Patent Publication Number: US-2013237988-A1

Title: Revision tool and method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority to U.S. Provisional Application No. 61/609,187, titled “REVISION TOOL AND METHOD”, filed on Mar. 9, 2012. This patent application may be related to one or more of the following patent applications: U.S. Patent Publication No. 2009/0259261, titled “SYSTEMS AND METHODS FOR THE FIXATION OR FUSION OF BONE AT OR NEAR A SACROILIAC JOINT”, filed on Dec. 4, 2008; U.S. Patent Publication No. 2010/0292738, titled “SYSTEMS AND METHODS FOR THE FIXATION OR FUSION OF BONE”, filed on Jul. 22, 2010; U.S. Patent Publication No. 2011/0087294, titled “SYSTEMS AND METHODS FOR THE FUSION OF THE SACRAL-ILIAC JOINT”, filed on Oct. 5, 2010; U.S. Patent Publication No. 2011/0118785, titled “APPARATUS, SYSTEMS, AND METHODS FOR ACHIEVING ANTERIOR LUMBAR INTERBODY FUSION”, filed on Dec. 6, 2010; and U.S. Patent Publication No. 2011/0118796, titled “SYSTEMS AND METHODS FOR THE FIXATION OR FUSION OF BONE”, filed on Jan. 18, 2011. Each of these references is herein incorporated by reference in its entirety. 
    
    
     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. 
     FIELD 
     The present invention relates generally to an implant revision tool. In various respects, the invention is directed to revision of a sacroiliac joint fusion device for connecting the sacrum to the ilium. 
     BACKGROUND 
     Many types of hardware are available both for the fixation of bones that are fractured and for the fixation of bones that are to be fused. A fusion is an operation where two bones, usually separated by a joint, are allowed to grow together into one bone. The medical term for this type of fusion procedure is arthrodesis. 
     For example, lumbar fusion procedures have been used in the treatment of pain and the effects of degenerative changes in the lower back. An example of a lumbar fusion is a fusion in the S1-L5-L4 region in the spine. 
     Another example, the human hip girdle (see  FIGS. 1 and 2 ) is made up of three large bones joined by two relatively immobile joints. One of the bones is called the sacrum and it lies at the bottom of the lumbar spine, where it connects with the L5 vertebra. The other two bones are commonly called “hip bones” and are technically referred to as the right ilium and the left ilium. The sacrum connects with both hip bones at the left and right sacroiliac joints (SI-Joint). 
     The SI-Joint functions in the transmission of forces from the spine to the lower extremities, and vice-versa. The SI-Joint has been described as a pain generator for up to 22% of lower back pain. To relieve pain generated from the SI Joint, sacroiliac joint fusion is typically indicated as a surgical treatment, e.g., for degenerative sacroiliitis, inflammatory sacroiliitis, iatrogenic instability of the sacroiliac joint, osteitis condensans ilii, or traumatic fracture dislocation of the pelvis. 
     Occasionally, after an implant device or implant fusion device has been implanted and secured into position, revision procedures are required to modify or remove the device that is impacted or has bony in-growth. Therefore, a method and apparatus are needed that allow safe and efficient removal of the implant device. 
     SUMMARY OF THE DISCLOSURE 
     This application relates generally to an implant revision tool. In various respects, the application is directed to revision of a sacroiliac joint fusion device for connecting the sacrum to the ilium. 
     Some embodiments described herein provide for an orthopedic revision instrument for revising a bone implant including a revision rod having a proximal end, a distal end and a length extending between the proximal and distal ends, the revision rod includes an implant engagement portion having an implant pin and an implant thread, the implant pin adapted to enter an interior of the bone implant and the implant thread configured to mate with corresponding threads on the bone implant; and an osteotome for sheering bone and tissue surrounding the bone implant. 
     In some embodiments, the implant thread is located at the distal end of the revision rod. In other embodiments, the implant thread has a length between about 4 mm to about 6 mm. In further embodiments, the implant thread has a tapered distal end. 
     In some embodiments, the length of the revision rod is between about 200 mm and about 400 mm. Additionally, the revision rod may include a shaft member and an advancing device thread adjacent to the shaft member. In other embodiments, the revision rod also includes a revision thread located at the proximal end of the rod, the revision thread adapted to engage a slap hammer. In some variations, the revision thread includes a distal end that is adjacent to a proximal end of a gripping member on the rod. The gripping member may have a length between about 13 mm to about 15 mm. In some variations, the gripping member is knurled. In further embodiments, the advancing device thread extends from a distal end of the gripping member to a proximal end of the shaft. In any of the preceding embodiments, the advancing device thread has a length between about 80 mm to about 100 mm. The advancing device may include a diameter between about 6.5 mm to about 8 mm. 
     The orthopedic revision instrument may also include a crank configured to drive the osteotome into bone and tissue surrounding the implant. In other embodiments, the revision instrument includes a shank configured to align the osteotome with the bone implant. In any of the preceding embodiments, the orthopedic revision instrument may include or may couple to a slap hammer configured for removing the bone implant from bone and tissue surrounding the bone implant. The revision instrument may include a stopping member configured to engage a slap hammer at the proximal end of the rod. 
     In any of the preceding embodiments, the osteotome includes a shank portion and a sheering portion. The shank portion may include a lever socket for engaging a shank lever configured to align the osteotome with the bone implant. In other embodiments, the sheering portion includes a cutting edge at a distal end of the sheering portion, the cutting edge adapted to sheer bone as the osteotome is driven into bone. In some embodiments, the cutting edge is corrugated. In other embodiments, the cutting edge is tapered. In any of the preceding embodiments, the sheering portion comprises a triangular cross-section. 
     In any of the preceding embodiments, the bone implant removed may be removed from the sacroiliac joint. 
     Further embodiments provide a method for revising an implant. These methods include providing an orthopedic revision instrument comprising a revision rod and a osteotome coupled to the revision rod, the revision rod having an implant engagement portion for engaging a bone implant residing in a sacroiliac joint; inserting the revision rod into the sacroiliac joint and engaging the implant engagement portion with the bone implant, the implant engagement portion comprising a first threaded portion configured to mate with a second threaded portion on the bone implant; sheering bone in the sacroiliac joint that is surrounding the bone implant; and removing the bone implant from the sacroiliac joint. 
     In any of the preceding embodiments, inserting the revision rod includes driving the implant engagement portion into the implant. In some embodiments, the implant engagement portion comprises an implant pin adapted to fit inside the implant. 
     In any of the preceding embodiment, sheering bone includes driving the osteotome into bone of the sacroiliac joint. 
     In other embodiments, driving the osteotome includes rotating a T-crank to drive a sheering portion of the osteotome into bone in the sacroiliac joint. In some embodiments, the osteotome is driven over an exterior surface of the bone implant. In further embodiments, sheering bone includes cutting bone surrounding the bone implant with a cutting edge located at a distal end of the osteotome. Additionally, in some embodiments, removing the bone implant includes engaging a slap hammer to a proximal end of the revision rod to extract the bone implant from the sacroiliac joint. 
     Any of the preceding methods may include comprising aligning the osteotome with the bone implant. In some embodiments, aligning the osteotome further comprises engaging a lever to a shank portion of the osteotome to adjust the orientation of the osteotome. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
         FIGS. 1A-B  illustrate exemplary embodiments of an implant device. 
         FIGS. 2-3  are, respectively, anterior and posterior anterior views of the human hip girdle comprising the sacrum and the hip bones (the right ilium, and the left ilium), the sacrum being connected with both hip bones at the sacroiliac joint. 
         FIGS. 4-6B  are anatomic views showing, respectively, in pre-implanted perspective, implanted perspective, implanted anterior view, and implanted cranio-caudal section view, the implantation of three implant devices for the fixation of the SI-Joint using a lateral approach. 
         FIG. 7  illustrates an exemplary revision rod. 
         FIG. 8  illustrates an exemplary revision rod with an implant. 
         FIG. 9A  is a perspective view of an exemplary revision tool. 
         FIG. 9B  is a perspective view of an exemplary revision tool with a shank lever. 
         FIG. 10  is an enlarged distal end of an exemplary osteotome and an implant. 
         FIG. 11  is a perspective view of an exemplary revision tool with a slap hammer. 
         FIGS. 12A-C  illustrate an exemplary method of revising an implant. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the exemplary embodiments, it will be understood that they are not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as described herein. 
     Various aspects of the present invention relate to a revision tool having a revision rod, crank and osteotome. In various embodiments, the revision tool may be used to remove an implant device from the sacroiliac joint. The revision tool discussed herein may also be used to remove an implant device from other bones within a human patient. For example, the revision tool may be used to remove an implant device from the lumbar region of the spine and other bones. As such, those of ordinary skill in the art will realize that exemplary embodiments related to removing an implant device from the sacroiliac joint are not limited to this joint, but rather set forth as examples. 
       FIGS. 1A-B  illustrate exemplary embodiments of an implant device. Elongated, stem-like implant devices  20  like that shown in  FIGS. 1A-B  make possible the fixation of the SI-Joint (shown in anterior and posterior views, respectively, in  FIGS. 2 and 3 ) in a minimally invasive manner. Implant devices may have various shapes and have various cross-sectional geometries. For example, integrated implant  20  may have a generally curvilinear (e.g., round or oval) cross-section as illustrated in  FIG. 1A  or a generally rectilinear cross section (e.g., square or rectangular or triangular) as illustrated in  FIG. 1B  or combinations thereof. Implant devices  20  may be effectively implanted into the SI-Joint through the use of two alternative surgical approaches; namely, a lateral approach or a postero-lateral approach. Either procedure is desirably aided by conventional lateral and/or anterior-posterior (A-P) visualization techniques, e.g., using X-ray image intensifiers such as a C-arms or fluoroscopes to produce a live image feed that is displayed on a TV screen. 
       FIGS. 2-3  are, respectively, anterior and posterior views of the human hip girdle comprising the sacrum and the hip bones (the right ilium, and the left ilium), the sacrum being connected with both hip bones at the sacroiliac joint (SI-Joint). 
       FIGS. 4-6B  are anatomic views showing, respectively, in pre-implanted perspective, implanted perspective, implanted anterior view, and implanted cranio-caudal section view, the implantation of three implant devices for the fixation of the SI-Joint using a lateral approach. In one embodiment, one or more implant devices  20  are introduced laterally through the ilium, the SI-Joint, and into the sacrum. In the illustrated embodiment, three implant devices  20  are placed in this manner. Also in the illustrated embodiment, the implant devices  20  are triangular in cross section, but it should be appreciated that implant devices of other geometrical cross sections may be used. 
       FIG. 7  illustrates an exemplary revision rod. The exemplary revision rod  10  includes a proximal end  6 , distal end  8 , shaft  12 , implant thread  14 , advancing device thread  16 , gripping member  24  and revision thread  18 . The revision rod  10  may have a length extending from the proximal end  6  to the distal end  8  in the range of about 200 and 400 mm. In various embodiments, the length of revision rod  10  is about 335 mm. Implant thread  14  is located adjacent the distal end of shaft  12 . When engaging implant  20 , implant pin  22  may be inserted into implant  20  and implant threads  14  may engage a threaded portion inside of implant  20 . The distal end of implant pin  22  may be rounded. Implant pin  22  may have a length in the range of about 14 to 16 mm and a diameter in the range of about 2 to 4 mm. 
     Revision thread  18  may be located at the proximal end  6  of revision rod  10 . The revision thread  18  may have a length in the range of about 7 to 9 mm and a diameter of about 6.5 mm. In various embodiments, revision thread  18  engages a slap hammer. The distal end of revision thread  18  is adjacent to the proximal end of gripping member  24 . Gripping member  24  may extend between revision thread  18  and the proximal end of advancing device thread  16 . Gripping member  24  may have a length in the range of about 13 to 15 mm and a diameter of about 6.5 mm. In various embodiments, the gripping member is implemented as a light, straight knurl. 
     Advancing device thread  16  extends from the distal end of gripping member  24  to the proximal end of shaft  12 . Advancing device thread  16  may have a length in the range of about 80 to 100 mm and a diameter in the range of about 6.5 to 8 mm. 
     Implant thread  14  may have a tapered distal end. Implant thread  14  may have a length of about 10 mm. The proximal diameter of the implant thread  14  may range from about 4 to 6 mm and the distal diameter may range from about 2 to 4 mm. 
     Additionally, although described as an implant pin and implant thread for mechanically engaging the implant, this is not intended to limit the manner in which the contemplated embodiments connect or couple to an implant. As can be appreciated, any suitable engagement mechanism or element can be used to couple the revision tool to an implant. For example, the revision tool may include an implant engagement portion adapted to form a friction-fit, interference-fit, press-fit, mated-fit, interlocking or locking-fit, keyed fitting etc. with the implant. Suitable mechanisms included threaded connections, cam locks/clamps, bayonet fittings, retaining or snap rings, ball-and-detect configurations, and/or mating/interference elements that are configured to engage and retain/lock/secure the implant to the revision tool. 
       FIG. 8  illustrates an exemplary revision rod with an implant. Implant  20  may be attached to distal end  8  of revision rod  10 . Implant  20  may be positioned over implant pin  22  and may engage implant thread  14 . 
       FIG. 9A  is a perspective view of an exemplary revision tool.  FIG. 9B  is a perspective view of an exemplary revision tool with a shank lever. Revision tool  30  may include revision rod  10 , T-crank  32 , osteotome  34 , cutting edge  36 , and stopping member  38 . T-crank  32  may engage advancing device threads  16 . When T-crank  32  rotates around advancing device threads  16 , osteotome  34  may be driven towards distal end  8  of the revision tool  30 . Osteotome  34  may have a hollow portion  41  to allow revision rod  10  to be passed through the hollow portion  41 . 
     Osteotome  34  may include a shank portion  40  and sheering portion  42 . In various embodiments, shank portion  40  and sheering portion  42  may be formed as separate pieces. When formed as separate pieces, the distal end of shank  40  may also include a socket (not shown) to engage the proximal end of sheering portion  42 . The shank portion  40  is located at or near the proximal end of the osteotome  34 . Shank  40  may include lever socket  46  that may engage shank lever  44 . Shank lever  44  may be used to rotationally position osteotome  34  to align with implant  20  (see  FIG. 9B ). Shank  40  may have a length in the range of about 83 to 85 mm and a diameter of about 18 mm. 
     Sheering portion  42  is located at or near the distal end of the osteotome  34 . Sheering portion  42  may have a length in the range of about 190 to 210 mm. The distal end of sheering portion  42  may include cutting edge  36 . Cutting edge  36  is configured to sheer bone as osteotome  34  is driven by T-crank  32 . Sheering portion  42  may have a cross-section shape similar to the cross-section shape of implant  20 . In the embodiment of  FIG. 9A , sheering portion  42  has a triangular cross-section corresponding to a triangular shaped implant  20 . 
     Stopping member  38  may engage the distal end of revision threads  18  and the proximal end of the gripping member  24 . In various embodiments, the stopping member  38  is used with a slap hammer. 
       FIG. 10  is an enlarged distal end of an exemplary osteotome and an implant. Cutting edge  36  may be corrugated and may include a tapered distal end. Osteotome  34  is aligned by shank  40  such that cutting edge  36  is aligned with implant  20 . As such, driving osteotome  34  causes cutting edge  36  to sheer bone and encompass implant  20  as osteotome  34  is driven by T-crank  32 . 
       FIG. 11  is a perspective view of an exemplary revision tool with a slap hammer. Revision tool  30  may be coupled to slap hammer assembly  44 . Slap hammer assembly  44  may engage the proximal end of revision thread  18 , which is shown in  FIG. 9B . A physician may use slap hammer assembly  44  in conjunction with stopping member  38  to remove implant  20  attached to the revision rod  10 . 
     Revision tool  30  may be implemented effectively through the use of alternative surgical approaches. A lateral approach and a postero-lateral approach are discussed herein. Revision tool  30  may also be implemented using other surgical approaches. As such, those of ordinary skill in the art will realize that exemplary embodiments related to the revision tool are not limited to this type of surgical approach, but rather set forth as examples. 
     Before undertaking a lateral revision procedure, the physician identifies the implant device that is to be revised using conventional imaging techniques, e.g., using X-ray image intensifiers such as a C-arms or fluoroscopes to produce a live image feed that is displayed on a TV screen. In addition, local biopsies and tests may be performed if conditions such as an infection are suspected. 
     Aided by lateral, inlet, and outlet C-arm views, and with the patient lying in a prone position, the physician aligns the greater sciatic notches using lateral visualization to provide a true lateral position. An incision is made starting aligned with the posterior cortex of the sacral canal, followed by blunt-tissue separation to the implant(s) to be removed. From the lateral approach, the revision rod  10  is advanced to the lateral end of the implant  20  to be removed. The implant pin  22  is advanced into the implant guide hole and fastened to the implant  20  by turning the revision rod  10  clockwise until it is secured to the implant  20 . 
     The set-up for a postero-lateral approach is generally the same as for a lateral approach. The physician identifies the implant device  20  that is to be revised. This exemplary procedure is typically performed with the patient lying in a prone position and may be aided by lateral and anterior-posterior (A-P) c-arms. The same surgical tools may be used except the insertion path now starts from the posterior iliac spine of the ilium, angles through the SI-Joint, and terminates in the sacral alae. The revision rod  10  is inserted from the posterior iliac spine of the ilium, angling through the SI-Joint, and terminating in the sacral alae, until the distal end of the revision rod  10  engages the proximal end of the implant structure  20 . 
       FIGS. 12A-C  illustrate an exemplary method of revising an implant. Implant device  20  may be revised using revision tool  30 .  FIG. 12A  illustrates an implant device  20  installed between a first bone segment and a second bone segment. In various embodiments, the first bone segment is an ilium and the second bone segment is a sacrum.  FIG. 12B  illustrates a revision rod  10  engaging implant  20 . Revision tool  30  may be positioned at the location of the implant. Implant pin  22  may inserted into the proximal end of the implant  20  until implant thread  14  reaches implant  20 . Revision rod  20  is then rotated using gripping member  24  so that implant thread  14  engages the threading inside implant  20 . 
       FIG. 12C  illustrates osteotome  34  engaging implant  20 . After revision rod  10  has engaged implant  20 , osteotome  34  and T-crank  32  are positioned over revision rod  10  until advancing device thread  16  engages T-crank  32 . T-crank  32  is then rotated to drive sheering portion  42  of the osteotome  34  into the patient and toward implant  20 . Visualization techniques as described previously are used to determine the position of the revision tool  30  and implant  20  during the advancement of revision tool  30 . Shank lever  44  may be attached to shank  40  and used to align cutting edge  36  with the proximal end of implant  20 . 
     Once cutting edge  36  is aligned with implant  20 , T-crank  32  is rotated further to drive sheering portion  42  and cutting edge  36  over the exterior surface of implant  20  removing bone and tissue growth. Slap hammer  44  or other removal device is then attached to revision thread  18  as previously shown and described to remove implant  20 . If one or more implants are to be revised, the revision process is performed in the same manner for the remaining implants. 
     The revision tool described herein makes possible a revision of an implant device which is impacted or has bony in-growth. The design and configuration of the revision tool allow the osteotome to be aligned directly with the implant device to sheer bone from an implant device by the cutting edge as the osteotome is advanced. The revision tool optimizes bone removal while minimizing trauma to surrounding tissue. Additionally, the non-impact advancement of the osteotome minimizes the risk of over advancement of the revision tool and may be a safer option. 
     Additional details pertinent to the present invention, including materials and manufacturing techniques, may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the examples described herein, but only by the plain meaning of the claim terms employed.