Patent Publication Number: US-2021169660-A1

Title: Sacro-iliac joint stabilizing implants and methods of implantation

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of U.S. Application No. 62/945,653, filed Dec. 9, 2019, the entire disclosure of which is fully incorporated by reference herein for all purposes. 
    
    
     INCORPORATION BY REFERENCE 
     All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
     BACKGROUND 
     Implants may be positioned across a sacro-iliac (“SI”) joint to help stabilize the joint. Regions of the ilium may have greater density than regions of the sacrum. Depending on one or more of the delivery trajectory, the target location for implantation, and the configuration of the implant, the differences in bone density may present challenges while advancing some SI joint implants across the SI joint. Implantation methods are needed that accommodate for the differences in bone density and can facilitate the successful delivery of the SI joint implant from a dorsal approach. 
     SUMMARY OF THE DISCLOSURE 
     One aspect of the disclosure is a method of positioning a SI joint stabilization implant across a SI joint from a dorsal approach. The method may include advancing an elongate implant positioning guide (“positioning guide,” or “guide”) in a dorsal trajectory into an ilium of a subject, engaging a guide interface member of a SI joint stabilization implant with the positioning guide to restrict movement of the implant with respect to the positioning guide in at least one direction, at a time subsequent to the engaging step, advancing the implant across the SI joint while guiding the implant with the positioning guide, and removing the positioning guide from the ilium. 
     In this aspect, the engaging step may limit the amount of implant migration towards the sacrum while advancing the implant across the SI joint. 
     In this aspect, advancing the positioning guide into an ilium may comprise advancing the positioning guide into the ilium between lateral and medial cortical walls of the ilium. In this aspect, advancing the positioning guide may comprise advancing the positioning guide only into the ilium. 
     In this aspect, the method may optionally further comprise, at a time subsequent to positioning the positioning guide into the ilium, advancing a sacrum positioning guide into a sacrum of the patient, engaging a second guide interface member of the implant with the sacrum positioning guide, wherein the implant advancing step occurs while also guiding the implant with the sacrum positioning guide, and removing the sacrum positioning guide from the sacrum. Engaging a second guide interface section of the implant with a sacrum positioning guide may occur prior to advancing a sacrum positioning guide into a sacrum of the patient. The method may further include advancing a second sacrum positioning guide in a dorsal trajectory or dorsal approach into the sacrum of a subject, and engaging a second sacrum guide interface member of the implant with the second sacrum positioning guide to restrict movement of the implant with respect to the second sacrum positioning guide in at least one direction. 
     In this aspect, the method may optionally further include, at a time prior to engaging the guide interface member with the positioning guide, engaging a sharpened broach with the positioning guide, and advancing the broach towards the SI joint to create a space for the implant while guiding the broach with the positioning guide, and removing the broach to allow dorsal access to the space. 
     In this aspect, engaging a guide interface member of the implant with the positioning guide may comprise positioning an annular member of the implant over a proximal region of the positioning guide. 
     In this aspect, engaging a guide interface member of the implant with the positioning guide may comprise positioning an arcuate member of the implant around a proximal region of the positioning guide. 
     In this aspect, the method may further comprise advancing a second ilium positioning guide in a dorsal trajectory into the ilium of a subject, and engaging a second guide interface member of the implant with the second ilium positioning guide to restrict movement of the implant with respect to the second ilium positioning guide in at least one direction. 
     One aspect of this disclosure is a method of implanting a SI joint implant across a SI joint from a dorsal approach while preventing the SI joint implant from migrating away from the ilium and towards the sacrum. This aspect may include any other method step or sequence of steps claimed and/or described herein. In this aspect, the preventing step may include engaging a positioning guide with a portion of the implant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  illustrate an exemplary SI joint implant engaged with a positioning guide. 
         FIGS. 2A and 2B  illustrate an exemplary SI joint implant engaged with first and second positioning guides. 
         FIGS. 3A and 3B  illustrate an exemplary SI joint implant engaged with a positioning guide. 
         FIGS. 4A and 4B  illustrate an exemplary SI joint implant engaged with first and second positioning guides. 
         FIGS. 5A and 5B  illustrate an exemplary SI joint implant engaged with a plurality of positioning guides. 
         FIGS. 6A and 6B  illustrate an exemplary SI joint implant engaged with a positioning guide. 
         FIG. 7  illustrates an exemplary SI joint implant. 
         FIG. 8  illustrates a portion of an exemplary SI joint implant engaged with a positioning guide. 
         FIG. 9  illustrates a portion of an exemplary SI joint implant engaged with a positioning guide. 
         FIG. 10  illustrates an exemplary SI joint implant engaged with a plurality of positioning guides. 
         FIG. 11A  illustrates a posterior view and exemplary locations for positioning guides. 
         FIG. 11B  illustrates an exemplary implantation location for a SI joint implant across a SI joint. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure herein is related to SI joint stabilizing implants and methods of implanting SI joint stabilizing implants across a SI joint. The methods include implanting a stabilizing implant from a dorsal approach across the SI joint with a first portion of the implant positioned in the ilium and a second portion of the implant positioned in the sacrum. The implants herein are sized and configured to be implanted according to any of the methods of implantation herein, unless indicated to the contrary. 
     Regions of the ilium into which a portion of the implant is positioned may have greater density than regions of the sacrum into which a second portion of the implant is positioned. When positioning a SI joint implant across a SI joint from a dorsal approach, the implant may tend to deflect away from denser cortical iliac bone and migrate towards and into the less dense sacrum, preventing proper positioning of the implant across the SI joint. Implantation methods and implants are described herein that can maintain proper implant trajectory when advancing the SI joint implant across the SI joint from a dorsal approach. The methods and approaches herein can account for the differences in bone density between the ilium and sacrum and prevent the implant from migrating away from denser iliac bone during implantation. 
     The methods herein may include advancing one or more positioning guides, any of which may be referred to herein as a “guide,” into an ilium from a dorsal approach, and in some embodiments between lateral and medial cortical walls of the ilium.  FIG. 11A  illustrates a posterior view and a general dorsal approach for implanting the SI joints herein across the SI joint.  FIG. 11B  illustrates an exemplary implant  1106  implanted across a SI joint  1114 ′ with a first region of the implant disposed in ilium  1110 , a second region of the implant disposed in sacrum  1112 , and a central region extending across the SI joint  1114 ′.  FIGS. 11A and 11B , which are referenced in more detail below, illustrate ilium  1110 , sacrum  1112 , the SI joints  1114  and  1114 ′, and lumbar vertebrae  1116 .  FIG. 11A  also illustrates a general region  1120  for a starting point for advancing an ilium positioning guide into the ilium, and a general region  1130  for a starting point for advancing a sacrum positioning guide into the ilium.  FIG. 11A  further illustrates an exemplary ilium starting point  1122  for an ilium positioning guide, as well as an exemplary sacrum starting point  1132  for a sacrum positioning guide. Any of the ilium positioning guides herein may have a starting point in general region  1120 , such as ilium starting point  1122 . Any of the sacrum positioning guides herein may have a starting point in general region  1130 , such as sacrum starting point  1132 . A radiographic view image may be obtained and utilized to help guide the positioning guide into the ilium between lateral and medial cortical walls of the ilium, which are illustrated generally in  FIGS. 11A and 11B . Methods herein include interfacing the ilium positioning guides herein with a portion of the SI joint implant, such as an interface member of the implant, to guide the implant across the SI joint. By positioning an ilium positioning guide in the relatively dense region of the ilium, and interfacing and engaging the positioning guide with the implant, the guide can help ensure a portion of the implant will stay on course during advancement during implantation in the dorsal approach, rather than migrating away from the relatively dense cortical ilium bone and towards the sacrum. The positioning guides herein thus interface directly with the implant and are sized and configured to act as a guide for a portion of the implant to ensure that the ilium portion of implant is properly positioned in the ilium and that the implant is properly implanted across the SI joint. 
     The positioning guides are sized and configured to generally restrict movement of the implant with respect to the positioning guide in at least one direction. The implant may be free to move relative to the positioning guide in other ways or directions. For example, once interfaced, the implant may still be able to rotate relative to the guide, such as in  FIGS. 1A and 1B , but the guide can still maintain the desired trajectory of at least a portion of the implant when the implant is advanced in the dorsal trajectory over the guide. 
     The methods herein include advancing the implant across the SI joint, while the guide helps guide a portion of the implant into the ilium. The methods may also include removing the positioning guide from the ilium after the implant has been positioned across the SI joint. 
     The methods herein may include positioning more than one positioning guide, optionally more than one guide in the ilium, and optionally one or more guides into sacral bone. Any of the one or more guides herein may be sized and configured to function as a positioning guide to help guide a portion of the implant into ilium bone or sacral bone. 
     In some alternative methods and implants, it may be possible to advance a SI joint stabilizing implant from a dorsal approach across a SI joint without using a positioning guide. For example, these methods may include radiographically visualizing a teardrop view of the ilium and advancing the implant while visualizing the teardrop view to ensure a portion of the implant stays sufficiently on course into the teardrop region of the ilium. Any of the methods herein may thus optionally exclude an ilium positioning guide, and may rely on a radiographic image, such as a teardrop view, to help maintain a desired implant trajectory into a teardrop region of the ilium. Implants implanted according to these methods may be implanted with or without a broach (described in more detail below), and if implanted without the use of a broach, the implants may have distal end regions that are configured to penetrate into bone, optionally having sharpened distal ends. 
     The SI joint stabilizing implants herein, such as any of those shown in  FIGS. 1A-10 , are generally sized and configured to be able to interface with an elongate ilium positioning guide, and may be sized and configured to interface with one or more additional positioning guides, which may be ilium or sacral guides. 
     The following exemplary SI joint stabilizing implants may be used in any of the methods of SI joint stabilization herein. Even if the textual description of an embodiment does not expressly include it, it is understood that features shown in different embodiments may be incorporated together. For example, the implants shown in  FIGS. 1A, 1B, 2A and 2B  each have an interface member with an annular inner surface that defines a lumen, even if the text does not expressly include this description. Additionally, similar components may be similarly labeled in different embodiments. For example, it is understood that references to elements  10 ,  20 ,  30 ,  40 , etc., in the figures may illustrate systems, even if the text related to any particular embodiment is silent with reference to a reference number shown in the figure. 
       FIGS. 1A and 1B  illustrate (dorsal view and perspective view, respectively) an exemplary system  10  that includes SI joint stabilizing implant  14  that includes an ilium guide interface member  18  interfacing, which may be also referred to herein as engaging, with elongate ilium guide  12 . Implant  14  includes main body  16 , a portion of which is disposed across the joint when the implanted is implanted. The interface member  18  includes a surface  19  that has a configuration, in this example annular, that is sized and configured to interface with the corresponding configuration of elongate ilium guide  12 . In these figures, the guide may or may not already be positioned in an ilium, such as at the exemplary general location shown in  FIG. 11 . The interface between the guide and the interface member of the implant restricts the movement of the implant interface guide member with respect to the elongate ilium guide in one or more directions. In this example, implant may still be rotated relative to the guide. In this embodiment, the guide has a cylindrical configuration, with an annular outer profile in cross section along almost all of its length (except for the distal tip region, which may be configured to penetrate into bone). In figures herein, including  FIG. 1A and 10 , “S” refers to sacrum, and “I” refers to ilium. Any of the guides herein may be considered to have a cylindrical configuration along all or substantially all of its length. 
     Any of the guides herein may include a sharpened or pointed distal end (e.g., as shown in  FIGS. 1B, 2B, 3B , etc.) that may be configured to help penetrate into bone, such as iliac bone and/or sacral bone. 
       FIGS. 2A and 2B  illustrate exemplary system  20  that includes SI joint stabilizing implant  24 , ilium guide  22 , and an optional elongate sacral guide  21 . In the figures shown, the ilium guide  22  and the sacral guide  21  may or may not yet be positioned within the ilium and sacrum, respectively. In some methods, the one or more guides may be inserted into bone, and then the implant may be advanced over the guides. In some embodiments, the implant is interfaced with the one or more guides, and subsequently the one or more guides can be inserted into bone. Interfacing the implant to a plurality of guides (in examples with more than one guide) before guide insertion may help prevent the guides from being inserted into bone and spaced apart at positions that prevent the implant from then be interfaced with the guides and successfully advanced along the guides and across the SI joint. Interfacing the implant with the guides first may help the guides being properly spaced apart to accommodate the implant during implantation. In any embodiment herein, an ilium guide may be inserted into iliac bone, followed by interfacing the guide with the implant, followed by interfacing the implant with a sacrum guide, and followed by inserting the sacrum guide into a sacrum. The implant may then be advanced across the SI joint. 
     Any of the dashed lines herein (such as in  FIGS. 1A, 2A, 3A and 4A ) in an implant body can indicate an optional bore or opening within a main body portion of the implant, which may extend through distal and proximal implant body surfaces. 
       FIGS. 3A and 3B  illustrate an exemplary system  30  that includes implant  34 , which is configured to interface with guide  32 . Implant  34  includes guide interface member  33  that has a surface  35  sized and configured to interface with guide  32 , which may be an ilium guide. Member  33  is in this embodiment curvilinear and has an almost completely annular configuration. 
       FIGS. 4A and 4B  illustrate exemplary system  40  that includes implant  44  with first and second ilium guide interface members  43  and  45 , each of which has a surface configured to interface with guide  41  and guide  42 , respectively. Members  43  and  45  in this embodiment extend away from the main body region further than the guide interface members in  FIGS. 1A, 1B, 2A and 2B , for example. 
       FIGS. 5A and 5B  illustrate an exemplary system  50  that includes exemplary implant  54 , and exemplary ilium guides  51  and  52  and sacral guides  53  and  55 . Implant  50  includes four guide members  56 ,  57 ,  58  and  59 , each configured to interface with a separate guide. The implant main body has a general “X” or crossing configuration, but could have other main body configurations, such as square, rectangular, oval, etc., and may still have four (or more) guide interface members. 
       FIGS. 6A and 6B  illustrate an exemplary system  60  that includes implant  64  configured to interface with guide  62 . In this embodiment guide  62  includes a recessed region that is configured to stably interface with interface member  63  that in this example is a protrusion or extension from a main body region of the implant. This is an example of the implant having a guide interface member that extends within the guide, compared with guide interface members that extend around a portion of the guide, such as in  FIGS. 1A-5B . The interface in this embodiment causes guide  62  to act as a guide for implant  64  during implantation. 
       FIG. 7  illustrates an exemplary implant  70  or broach  70  with a sharpened distal end. If used as a broach, the broach  70  may be configured with any of the guide members herein, and in methods of use can be guided over one or more guides (before the implant is implanted) to create a space across the SI joint for the implant. The broach can be removed, and an implant can then be advanced over the guides, which is described in more detail below. 
     If used as an implant, the implant  70  may be configured with any of the guide members herein (e.g., including a lumen), and in methods of use can be guided over one or more guides to position the implant. The sharpened region of the implant may create the space as well as function as the implant. 
       FIG. 8  illustrates an exemplary implant  84  that includes guide interface member  86 , which is configured to interface with guide  82 . In this exemplary embodiment, guide  82  has a triangular configuration (which may have other rectilinear configurations), and member  86  includes an inner surface triangular configuration (which may have other rectilinear configurations), as shown. Implant  84  may also have any number of members  86 , each of which can be configured to interface with a different guide. 
     Any of the implants herein may also have a guide interface member with a first configuration and a second guide interface member with a second configuration different than the first. For example, any of the implants herein may have one or more interface members the same or similar to member  23 , the same or similar to member  33 , the same or similar to member  63 , and/or the same or similar to members  86 . 
       FIG. 9  illustrates an exemplary system  90  that includes implant  94 . Implant  94  has a plurality of arms, and not all of the arms include a guide interface member at the respective arm end. In this embodiment only one of the arms has a guide interface member (in this embodiment member  96 ), but in other embodiments the implant may have any number of members less than the number of arms extending from a main body portion (e.g., two, three, four, etc.) 
       FIG. 10  illustrates an exemplary system  100  that includes an implant  104  (shown in end view) that includes ilium guide interface member  106  and sacrum guide interface member  108 , each of which is configured to interface with guides  110  and  112 , respectively. The position shown illustrates an as-implanted positioned across a SI joint, illustrating that any of the implants herein may be implanted with one guide member in one type of bone (e.g.,  106 ) superior to another guide member in a different type of bone (e.g., ilium versus sacrum). For example, guide  110  may be positioned in iliac bone, and guide  112  may be positioned in a sacrum, either inferior to guide  110  as shown, or in other embodiments superior to guide  110 , which is not shown, but which would be above guide  110  in  FIG. 10 . 
     Any of the implants herein may have one or more surfaces that are configured and adapted to facilitate at least one of bony ingrowth and ongrowth. For example, without limitation, any of the implants herein may include one or more of fenestrations, apertures, porous surfaces, irregular surfaces, etc., such as any that may be described in U.S. Pat. No. 9,044,321, U.S. Published Application 2013/0296953, U.S. Pat. No. 9,662,157, U.S. Pat. No. 10,166,033, U.S. Published Application 2016/0287171, the disclosures of which are incorporated by reference herein for all purposes. 
     As is set forth herein, SI joint implants herein may include one or more interface members, which may be configured as lumens or bores. The interface members are generally sized and configured to accommodate passage of one or more guides (such as an ilium guide), which are positioned within one or more of an ilium or a sacrum. In this way, the SI joint implants may be guided by the positioning guides to the intended implantation location across the SI joint without migrating (or at least minimizing migration) away from the denser iliac bone. 
     In some embodiments, the SI joint implants may include interface members in opposing sides or side regions of the SI joint implant, an example of which is shown in  FIG. 2A and 2B . In this arrangement, the implant is advanced over the guides to position the implant across the SI joint. The guides may be removed after the SI joint implant is delivered to its desired position, leaving the implant implanted across the SI joint. 
     One aspect of the disclosure is related to methods of positioning a SI joint stabilization implant across a SI joint from a dorsal approach. In these methods, the SI joint implant may be any of the SI joint implants herein. The methods may include advancing an elongate ilium positioning guide from a dorsal starting point, such as starting point  1122  shown in  FIG. 11A , and into an ilium of a subject. For example only,  FIGS. 2A and 2B  illustrate exemplary ilium guide  22 , but other types of ilium guides may be positioned from a dorsal approach into an ilium of the subject.  FIG. 11A  also illustrates a general region  1120  into which any of the ilium guides herein may be started and advanced into an ilium to function as a guide for the SI joint implant. The methods herein may include engaging a guide interface member of the SI joint implant with a positioning guide to restrict movement of the implant with respect to the positioning guide in at least one direction. For example only,  FIGS. 1A and 1B  illustrate ilium guide interface member  18  of SI joint implant  14 , but other interface members herein may be engaged with any of the guides herein to restrict movement of the SI joint implant with respect to the positioning guide in at least one direction. The methods may include, at a time subsequent to the engaging step, advancing the implant across the SI joint while guiding the implant with the positioning guide to implant the implant across the SI joint. The methods further include removing the positioning guide from the ilium and leaving the implant implanted across the SI joint. The methods may include advancing a positioning guide into an ilium between lateral and medial cortical walls of the ilium, descriptions and locations of which are generally known and shown generally in  FIGS. 11A and 11B . in these methods, engaging the implant with an ilium positioning guide helps maintain the implantation trajectory and limits the extent to which the implant migrates towards the sacrum while advancing the implant across the SI joint. 
     Some methods may also include advancing a sacrum positioning guide into a sacrum of the patient, and further engaging a second guide interface member of the implant with the sacrum positioning guide. In these examples, the implant advancing step may occur while also guiding the implant with the sacrum positioning guide. In these examples, the method also includes removing the sacrum positioning guide from the sacrum. Any of the methods herein may include positioning a sacrum positioning guide into a sacrum before or after an ilium positioning guide is positioned in an ilium. 
     In some methods, prior to implanting the implant, a sharpened broach may he guided over any of the positioning guides herein and advanced towards the SI joint to create a space for the SI joint implant while guiding the broach with the positioning guide. In these examples, the methods include removing the broach to allow dorsal access to the space. The implant may then be advanced over one or more positioning guides as described elsewhere herein. 
     Depending on the implant being implanted across the SI joint, any of the methods herein may also include positioning a second ilium positioning guide from a dorsal approach into the ilium of a subject. These examples may also include engaging a second guide interface member of the implant with the second ilium positioning guide to further restrict movement of the implant with respect to the second ilium positioning guide in at least one direction. 
     Depending on the implant being implanted across the SI joint, any of the methods herein may include positioning first and second sacral positioning guides from a dorsal approach into the sacrum of a subject. These examples may also include engaging first and second sacrum guide interface members of the implant with the first and second sacrum positioning guides to further restrict movement of the implant with respect to the first and second sacrum positioning guides in at least one direction. 
     Any of the individual method steps set forth herein may be combined with any other suitable method step or sequence of steps, unless the disclosure herein indicates to the contrary.