Abstract:
A soft tissue fixation assembly comprises an anchor element which is installed in a bone or other tissue and a suture joiner element which mates with the anchor element. The suture joiner element includes a suture retaining element that securely retains suture and which is connected to the anchor element. Energy is transmitted through the suture joiner element to cause relative vibratory motion between the respective components and localized collapsing and compressing of the suture joiner element to secure the suture within the suture joiner element and to secure the suture joiner element within the anchor element. The soft tissue segment is thus fixed to the bone via the sutures secured in the bone anchor.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention is related to surgical fixation devices for fixing soft tissue to bone, and in particular to soft tissue fixation devices that include a bone anchor and suture. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the surgical repair of soft tissue, such as, for example, the surgical reattachment of a torn ligament to bone, it is known to use multi-part devices to fix the soft tissue to the bone. The multi-part devices typically include a screw or other bone anchoring device, and a button-like device for anchoring the suture therein. The anchor is installed in a predrilled hole in the bone, and the soft tissue is fixed to the anchor in the bone with sutures, which are fastened together with the button instead of with knots. 
         [0003]    A disadvantage of such devices is that the quality and strength of the device may be limited by the quality and strength of the suture, and/or by the integrity of the attachment of the device to the bone. The soft tissue will detach from the anchor in the bone if the suture slips or breaks. If the anchor or the button slips or becomes dislodged, the soft tissue will not remain anchored to the bone. 
         [0004]    U.S. Pat. No. 6,056,751 (Fenton) attempts to address this problem of slipped suture by providing a sutureless soft tissue fixation assembly. However, that invention may not work well in situations where the configuration of the tissue does not allow proper alignment of the tissue relative to the anchor. There remains a need for a suture device and method for securing soft tissue, such as labrum tissue. 
         [0005]    It would therefore be an advantage to provide a surgical soft tissue fixation device which overcomes the disadvantages of the prior art devices. 
       SUMMARY OF THE INVENTION 
       [0006]    The invention provides an integrated soft tissue fixation assembly which attaches securely soft tissue segments to bone. The assembly includes two pieces which are fused together in situ in a patient, which allows for securely holding tissue in place with the use of sutures. 
         [0007]    According to one aspect of the invention, the assembly comprises a bone anchor element, adapted for installation into a hole in a bone and including an anchor portion at a distal end and a drive portion at a proximal end, and a suture joiner element. The anchor element and the joiner element are adapted to be joined together in situ. The joiner element, in one embodiment, includes a suture retaining element at or near the proximal end thereof, which suture retaining element includes a groove extending at least partially circumferentially thereabout for receiving suture. 
         [0008]    The anchor element preferably includes threads or barbs at its distal end for effecting a substantially permanent installation of the anchor portion into a bone. The anchor element is adapted for mating engagement with the joiner element and includes a radially extending hub and, in one embodiment, at least one bore for receiving a corresponding connection element of the joiner element. One or both of the anchor element and the joiner element includes one or more energy directors for focusing energy applied to either component of the assembly. 
         [0009]    The energy directors preferably focus ultrasonic energy applied to the assembly and comprise a plurality of protruding elements that extend outwardly from one or both components. In addition, the suture joiner element is adapted to fuse to or around suture positioned in the groove upon application of energy to the joiner element. 
         [0010]    According to another embodiment, the joiner element includes a bore for receiving a complementary pin or leg of the anchor element. At least one of the bore of the joiner element and the anchor element includes one or more energy directors for focusing energy applied to the assembly. 
         [0011]    According to another aspect of the invention there is provided a method of fixing soft tissue to a bone. The method comprises the steps of: 
         [0012]    providing a soft tissue fixation assembly as described above for attachment of soft tissue to bone; 
         [0013]    drilling a hole into a bone at a desired location for installation of the anchor element therein; 
         [0014]    installing the anchor element into the drilled hole; 
         [0015]    securing suture that is fixed to tissue in the joiner element; 
         [0016]    assembling the joiner element into the anchor element through the segment of soft tissue to hold the soft tissue segment within the tissue capture region; and 
         [0017]    bonding the joiner element to the anchor element, thereby fixing the soft tissue segment to the bone. 
         [0018]    These and other features of the invention will be more fully appreciated with reference to the following detailed description which is to be read in conjunction with the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The invention is further described by the following description and figures, in which: 
           [0020]      FIGS. 1A and 1B  are perspective views of embodiments of the soft tissue fixation assembly of the present invention; 
           [0021]      FIG. 2  is a perspective view of an embodiment of the suture joiner element of the present invention; 
           [0022]      FIG. 3  is a perspective view of an embodiment of the soft tissue fixation assembly of the present invention; 
           [0023]      FIG. 4  is a perspective view of an alternate embodiment of the soft tissue fixation assembly of the invention; 
           [0024]      FIG. 5  is a partial sectional and partial perspective view of the assembly, showing the pre-drilling step of the claimed method; 
           [0025]      FIG. 6  is a partial sectional and partial perspective view of the assembly of  FIG. 1B , showing the bone anchor positioning step of the claimed method; 
           [0026]      FIG. 7  is a partial sectional and partial perspective view of the assembly of  FIG. 1B , showing the bone anchor element in position in the target bone, and the suture joiner element moving into position for securing suture thereto; 
           [0027]      FIG. 8  is a partial sectional and partial perspective view of the assembly of  FIG. 1B , showing the suture positioned in the suture retaining element as the suture joiner element is moved into position; 
           [0028]      FIG. 9  is a partial sectional and partial perspective view of the assembly of  FIG. 1B , showing the step of connection the suture joiner element to the bone anchor element; and 
           [0029]      FIG. 10  is a partial sectional and partial perspective view of the assembly of  FIG. 1B , showing the final step of using ultrasonic energy to secure the suture joiner element with the bone anchor element. 
       
    
    
       [0030]    Like elements in the respective FIGURES have the same reference numbers. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]    One embodiment of the soft tissue fixation assembly of the present invention is illustrated in  FIG. 1A . The assembly  10  comprises an elongated bone anchor element  20 , with central bore  30 , which extends along an axis A between proximal end  22  and distal end  24 . The anchor element  20  includes an anchor portion  26  at its distal end  24  and a drive portion  28  at its proximal end  22 . This element  20  is adapted, such as by threads or barbs  32  on the outer surface thereof, to grip a bone into which the anchor element is to be installed. In this embodiment, the anchor portion  26  has a hub  34  at the proximal end  22 , which has a diameter greater than the nominal diameter of the anchor portion  26  so that, in one embodiment, the hub  34  acts as a stop for the anchor element  20  during installation into bone. 
         [0032]    An alternative embodiment is shown in  FIG. 1B . That embodiment is the same as the embodiment of  FIG. 1A  except that it has concentric rings (or “threads”)  32 , instead of a helical thread pattern. The embodiment of  FIG. 1B  is adapted to be pushed into a hole in a bone, with the rings forming an interference fit. 
         [0033]    The assembly  10  of  FIGS. 1A and 1B  further include a suture joiner element  40  which also extends along the axis A between its distal end  42  and its proximal end  44 . The suture joiner element  40  is shown in greater detail in  FIG. 2 . The joiner element  40  includes a suture retaining element  50  extending radially with respect to the axis A. The retaining element  50  includes a groove  52  that extends circumferentially around the retaining element  50  for securing suture therewithin, and as described in further detail below. The nominal diameter of the retaining element  50  preferably is at least equivalent to the diameter of the anchor element  20 , depending on the specific configuration of the anchor element, as described further below. 
         [0034]    Each of the bone anchor element  20  and the suture joiner element  40  are adapted for substantially permanent attachment to each other. In the illustrated embodiments of  FIGS. 1A ,  1 B, and  2 , the suture joiner element  40  includes a joiner connection rod  46  that extends along the axis A from the retaining element  50  toward the distal end  42  of the joiner element  40 . The connection rod  46  preferably includes one or more flanges for securing the joiner element  40  to the anchor element  2 . In the illustrated embodiment, the flange  48  essentially is a ring of material extending from rod  46  that effects an interference fit (or a snap fit into a recess in anchor portion  26 ) as the rod  46  is introduced into anchor portion  26 . In alternate embodiments, the flange  48  may be multiple pieces of the same materials positioned about or along the connection rod  40 . The connection rod  46  also may include one or more energy directors  49  extending radially from the connection rod  46 , as shown in  FIG. 2 . In one embodiment, the flange  48  may function as an energy director, such that the connection rod  46  includes a single structure that functions as a flange to hold the two elements  20 ,  40  in secure position, and function as an energy director to direct ultrasonic or other energy to connect the two elements  20 ,  40 . Thus, the energy directors  49  may take the form of axial ribs or spines, helical ribs, or threads on the surface of either the connection rod  46  or within the bore  30 . 
         [0035]    In the illustrated embodiments of  FIGS. 1A ,  1 B, and  2 , the suture joiner element  40  includes a drive rod  60  attached to or positioned in the suture retaining element  50 . The drive rod  60  is used to insert the suture joiner element  40  in the bone anchor element  20  after the anchor element  20  is positioned in bone, as described in further detail below. In a preferred embodiment, the drive rod  60  is detachably connected to the retaining element  50 . In alternate embodiments the drive rod  60  is permanently fixed to the suture retaining element  50 , or a single rod that extends through the suture retaining element  50  to form, at its proximal end, the connection rod  46  and at the distal end the drive rod  60 . 
         [0036]    As shown in  FIG. 2 , the suture retaining element  50  includes a groove  52  extending at least partially about the circumference of the element. The groove  52  is of sufficient dimensions to accept a suture therein. Elements  50  may have customized grooves to accommodate sutures of different widths and materials, depending on the specific intended use. In the illustrated embodiment, the groove  52  extends partially around the element  50 . In alternate embodiments there may be two grooves, each of which extends partially and end-to-end around the circumference of the retaining element  50 . In a preferred embodiment, the grooves include a terminal notch  54  which serves to securely hold or lock suture in place once it wraps through the grooves  52 . Alternatively, the groove  52  may be a single continuous recess around the circumference of the element  50 . The retaining element  50  is manufactured of materials that are formable or that melt upon application of energy such as heat, ultrasonic energy, or other energy, such that application of energy causes the groove to shrink or fuse about suture retained therein. The energy may be directed to the retainer element  50  through energy directors  49  located on the connection rod  46 , or by other means as known to those skilled in the relevant art. 
         [0037]      FIG. 3  illustrates the soft tissue fixation assembly of  FIGS. 1A and 2  connected and deployed in situ in bone  51 . In an alternate embodiment, and as shown in  FIG. 4 , the connection rod  46  is attached to or integral with the bone anchor element  20  at its distal end. In this embodiment, the connection rod  46  includes a flange  48  and energy directors  49 , as described above. In practice, once the anchor element  20  (shown in section in  FIG. 3 ) is securely positioned in bone  51 , connection rod  46  is inserted into a joiner bore  62  in suture retaining element  50  where it is held in position by the flange  48 . The energy directors  49  then are activated to fuse or otherwise join the connection rod  46  within the joiner bore  62  to fixedly attach the anchor element  20  to the joiner element  40 . The ultrasonic welding is performed in situ, once the two elements  20 ,  40  are securely positioned together. 
         [0038]    In both illustrated embodiments, the energy directors  49  focus ultrasonic energy directed into the joiner element  40  or anchor element  20  from an ultrasonic weld horn  64 , shown in  FIG. 3 . The application of this energy establishes an interface between the two elements. In the embodiment of  FIGS. 1A and 2 , the interface is between the connection rod  46  attached to the suture joiner element  40  and the anchor bore  30 , whereas in the embodiment of  FIG. 4 , the interface is between the anchor rod  46  attached to the bone anchor element  20  and the joiner bore  62 . In both embodiments, the effect is to securely connect the bone anchor element  20  and the suture joiner element  40 . 
         [0039]    The inventive assembly  10  is shown in practice in  FIGS. 5 through 10 . The method of using the assembly  10  is substantially the same regardless of which embodiment of bone anchor element  20  or suture joiner element  40  is used. As shown in  FIG. 5 , a bore  72  is drilled into bone  70 , using a bone drill  76  generally known and available to those skilled in the relevant art. Alternatively, the anchor portion  26  of the bone anchor element  20  may include a self-drilling tip so that the anchor element  20  can be driven directly into a bone  70  without predrilling a hole  72 . 
         [0040]    Also as shown in  FIG. 5 , suture  80  is drawn through the target soft tissue  74  in a manner specific to the type of tissue, the location, and other factors readily discernible by those surgeons in the relevant art. Thus, a preliminary step includes pre-drilling the anchor hole  72  and securing suture  80  through the target soft tissue  74 . 
         [0041]    In the illustrated embodiment of  FIG. 6 , a push rod  78  is positioned against the distal end  22  of the borne anchor element  20 , and force is applied thereto to push the bone anchor element  20  into the bone hole  72 . The push rod  78  may be positioned within a groove (not shown) at the distal tip of the anchor element  20 , or may be screwed into a threaded recess (not shown) at the distal end of the anchor element  20  to prevent the push rod  78  from slipping from position as it pushes the anchor element into the bone hole  72 . In the embodiment where the anchor element  20  includes a self-drilling tip, the push rod  78  may be a screwdriver or other element used to drill the anchor element directly into the bone  70 . 
         [0042]    As shown in  FIG. 7 , once the anchor element  20  is positioned into the bone hole  72 , the push rod  78  is removed from the anchor element  20 , and the suture joiner element  40  is brought into position proximal to the suture  80 .  FIG. 8  shows suture  80  securely fed into the grooves  52  of the suture retaining element  50 . The suture joiner element then is rotated into position to align the connection rod  46  along axis A and proximal to the distal end  22  of the bone anchor element  20 . Using the connection rod  46 , and as shown in  FIG. 9 , the suture joiner element  40  is pushed into position within the bone anchor element  20 . Because the bone anchor element  20  is securely positioned within the bone  70 , it acts as a stationary anvil against which the user can apply force, such that by applying downward force on the connection rod  46 , it forces the flange  48  to fit within the anchor bore  30 . 
         [0043]    In a final step, and as shown in  FIG. 10 , a weld horn  64  is moved into position against the drive rod  60 . Transmission of ultrasonic energy into the connection rod  60  causes the groove  52  to fuse to or around suture contained therewithin, thus essentially permanently securing the suture within the groove. In alternate embodiments, the groove  52  fuses closed around the suture, fuses the groove walls with the suture or partially closes the suture sufficiently to secure the suture. In alternative embodiments heat energy or physical energy is applied to the joiner element  50  sufficient to at least partially close the groove  52  around the suture therewithin. 
         [0044]    In a preferred embodiment, and as shown in  FIG. 10 , a next step may include transmission of ultrasonic energy into the connection rod  60  or the anchor element  20  from the well horn  64 . Such transmission causes vibration of the joiner element  40  relative to the anchor element  20 , and in particular the relative movement of the energy directors (not shown in this  FIG. 10 ) against the interfering portions of the stationary component, causes localized melting of the energy directors and the corresponding interfering portions of the stationary component to create weld regions. This welding step may not be necessary if the snap fit is sufficient to permanently secure the anchor element  20  with the suture joiner element  40 . 
         [0045]    The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of the equivalency of the claims are therefore intended to be embraced therein.