Abstract:
A suture anchor is disclosed which has an elongated body having a distal end, a proximal end and an exterior surface. An axially oriented bore extends into the body from the proximal end and a proximal portion of the bore has a plurality of abutment surfaces for engaging a tool. The bore includes one or more axially oriented suture passages leading to a suture attachment within the bore. A length of suture extends into the at least one suture passage from the body proximal end and extends to the suture attachment. A screw thread spirals about a portion of the exterior surface of the body adjacent the at least one suture passage. Between the bore and the exterior surface of the body the body has a wall thickness and wherein the suture passage comprises the area where the wall thickness goes to zero.

Description:
BACKGROUND 
       [0001]    The present application relates to systems and methods for performing a repair of a partial thickness rotator cuff tear. 
         [0002]    A PASTA (Partial Articular Surface Tendon Avulsion) lesion in a rotator cuff of a shoulder can be particularly difficult to repair. The rotator cuff comprises a group of muscles which surround the shoulder and tendons which attach those muscles to the humeral head. The tendons have a footprint where they attach to the humeral head and in a PASTA lesion a portion of the tendon&#39;s footprint becomes detached from the humeral head. Such lesions are most commonly found on the supraspinatus tendon. One option for treatment is completion of the tear and repair using standard techniques for a full thickness tear. Preservation of the existing attachment is thus lost and the entire tendon must be reattached. A further option is to create an incision through the tendon and place a standard suture anchor therethrough. This creates significant trauma to the tendon. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention provides systems and methods for repairing a PASTA lesion which provides advantages over current treatment options. A suture anchor according to the present invention comprises an elongated body having a distal end, a proximal end and an exterior surface. An axially oriented bore extends into the body from the proximal end and a proximal portion of the bore has a plurality of abutment surfaces for engaging a tool. The bore has at least one axially oriented suture passage. A suture attachment is associated with the bore. A screw thread extends about a portion of the exterior surface of the body adjacent the at least one suture passage. The body has a wall thickness between the bore and the exterior surface of the body, the suture passage comprising an area where the wall thickness goes to zero. 
         [0004]    Preferably, the wall thickness is zero along substantially an entire length of the bore. 
         [0005]    Preferably, the abutment surfaces form a tool receiving recess and wherein the at least one suture passage comprises a first suture passage on a first side of the tool receiving recess and a second suture passage on a second side of the tool receiving recess. A length of suture can pass down the first suture passage to the suture attachment and then back out the second suture passage. Preferably, the tool receiving recess extends substantially from the body proximal end to the suture attachment providing good purchase for the tool and reducing stress upon the anchor body during tool use. In one embodiment, the threads have a maximum outer diameter less than 4 mm and wherein the suture is of gauge #2 or lower. Preferably, the threads have a maximum outer diameter less than 3.5 mm, and more preferably, a maximum outer diameter of 2.8 mm. 
         [0006]    Preferably, the suture anchor has a pullout resistance of at least 25 lbs. 
         [0007]    In one embodiment, the body is formed of a bioabsorbable polymer and in an alternative embodiment of Titanium. 
         [0008]    Preferably, the suture attachment comprises a cross member disposed within the bore allowing sliding of the suture therethrough. 
         [0009]    Preferably, the suture anchor further comprises a driver inserted into a tool receiving recess formed between the abutment surfaces, the driver comprising complementary surfaces in engagement with the abutment surfaces whereby to apply torque to the suture anchor body. Preferably, the driver further comprises at least one suture receiving groove adjacent the complementary surfaces and in registry with the at least one suture passage in the anchor body. 
         [0010]    A method according to the present invention provides for performing a partial thickness rotator cuff repair. The method includes the steps of: inserting a first suture anchor having a maximum diameter of 4.0 mm through a tendon of the rotator cuff and anchoring it into the humerus; inserting a second suture anchor into the humerus; passing a first length of suture from the first suture anchor through the tendon and to the second suture anchor whereby to hold the tendon to the humerus. 
         [0011]    In one embodiment of the method, the first suture anchor is formed of a bioabsorbable material. Preferably, after insertion, the first suture anchor is not proud of a surface of the humerus. Preferably, the method further comprises the step of passing a second length of suture from the first suture anchor and through the tendon. It can further comprise anchoring a third suture anchor into the humerus and passing the second suture to the third suture anchor. 
         [0012]    Preferably, the first suture anchor has a maximum diameter of 3.5 mm, and more preferably 2.8 mm. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a suture anchor according to the present invention; 
           [0014]      FIG. 2  is a side elevation view of the suture anchor of  FIG. 1  loaded onto a driver; 
           [0015]      FIG. 3  is a top plan view of the suture anchor of  FIG. 1 ; 
           [0016]      FIG. 4 . is a side elevation view of a humerus and associated rotator cuff tendon suffering a PASTA lesion showing a K wire being inserted through the tendon to a desired location for placing a suture anchor; 
           [0017]      FIG. 5 . is a side elevation view of the tendon of  FIG. 4  showing a cannula system being passed through the tendon over the K wire; 
           [0018]      FIG. 6  is a perspective view of the cannula system of  FIG. 5 ; 
           [0019]      FIG. 7  is a side elevation view of the tendon of  FIG. 4  a suture anchor loaded onto a driver being passed therethrough via an outer portion of the cannula system; 
           [0020]      FIG. 8  is a side elevation view of the tendon of  FIG. 4  showing the suture anchor implanted into the humerus beneath the tendon and a limb of suture passing from the suture anchor out of an anterior cannula; 
           [0021]      FIG. 9  is a side elevation of the tendon of  FIG. 4  showing a spinal needle passed through a location on the tendon and a suture retriever being passed through the spinal needle and out of the anterior cannula; 
           [0022]      FIG. 10  is a side elevation of the tendon of  FIG. 4  showing both suture limbs passed from the suture anchor and through the tendon at different locations; and 
           [0023]      FIG. 11  is a side elevation of the tendon of  FIG. 4  showing the suture limbs knotted together to compress the tendon to the humerus thus effecting repair of the PASTA lesion. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  depicts a suture anchor  10  according to the present invention. It comprises an elongated body  12  having a pointed distal tip  14  and a proximal end  16 . An axial passageway  18  extends into the body  12  from the proximal end  16 . The passageway  18  is open along its sides  20 . A thread  22  encircles the body  12 . A suture bridge  24  spans the passageway  18  laterally at a distal portion  26  thereof. 
         [0025]    Turning also now to  FIGS. 2 and 3 , an inserter  28  fits into the passageway  18 . A length of suture  30  passes around the suture bridge  24  and is received within longitudinal grooves  32  on the inserter  28 . As best seen in  FIG. 3 , the cross-sectional shape of the passageway  18  at the proximal end  16  is essentially a hexagon  34  with a pair of suture passages  36  on opposite corners thereof. The suture passages  36  lead to either side of the suture bridge  24 . The inserter  28  has a complimentary shape to fit within the hexagon  34  with its grooves  32  in alignment with the suture passages  36  on the anchor  10 . 
         [0026]    The suture anchor  10  as shown with the suture passages  36  penetrating the body  12  to leave the passageway  18  open except for the thread  22  minimizes its cross section to provide the least trauma to soft tissue through which it will pass while still having sufficient mechanical strength for the driver  28  to drive it into bone. Where additional fixation strength within the bone may be required the cross section of the anchor  10  could be enlarged, in which case the suture passages  36  need then not necessarily penetrate the body  12  laterally. The anchor  10  can be formed of any suitable biocompatible material such as stainless steel, titanium, cobalt chrome, PEEK (polyaryletheretherketone), other biocompatible polymers, polymer-ceramic composites, bioabsorbable polymers and the like. 
         [0027]      FIGS. 4 to 10  illustrate a procedure to repair a PASTA lesion using the suture anchor  10  of  FIG. 1 . As seen in  FIG. 4 , either percutaneously or arthroscopically, a Kirschner wire (K wire)  38  is inserted at a first location  39  through a tendon  40  of a rotator cuff to a desired anchor site  42  beneath its attachment footprint  44  and positioned upon an associated humeral head  46 . The K wire  38  can be tapped in or merely positioned at the site  42 . To ease manipulation of the K wire  38  it is preferably textured on its outer surface and may be provided with a removable proximal handle (not shown). This site  42  on the humeral head  46  is where the suture anchor  10  (see  FIG. 1 ) will be implanted. 
         [0028]    As seen in  FIG. 5 , a cannula system  48  is passed over the K wire  38  and through the tendon  40  to the site  42 .  FIG. 6  shows the cannula  48  in more detail. It comprises an inner cannula  50  having a sharp distal tip  52 , proximal handle  54  and a lumen  56  therethrough. The inner cannula  50  fits within an outer cannula  58  which has a distal end  60 , proximal handle  62  and lumen  64  therethrough. The distal tip  52  of the inner cannula  50  extends slightly beyond the distal end  60  of the outer cannula  58  and the distal end  60  is tapered so that rather than core through the tendon  40  the distal tip  52  creates a small hole and the tapering on the distal tip  52  and distal end  60  allow the cannula system  48  to push aside the tissue and create the smallest hole through the tendon  40  with the least damage thereto. Prior cannulas were inserted through a slit cut into the tissue. The cannula system  48  dilates the tissue gently to minimize trauma to the tissue. The outer cannula  58  has lines  66  which provide a visual indication of depth penetration and also a visualization window  68  which aids in anchor insertion and assessment of appropriate depth into the bone. To prevent slippage of the inner cannula  50  relative to the outer cannula  58  during insertion so provision is preferably provided to help keep them together. Shown are an interlocking nub  70  and groove  72 , but other options such as a friction fit, threading, magnets etc. could be employed. 
         [0029]    As seen in  FIG. 7 , in preparation for insertion of the anchor  10 , the K wire  38  and inner cannula  50  are removed leaving the outer cannula  58  positioned at the anchor site  42 . The suture anchor  10  is preloaded onto the inserter  28 , with the suture  30  in place around the suture bridge  24  and passing through the suture passages  36  and grooves  32  (see  FIG. 2 ), is passed down through the outer cannula lumen  60  to the anchor site  42  and is then driven into the humeral head  46 . If the anchor  10  is formed of a biocompatible metal such as stainless steel or titanium it can be simply twisted in via the inserter  28 . If instead it is formed of a bioabsorbable polymer or other material having less strength a pilot hole should be prepared such as with a drill, tap or awl, at the site  42  through the cannula  46  prior to inserting the anchor  10  through the lumen  60 . The inserter  28  and outer cannula  58  can then be removed leaving first and second suture limbs,  74  and  76  respectively, passed up through the tendon  40  at the first location  39  through which the cannula  48  had passed. As seen in  FIG. 8 , the first suture limb  74  is then retrieved through an auxiliary cannula  78  such as via a grasper (not shown). 
         [0030]    As seen in  FIG. 9  a spinal needle  80  is passed through the tendon  40  at a second location  82  spaced apart from the first location  39 . A flexible wire suture capture device  84  having a suture capture loop  86  (such as a Chia Percpasser available from DePuy Mitek, Inc. of Raynham, Mass.) is passed through the spinal needle  80  and retrieved out through the auxiliary cannula  78  so that the first suture limb  74  can be threaded through the suture capture loop  86 . When the spinal needle  80  and suture capture device  84  are pulled back through the skin this pulls the first suture limb  74  through the tendon  40  at the second location  82 . For a quick procedure, the first and second suture limbs  74  and  76  could now be knotted together tying down the tendon  40 . However, it is preferable to repeat the procedure of  FIGS. 8 and 9  with the second suture limb  76  to pass it through the tendon  40  at a third location  88  on an opposite side of the first location  39  as shown in  FIG. 10 . To ease in knot tying both suture limbs  74  and  76  are preferably pulled out through a single portal such as the auxiliary cannula  78  or other portal through the skin. A knot  90  can then be tied and pushed down to tightly secure the tendon  40  to the humeral head  46  as shown in  FIG. 11 . By passing the suture limbs  74  and  76  through the tendon  40  at locations  82  and  88  on opposite sides of the first location  39  and defect caused at that location via the passing of the cannula system  48  will be naturally pulled together when the knot  90  is tightened. 
         [0031]    Depending upon the extent of the PASTA lesion it may be desirable to place more than one suture anchor  10  beneath the tendon  40 . In such case the suture limbs therefrom can be tied together. It would still be preferable to pass them through the tendon at separate locations as illustrated in  FIGS. 9 and 10  prior to tying them together, preferably in a mattress pattern. Also, a repair could be fashioned employing one or more knotless suture anchors (not shown) such as disclosed in U.S. Published Application No. 2008/0033486, incorporated herein by reference placed at a location  92  laterally of the tendon  40  and wherein the suture limbs  74  and  76  from the one or more anchors  10  can be passed in a dual row procedure, preferably also employing a mattress pattern. If a lateral anchor is employed, one such method is to put the a pair of present suture anchors  10  anterior and posterior and have one limb  74  from each tied to each other and the other limbs  76  spanned to the lateral anchor (preferably knotless) such that it forms a triangle. 
         [0032]    The suture anchor  10  and cannula system  48  may also be used to effect repair of a SLAP (Superior labral tear from Anterior to Posterior) lesion. Typically a much larger traditional cannula (7-8 mm) is placed thru the rotator cuff to access the superior labrum for a SLAP repair. The present cannula system is much smaller and also due to its tendency to dilate the tissue rather than be inserted through a large slit would inflict less trauma to the rotator cuff. Such a procedure may be as follows: insert the K wire  38 , and then the cannula system  48  in the fashion heretofore described through the rotator interval; drill a hole in the glenoid rim; insert the anchor  10 ; remove the cannula system  48 ; pass suture through the labrum using a suture shuttle; and tie knots. 
         [0033]    While the invention has been particularly described in connection with specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and that the scope of the appended claims should be construed as broadly as the prior art will permit.