of a drill sleeve 202, a guide pin sleeve 204, a handle 206, and a soft tissue protector, expander, or delivery sleeve 200. In some embodiments, the drill sleeve 202 and the guide pin sleeve 204 can be inserted into the soft tissue protector 200 to form a soft tissue protector assembly 210 that can be slid over the guide pin 208 until bone contact is achieved. The soft tissue protector 200 can be any one of the soft tissue protectors or expanders or delivery sleeves disclosed herein. In some embodiments, an expandable expander or delivery sleeve 200 as disclosed herein can be used in place of a conventional soft tissue expander. In the case of an expandable expander, in some embodiments, the expandable expander is slid over the guide pin and then expanded before the drill sleeve 202 and / or the guide pin sleeve 204 are inserted into the expandable expander. In other embodiments, inserting the drill sleeve 202 and / or guide pin sleeve 204 into the expandable dilator can be used to expand the expandable dilator.

[0050] In some embodiments, a dilator can be used to open a channel through the tissue before sliding the soft tissue protector assembly 210 over the guide pin. The dilator can be placed over the guide pin using an expandable dilator, for example using multiple successively larger dilators. After the channel is formed through the tissue, the dilator can be removed. The soft tissue protector assembly can then be slid over the guide pin. In some embodiments, the expandable dilator can act as a soft tissue protector after expansion. For example, after expansion, a drill sleeve and a guide pin sleeve can be inserted into the expandable dilator.

[0051] As shown in Figures 5 and 6, the triangular implant structure 20 can be tapped through the ilium, across the SI joint, and through the soft tissue protector over the guide pin 38 into the sacrum until the proximal end of the implant structure 20 is flush against the lateral wall of the ilium (see also Figures 7A and 7B). The guide pin 38 and soft tissue protector are removed, leaving the implant structure 20 in the broached passage and flush against the lateral wall of the ilium (see Figures 7A and 7B). In the illustrated embodiment, two additional implant structures 20 are implanted in this manner, as best shown in Figure 6. In other embodiments, the proximal end of the implant structure 20 is left proud of the lateral wall of the ilium, such that the proximal end of the implant structure 20 extends 1 mm, 2 mm, 3 mm, or 4 mm beyond the ilium. This ensures that the implant 1020 engages the hard cortical portion of the ilium bone rather than just the soft cancellous portion. Without structural support from the hard cortical bone, the implant 1020 may shift. The hard cortical bone can also withstand the loads or forces typically applied to the bone by the implant 1020.

[0052] The implant structure 20 is sized according to the local anatomy. For the SI joint, a typical implant structure 20 size is about 35 mm to about 70 mm in length, depending on the local anatomy, and an inscribed diameter of about 7 mm (i.e., a triangle with a height of about 10.5 mm and a base of about 12 mm). The morphology of the local anatomy is generally understood by medical professionals using textbooks of human skeletal anatomy along with their knowledge of the site and its disease or injury. A physician may also confirm the size of the implant structure 20 based on prior analysis of the morphology of the target bone using, for example, plain film x-ray, fluoroscopy x-ray, or MRI or computed tomography.

[0053] Using the outside approach, as described, one or more implant structures 20 are individually inserted in a minimally invasive manner across the SI joint. Conventional tissue access tools, obturators, cannulas, and / or drills can be used for this purpose. Alternatively, the novel tissue access tools described in co-pending U.S. application Ser. No. 61 / 609,043, filed Mar. 9, 2012, entitled "Tissue Expanders and Protectors," mentioned above, can be used. No joint preparation, cartilage removal or scraping is required prior to creation of an insertion path or insertion of the implant structures 20. Thus, a minimally invasive insertion path is created that is sized at approximately the maximum outer diameter of the implant structures 20.

[0054] The implant structure 20 may eliminate the need for autogenous bone graft material, additional screws and / or rods, hollow modular fixation screws, cannulated compression screws, intra-articular threaded cages or fracture fixation screws. Additionally, at the physician's option, bone graft material and other fixation devices may be used in conjunction with the implant structure 20.

[0055] In a typical procedure, one to six, or perhaps up to eight, implant structures 20 may be used depending on the size of the patient and the size of the implant structures 20. After placement, the patient will be counseled to prevent or reduce loading of the SI joint while fusion occurs. This can be from about six weeks to about twelve weeks or longer, depending on the patient's health and adherence to post-operative protocols.

[0056] The implant structure 20 allows for a less invasive surgical technique than traditional open surgery without extensive soft tissue dissection. The lateral approach to the SI joint provides a straightforward surgical approach that complements minimally invasive surgical techniques. The profile and design of the implant structure 20 minimize or reduce rotation and micromotion. The rigid implant structure 20 made from titanium alloy provides immediate post-operative SI joint stabilization. The bone ingrowth region 24 with a porous plasma spray with an irregular surface supports stable bone fixation / fusion. The implant structure 20 and surgical approach allow for the placement of a larger fusion surface area configured to maximize post-operative weight bearing capacity and provide a biomechanically rigid implant specifically designed to stabilize the heavily loaded SI joint.

[0057] In some embodiments, as illustrated in FIGS. 8A and 8B , the implant structure 800 can have a rectilinear profile formed from multiple walls 802 having a thickness of approximately 2 mm to 3 mm, approximately 1 mm to 5 mm, or approximately 5 mm, 4 mm, 3 mm, or less than 2 mm. In some embodiments, the rectilinear profile can be triangular, square, or rectangular. In some embodiments, the implant structure 800 can have a substantially rectilinear profile formed by multiple apices connected together by multiple walls. The thin-walled implant structure 800 can be advanced through bone with little or no bone preparation. For example, in some embodiments, the implant structure 800 can be driven into bone without first forming a hole shaped similar to the implant structure 800. In some embodiments, the distal end 804 of the implant structure 800 can have a pointed and / or chisel-like cutting edge to facilitate cutting the bone as the implant structure 800 is advanced. In some embodiments, an osteotome is used to cut the bone before the implant structure 800 is inserted into the bone. An osteotome, such as that described in U.S. Provisional Application No. 61 / 800,966, filed March 15, 2013, entitled "Systems and Methods for Removing Implants," which is incorporated herein by reference in its entirety for all purposes, is configured to pre-cut the bone to facilitate insertion of the implant structure 800 without forming a complete hole. In some embodiments, a hole is formed as described above and the implant structure 800 is inserted into the hole.

[0058] In some embodiments, as illustrated in FIGS. 8A and 8B, distal portions of the walls 802 forming the implant structure 800 can have fenestrations 806. For example, the distal portion of the implant structure 800 configured to be implanted in the sacrum or second bone segment can be fenestrated, while the proximal portion of the implant structure 800 configured to be implanted in the ilium or first bone segment can be non-fenestrated. In other embodiments, the distal portion of the implant structure 800 can be non-fenestrated, while the proximal portion of the implant structure 800 is fenestrated. In other embodiments, the fenestrations can be distributed over the entire surface of each wall or each side of the implant structure, as illustrated in FIGS. 9A and 9B and in other embodiments described herein. In some embodiments, the concentration or number of fenestrations can be greater in some portions of the implant structure than in other portions of the implant structure.

[0059] In some embodiments, the fenestrations 806 may be elliptical, circular, or curvilinear, such that the fenestrations 806 do not have corners, as illustrated in Figures 8A and 8B. In some embodiments, the fenestrations 806 are staggered, interleaved, or distributed in a non-aligned pattern across each wall 802. For example, in some embodiments, each longitudinal row of fenestrations may be staggered or offset from an adjacent longitudinal row of fenestrations. In some embodiments, the fenestrations may alternatively or additionally be staggered along the longitudinal axis of the implant structure 800. This non-aligned arrangement of fenestrations may provide improved structural strength to the implant structure.

[0060] In some embodiments, the implant structure 800 is sized like other implant structures described herein. In some embodiments, the implant structure 800 is sized so that it has walls inscribed in a circle with a diameter of about 8 mm, or about 4 mm to 12 mm, as illustrated in FIG. 8B. In some embodiments, the implant structure 800 is sized so that the walls inscribe in a circle with a diameter equal to or approximately equal to the diameter of the guide pin. In some embodiments, the implant structure 800 can have a proximal end 808 with a cap 810 with a circular opening 812 to allow passage of a guide pin.

[0061] In some embodiments, as illustrated in Figures 9A and 9B, the implant structure 900 can be similar to the embodiment described in Figures 8A and 8B, except that the fenestrations 902 are evenly distributed across the surface of the implant structure. Figure 9B illustrates bone growing into and / or through the fenestrations 902 and through the lumen of the implant structure 900. In some embodiments, the bone illustrated in the lumen of the implant structure 900 can be natural bone that remains after the implant structure 900 is advanced into the bone (i.e., a self-grafted implant). In some embodiments, as with other implant structures described herein, the lumen of the implant structure 900 illustrated in Figures 9A and 9B can be filled with bone material and / or biological aids, such as morselized bone, allograft bone, autograft bone, hydroxyapatite, bone morphogenetic proteins, etc., to promote bone ingrowth within the implant structure 900. This may be appropriate when the implant structure 900 is inserted into a hole such that after implantation, the lumen of the implant structure 900 is hollow or substantially hollow and filled with bone growth promoting material. Furthermore, as described above, the inner and / or outer surfaces of the implant structure may be roughened and / or coated, for example using a plasma coating process, to provide a porous or roughened surface.

[0062] The terms "about" and "approximately" and the like mean within 10%, 20%, or 30% of a stated value or range.

[0063] Variations and modifications of the apparatus and methods disclosed herein will be readily apparent to those skilled in the art. It should therefore be understood that the foregoing detailed description and accompanying drawings are made for clarity and understanding, and are not intended to limit the scope of the present invention, which is defined by the claims appended hereto. Any feature described in any one embodiment described herein, whether preferred or not, may be combined with any other feature of any other embodiment.

[0064] It is understood that the examples and embodiments described herein are for illustrative purposes only, and in that respect, various modifications or changes will be suggested to those skilled in the art and are to be included within the spirit and scope of this application and the appended claims. All publications, patents, and patent applications cited in this application are hereby incorporated by reference for all purposes.

[0065] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 61 / 642,681, entitled "Fenestrated Implant," filed May 4, 2012, which is incorporated by reference in its entirety for all purposes.

[0066] Incorporation by Reference All publications and patent applications referenced in this specification are incorporated herein by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. For example, this application incorporates by reference U.S. Patent Publication Nos. 2011 / 0087294 and 2011 / 0118785 in their entireties.

Claims

1. An implant for bone fixation, the implant comprising: an elongated body having a longitudinal axis and a linear cross section perpendicular to the longitudinal axis; With multiple aspects, A plurality of vertices connecting the plurality of faces; a central lumen extending along the longitudinal axis of the elongate body; a plurality of holes having openings on the plurality of faces; The hole is in fluid communication with the central lumen.

2. The implant of claim 1 , wherein the holes are circular.

3. The implant of claim 1 , wherein the hole is elliptical.

4. The implant of claim 1 , wherein the holes are arranged in one longitudinal row on each of the faces.

5. The implant of claim 1 , wherein the holes are arranged in a plurality of longitudinal rows in each of the faces.

6. The implant of claim 1 , wherein the elongated body is covered with a biological support.

7. The implant of claim 1 , wherein the hole has a diameter approximately equal to a diameter of the central lumen.

8. 10. The implant of claim 1, wherein the hole has a diameter of about 0.2 to about 0.5 times the width of the face.

9. An implant for bone fixation, the implant comprising: an elongated body having a longitudinal axis and a linear cross section perpendicular to the longitudinal axis; With multiple aspects, A plurality of vertices connecting the plurality of faces; a central lumen extending along the longitudinal axis of the elongate body; a plurality of side pockets extending along a portion of each of the plurality of faces; The side pocket has a depth that does not extend into the central lumen.

10. The implant of claim 9 , wherein each of the plurality of faces has only one side pocket.

11. The implant of claim 9 , wherein each of said side pockets is centered on each of said faces.

12. 10. The implant of claim 9, wherein the side pocket has a width of about 0.2 to about 0.8 times the width of the face and a length of about 0.5 to about 0.9 times the length of the face.

13. 10. The implant of claim 9, further comprising a plurality of holes within the side pockets, the holes being in fluid communication with the central lumen.

14. An implant for bone fixation, the implant comprising: an elongated body having a longitudinal axis and a linear cross section perpendicular to the longitudinal axis; With multiple aspects, A plurality of vertices connecting the plurality of faces; a central lumen extending along the longitudinal axis of the elongate body, The implant, wherein each of the plurality of apices includes a groove extending along a length of the apices.

15. An implant for bone fixation, said implant comprising: an elongated body having a longitudinal axis and a linear cross section perpendicular to the longitudinal axis; With multiple aspects, A plurality of vertices connecting the plurality of faces; a central lumen extending along the longitudinal axis of the elongate body, The implant, wherein each of the plurality of apices includes a plurality of pockets located at discrete points along the length of each of the apices.

16. An implant for bone fixation, said implant comprising: an elongate body having a longitudinal axis, a distal end, a proximal end, and a linear cross section perpendicular to the longitudinal axis; a plurality of faces formed from walls, each face having a thickness of about 2 mm to about 3 mm; a plurality of fenestrations disposed on each of said surfaces.

17. 17. The implant of claim 16, wherein the distal end of the elongate body is formed into one or more cutting edges.

18. 17. The implant of claim 16, wherein the straight cross section has three sides.

19. 17. The implant of claim 16, wherein the straight cross section has four sides.

20. 17. The implant of claim 16, wherein a proximal portion of the elongate body configured to be implanted within an ilium is devoid of the fenestration, but the fenestration is disposed at a distal portion of the elongate body configured to be implanted within a patient's sacrum.

21. 17. The implant of claim 16, wherein the fenestrations are arranged in a staggered pattern.

22. 17. The implant of claim 16, further comprising a cap at the proximal end of the elongate body, the cap having a hole sized to receive a guide pin.

23. 17. The implant of claim 16, wherein the elongate body has porous inner and outer surfaces.

24. 17. The implant of claim 16, wherein the elongated body has roughened inner and outer surfaces.

25. 17. The implant of claim 16, wherein the elongated body has plasma coated inner and outer surfaces.

26. 17. The implant of claim 16, wherein the elongated body has inner and outer surfaces covered with a biological support.

27. 27. The implant of claim 26, wherein the biological aid is a bone morphogenetic protein.

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