Patent Abstract:
An anchor element serves for knotless fixing of a tissue to a bone by at least one suture threaded through the anchor element. A body of that anchor element has an outer surface with projections. A transverse bore is arranged in a distal end section of the body for receiving a threading passing therethrough. A clamp element serves for clamping the suture threaded transversely through the bore. The clamping element has a portion arranged within the body and is movable within the body towards that transverse bore.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to an anchor element for knotless fixing of tissue to a bone by means of at least one suture threaded through the anchor element. 
         [0002]    Generally, such anchor elements, also called suture anchors, are used in the medical field to ensure that tissues, mostly tendons, that have become detached from a bone can be fixed back onto the bone. 
         [0003]    For this purpose, the anchor element and a suture connected to the anchor element are driven firmly into the bone. The protruding suture ends are connected to the detached tissue, by which means the detached tissue is fixed to the bone. 
         [0004]    In a first operating technique, known in particular from U.S. Pat. No. 5,690,676, the anchor element is designed such that it has an approximately cylindrical body on whose outer face there are projections that prevent removal of the anchor element after it has been inserted into the bone. These projections can be designed as barb-like elements, for example if the anchor element is driven into the bone, or they can also be designed as an outer thread if the anchor element is turned into the bone in the manner of a screw. The suture is threaded through the transverse bore extending through the body, and the two suture ends are placed in outer longitudinal grooves on the body and guided in the proximal direction. A device called a driver is engaged on the proximal end of the anchor element, and it is usually mounted onto the proximal end of the anchor element. The two suture ends are guided along the driver device and are wound there onto radially projecting stubs for the driving-in procedure. 
         [0005]    After the anchor element has been driven into the bone and the driver device has been removed, the two free suture ends are used to secure the detached tissue. To do so, the two suture ends are knotted onto the detached tissue, for example a tendon, lying closely on the bone. 
         [0006]    The anchor element anchored in the bone, and the bone itself, form the force/abutment points between which the tissue is fixed. 
         [0007]    A disadvantage of this operating technique is that the knotting requires considerable experience and dexterity on the part of the operating surgeon. Such knots can come undone, or soft-tissue bridges can form around the knot because the knot is arranged on the outside of the operating site. 
         [0008]    In a development of this operating technique, so-called knotless anchors were developed, which are known for example from US 2004/0138706 A1 and which form the subject matter of the present invention. 
         [0009]    This anchor element has a body on whose outer face there are projections that prevent removal of the anchor element inserted in the bone. A transverse bore is arranged in the distal end area of the body and extends through the latter. A suture is threaded transversely through the body. A clamp element is provided which is moveable along the body and is used to clamp the suture. The clamp element is designed as an outer axially moveable sleeve. 
         [0010]    In this operating technique too, the suture is first threaded through the anchor element. One of the free suture ends is pushed, mostly with the aid of a needle, through the tissue to be fixed, and the pushed-through end is then threaded back in the opposite direction through the transverse bore in the anchor element. The connection between the anchor element and the tissue to be fixed takes the form of a suture loop. The anchor element can now be introduced into the bone, together with the suture after which the free suture ends are pulled so that the protruding loop of the suture, connected to the tissue, is drawn toward the fixing location. 
         [0011]    The relative position between the suture and tissue connected to it, and the anchor element is now fixed not by forming a knot, but instead by moving a clamp element through which the suture is fixed or as it were clamped in a defined position on the anchor element. In this way, the loop holding the tissue is also fixed. The protruding free ends can then be cut off, for example, and there is no need to apply a knot. 
         [0012]    In the US 2004/0138706 A1, the clamp element is designed as a sleeve which is mounted on the outside of the body of the anchor element. The sleeve and body are displaceable relative to one another. 
         [0013]    In one position of displacement of the sleeve, the suture threaded through the body is freely movable, for example so that the tissue pierced by the suture can be drawn onto the bone and fixed in its position. The sleeve is then moved in order to clamp the suture and fix it in its relative position. 
         [0014]    As can be seen in particular from moving from FIG. 4 to FIG. 5 of US 2004/0138706 A1, there are several relatively sharp-edged clamp points between which the suture is squeezed. This results in relatively high shearing forces, which means that damage to the suture, and therefore tearing-off of the suture, cannot reliably be ruled out. 
         [0015]    In addition, the outer sleeve is a very complicated structural part which, in order to exert a clamping force, has to be slightly spread open by the anchor element. For this purpose, suitable lock-type bridges are needed between the outer face of the body of the anchor element and the inner face of the sleeve, which make release from this locked position difficult or impossible. For this reason, corrective measures, for example during temporary release of the clamping connection, can only be carried out with difficulty, if at all. 
         [0016]    It should be borne in mind that the dimensions of such clamp elements involve lengths in the range of several centimeters and diameters of several millimeters. 
         [0017]    Therefore, not only is the production of such parts extremely complex, their handling is also very difficult and, in particular, their stability in respect of the holding or fixing force is extremely problematic. 
         [0018]    If a tendon subjected to high loading, for example a tendon from the shoulder area or the knee area, is fixed, it is evident that considerable tensile forces from the tendon act on the assembled structure introduced into the bone and composed of body, clamp element and clamped suture. 
         [0019]    If one considers the aforementioned dimensions, it will be evident that the wall thickness of the outer sleeve may at best be in the range of fractions of millimeters, although it is this structural part that is intended to provide the clamping force for holding the suture. 
         [0020]    Since the sleeve, because of its construction, covers a certain proportion of the outer face of the body of the anchor element, but this anchor element serves to hold the whole assembly in the bone via the projections present on its outer face, suitable structural measures have to be taken to ensure that the body of the anchor element as such can in fact be safely anchored in the bone. 
         [0021]    This leads to additional and considerable outlay in terms of construction. 
         [0022]    It is an object of the present invention to provide an anchor element for knotless fixing a tissue, which is of simple construction, ensures effective anchoring of the anchor element and, at the same time, allows the suture to be fixed efficiently and without damaging it. 
       SUMMARY OF THE INVENTION 
       [0023]    The object is achieved by an anchor element having a body with an outer surface, which has projections projecting from said outer face for preventing removal of said anchor element when inserted in a bone. A transverse bore is arranged in a distal end section of said body, said transverse bore extending through that body. The transverse bore serves for threading said at least one suture transversely through that body A clamp element is provided for clamping said suture threaded transversely through said bore. Said clamping element having a portion arranged within said body, said clamping element being arranged moveable within said body and being moveable towards said transverse bore for clamping said suture in said transverse bore. 
         [0024]    An important advantage of arranging a portion of the displaceable clamp element in the inside of the body is that the outside of the body is not covered by this clamp element, such that the outside of the body of the clamp element is available fully for anchoring to the bone. When the portion of the clamp element arranged in the inside is moved away from the transverse bore, the suture threaded through the transverse bore can be freely moved. By moving the inner portion of the clamp element in the direction of the transverse bore, the portion of the suture received in the transverse bore can then be clamped. 
         [0025]    This can be done directly by the clamp element itself, or the clamp element can squeeze a further element, for example a clamping aid received in the transverse bore. Since the outside of the anchor element does not have to be covered during these movements, these maneuvers can be performed in the inside of the body after the anchor element has already been driven into the bone. In this way, it is also possible, for example, to correct the lie of the suture when the anchor element is already inserted, without the anchor element as such having to be moved relative to the bone for this purpose. 
         [0026]    The maneuvering of the clamp element in the inside of the body can be done from the proximal end of the anchor element, for which purpose the clamp element could also protrude at the proximal end. As regards its outer structural features, the body of the anchor element can be constructed exactly like an anchor element that works with knotting. The inside of the body simply has to be provided with a suitable cavity, which is very easy to produce and into which the inner portion of the clamp element can be introduced. This inner portion of the clamp element can be made solid in order to be able to exert the sufficient clamping force on the suture received in the transverse bore. 
         [0027]    The existing inner wall of the transverse bore is available as an abutment for the clamping by the clamp element. This wall provides the suture with a sufficiently large contact surface on which the suture to be clamped can be applied or fixed by the displaced clamp element. In other words, the suture can wedge itself on the inner wall of the transverse bore, such that the clamping forces are distributed over a relatively large surface area, with the result that the danger of damage and shearing of the suture is greatly reduced. 
         [0028]    In an embodiment of the invention, the body of the anchor element has an axially extending inner bore for receiving said clamping element. 
         [0029]    This measure allows to securely receive at least said portion of the clamping element arranged within the axially extending inner bore. 
         [0030]    In a further embodiment of the invention said inner bore opens into said transverse bore. 
         [0031]    This measure has the advantage that the portion of the clamping element arranged within the body can be guided securely into the transverse bore for clamping the suture therein. 
         [0032]    In another embodiment of the invention, a distal end of the clamp element is rounded. 
         [0033]    This measure has the advantage that the aforementioned pressing on the suture in the transverse opening can be exerted with low shear force and without damaging the suture. 
         [0034]    In a further embodiment of the invention, a gentle hollow is provided in said transverse bore opposite to said rounded distal end of said clamping element. The gentle hollow approximately corresponds to the rounded distal end. 
         [0035]    This method has advantage that parts of the suture can be pressed or squeezed into the gentle hollow enhancing the clamping of the suture between clamping element and transverse bore. 
         [0036]    In another embodiment of the invention, the portion of the clamp element arranged inside the body is designed as a pin. 
         [0037]    This measure has the advantage that this geometry permits a compact, stable clamp element which is able to transmit the necessary clamping force, even when the overall dimensions of the anchor element are very small. 
         [0038]    In another embodiment of the invention, the pin is designed as a headless screw. 
         [0039]    This measure has the advantage that a very compact clamp element is provided which is easy to control and which, by simple turning, can be moved to and fro within the body of the anchor element. 
         [0040]    In another embodiment of the invention, the clamp element is received completely in the body. 
         [0041]    This measure has the considerable advantage that the outer contour of the anchor element is not in any way impaired by the provision of the clamp element, that is to say the entire outer contour of the anchor element can be used for the actual function, namely that of anchoring in the bone. Seen from the outside, an anchor element according to the invention can appear, structurally, like an anchor element of the kind known for example from U.S. Pat. No. 5,690,676, but now used in the knottless technique. With the latter, there is already sufficient experience regarding the structural designs that provide a sufficient anchoring force, and this wealth of experience can be exploited here. 
         [0042]    In another embodiment of the invention, the clamp element is designed as a conical element. 
         [0043]    This measure has the advantage that such an element is very easy to produce and simply has to be driven forward in the inside of the body in order to fix the suture. By suitable choice of the cone angle and of the length of the inner portion, the sufficient holding force or clamping force can be exerted. 
         [0044]    In another embodiment of the invention, the clamp element has an assembly feature onto which a tool of a driver device for the anchor element can be attached. 
         [0045]    This measure then has the considerable advantage that the same tool with which the anchor element is driven in can also be used to control the clamp element, in other words to move it in the direction of the transverse bore for clamping the suture. 
         [0046]    As regards production and handling, this measure has the advantage that it is not necessary to provide two tools, one for driving in the anchor and one for moving the clamp element. The insertion of the anchor element and the displacement of the clamp element can be carried out in succession using one tool. 
         [0047]    This is especially of help to the operating surgeon and facilitates this operating technique. 
         [0048]    The materials used for the structural elements can, depending on the requirements, be metals, in particular titanium, or said structural elements can be made of bioabsorbable materials, if so desired. 
         [0049]    It will be appreciated that the aforementioned features and the features still to be explained below can be used not only in the cited combinations, but also in other combinations or singly, without departing from the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0050]    The invention is described and explained in more detail below on the basis of a number of selected illustrative embodiments and with reference to the attached drawings, in which: 
           [0051]      FIG. 1  shows an exploded view of an anchor element according to the invention and its clamp element, and with the maneuvering tool for fitting the anchor element into the bone being depicted at the lower end, 
           [0052]      FIG. 2  shows a longitudinal section through the anchor element from  FIG. 1  with the clamp element inserted, with the maneuvering tool applied, and with a suture threaded through the anchor element but still freely movable, 
           [0053]      FIG. 3  shows a snapshot of the operating technique for fitting the anchor element, in which view the assembly shown in  FIG. 2  can be seen, with the threaded suture having already been connected to a tissue and having been threaded back through the transverse bore, 
           [0054]      FIG. 4  shows a cross section after the anchor element has been fitted and the tendon has been fixed by means of the suture, and the suture has been fixed in the bone by means of the clamp element, and 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0055]    An anchor element shown in  FIGS. 1 to 4  is designated in its entirety by reference number  10 . 
         [0056]    The anchor element  10  has an elongate, roughly cylindrical body  12  from whose outer face  14  a number of projections  16  to  16 ′″ protrude. The projections  16  to  16 ′″ are designed as protruding annular flanges which, viewed in the distal direction, each merge with the next annular flange via approximately conically tapering portions. A distal end area  18  of the body  12  is provided with a rounded tip  20 . A proximal end  22  is formed by the cross-sectional surface area of the last projection  16 ′″. 
         [0057]    In the distal end area  18  of the body  12 , a transverse bore  24  is arranged extending through the latter. Starting from the mouth of the transverse bore  24 , two diametrically opposite longitudinal grooves  25 , cut into the projections  16 ′ to  16 ′″, extend proximally along the longitudinal axis  26  of the body  12 . 
         [0058]    The transverse bore is used for threading a suture  60  through the body  12 , as shown in  FIG. 2 . The suture portions protruding from both ends of the transverse bore  24  can be placed into the longitudinal grooves  25 , such that these suture portions can be guided proximally from the direction of the transverse bore  24  while bearing closely on the body  12 . 
         [0059]    From the proximal direction, an axial bore  28  is formed centrally within the body  12  (see  FIG. 2 ) and opens at the distal end into the transverse bore  24 . 
         [0060]    An inner thread  30  is cut in the axial bore  28 . 
         [0061]    This axial bore  28  is used for receiving a clamp element  32 . 
         [0062]    The clamp element  32  is composed of a pin  34  on whose outer face there is an outer thread  36 , which meshes with the inner thread  30  of the axial bore  28 . 
         [0063]    Formed at the proximal end of the pin  34 , there is a recess  38 , here in the form of a diametrical incision, whose purpose will be explained below. At the distal end  40 , the clamp element  32  is provided with a rounded part  42 . With that design, the pin  34  is a headless screw. 
         [0064]    A device referred to as a driver  50 , with which the anchor element  10  is maneuvered, is shown at the bottom end of  FIG. 1 . 
         [0065]    The driver device  50  comprises a rod  52  from whose distal end face  54  a tool  56  projects which is designed such that it can be inserted with a form-fit into the recess  38  of the clamp element  32 . The end face  54  of the driver device  50  is moreover designed such that it can be placed on the proximal end  22  of the body  12  of the anchor element  10 . 
         [0066]    At a distance axially from its end face  54 , the driver device  50  is provided with two diametrically protruding stubs  58 ,  59  around which the two protruding suture ends can be wound. At the proximal end, the rod  52  ends in a handpiece (not shown here) via which the driver device  50  can be gripped by hand by the person operating it. 
         [0067]      FIG. 2  now shows a situation in which the clamp element  32  is received in the inside of the body  12 , with the outer thread  36  inserted into the inner thread  30 , specifically such that the suture  60  guided through the transverse bore  24  is freely movable, as indicated by the double arrows. 
         [0068]    The proximal end  22  of the body  12  sits on the end face  54  of the driver device  50 , of which the tool  56  engages in the recess  38  of the clamp element  32 . 
         [0069]    As has been mentioned above, the longitudinal grooves  25  on the outer face  14  of the body  12  allow the suture ends to be guided in the proximal direction while bearing closely on the body  12 . Correspondingly, grooves  62  are cut into the rod  52  of the driver device  50  in order to guide these suture ends as far as the diametrically protruding stubs  58 ,  59  around which they are wound. 
         [0070]    As will be evident in particular from the cross-sectional view in  FIG. 2 , turning the driver device  50  about the longitudinal axis  26  of the assembled structure causes the clamp element  32  to turn in the inside of the anchor element  10 , as a result of which the clamp element  32  is moved in the direction toward the transverse bore  24  and into the latter. The portion of the suture  60  received in the transverse bore  24  is applied, by the rounded part  42 , against the opposite inner wall of the transverse bore  24  and, when driven further forward, correspondingly clamped. 
         [0071]    By means of the round and gentle profile of the rounded part  42  of the clamp element  32  and the corresponding profile of the inner wall of the transverse bore  24 , the clamping force on the suture can be distributed across a relatively large surface area, as a result of which a squeezing or shearing off of the fixed suture  60  in the transverse bore  24  can be avoided. 
         [0072]    It will be evident from the cross-sectional view in  FIG. 2  that, on the distal side of the transverse bore  24 , the axial bore  28  is continued in the form of a gentle hollow  29  which corresponds approximately to the contour of the rounded part  42 , such that the suture  60  can be fixed particularly gently, but still securely between hollow  29  and rounded part  42 . 
         [0073]    As will be seen from  FIG. 2 , the anchor element  10  bearing on the end face  54  of the driver device  50  can be driven into a bone by means of the latter, for example with a hammer. 
         [0074]    The length of the tool  56  and the depth of the recess  38  in the clamp element  32  are chosen such that the clamp element  32  is not damaged in this process, but such that there is sufficient engagement between these two structural elements to be able to subsequently turn the clamp element  32  and thus produce the clamping action. 
         [0075]      FIG. 3  shows a snapshot of an operating technique in which an anchor element  10  according to the invention is fitted. 
         [0076]    Part of a tissue  74 , for example a tendon, has become detached from a bone  70  and is now to be fixed back onto the bone  70 . 
         [0077]    In the illustrative embodiment shown, an opening  72 , for example a bore, has been formed in the bone  70  in the area of tissue detachment, the internal diameter of the opening  72  being slightly smaller than the external diameter of the projections  16  on the body  12  of the anchor element  10 . The assembly made up of the anchor element  10 , and clamp element  32  received therein, and of the driver device  50  is brought to the operating site, and the suture  60  is threaded once through the transverse bore  24 , as shown in  FIG. 2 . One of the free ends is pushed, if appropriate with the aid of a needle, through a detached portion of the tissue  74 , the resulting cut  76  being shown in cross section in  FIG. 3 . The suture portion emerging through the cut  76  is guided once again through the transverse bore  24 , specifically in the opposite direction to the previous one. 
         [0078]    As can be seen from  FIG. 3 , this creates a loop  61  via which the tissue  74  is connected to the clamp element  10 . The two free suture ends are now guided closely along the surface of the structure composed of driver device  50  and anchor element  10  to the stubs  58 ,  59  and are threaded around these. 
         [0079]    The anchor element  10  is then driven into the opening  72  of the bone  70  by means of the driver device  50 . By pulling on the free ends of the suture  60 , the detached tissue portion  74  can be brought into the desired position relative to the bone and to the anchor element. By turning the driver device  50 , the clamp element  32  is now moved into the transverse bore  24  and clamps the two suture portions received in the transverse bore. The driver device  50  is removed, and the protruding suture portions can be cut off. 
         [0080]    It is still entirely possible here to make certain corrections to the lie of the suture, even with the anchor element  10  already fitted, by means of slightly loosening the clamp element  32  again. After the driver device  50  has been removed, the tissue  74  to be fixed lies once again on the bone  70 , as shown in  FIG. 4 . Only the loop  61  of the suture  60  is visible, and there is therefore no bulky knot. In the inside of the body  12 , the portions of the suture  60  received in the transverse bore  24  are fixed in position by the rotated clamp element  32 .

Technology Classification (CPC): 0