Patent Publication Number: US-2005119698-A1

Title: Suture screw

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application claims priority to U.S. Provisional Application Ser. No. 60/257,813, filed Dec. 22, 2000, and entitled SUTURE SCREW. 
    
    
     BACKGROUND  
      1. Technical Field  
      The present disclosure relates to suture anchors and, more particularly, to self-tapping screw type suture anchors and methods of use.  
      2. Background of Related Art  
      During surgery it is often necessary to attach prosthetic implants or soft tissue such as muscle tissue, ligaments, or tendons to hard tissue such as bone. Various types of surgical fasteners are employed for accomplishing this function, including staples, screw and washer systems, suture anchoring devices, and tissue anchors.  
      The first of these types is illustrated in U.S. Pat. Nos. 4,454,875 and 4,570,623, which show metal staples with spikes on the underside of the crosspiece to secure ligaments.  
      Fasteners included in the second of these types are available as screw-washer combinations wherein the screw is fabricated from a surgically suitable metal, such as titanium or stainless steel alloy, and is usually of self-tapping design. Suture anchors are adapted to be inserted into predrilled holes in bone and can be made of bioabsorbable material. When securing a ligament or suture within a bore drilled in bone, the self tapping screws may abrade the ligament or suture if the ligament or suture is positioned adjacent the screw within the bore as the screw is threaded into the bone.  
      Suture anchors are also used to draw tissue adjacent bone. The anchor, having a first end and a suture fixedly attached thereto, is anchored in bone and a second end of the suture is threaded through tissue and a knot is tied to secure the tissue to bone.  
      What is needed is a suture screw capable of freely receiving lengths of suture material therein so as to draw tissue adjacent bone and/or provide the ability to add or substitute suture material after the suture screw has been positioned within the bone.  
     SUMMARY  
      A two part suture screw for anchoring tissue and bone is disclosed. The suture screw includes a threaded outer sleeve having a longitudinal bore extending therethrough. Preferably a distal end of the sleeve threads are interrupted to form cutting edges making the suture screw self-tapping. The longitudinal bore has a hexagonal shape and includes a countersunk portion at its proximal end to receive an insertion tool.  
      A pin having a conical insertion tip is provided and includes a proximally extending shaft configured for insertion in the longitudinal bore of the outer sleeve. An insertion tip of the pin preferably has a smooth conical surface to ease insertion in a pilot hole in bone. Proximal interrupted cutting threads may be formed on the insertion tip and mate with the interrupted threads on the sleeve. The shaft includes at least one transverse bore though the pin for slidingly receiving a length of suture.  
      A pair of channels extend from the transverse bore proximally along the outer surfaces of the shaft forming half a suture receiving channel. The sleeve is provided with corresponding channels which extend proximally from a point adjacent the throughbore in the pin to form a complete bore for free sliding receipt of the suture within the suture screw. The suture contemplated for use with the disclosed suture screw has a diameter smaller than that of the transverse bore and the bores formed by the channels of the pin and sleeve to allow the suture to freely slide therein.  
      A method of using the suture anchor to anchor tissue to bone is also disclosed and includes providing the disclosed suture screw with a length of suture slidably positioned within the throughbore and channels. The self-tapping suture screw is threaded into bone, preferably with the assistance of a pilot hole drilled in the bone. A free end of the suture is affixed to tissue and the opposite end of the suture tensioned to draw the tissue against the bone. The suture can then be tied off or passed back through the tissue and tied off to secure the tissue to bone. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Various embodiments are described below with reference to the drawings wherein:  
       FIG. 1  is a perspective view of a self-tapping two part suture screw;  
       FIG. 2  is a perspective view of the two part suture screw with parts separated;  
       FIG. 3  is another perspective view of the two part suture screw with parts separated;  
       FIG. 4  is a rear perspective view of a first embodiment of the assembled sleeve component and pin component of the suture screw;  
       FIG. 5  is a side view, partially shown in section, of the pin component taken along line  5 - 5  of  FIG. 3 ;  
       FIG. 6  is a side view, partially shown in section, taken along line  6 - 6  of  FIG. 3 ;  
       FIG. 7  is a perspective view of the two part suture screw being assembled with lengths of suture;  
       FIG. 8  is a perspective view similar to  FIG. 7  with tension on the sutures;  
       FIG. 9  is a side view of the assembled two part suture screw being inserted in a pilot hole in bone;  
       FIG. 10  is a side view of the suture screw fully seated in the bone;  
       FIG. 11  is a side view of the suture being passed back through tissue;  
       FIG. 12  is a side view similar to  FIG. 11  with the suture tensioned;  
       FIG. 13  is a side view of the suture screw and suture tied to anchor and the tissue to the bone;  
       FIG. 14  is a perspective view of the suture screw and an insertion tool;  
       FIG. 15  is a rear end view of a second embodiment of the sleeve component of the suture screw; and  
       FIG. 16  is a perspective view of a self-tapping suture screw with a third embodiment of a sleeve component. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      The preferred embodiments of the device and methods disclosed herein are applicable to a wide variety of procedures including, but not limited to, tissue to bone fastening, ligament repair, joint repair or replacement, non-union fractures, facial reconstruction, etc. In addition, it is believed that the present device finds application in both open and minimally invasive procedures wherein access to the surgical site is achieved through a cannula or small incision.  
      In the description which follows, the term “proximal”, as is traditional, will refer to the portion of the device or structure which is closest to the operator or user, while the term “distal” refers to the portion which is further from the user.  
      The device and method described herein is specifically configured for self-tapping into hard structure, such as bone, and slidably receiving lengths of suture material so as to draw tissue, affixed to one end of the suture material, adjacent the suture screw. Additionally, the ability to slidably receive suture material allows the addition or exchange of one type of suture material for another.  
      Referring now to  FIG. 1 , suture screw  10  includes a pin component  12  and a sleeve component  14  extending proximally from pin component  12 . Pin component  12  and/or sleeve component  14  are preferably formed of a biocompatible material. The Material may be bioabsorbable, nonbioabsorbable, an allograft or a xenograft. Suitable bioabsorbable materials include glycolide, lactide, trimethilene carbonate, dioxanone, dioxatanone, and copolymers and blends thereof. Suitable nonbioabsorbable materials include polypropylene, polyethylene, and metals. Pin component  12  has a smooth conical distal tip  16  and interrupted threads  18 . Interrupted threads  18  are separated by opposing faces  20  and  22 . Faces  20  and  22  form cutting surfaces which allow distal tip  16  of pin component  12  to be self-tapping with respect to hard structure such as, for example, bone.  
      Sleeve component  14  also has interrupted threads  24  at a distal end thereof which are separated by opposing faces  26  and  28  which allow the distal end of sleeve component  14  to be self-tapping. Sleeve component  14  also includes a continuous thread  30  on the outer surface thereof. Thread  30  extends from a proximal end of interrupted thread  24  to a proximal end of sleeve component  14 . As shown, when assembled, interrupted threads  18  of pin component  12  match with the interrupted threads  24  of sleeve component  14 .  
      Referring to  FIGS. 2 and 3 , pin component  12  includes an elongated shaft  32  extending and channels  36   a  and  36   b  are connected by a transverse bore  40  through a different face or part of shaft  32 . Preferably transverse bores  38  and  40  are angled in a proximal/distal direction relative to the longitudinal axis of the shaft. Additionally, bores  38  and  40  are angled relative to each other. Channels  34   a ,  34   b  and  36   a ,  36   b  are preferably semi cylindrical and of greater diameter than the largest diameter suture to be used therein. Similarly, transverse bores  38  and  40  are also of a greater diameter than the largest suture to be used therein. Thus, the sutures used with suture screw  10  are freely slidable therein. While the cross section of shaft  32  is shown to be hexagonal, other configurations of cross sections, such as, for example, oval square, are also contemplated. The non-circular cross sections prevent rotation of pin  12  relative to sleeve  14  during insertion into bone.  
      Tip  16  of pin component  12  has a flat face  42  at a proximal end thereof which mates flush with a similar flat face on a distal end of sleeve component  14 . Pin component  12  also has a chamfered or rounded proximal end  44  to prevent fraying of sutures.  
      Referring now to  FIG. 3 , sleeve component  14  is shown with interrupted threads  24  and continuous threads  30 . Sleeve component  14  has a longitudinal throughbore  46  having a hexagonal cross section for receipt of elongated shaft  32  of pin component  12 . When assembled, a flat distal face  48  of sleeve component  14  mates flush with flat face  42  of pin component  12 .  
      Referring now to  FIG. 4 , there is shown a rear perspective view of assembled pin component  12  and sleeve component  14 . Sleeve component  14  includes opposed pairs of semi cylindrical channels  50   a ,  50   b  and  52   a ,  52   b  which are complementary to channels  34   a ,  34   b  and  36   a ,  36   b  to form cylindrical longitudinal bores in a distal section of assembled suture screw  10 . Preferably, the bores so formed are of a constant diameter larger than the largest suture to be used there through. Sleeve component  14  has an enlarged countersunk hexagonal bore  54  configured to receive and mate with a driver tip of an installation tool for driving suture screw  10  into bone. In this embodiment, it is envisioned that the sutures running through suture screw  10  would pass through a hollow bore in the tip of the installation tool and out of the tool so as to be freely manipulated.  
      The use of suture screw  10  to secure a tissue section adjacent a portion of bone will now be described. The desired location on the bone to which the tissue section is to be secured is located and appropriately prepared by scraping, etc. It may be helpful to form a small diameter pilot hole into which screw  10  can be threaded. Referring to  FIG. 7 , suture screw  10  is prepared by disassembling pin component  12  from sleeve component  14 . Sutures  100  and  120  are then threaded through bores  30  and/or  40  and the sutures are positioned in channels  34   a ,  34   b  and  36   a ,  36   b . The free ends of the sutures are threaded through longitudinal throughbore  46  of sleeve component  14  and pin component  12 .  
      Referring to  FIG. 8 , sleeve component  14  and pin component  12  are assembled by inserting shaft  32  into longitudinal throughbore  46  until flat faces  42 ,  48  meet flush. Care should be taken to ensure channels  50   a ,  50   b  and  52   a ,  52   b  align with the corresponding channels in pin component  12  so that the sutures remain freely slidable within suture screw  10 .  
      Referring to  FIG. 9 , the free ends of the sutures  100 ,  120  are then passed through a bore  130  in installation tool  140  and a hexagonal tip  150  of tool  140  is positioned in hexagonal counter bore  54  of sleeve component  14 . Proximal tension on the sutures and distal pressure on sleeve component  14  by the installation tool help maintain suture screw  10  in its assembled state. The installation tool is then used to drive suture screw  10  into a predrilled pilot hole B in bone A.  
      Referring to  FIG. 10 , as discussed above, suture screw  10  is self-tapping. When suture screw  10  has been fully inserted in bone B, installation tool  140  is removed and one set of the free ends of sutures  100 ,  120  are affixed to tissue C. Thereafter, the opposing free ends of the sutures not attached to tissue are tensioned or pulled through suture screw to draw the attached tissue adjacent the bone. Alternatively, additional or substitute suture material of the same or differing type may be attached to the original sutures and pulled into and through suture screw  10  to provide more or a different type of suture for attachment to the tissue section. Once the tissue section has been properly positioned adjacent the bone the opposing ends of sutures may be tied off adjacent the proximal end of suture screw  10  in known manner or otherwise secured adjacent screw  10  and the remaining excess suture material trimmed. Preferably, sutures  100 ,  120  are reinserted through tissue C ( FIG. 11 ), tensioned to draw tissue C tight ( FIG. 12 ) and tied off  FIG. 134  to secure the tissue to bone A.  
      Referring to  FIG. 14 , there is disclosed an alternative driving tool  120  for use with suture screw  10 , tool  170  includes a proximal shaft  172  and a distal hexagonal driving head  174  to fit in countersunk bore  54  of sleeve component  12 . Cutouts  176   a ,  176   b  and  1768   a ,  178   b  are provided for suture clearance.  
      Referring now to  FIG. 15 , there is shown an alternate sleeve component  56  having interrupted threads  58  (not shown) separated by faces  60 ,  62  (not shown) and continuous thread  64  along a proximal section thereof similar to that of sleeve component  14 . Sleeve component  56  also has a hexagonal longitudinal bore  66  which extends completely through sleeve component  56 . In contrast to sleeve component  14 , sleeve component  56  does not have a countersunk bore and includes channels  68   a ,  68   b  and  70   a ,  70   b  which extend completely along the inner surface of bore  66 . Similar to that of sleeve component  14 . Channels  68   a ,  68   b  and  70   a ,  70   b  cooperate with the corresponding channels in pin component  12  to form bores for sliding receipt of sutures. It is envisioned that the installation tool used with sleeve component  56  would have a corresponding hexagonal shaped driving tip for driving insertion in bore  66 . To allow sutures to remain slidable, it would be necessary to form complimentary channels in the outer surface of the installation tool tip.  
      Referring now to  FIG. 16 , there is disclosed an alternative embodiment of an assembled suture screw  72 . Suture screw  72  utilizes pin component  12  but has an alternative embodiment of a sleeve component  74 . Sleeve component  74  has similar outer surface characteristics as previously described sleeve components but has a proximal hexagonal shaped projection  76  for engagement with driver tool  160 . As shown, suture channels  78  etc. extend along the outer surface of projection  76  for free receipt of sutures positioned therein.  
      Alternatively, a modified pin component having an elongated proximally extending shaft, having suture channels, could be assembled with a corresponding sleeve component such that the proximal end of the shaft extends proximally out of the proximal end of the sleeve component.  
      It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the threads of the pin and/or sleeve component may be partially or completely threaded or continuous. Additionally, there may be provided only a single pair of channels and accompanying through bore or many complimentary pairs greater than the two disclosed. As discussed, the connecting and driving hexagonal bores may be substituted by bores of other cross sections as well as providing corresponding substitute driving tools. The above description should not be construed as limiting, but merely as exemplifications of preferred embodiments and methods. Those skilled in the art will envision other modifications and uses within the scope and spirit of the claims appended hereto.