Patent Publication Number: US-2020297496-A1

Title: Sacroiliac joint fusion implants and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/820,345, filed Mar. 19, 2019, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present disclosure relates to fusion surgery, and more particularly, to sacroiliac joint fusion. 
     The sacroiliac joint (the “SI joint”) is a low-motion joint that connects the hip bones to either side of the sacrum, acting primarily as a shock-absorber between the lower body and torso. Dysfunction in the SI joint can produce significant lower back pain, as well as pelvic, groin, and hip pain. This dysfunction can be the result of too much motion, too little motion, or inflammation of the joint. 
       FIGS. 1A-1B  illustrate an SI joint  100 , and  FIG. 1A  is a cross-sectional view of the SI joint  100  from an anterior approach. As shown, the SI joint  100  is located between the sacrum  102  at the base of the spine  104  (see  FIG. 1B ) and the ilium  106 , which is the upper bone of the pelvis  108  (see  FIG. 1B ), and various ligaments  110  (i.e., sacroiliac ligaments) support the SI joint  100 .  FIG. 1B  illustrates the location of the SI joint  100  from a lateral approach, relative to the spine  104  and the pelvis  108 . As shown in  FIG. 1B , impact force F from walking and other movements applies a torque T on the SI joint  100 , which is depicted with phantom lines between the spine  104  and the pelvis  108 . This torque T acting on the SI joint  100  may result in pain if there is dysfunction in the SI joint  100 . 
     Increasingly, fusion procedures (i.e., SI joint fusions) are being performed on the SI joint  100  as a treatment for various conditions and disorders. SI joint fusion immobilizes the SI joint  100  by rigidly connecting the sacrum  102  to the ilium  106 , and thereby inhibits application of the torque T on the SI joint  100 . Current SI joint fusion techniques incorporate a lateral approach to access the SI joint  100 , as illustrated in  FIG. 1B , so that a physician may drive a dowel rod or pin through the crest of the ilium  106  (i.e., the iliac crest) into the ala of the sacrum  102  to immobilize the SI joint  100 . While the lateral approach is widely utilized by physicians in the field of orthopedics, it is much less common in the field of neurosurgery where physicians often utilize a posterior approach. Thus, physicians performing SI joint fusion tend to be more familiar with posterior approaches than lateral approaches, however, the posterior approach is not presently utilized during SI joint fusion operations. Also, performing SI joint fusion via the lateral approach may not be performed simultaneous with lumbar or spinal operations using posterior approaches. Thus, for example, a physician performing a spinal fusion through a posterior approach to correct a patient&#39;s scoliosis will need to perform a separate operation on the patient to fuse the SI joint  100  through the lateral approach. 
     In addition, many current SI joint fusion techniques do not incorporate bone grafts to strengthen the SI joint  100  when fused, but instead only rely on the strength of the dowel rods and pins to secure the SI joint  100 . These dowel rods and pins deteriorate over time and ultimately fail, unless there is a bony fusion, thereby subjecting patients to additional surgery. Also, these dowel rods and pins provide minimal surface contact between the sacrum  102  and the ilium  106  when the SI joint  100  is pulled together, thereby resulting in less bone fusion and less strength in the fused SI joint after healing. Moreover, to the extent that fusion occurs between the sacrum  102  and the ilium  106 , these SI joint fusion procedures attempt to fuse cortical bone that does not fuse as well as the cancellous bone underlying the cortical bone. 
     Accordingly, there remains a need for improved SI joint fusion devices and techniques that overcome the challenges of these prior solutions. 
     SUMMARY OF THE INVENTION 
     Presently disclosed is a joint implant. In an embodiment, a joint implant includes a porous body configured to promote bone growth, the body having a porous body with a first face, a second face, and a window extending between the first and second faces. The window is configured to hold a graft material that facilitates bone growth when the implant is maintained in compression with the first face contacting the sacrum and the second face contacting the ilium. 
     In some embodiments, the implant comprises porous titanium. In some embodiments, the implant includes ridges or rails extending on either or both of the first and second faces, and, in some of these embodiments, the rails extend in the direction of insertion of the implant. In some embodiments, the implant includes a lip extending around the window and, in some of these embodiments, the lip is arranged on the first and/or second face. 
     Also disclosed herein is a SI joint fusion method. The SI joint fusion method includes the steps of preparing the joint, placing the implant within the SI joint, and then compressing the SI joint. The step of preparing the joint may include reaming or cutting the joint to form a space therein in which the implant may be received. 
     Also disclosed herein is a sacroiliac joint implant system. The sacroiliac joint implant system may include a pair of fasteners configured to be fixed to opposite sides of the SI joint and a rod extending between and secured by the pair of fasteners. For example, a first fastener may be anchored to the sacrum and a second fastener may be anchored to the ilium and, in some examples, the first fastener is either an S-1 screw or an S-2 alar screw and the second fastener is an iliac screw. The sacroiliac joint implant system also includes an implant having a porous body that is placed within the SI joint and configured to promote bone growth. The porous body of the implant includes a first face configured to contact a sacrum of the sacroiliac joint when the implant is compressed within the sacroiliac joint, a second face configured to contact an ilium of the sacroiliac joint when the implant is compressed within the sacroiliac joint, and a graft window extending between the first and second faces and configured to hold a graft material. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention can be understood from the following detailed description of exemplary embodiments of the invention taken in conjunction with the accompanying drawings. 
         FIG. 1A  is a cross-section of the pelvis illustrating the SI joint from an anterior approach. 
         FIG. 1B  illustrates the SI joint from a posterior approach. 
         FIG. 2  illustrates the SI joint from a posterior approach. 
         FIG. 3  illustrates the SI joint  100  of  FIG. 2  after having been prepared by forming a space therein. 
         FIG. 4A  illustrates a guiding tool that may be utilized in a reaming procedure to form the space in the SI joint as illustrated in  FIG. 3 , according to one or more embodiments of the present disclosure. 
         FIG. 4B  illustrates a posterior view of the guiding tool of  FIG. 4A  positioned parallel to the SI joint prior to the reaming procedure to form the space in the SI joint as illustrated in  FIG. 3 . 
         FIG. 4C  is a superior anterior view of  FIG. 4B . 
         FIG. 5A  is an exemplary implant that may be utilized in a SI joint fusion, according to one or more embodiments. 
         FIG. 5B  illustrates a posterior view of the implant of  FIG. 5A  placed within the space of the SI joint as illustrated in  FIG. 3 . 
         FIG. 5C  illustrates a posterior view of the implant of  FIG. 5A  inserted through the guiding tool of  FIG. 4A  and placed within the space of the SI joint as illustrated in  FIG. 3 . 
         FIG. 6A  illustrates exemplary placement of fasteners about the SI joint. 
         FIG. 6B  illustrates exemplary placement of a rod installed within the fasteners of  FIG. 6A  to apply compression to the SI joint. 
         FIG. 6C  illustrates an exemplary placement or a rod and lateral rod within the fasteners of  FIG. 6A  to apply compression to the SI joint during a long segment operation, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates in general to SI joint fusions and, more particularly, to implants and methods for posterior SI joint fusion. 
     The embodiments described herein provide methods of performing SI joint fusions via posterior approaches (i.e., posterior SI joint fusions). The embodiments described herein also provide reaming guides utilizable in posterior SI joint fusions for defining the tool path and limiting the depth of cut as needed for a particular physiology. In some embodiments, the reaming guides are boxes oriented parallel to the SI joint. Other embodiments described herein provide a fusion plate utilizable in a posterior SI joint fusion and having a window for holding graft material that helps bone grow across the porous fusion plate through the window. In some embodiments, the fusion plate is made from a porous material that helps bone grow into and across the fusion plate, which thereby facilitates bone growth through the plate and bone fusion within the SI Joint. 
       FIG. 2  is a posterior view of the SI joint  100 . Thus,  FIG. 2  illustrates the SI joint  100  when accessed posteriorly (i.e., with a posterior approach). Physicians performing spinal fusions in the lumbar region, for example, to correct scoliosis, will utilize the posterior approach and may be provided access to the SI joint  100  as depicted in  FIG. 2 . In addition,  FIG. 2  illustrates the ala  202  of the sacrum  102  and the iliac crest  204  of the ilium  106 , and further depicts how the SI joint  100  generally extends along an axis X. The SI joint  100  of  FIG. 2  is shown prior to any bone removal as described below. Thus,  FIG. 2  shows the cortical bone of the sacrum  102  and the ilium  106 . 
     When performing posterior SI joint fusions, an implant (see  FIG. 5 ) may be placed in the SI joint  100 . As described below, such implants may facilitate fusion of the SI joint  100  by providing a scaffold for a graft material that will generate bone across the SI joint  100  and, after fully healing, strengthen the fusion across the SI joint  100 . Before placing the implant within the SI joint  100 , however, the SI joint  100  may be prepared such that there is sufficient space to receive the implant. 
       FIG. 3  illustrates the SI joint  100  of  FIG. 2  after being prepared, according to one or more embodiments of the present disclosure. As illustrated, a space  300  was formed at the SI joint  100  for receiving the implant. The space  300  has a length dimension L, a width dimension W, and a depth dimension (not illustrated) that is normal to the length and width dimensions W,L. Here, the space  300  is formed generally parallel the SI joint  100 , meaning that the length dimension L of the space  300  is parallel to the axis X of the SI joint  100 . Also, the dimensions of the space  300  may vary depending on the size of the implant. For example, the width dimension W of the space  300  may be sized to correspond with a width of the implant such that the implant may be inserted into the space  300 . 
     A variety of methods and tools may be utilized to form the space  300  in the SI joint  100 . In the illustrated examples, the SI joint  100  was prepared via a reaming procedure. In the reaming procedure, a rotational cutting tool (e.g., a reamer) is utilized to cut portions of the sacrum  102  and the ilium  106  on either side of the SI joint  100 , and thereby define the space  300  into which the implant may be inserted. During the reaming procedure, the cortical bone layers of the sacrum  102  and the ilium  106  are removed to expose the underlying cancellous bone, which more readily fuses across the SI joint  100  as compared to the cortical bone. Thus, the width dimension W of the space  300  is mostly defined by the distance between exposed cancellous bone of the sacrum  102  and the ilium  106 . 
     A guiding tool may be utilized in the reaming procedure to control the dimensions of the space  300 . The guiding tool may provide an envelope or template that guides and limits movement of the rotary cutting tool as it cuts the space  300 . For example, the guiding tool may be utilized to form the space  300  according to specific length and width dimensions L, W, and may also limit the rotary cutting tool&#39;s depth of cut to control the depth dimension of the space  300 . The guiding tool may be made from various materials, including without limitation, stainless steel alloys, commercially pure titanium, titanium alloys, etc. 
       FIG. 4A  illustrates an exemplary guiding tool  400 , according to one or more embodiments of the present disclosure. Here, the guiding tool  400  includes a body  402  having a proximal side  404  and a distal side  406 . Here, the body  402  is configured as a box shaped member with an opening  408  extending through the body  402  from the proximal side  404  to the distal side  406 . The body  402  includes a rim  410  extending around the opening  408  at the proximal side  404 . The guiding tool  400  also includes at least one mounting feature for securing the guiding tool  400  to bone relative to the SI joint  100 . Here, the guiding tool  400  includes a pair of mounting posts  412  that may be driven into the bone of the pelvis  108  with a mallet to anchor the guiding tool  400  relative to the SI joint  100 ; however, the mounting feature may be differently configured. For example, the mounting features may include one or more phalanges, screws, etc. or combinations of the same. In the illustrated example, the mounting posts  412  include flat surfaces that are oriented with the SI joint  100 , generally parallel to the axis X of the SI joint  100 , such that they may more easily slide into the SI joint  100 . Here, the mounting posts  412  are positioned centered on a sidewall of the body  402 , but they may be positioned differently along the sidewall (or another sidewall) of the body  402 . Thus, the guide  400  may be configured to slide into the SI joint  100 , with the mounting posts  412  sliding therein between the cortical surfaces of the SI joint  100  to keep the guiding tool  400  oriented so that there is an even cut from both the iliac crest surface and the sacral surface. However, the mounting posts  412  may have various other configurations relative to the axis X of the SI joint  100 , which may help secure the guiding tool  400  within the SI joint  100 . 
     During the reaming procedure, the distal side  406  of the guiding tool  400  is secured over the SI joint  100  and a rotary cutting tool  420  may be inserted through the opening  408  such that the rotary cutting tool  420  may access the SI joint  100  positioned beneath the guiding tool  400 . As illustrated, the rotary cutting tool  420  includes a cutting edge  422  positioned at a distal end thereof, a shaft portion  424  extending proximally from the cutting edge  422 , and a shank  426  extending proximally from the shaft portion  424  for mounting the rotary cutting tool  420  within a driver or other equipment. The rotary cutting tool  420  also includes a stopper  428  positioned on the shaft portion  424  and is configured to limit the depth that the cutting edge  422  may extend distally beneath the guide tool  400 . In the illustrated example, the stopper  428  is a flange member that, during the reaming procedure, abuts and contacts the rim  410  of the body  402 , thereby inhibiting further distal translation of the cutting edge  422  and limiting the depth at which it extends into the SI joint  100 . 
     The size of the space  300  formed in the SI joint  100  during the reaming procedure is controlled by the guiding tool  400 . More particularly, the rotary cutting tool  420  cuts the space  300  with length and width dimensions L, W corresponding to a width W′ and length L′ of the opening  408  in the box shaped body  402  of the guiding member  400 . In addition, the depth dimension of the space  300  formed in SI joint  100  is controlled by a vertical dimension Z′ of the guiding tool  400 , which may be influenced by various parameters of the rotary cutting tool  420 , such as the distance at which the cutting edge  422  extends distally from the stopper  428 , etc. 
     As illustrated in  FIG. 4B , the guiding tool  400  is positioned parallel to the SI joint  100 . Thus, the length L′ of the opening  408  is aligned with the axis X of the SI joint  100  such that the guiding tool  400  and the SI joint  100  are parallel. Various techniques and/or equipment may be utilized to position the guiding tool  400  before anchoring it to the SI joint  100 . In one example, a stereotactic computer aided guidance system (not illustrated) is utilized. Here, the guiding tool  400  may include one or more sensors that communicate with the stereotactic computer aided guidance system to allow placement of the guiding tool  400  in a desired position and orientation relative to the SI joint  100 . 
     After the SI joint  100  has been prepared by cutting the space  300  therein, the implant may be placed therein to facilitate fusing the SI joint  100 .  FIG. 5A  illustrates an exemplary implant  500  that may be fused in the SI joint  100 , according to one or more embodiments of the present disclosure. Here, the implant  500  is a plate  502  with first face  504 , a second face (obscured from view) opposite from the first face  504 , and a graft window  506  extending there through between the first face  504  and the second face. The plate  502  may be made from a porous material.  FIG. 5B  illustrates the implant  500  of  FIG. 5A  having been inserted into the space of  FIG. 3  via a posterior approach.  FIG. 5C  illustrates the implant  500  of  FIG. 5A  having been inserted through the guiding tool  400  of  FIG. 4A  and into the space of  FIG. 3  via a posterior approach. 
     The implant  500  may have various geometries and shapes. For example, the first face  504  and/or the second face may be concave or convex. In one example, the first face  504  and the second face are both flat, but in other examples, they are biconvex and, in some of these latter examples, the the implant  500  is pointed in the direction of insertion and opens up posteriorly like a cup. In some examples, the first face  504  and/or the second face include both concave and convex portions that correspond with the particular geometry of the portion of the SI joint  100  that they are configured to abut when compressed therein. For example, a particular patient&#39;s SI joint  100  may be scanned and modeled in a CAD software, and then the implant  500  may be designed to best correspond and fit that particular patient&#39;s SI joint  100  geometry and then printed and surgically installed in the patient&#39;s SI joint  100 . Thus, the implant  500  may have a customized geometry and size corresponding with the actual geometry of a patient&#39;s SI joint  100  and the first face  504  and/or the second face may be contoured to correspond with contours of the particular patient&#39;s SI joint  100 . However, the implant  500  also be provided in standard sizes and geometries. 
     The implant  500  may also have various shapes. Here, the plate  502  is square shaped with approximately ninety degree (90°) corners, but the corners may have various other geometries. For example, one or more of the corners may be rounded, chamfered, etc. Also, the plate  502  may have various other non-square or non-rectangular shapes, such as circular, oval, etc., however, the implant  500  may be custom 3D printed such that the plate  502  may conform or fit anatomic variants or joints that had previous surgeries. Thus, the implant  500  and the plate  502  thereof may be customized to the particular patient and may thus have any number of shapes or geometries. In some examples, the plate  502  is shaped to fit a particular patient&#39;s SI joint  100 . Here, the implant  500  includes various dimensions, including a width dimension W″, a length dimension L″, and a vertical dimension Z″. The implant  500  may be provided with various sizes depending on the particular size of the space  300  into which the implant  500  is to be placed. However, the thickness of the plate  502  should be sufficient to cross the SI joint  100  and enter the cancellous bone exposed after the reaming procedure cut away the layer of cortical bone. For example, the thickness of the plate  502  may vary to allow maximum bony surface contact between the implant  500  and the SI joint  100 . Also, where the guide tool  400  is utilized to form the space  300  in the SI joint  100 , the implant  500  may be inserted into the space  300  in the SI joint  100  through the opening  408  in the box shaped body  402  ( FIG. 5C ). Thus, in such embodiments, the implant  500  may be sized to fit within the guiding tool  400  and may even be provided together as a kit for SI joint fusions. Alternatively, the implant  500  may be inserted directly into the SI joint  100  ( FIG. 5B ) and, in such examples, the guiding tool  400  would be removed from the SI joint  100  or not utilized at all to form the space  300  therein. 
     The plate  502  may be formed of a porous material selected to promote bone growth. In one embodiment, the plate  502  is formed of porous titanium with a modulus similar to natural bone. In other embodiments, selected portions of the plate  502  are formed of porous material while other portions are formed of non-porous materials. In some embodiments, the plate  502  is formed by an additive manufacturing process, such as 3D printing. In some embodiments, the porous material forms a lattice having pores of approximately 0.75 millimeter in diameter. The graft window  506  is configured to receive a graft material. For examples, the graft window  506  may be filled with either autologous or allograft. The graft window  506  allows for the fusion to grow through the implant  500  and the porous material from which the body  502  is manufactured allows fusion to grow into and through the plate  502 . 
     The implant  500  may include various features for strengthening the plate and/or helping secure the plate within the SI joint  100 . For example, the implant  500  may have various features and/or designs that prevent micro-motion and allow maximum contact with the bone of the SI joint  100 . In the illustrated examples, the implant  500  includes a plurality of rails or ridges  508  oriented in the direction at which the implant  500  is to be inserted into the space  300  of the SI joint  100 . The rails or ridges  508  may be made of the same porous material as the remainder of the implant  500  to allow in growth into and through the ridges  508 . Thus, the ridges  508  extend from a top edge  510  to a bottom edge of the plate  502 . The ridges  508  may help secure the implant  500  within the SI joint  100  by providing a friction fit and inhibit it from sliding such that the ridges  508  remove at least one degree of freedom of movement of the implant  500  when installed in a patient&#39;s SI joint  100 . In addition, the ridges  508  may help the implant  500  slide down, with the top edge  510  or the bottom edge  510  leading, into the SI joint  100 . In some examples, the ridges  508  may include serrations or other features that allow the implant  500  to slide into the SI joint  100  but inhibit the implant  500  from backing out after being inserted into the SI joint  100 . For example, the ridges  508  may include triangular serrations with a flat side posterior and pointed anterior to ease insertion into the SI joint  100 . Here, four (4) ridges  508  extend from the first face  504  of the plate  502  and four (4) ridges  508  extend from the second face of the plate  502 . As illustrated, the ridges  508  provide the implant  500  with an “I-beam” configuration, and are positioned proximate to the lateral edges of the plate  502  and proximate to the lateral edges of the graft window  506 . However, more or less of the ridges  508  may be utilized. For example, just the lateral edge ridges  508  or the ridges  508  sandwiching the graft window  506  may be included, or the implant may include ridges  508  on only one side (e.g., the first side  504 ) of the plate  502 . Also, the ridges  508  may have one or more different geometries than the generally straight rail members illustrated in the figures. Moreover, the plate  502  may have various textures, such as asperities or other features that help create friction. For example, the first face  504  and/or second face may include asperities. 
     The implant  500  may include various features for helping secure the graft material within the graft window  506 . Where utilized, the ridges  508  disposed proximate the graft window  506  may also help maintain the graft material within the graft window  506 . In addition, the plate  502  may include a lip portion (not illustrated) extending around at least a portion of the graft window  506  to help maintain the graft material within the graft window  506 , and such lip portion may be included with or without the one or more ridges and/or other features. In some examples, one or more sutures (not illustrated) may be wrapped around the plate  502  to help retain the graft material within the graft window  506 . For example, a first suture may be wrapped around the plate  502  in the length dimension L″ and a second suture may be wrapped around the plate  502  in the vertical dimension Z″ such that the first and second sutures cross each other at the graft window  506 . More or less sutures may be utilized, however, and they may be wrapped differently around the plate  502  without departing from the present disclosure. Also, in some examples, one or more structures (not illustrated) connected to the plate  502  may be arranged across the graft window  506 . Where utilized, such structures may have various orientations (e.g., arranged along the length, vertical, and/or width dimensions L″, Z″,W″), and such structures may support various sub-structures suspended within the graft window  506 , any of which may be provided to facilitate bone growth and fusion. 
     When the implant  500  is installed in a patient, the plate  502  contacts the sacrum  102  and the ilium  106  under pressure. By applying pressure at the points of contact, the implant  500  achieves compression that promotes bone growth in a manner not previously possible with posterolateral vertebrae fusion devices. In this manner, the presently disclosed implant  500  may achieve an improved rate of fusion. Thus, after the SI joint  100  has been prepared and the implant  500  has been placed within the space  300  cut into the SI joint  100 , the SI joint  100  will be compressed. Compression will facilitate SI joint fusion because, pursuant to Wolf&#39;s law, compression across a fusion device yields the greatest fusion. 
     Various fasteners may be utilized to compress the implant  500  within the space  300  of the SI joint  100 . For example, pedicle screws may be installed within the surgical site of the patient and connected with rods that are compressed with compression devices to squeeze the SI joint  100  and sandwich the implant  500  therein. The various pedicle screws may be placed at various times during the SI joint fusion. For example, they may be placed at the beginning of the procedure, at various times before preparing the joint, at various times after preparing the joint but before inserting the implant  500  therein, or after inserting the implant  500  within the space  300  previously formed in the SI joint  100 , etc. 
       FIG. 6A  illustrates exemplary screw placement about the SI joint  100 , according to one or more embodiments. In particular,  FIG. 6A  illustrates placement of an iliac screw  602  in the iliac crest  204 , as well as an S-1 screw  604  and an S-2 alar screw  606  placed in the sacrum  102 . As described below, a rod may be placed to bridge the SI joint  100  and interconnect either the iliac screw  602  and the S-1 screw  604  or the iliac screw  602  and the S-2 alar screw  606 . Thus, both the S-1 screw  604  and the S-2 alar screw  606  need not be placed during the same SI joint fusion operation to apply compression to the implant  500  placed in the space  300  of the SI joint  100 , and either the S-1 screw  604  or the S-2 alar screw  606  may be utilized depending on which may provide best compression in a particular fusion operation. For example, either the S-1 screw  604  or the S-2 alar screw  606  may be utilized depending on which will orient the rod more perpendicular to the structure of a patient&#39;s SI joint  100  when connected to the iliac screw  602 . However, in some long segment operations, such as a scoliosis operation, a first rod may be placed between the S-1 screw  604  and the S-2 alar screw  606  and then a lateral rod may attach to a mid-point of the first rod and connect to the iliac screw  602  and thereby bridge the SI joint  100  as described below with reference to  FIG. 6C . 
       FIG. 6B  illustrates an exemplary lateral rod  608  placement, according to one or more embodiments. Here, the lateral rod  608  has been placed in the screw heads of the iliac screw  602  and the S-1 screw  604 . However, as mentioned above, the lateral rod  608  may instead be installed in the head of the S-2 alar screw  606  and bridge the SI joint  100  to interconnect to the head of the iliac screw  602 , or the lateral rod  608  may be a lateral connecting rod spanning between the head of the iliac screw  602  and another rod (i.e., a long segment rod) installed between S-1 screw  604  and the S-2 alar screw  606 . Once the one or more rods have been placed in the screw heads, a compression device (not illustrated) may be utilized to compress the SI joint  100  via the pedicle screws and rods and thereby squeeze the implant  500  within the space  300  of the SI joint  100 . 
       FIG. 6C  illustrates an exemplary placement of a long segment rod  610  and a lateral rod  612  in a long segment operation, according to one or more embodiments. As illustrated, the long segment rod  610  is placed between the S-1 screw  604  and the S-2 alar screw  606 , and the lateral rod  612  is secured within the head of the iliac screw  602  and spans the SI joint  100  by connecting to a portion of the long segment rod  610  between the S-1 screw  604  and the S-2 alar screw  606 . While not illustrated, in these long segment operations, additional rods similar to the long segment rod  610  may extend superiorly and/or inferiorly, from either or both the S-1 screw  604  and the S-2 alar screw  606 , to other pedicle screws secured along other portions of the spine. Once the lateral rod  612  has been placed in the screw head of the iliac screw  602  and connected to the long segment rod  610 , a compression device (not illustrated) may be utilized to compress the SI joint  100  and thereby squeeze the implant  500  within the space  300  prepared therein. 
     Also disclosed herein is a method for performing an SI joint fusion. The method of fusing the SI joint, sometimes referred to as the SI joint fusion method, includes a first step of preparing the joint, a second step of placing an implant within the SI joint, and a third step of compressing the SI joint. The SI joint fusion method, however, may include one or more additional steps performed before or after the SI joint fusion method, or performed in between any of the foregoing steps. For example, the SI joint fusion method may include an additional step of placing pedicle screws about the SI joint, and such additional step of placing the pedicle screws may be performed at any time before the step of compressing the SI joint or it may be included as part of the step of compressing the SI joint. 
     The first step of preparing the joint is performed to ensure that there is adequate space within the SI joint to receive the implant. As previously described, a reaming procedure may be utilized to cut the space  300  within the SI joint  100 . Also as previously described, the guiding tool  400  may be utilized to control the dimensions of the space  300  cut into the SI joint  100  during the reaming procedure. Thus, the first step of preparing the joint may include placing and installing the guiding tool  400  relative to the SI joint  100 . In addition, the pedicle screws may be placed about the SI joint  100  during this step, or at other times during the SI joint fusion method. 
     The second step of placing an implant within the SI joint is performed to place an implant within the SI joint that permits a bone graft to grow across the SI joint  100 , thereby improving and strengthening the fusion after healing. Various types of implants may be utilized, such as the implant  500  described above. Also, in examples where the guiding tool  400  is utilized, the implant  500  may be inserted into the SI joint  100  through the opening  408  in the guiding tool  400 . Thus, the second step of placing an implant within the SI joint may include inserting the implant  500  through the guiding tool  400  and into the space  300  prepared in the SI joint  100  and/or positioning the implant  500  within the space  300  prepared in the SI joint  100  via the guiding tool  400 , etc. In addition, the pedicle screws may be placed about the SI joint  100  during this step, or at other times during the SI joint fusion method. 
     The third step of compressing the SI joint is performed to compress the implant across the SI joint  100  because, according to Wolf&#39;s law, such compression will provide the greatest fusion. This step may include placing the pedicle screws about the SI joint  100 ; however, such pedicle screws may be placed during any of the preceding steps, or before the SI joint fusion method altogether, for example, during a long segment operation to correct scoliosis, which may be conducted immediately prior to the SI joint fusion method. This step may include bridging the SI joint  100  by placing a lateral rod (e.g., the lateral rod  608  or the lateral rod  612 ) across the SI joint  100 , as previously described, and then using a compression device to compress the SI joint  100  and the implant  500  previously inserted therein. As described above, the lateral rod  608  may be placed within the heads of the iliac screw  602  and the S-1 screw  604  ( FIG. 6B ) or within the heads of the the iliac screw  602  and the S-2 alar screw  606 . Alternatively, the lateral rod  612  may be placed in the head of the iliac screw  602  and connect to the long segment rod  610  spanning between the S-1 screw  604  and the S-2 alar screw  606  ( FIG. 6C ). Thus, this step may also include placing the long segment rod  610  before bridging the SI joint  100  with the lateral rod  612 , as previously described; however, placing the long segment rod  610  may be performed during any of the preceding steps or before the SI joint fusion method altogether. 
     Also disclosed herein is a sacroiliac joint implant system. The sacroiliac joint implant system may include a pair of fasteners configured to be fixed to opposite sides of the SI joint  100  and a lateral rod securable within the pair of fasteners. For example, a first fastener may be anchored to the sacrum and a second fastener may be anchored to the ilium and, in some examples, the first fastener is either an S-1 screw or an S-2 alar screw and the second fastener is an iliac screw. In some examples, the sacroiliac joint implant system includes three or more fasteners. For example, the sacroiliac joint implant system may include an S-1 screw, an S-2 alar screw, and an iliac screw; and, in such embodiments, the sacroiliac joint implant system may also include one or more long segment rods and/or a lateral rod configured to attach to a long segment rod, as described above. 
     The sacroiliac joint implant system may also include one or more implants, any of which may be configured as described with reference to the implant  500 . Thus, the implant of the sacroiliac joint implant system may have a porous body that is placed within the SI joint and configured to promote bone growth. The porous body of the implant includes a first face configured to contact a sacrum of the sacroiliac joint when the implant is compressed within the sacroiliac joint, a second face configured to contact an ilium of the sacroiliac joint when the implant is compressed within the sacroiliac joint, and a graft window extending between the first and second faces and configured to hold a graft material. 
     The sacroiliac joint implant system, or portions thereof may be provided as a “kit.” For example, a kit of implants may also be provided that includes a selection of implants of different sizes. In some examples, the kit includes digital instructions or schematics for a 3D printer, or the like, which a user may utilize to print (or create) the implant. The kit may also include one or more guiding tools having corresponding sizes to receive the implant(s), and may also include a rotary cutting tool configured to operate within the envelope defined by the guiding tool. In some examples, the kit includes digital instructions or schematics for a 3D printer, or the like, which a user may utilize to print (or create) the guiding tool. In addition, the kit may include various pedicle screws and various types of connecting rods for applying compression to the SI joint. A surgeon may select the implant, guiding tool and rotary cutting tool, screws, connecting rods best suited to the particular size and geometry of the patient&#39;s SI joint. In this manner, the presently disclosed implant may be used in treatment of a wide variety of applications. 
     The presently disclosed implant may provide numerous advantages for SI joint fusion. An implant formed of porous titanium manufactured with an additive manufacturing process may allow bone growth into it and participate in the fusion. The implant has a pore structure that allows bone growth. Local bone may be trapped within the implant creating a compressed area that would further augment the fusion. 
     The components of the implant  500  and/or the guiding tool  400  may be fabricated from biologically acceptable materials suitable for medical applications, including metals, synthetic polymers, ceramics and bone material and/or their composites. For example, the components of the implant  500  and/or the guiding tool  400 , individually or collectively, can be fabricated from materials such as stainless steel alloys, commercially pure titanium, titanium alloys, Grade 5 titanium, super elastic titanium alloys, cobalt-chrome alloys, stainless steel alloys, super elastic metallic alloys (e.g., Nitinol, super elasto-plastic metals, such as GUM METAL®. manufactured by Toyota Material Incorporated of Japan), ceramics and composites thereof such as calcium phosphate (e.g., SKELITE™ manufactured by Biologix Inc.), thermoplastics such as polyaryletherketone (PAEK) including polyetheretherketone (PEEK), polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEK composites, PEEK-BaSO.sub.4 polymeric rubbers, polyethylene terephthalate (PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers, polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigid materials, elastomers, rubbers, thermoplastic elastomers, thermoset elastomers, elastomeric composites, rigid polymers including polyphenylene, polyamide, polyimide, polyetherimide, polyethylene, epoxy, bone material including autograft, allograft, xenograft or transgenic cortical and/or corticocancellous bone, and tissue growth or differentiation factors, partially resorbable materials, such as, for example, composites of metals and calcium-based ceramics, composites of PEEK and calcium based ceramics, composites of PEEK with resorbable polymers, totally resorbable materials, such as, for example, calcium based ceramics such as calcium phosphate such as hydroxyapatite (HA), corraline HA, biphasic calcium phosphate, tricalcium phosphate, or fluorapatite, tri-calcium phosphate (TCP), HA-TCP, calcium sulfate, or other resorbable polymers such as polyaetide, polyglycolide, polytyrosine carbonate, polycaroplaetohe and their combinations, biocompatible ceramics, mineralized collagen, bioactive glasses, porous metals, bone particles, bone fibers, morselized bone chips, bone morphogenetic proteins (BMP), such as BMP-2, BMP-4, BMP-7, rhBMP-2, or rhBMP-7, demineralized bone matrix (DBM), transforming growth factors (TGF, e.g., TGF-(3), osteoblast cells, growth and differentiation factor (GDF), insulin-like growth factor 1, platelet-derived growth factor, fibroblast growth factor, or any combination thereof. 
     Various components of the implant  500  and/or the guiding tool  400  may have material composites, including the above materials, to achieve various desired characteristics such as strength, rigidity, elasticity, compliance, biomechanical performance, durability and radiolucency or imaging preference. The components of the implant  500  and/or the guiding tool  400 , individually or collectively, may also be fabricated from a heterogeneous material such as a combination of two or more of the above-described materials. The components of the implant  500  and/or the guiding tool  400  may be monolithically formed, integrally connected or include fastening elements and/or instruments, as described herein. In one embodiment, the implant  500 , as described herein, may be formed substantially of a biocompatible metal, such as titanium and selectively coated with a bone-growth promoting material, such as HA. In one embodiment, the implant  500 , as described herein, may be formed substantially of a biocompatible polymer, such as PEEK, and selectively coated with a biocompatible metal, such as titanium, or a bone-growth promoting material, such as HA. In some embodiments, titanium may be plasma sprayed onto surfaces of the spinal implant to modify a radiographic signature of the implant and/or improve bony on growth to the spinal implant by application of a porous or semi-porous coating of titanium. 
     Aspects of the presently disclosed implant and methods of SI joint fusion are further illustrated in the images and figures attached as an appendix, which is incorporated herein. 
     While principles and modes of operation have been explained and illustrated with regard to particular embodiments, it must be understood, however, that this may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.