Abstract:
A method of ankle syndesmosis repair according to an exemplary aspect of the present disclosure includes, among other things, drilling a hole through a fibula and a tibia of an ankle joint, pulling a first button device through the hole using a pull-through suture until the first button device exits on a medial side of the tibia, flipping the first button device so it rests against a medial cortex of the tibia, and positioning a second button device at a lateral side of the fibula.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is continuation of U.S. application Ser. No. 13/970,269, filed Aug. 19, 2013, which is a divisional of U.S. application Ser. No. 11/482,038, filed Jul. 7, 2006, now U.S. Pat. No. 8,512,376, which claims the benefit of U.S. Provisional Application No. 60/697,125 filed on Jul. 7, 2005, and which is a continuation-in-part of U.S. application Ser. No. 10/233,122, filed Aug. 30, 2002, now U.S. Pat. No. 7,235,091, which claims priority under 35 U.S.C. §119 to IE S2002/0504, filed Jun. 20, 2002. 
         [0002]    The entire disclosures of all of the above priority applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The present invention relates to an apparatus and a method for fixation of ankle syndesmosis. 
       BACKGROUND OF THE INVENTION 
       [0004]    Ankle syndesmosis disruptions are usually caused by severe external rotation ankle injuries. Surgery is recommended to reduce and internally fix the diastasis to prevent lateral talar shift, which could otherwise lead to post-traumatic arthrosis. Such surgical treatment usually involves tibio-fibular transfixation using a syndesmosis screw as recommended by the A.O. group (Arbeitsgemeinschaft für Osteosynthesefrage (Association for the Study of Internal Fixation)). Disadvantages of syndesmosis screw fixation include the need for a second operation for implant removal; implant fatigue and breakage; and loss of diastasis reduction following implant removal. Furthermore, prolonged non-weight bearing to avoid implant breakage prior to removal may cause further morbidity. In addition, studies have shown ligament healing to be inhibited by full immobilisation. 
         [0005]    Movement of the distal fibula relative to the tibia is seen in normal ankle motion. Rigid fixation of the ankle syndesmosis, therefore, prevents normal physiological movement, until the rigid fixation device is removed, loosens or breaks. 
         [0006]    Various methods of syndesmosis fixation have been studied before, including bioabsorbable implants (Thordarson D B, Hedman T P, Gross D, Magre G. “Biomechanical evaluation of polylactide absorbable screws used for syndesmosis injury repair” Foot Ankle Int 1997; 18: 622-7) and flexible implants (Miller R S, Weinhold P S, Dahners L E. “Comparison of tricortical screw fixation versus a modified suture construct for fixation of ankle syndesmosis injury: a biomechanical study” J Orthop Trauma 1999; 13: 39-42; Seitz W H Jr, Bachner E J, Abram L J, Postak P, Polando G, Brooks D B, Greenwald A S. “Repair of the tibiofibular syndesmosis with a flexible implant” J Orthop Trauma 1991; 5: 78-82). Seitz used a suture-button fixation using a large polyethylene button, as is commonly used for tendon repair pull-out sutures and a No. 5 braided polyester suture. Seitz&#39;s operative technique involved opening both the medial and lateral sides of the ankle. On biomechanical testing, failure occurred through the polyethylene button at an average of 20 kg of tension, and through the suture at 28 kg. Clinical testing in 12 patients showed good results, one patient having a symptomatic medial button. Buttons were routinely removed at 8 to 12 months, and were all found to be intact. Miller compared a modified suture construct against tricortical screw fixation at 2 cm and 5 cm above the ankle mortise. This method also required opening both the medial and lateral sides of the ankle. No. 5 braided polyester suture was looped through two holes drilled across the distal tibia and fibula. Similar results were seen for the suture and screw fixations, with a better holding strength for both groups at 5 cm. 
         [0007]    It is an object of the present invention to overcome the problems associated with the prior art, whilst permitting normal physiological movement of the fibula relative to the tibia. 
       SUMMARY OF THE INVENTION 
       [0008]    A method of ankle syndesmosis repair according to an exemplary aspect of the present disclosure includes, among other things, drilling a hole through a fibula and a tibia of an ankle joint, pulling a first button device through the hole using a pull-through suture until the first button device exits on a medial side of the tibia, flipping the first button device so it rests against a medial cortex of the tibia, and positioning a second button device at a lateral side of the fibula. 
         [0009]    In a further non-limiting embodiment of the foregoing method, the method includes reducing a fracture of the fibula prior to drilling the hole. 
         [0010]    In a further non-limiting embodiment of either of the foregoing methods, pulling the first button device includes connecting the first button device to a suture passing instrument with the pull-through suture and inserting the suture passing instrument through the hole to advance the first button device horizontally through the hole. 
         [0011]    In a further non-limiting embodiment of any of the foregoing methods, flipping the first button device includes applying traction to the pull-through suture while applying counter-traction to a flexible coupling connected to the first button device until the first button device pivots from a position generally parallel to the hole to a position generally transverse to the hole. 
         [0012]    In a further non-limiting embodiment of any of the foregoing methods, a flexible coupling is connected to the first button device and the second button device. 
         [0013]    In a further non-limiting embodiment of any of the foregoing methods, the flexible coupling includes a suture that is double looped through the first button device and the second button device. 
         [0014]    In a further non-limiting embodiment of any of the foregoing methods, positioning the second button device includes tightening down the second button device on the lateral side of the fibula by applying traction to a free end of a flexible coupling connected to each of the first button device and the second button device. 
         [0015]    In a further non-limiting embodiment of any of the foregoing methods, the first button device and the second button device each include at least one aperture. 
         [0016]    In a further non-limiting embodiment of any of the foregoing methods, pulling the first button device includes passing an elongated pull-through device that is connected to the pull-through suture through the hole. 
         [0017]    In a further non-limiting embodiment of any of the foregoing methods, the method includes reducing a syndesmosis disruption prior to performing the drilling, pulling, flipping and positioning steps. 
         [0018]    A method for internal fixation of an acromioclavicular joint dislocation of a shoulder according to another exemplary aspect of the present disclosure includes, among other things, drilling a hole through a first bone and a second bone of a shoulder joint, passing a first device through the hole, flipping the first device so it rests against a surface of the first bone, and positioning a second device against the second bone. 
         [0019]    In a further non-limiting embodiment of the foregoing method, a flexible coupling is connected to the first device and the second device. 
         [0020]    In a further non-limiting embodiment of either of the foregoing methods, the flexible coupling includes a suture that is double looped through the first device and the second device. 
         [0021]    In a further non-limiting embodiment of any of the foregoing methods, passing the first device includes passing an elongated device that is connected to the first device through the hole. 
         [0022]    In a further non-limiting embodiment of any of the foregoing methods, the first device is oblong and the second device is round. 
         [0023]    In a further non-limiting embodiment of any of the foregoing methods, one of the first bone and the second bone is a clavicle and the other of the first bone and the second bone is a coracoid process. 
         [0024]    These and other features and advantages of the present invention will become apparent from the following description of the invention that is provided in connection with the accompanying drawings and illustrated embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The apparatuses, methods and buttons of the present invention are illustrated with respect to the following drawings: 
           [0026]      FIG. 1  shows a perspective view of a button of the present invention; 
           [0027]      FIG. 2  shows a perspective view of the kit of parts comprising an apparatus of the present invention; 
           [0028]      FIGS. 3-7  illustrate, in sequence, the steps of a method according to the second aspect of the present invention; 
           [0029]      FIG. 8  shows the mean diastasis in millimetres above the baseline with increasing intraosseous membrane (IOM) division with no fixation and a 5 kg (12.5 Nm) load, in which the error bars represent standard deviation and the use of ** indicates p&lt;0.001; 
           [0030]      FIG. 9  shows the apparatus, method and button of the present invention, when compared with A.O. screw fixation at 2 cm with increasing torque load following total IOM division and, again, the error bars represent standard deviation; 
           [0031]      FIGS. 10 and 10   a  show an anterior view and a schematic view, respectively, of a normal acromioclavicular joint; 
           [0032]      FIGS. 11 and 11   a  show an anterior view and a schematic view, respectively, of a Rockwood Type III acromioclavicular joint dislocation, with superior migration of the clavicle with respect to the acromium; 
           [0033]      FIG. 12  shows a plan view of a first or second suture anchor in the form of a button of the present invention; 
           [0034]      FIG. 13  shows perspective, plan and sectional view of an alternative embodiment of a button according to the invention; 
           [0035]      FIGS. 14 and 14   a  show a plan and an undersurface view, respectively, of a first or second suture anchor in the form of a washer of the present invention; 
           [0036]      FIG. 14   b  illustrates the mobile positioning of the washer against an arcuate undersurface of the screw-head of a bone anchor; 
           [0037]      FIG. 15  shows a perspective view of the kit of parts comprising an apparatus of the present invention; and 
           [0038]      FIGS. 16   a - 16   f  illustrate, in sequence, the steps of a method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    The present invention provides minimally invasive, flexible fixation of the ankle syndesmosis whilst resisting tibio-fibular diastasis. It allows physiological micromotion at the ankle syndesmosis. There is no need for routine removal of the implant and its use should enable patients to weight-bear at an earlier stage. 
         [0040]    The present invention is indicated for use in the fixation of ankle syndesmosis tibio-fibular diastasis (splaying apart). These are typically seen in Weber C-type ankle injuries, caused by severe pronation-external rotation forces. The fibula is fractured above the level of the syndesmosis. A medial ankle injury (malleolar fracture or deltoid ligament rupture) is also usually present. Reduction and fixation of the ankle syndesmosis is necessary to prevent lateral talar shift, which can lead to premature ankle osteo-arthritis. 
         [0041]    Thus, referring to the accompanying drawings, the apparatus of the present invention comprises a pair of buttons  10 , which, in the preferred embodiment illustrated are 9 mm by 3.5 mm in dimension, more particularly in length and width respectively. The buttons  10  are preferably formed from titanium or stainless steel, although it will of course be appreciated that any other suitable material could be used, in particular any suitable bioabsorbable material. The pair of buttons  10  each have a first aperture  12  and a second aperture  14  which, in the preferred embodiment illustrated, are triangular in shape, each of the first and second apertures  12 ,  14  having an apex  16 , the respective apices  16  preferably being directed away from one another and being located substantially about a longitudinal mid-line of the button  10 . Referring in particular to  FIG. 2 , the pair of buttons  10  are secured or pre-threaded together by means of a flexible coupling in the form of first suture  18 , preferably of no. 5 braided polyester, which is double looped through the first and second apertures  12 ,  14  of the pair of buttons  10 , as will be described in greater detail hereunder. It will be readily understood however that any suitable material could be used for the first suture  18 . A straight needle  22  with a second (pull-through) suture  20 , again of any suitable material, is also looped through either the first or second aperture  12 ,  14  of one of the pair of buttons  10 , hereinafter referred to as the leading (or first) button  10 . The needle  22  is preferably 100 mm in length. In the embodiment illustrated in  FIG. 2 , the second suture  20  is looped through the first aperture  12  of the first button  10 . 
         [0000]    
       
         
               
             
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Apparatus/Button of the Present Invention 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Button 10 overall dimensions: 
                 9.0 mm (length) × 3.5 mm (width) × 1.5 
               
               
                   
                 mm (thickness) 
               
               
                 Basic shape: 
                 Oblong in plan shape, with chamfered or 
               
               
                   
                 rounded corners and edges - this reduces 
               
               
                   
                 the chance of the button 10 being 
               
               
                   
                 palpated under the skin and, in addition, 
               
               
                   
                 eases the passage of the first button 10 
               
               
                   
                 through a drill hole 30 as will be 
               
               
                   
                 explained hereinafter. 
               
               
                 Button 10 material: 
                 Preferably titanium or stainless steel 
               
               
                 Button apertures 12, 14: 
                 2 apertures 12, 14 (triangular in plan 
               
               
                   
                 shape) 
               
               
                 Aperture 12, 14 dimensions: 
                 2 mm base × 2 mm perpendicular height 
               
               
                   
                 (equilateral triangle with chamfered 
               
               
                   
                 corners), 1 mm distance between first and 
               
               
                   
                 second apertures 
               
               
                 Syndesmosis suture 18 (first 
                 Number 5 braided polyethylene suture, 
               
               
                 suture): 
                 looped twice through the first and second 
               
               
                   
                 apertures 12, 14 of the first and second 
               
               
                   
                 buttons 10, leaving the two free ends of 
               
               
                   
                 suture 18 free for tying. 
               
               
                 Pull-through needle 22: 
                 100 mm long straight needle 22 with pull- 
               
               
                   
                 through (or second) suture 20 attached. 
               
               
                 Pull-through suture 20: 
                 Minimum 0-strength suture 20 looped 
               
               
                   
                 through the aperture 12 of the first button 
               
               
                   
                 10, the second suture 20 being secured to 
               
               
                   
                 the needle 22. 
               
               
                   
               
             
          
         
       
     
         [0042]    In the present embodiment, leading and trailing edges of the button  10  of the present invention are substantially symmetrical, although it will be appreciated that this is not a requirement of the present invention. Specifically, the leading edge  24  of the button  10  of the present invention should be blunt and should have a width sufficient to reduce the possibility that the leading edge  24  of the first button  10  follows the second or pull through suture  20  through the intact medial skin or to catch or skewer any soft tissue structures between the bone and the medial skin, as will be described in detail hereinafter. 
         [0043]    The button  10  of the third aspect of the present invention may be provided with apertures  12 ,  14  which are countersunk (not illustrated) so as to allow easier threading passage of the first and second sutures  18 ,  20 . Care needs to be taken in such countersinking, to avoid compromising the mechanical strength of the first and second apertures  12 ,  14  of the button  10  of the present invention. 
         [0044]    The first suture  18  used in the apparatus of the present invention can be of any material, which is suitable for this purpose, whether absorbable or non-absorbable, provided it is sufficiently strong. A number 5—strength braided polyester (ETHIBOND—Trade Mark) suture is preferred. This is a non-absorbable suture which knots easily without slipping. 
         [0045]    The second suture  20  used in the present invention can be of any material which is suitable for this purpose, provided it is of at least 0—strength. 
         [0046]    The pull through needle  22  can be of any dimensions, provided it is long enough to span the ankle. Its tip can be either “taper cut” or “cutting”. 
       Set-Up 
       [0047]    The patient is positioned supine on a radiolucent operating table (not shown). Intra-operative fluoroscopy is necessary during the procedure. The patient and all theatre personnel should be adequately protected for x-ray radiation. A sandbag (not shown) is placed under the ipsilateral buttock to facilitate internal rotation of the leg. Antibiotic prophylaxis and the use of a tourniquet are recommended. 
       Instrumentation 
       [0048]    An A.O. small fragment set (or equivalent) should be used for fracture osteosynthesis. The 3.5 mm drill bit is required for drilling the hole  30  through both the fibula  26  and tibia  28 , for the first button  10  and first and second sutures  18 ,  20  to pass through, as illustrated in  FIGS. 3 to 7 . This corresponds to the 3.5 mm drill bit which is part of the small fragment set routinely used to internally fix ankle fractures. It will, of course, be appreciated that the diameter of the hole  30  must be sufficient to permit the first button  10  to be pulled, lengthways, therethrough. 
       Fracture Fixation 
       [0049]    Osteosynthesis should be undertaken according to A.O. principles of internal fixation. It is recommended that fractures (not shown) in the lower half of the fibula  26  should be fixed. High fibular fractures (Maisonneuve injury) can be managed by addressing the syndesmosis diastasis only. Care should be taken not to injure the superficial peroneal nerve during the lateral approach to the fibula  26 ; the nerve passes posteriorly to anteriorly as it pierces the deep fascia. A one-third tubular plate usually provides sufficient stability and can be contoured easily to sit on the bone. The use of a lag screw for fracture compression is rarely required, once fibular length and rotation have been corrected. 
       Syndesmosis Reduction 
       [0050]    The syndesmosis is reduced by internal rotation of the ankle, at around 30° of plantar flexion. This does not result in an over-tightening of the syndesmosis. Reduction should be confirmed using the image intensifier. 
       Drilling 
       [0051]    All four cortices are drilled from the open lateral side using the 3.5 mm drill bit. The drill (not shown) should be angled at 30° upwards from the horizontal, at a distance of 2-3 cm above the ankle joint. Placing a finger on the medial aspect of the leg can help with aiming and feel when the drill has passed through. The drill hole  30  may go through one of the holes of a one-third tubular plate (not shown), if needed. To ensure accurate placement, drilling should be performed under image intensifier control. 
       Button Placement 
       [0052]    The long straight needle  22  with pull-through, second suture  20  is passed through the drill-hole  30  and out the intact medial skin (see  FIG. 3 ). The pull-through suture  20 , which engages the apex  16  of the first aperture  12  of the first button  10 , can now advance the first or leading button  10 , substantially horizontally through the drill hole  30  ( FIGS. 4 &amp; 5 ). Engagement of the second suture  20  in the apex  16  ensures that the second suture  20  is located adjacent the longitudinal mid-line of the first button  10  so that the second suture  20  stays central in the first aperture  12 . Once this first button  10  has exited the medial tibia  28 , the angle of traction on the pull-through, or second suture  20  is changed and counter-traction is exerted on the first suture  18 , in order to flip (pivot) and engage the first button  10  against the medial tibial cortex ( FIG. 6 ). Once the first button  10  is anchored, the pull-through (second) suture  20  can be cut and removed. The trailing or second button  10  is tightened down on the lateral side by further traction on the free ends of the first suture  18  and should be tied hand tight ( FIG. 7 ). This will further squeeze the syndesmosis but will not over-tighten it. 
       Post-Operative Management 
       [0053]    Following wound closure, the ankle should be placed in either a well-padded below-knee cast or backslab, ensuring the ankle is kept in a neutral position. The patient should be kept non-weight bearing for the first two weeks, and then allowed to partial weight-bear (50%) from two to six weeks in cast, depending on fracture stability. Full weight bearing can be allowed out of cast at six weeks. 
       Implant Removal 
       [0054]    Routine removal of the suture-button construct is not required. If, for any reason, it needs to be removed, this can be performed simply by small incisions over the medial and lateral buttons  10 , cutting the first suture  18  as it loops through the button  10  and removing the pair of buttons  10  and the first suture  18 . 
       EXAMPLE 1 
       [0055]    Phase One aims to reproduce a cadaver model of a syndesmosis injury, with a medial deltoid ligament rupture. An intact fibula simulates an anatomically fixed fracture. Phase two compares the suture-button versus conventional A.O. screw fixation following total intraosseous membrane (IOM) division, in a model resembling a Maisonneuve injury. 
       Material and Methods 
       [0056]    Sixteen embalmed cadaver legs (eight pairs) were used. For each leg (not shown), the tibia and foot were fixed to a customised jig using Steinman pins. The foot was fixed to a mobile footplate so that the centre of rotation was directly under the centre of the ankle joint. External rotation moment was applied tangential to the centre of rotation at a radius of 25 cm. 1 kg of weight used therefore corresponds to approximately 2.5 Newton-meters of torque. The syndesmosis was exposed via an antero-lateral approach. Marker pins were placed in the tibia and fibula at the level of the syndesmosis to aid clinical and radiographic measurements. Clinical measurements were made using vernier calipers. In order to reduce bias, x-rays received a coded label to help blind subsequent review. The distance between the tips of the marker pins was measured on the mortise view x-ray. The stress lateral view was found to be less reliable, due to lack of reproducibility. 
         [0057]    A 5 kg (12.5 Nm) load was used for all phase one measurements. Following baseline readings, the medial deltoid and syndesmotic ligaments were divided. Measurements of diastasis were taken following 5 cm, 10 cm and total intraosseous membrane division. 
         [0058]    In phase two, left and right ankles were randomised to receive a suture-button  10  (4 mm×11 mm; the button being a conventional button marketed by Smith &amp; Nephew Inc. under Endo-Button®) or A.O. standard (4.5 mm) screw fixation (not shown). In both groups, the syndesmosis was first reduced by internal rotation of the footplate. A hole was then drilled from lateral to medial, at 30° anterior to the horizontal, 2 cm superior to the ankle joint. 
         [0059]    In the suture-button group of the present invention, a 4 mm drill hole  30  was drilled through all four cortices. The no. 5 braided polyester first suture  18  was looped twice through first and second apertures  12 ,  14  of the first and second buttons  10 . The second suture  20  was threaded through the first aperture  12  of the first button  10  and also through the needle  22 . This needle  22  was passed into the drill hole  30  from the lateral side and out through the intact medial skin. Using the leading pull-through suture  20 , the first button  10  was advanced horizontally along the drill hole  30  until it has exited the medial tibial cortex. Using the leading pull-through second suture  20 , whilst maintaining traction on the braided polyester first suture  18 , the first button  10  was flipped to engage and anchor against the medial tibial cortex. The second suture  20  was then pulled out. The second button  10  was tightened against the lateral fibular cortex by further manual traction on the braided polyester first suture  18 . The first suture  18  was securely tied over the second button  10  when flush with the lateral fibular cortex. The progress of the first button  10  may be followed intra-operatively using an x-ray image intensifier (not shown), if available. 
         [0060]    In the comparative group (A.O. screw), a 3.2 mm drill hole was drilled through all four cortices. The hole was measured, tapped and an A.O. 4.5 mm cortical screw inserted to engage all four cortices, maintaining the reduction of the syndesmosis, without compression. 
         [0061]    Measurements of syndesmosis diastasis were taken both under direct vision and radiographically at increasing external rotation torques. Torque loads were increased in increments of 1 kg, to a maximum of 8 kg or until fracture or implant failure. In four ankles (two per group), fixations were also tested at 5 cm above the ankle joint, having removed the fixations at 2 cm, in order to determine the optimum level of fixation placement. 
       Results 
       [0062]    In phase one, the mean values of the measured diastasis above the baseline value at 5 cm, 10 cm and total intraosseous (IOM) division under 5 kg (12.5 Nm) load were 3.7 mm, 5.5 mm and 7.2 mm, respectively (see  FIG. 8 ). Each value showed significant increase in diastasis compared to the previous measurement, (p&lt;0.001, unpaired t-test). Radiographic measurements were less reliable than direct clinical measurements, but gave a similar picture. 
         [0063]    In phase two, there was a gradual diastasis with increasing torque load in both groups, which was probably due to the quality of the bone. The mean diastasis from baseline for the suture-Endo-Button® and the A.O. screw groups for torque loads increasing at 1 kg intervals, up to 8 kg, are shown in Table 2. These differences were not statistically significant (p=0.7, unpaired t-test,  FIG. 9 ). 
         [0064]    The apparatus and method of the present invention did give a more consistent performance, though. The distribution of standard deviations for A.O. screw fixation was 0.64 mm higher than that for the apparatus and method of the present invention (95% C.I. 0.46 to 0.84, Hodges-Lehmann estimation of shift). 
         [0065]    There were no implant failures in either group. There were two fibular fractures in the A.O. screw group, prior to reaching the 8 kg load (5 kg, 8 kg). Only measurements prior to fracture were used for analysis. By comparison, there was one fibular fracture in the group of the present invention (8 kg). Comparing fixation placement at 2 cm versus 5 cm showed no significant difference (Table 2). 
       Discussion 
       [0066]    The cadaver model in this study was tested using a jig (not shown) generating external rotation torque, which reproduces the mechanism of syndesmosis injury and, therefore, reflects the clinical situation. 
         [0067]    Syndesmosis diastasis is seen with increasing intraosseous membrane division, under an external rotation torque load. This corroborates the findings of previous studies, showing a significantly larger diastasis with greater intraosseous membrane division. 
         [0068]    Regarding the level of placement of the fixation, there was a trend towards better fixation at 2 cm, although only a small sample size was tested (Table 2). 
         [0069]    Flexible fixation gives a more physiological end-result, allowing for micromotion at the distal tibio-fibular joint. Implant fatigue or breakage is less likely and routine removal is not essential. This avoids the complication of loss of reduction following removal of fixation. Earlier weight-bearing may be allowed, depending on the overall fracture configuration. 
         [0070]    The advantages of the suture-button technique are that it is simple, flexible, minimally invasive as the medial side does not need to be opened, and has given a consistent performance on biomechanical testing. Clinical testing of the suture-button in ankle injuries that require reduction and fixation of a syndesmosis diastasis is recommended. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Mean diastasis in millimetres above baseline post-fixation, 
               
               
                 under increasing torque load. 1 kg is equivalent to 2.5 
               
               
                 Nm of torque. (Standard deviations are in parentheses.) 
               
             
          
           
               
                   
                 Button 
                 A.O. Screw 
                 Button 
                 A.O. Screw 
               
               
                   
                 [2 cm] n = 8 
                 [2 cm] n = 8 
                 [5 cm] n = 2 
                 [5 cm] n = 2 
               
               
                   
                   
               
             
          
           
               
                 1 kg 
                 1.0 mm (0.41) 
                 1.3 mm (0.58) 
                 2.5 mm 
                 2.0 mm 
               
               
                 2 kg 
                 2.0 mm (0.00) 
                 2.5 mm (0.87) 
                 3.0 mm 
                 3.0 mm 
               
               
                 3 kg 
                 2.8 mm (0.29) 
                 3.2 mm (1.04) 
                 3.5 mm 
                 4.0 mm 
               
               
                 4 kg 
                 3.6 mm (0.48) 
                 3.8 mm (1.25) 
                 4.0 mm 
                 5.0 mm 
               
               
                 5 kg 
                 4.2 mm (0.57) 
                 4.3 mm (1.30) 
                 5.0 mm 
                 5.5 mm 
               
               
                 6 kg 
                 4.9 mm (0.53) 
                 5.3 mm (1.04) 
                 6.0 mm 
                 6.0 mm 
               
               
                 7 kg 
                 5.4 mm (0.53) 
                 5.7 mm (1.25) 
                 6.5 mm 
                 7.0 mm 
               
               
                 8 kg 
                 5.9 mm (0.53) 
                 6.8 mm (1.05) 
                 7.0 mm 
                 8.0 mm 
               
               
                   
               
             
          
         
       
     
       EXAMPLE 2 
       [0071]    Patients with Weber C ankle fractures who had suture-button fixation, were compound with a cohort of patients who had syndesmosis screw fixation. 
       Methods 
       [0072]    8 patients had suture-button fixation. The buttons used in Example 2 were conventional buttons supplied by Smith &amp; Nephew Inc. and marketed under Endo-Button®. A retrospective cohort of 8 patients with similar Weber C fractures, treated using syndesmosis screw fixation, were recalled for clinical and radiological evaluation. Outcome was assessed using the American Orthopaedic Foot and Ankle Surgeons (AOFAS) score on a 100-point scale. 
       Results 
       [0073]    Patients with screw fixation had a mean AOFAS score of 79 (range: 61-100) at an average follow-up of four months (range: 3-6 months). The suture-button group had a mean score of 92 (range: 76-100) at three-month review (p=0.02, unpaired t-test). Six of the screw group required further surgery for implant removal, compared to none of the suture-button group (p=0.007, Fisher&#39;s exact test). 
       CONCLUSION 
       [0074]    Patients treated using the suture-button  10  regained a better functional outcome, within a shorter time frame. The technique is minimally invasive, as the medial side is not opened, and allows tibio-fibular micromotion whilst resisting diastasis. The need for secondary surgery for implant removal is significantly lessened. The suture-button technique may become the gold standard for syndesmosis diastasis injuries. 
         [0075]    The present invention also provides minimally invasive, flexible fixation of the AC joint dislocation by resisting superior migration of the clavicle with respect to the coracoid process. It allows physiological micromotion at the AC joint. There should be no need for routine removal of the implant. 
         [0076]    The present invention is indicated for use in the fixation of AC joint dislocation. These are typically seen in Rockwood type III AC joint dislocations, usually caused by severe downward blunt trauma to the point of the shoulder, or acromium. Typically, the clavicle is upwardly displaced as a result of the injury because of disruption to the AC and coracoclavicular ligaments. Reduction and fixation of displaced AC joint dislocations are necessary to prevent painful deformity and loss of function. 
         [0077]      FIGS. 10 and 10   a  show anterior and schematic views of a normal shoulder  10 .  FIGS. 11 and 11   a  show anterior and schematic views of a shoulder  10  that has suffered a Rockwood type III AC joint dislocation injury. 
         [0078]    Referring to  FIGS. 10 and 11 , the structure of a shoulder  10  relevant to a Rockwood type III dislocation injury includes the clavicle  12 , the coracoid process  14  and the acromium  16 . The acromium  16  and the clavicle  12  are connected by the acromioclavicular ligament  18 . The acromioclavicular ligament  18  extends from the lateral end  20  of the clavicle  12  to the medial surface  22  of the acromium  16 . The coracoid process  14  is connected to the clavicle  12  by the coracoclavicular ligaments  24 , which comprise the trapezoid ligament  26  and the conoid ligament  28 . The coracoclavicular ligaments  24  extend from the inferior surface  30  of the clavicle  12  to the superior surface  32  of the coracoid process  14 . 
         [0079]    A Rockwood type III AC joint dislocation is characterized by the disruption of the AC and the coracoclavicular ligaments  18 ,  24 , respectively. As shown in  FIGS. 11 and 11   a , the clavicle  12  separates from, and moves away from, the coracoid process  14  and the acromium  16 , accompanied by disruption of the coracoclavicular and the AC ligaments  18 ,  24 , respectively. The acromioclavicular joint  34  ( FIG. 11 ) is dislocated and the clavicle  12  is relatively displaced upwardly. The coraco-acromial ligament  36  ( FIG. 10 ) is not impacted in the type III shoulder dislocation. 
         [0080]    Repair of the type III shoulder dislocation according to the present invention is an out-patient procedure performed with a general anesthetic. The procedure is done with the patient lying supine on the operating table, preferably in the “deck-chair” position to allow the surgeon full access to the affected shoulder. 
         [0081]    Referring to  FIG. 12 , the apparatus of the present invention comprises a first or second suture anchor in the form of a button  50 , which, in the embodiment illustrated, is about 10.0 mm in length by about 3.5 mm in width. The button  50  is preferably formed from titanium or stainless steel, although it will be appreciated that any other suitable material could be used, in particular any suitable bioabsorbable material. The button  50  has a first aperture  52  and a second aperture  54  which, in the embodiment illustrated, are oblong in shape, the longitudinal mid-line of each of the first and second apertures  52 ,  54  being located substantially about a longitudinal mid-line of the button  50 . 
         [0082]    Referring to  FIG. 13 , there is illustrated an alternative first or second suture anchor, generally indicated as  150 . In the illustrated alternative embodiment, the button  150  is about 9.0 mm in length by about 3.5 mm in width, with a thickness of about 1.5 mm. The button  150  has first and second apertures  152  and  154 , respectively. In the illustrated alternative embodiment, each of the apertures  152 ,  154  are triangular in shape, the respective apices  155  being directed away from each other and being located substantially about a longitudinal mid-line of the button  150 . 
         [0083]    Reference is now made to  FIGS. 14 and 14   a  which illustrate a first or second suture anchor in the form of a washer  60 . In the illustrated embodiment, the washer  60  has an external diameter of about 10.0 mm. While the illustrated washer is disc-shaped, the washer is not so limited. The washer  60  is preferably formed from titanium or stainless steel although, as will be appreciated by those skilled in the art, any other suitable material, in particular any suitable bioabsorbable materials, may be used. The washer  62  also has at least two flexible coupling-locating apertures  64 . In the illustrated embodiment, there are four apertures  64  circumferentially arranged about the aperture  62 . In the illustrated embodiment, each of the apertures  64  has a diameter of about 1.0 mm. Each of the apertures  64  have beveled edges, above and below, while the aperture  62  has beveled edges above. 
         [0084]    The washer  60  also has a substantially centrally located bone screw-retaining aperture  62 . In the illustrated embodiment, the aperture  62  has a diameter of about 4.6 mm and the washer  60  is adapted to allow mobile positioning against an arcuate undersurface  69  of the head of the bone screw  68  (illustrated in  FIG. 14   b ). 
         [0085]    Referring to  FIGS. 14 and 14   a , the washer  60  of the fourth aspect of the present invention is provided with a screw-retaining aperture  62  and at least two flexible coupling-locating apertures  64  which are preferably countersunk so as to allow easier threading passage of the flexible coupling  70  (not shown in  FIGS. 14-14   b ). Care needs to be taken in such countersinking, to avoid compromising the mechanical strength of the apertures  62 ,  64  of the washer  60 . 
         [0086]      FIG. 15  illustrates the implant apparatus used for fixation of the AC joint dislocation. The button  50  and the washer  60  are secured or pre-threaded together by means of a flexible coupling in the form of first suture  70 , preferably of number 5-strength braided polyester, which is double looped through the first and second apertures  52 ,  54  of the button  50  and the peripheral apertures  64  of the washer  60 , as will now be described in greater detail. Specifically, the first suture  70  is fed through to aperture  64   a  of the washer  60 ; through the second and first apertures  54 ,  52  of the button  50 ; through the aperture  64   b , under the washer  60  and back out the aperture  64   c ; through the second and first apertures  54 ,  52  of the button  50  again; and finally through the aperture  64   d  of the washer  60 . A needle  72 , which may be straight or curved, with a second, pull-through suture  74  is also looped through either the first or second apertures  52 ,  54  of the button  50 . The second suture  74  is looped through the first aperture  52  of the button  50 . 
         [0087]    The first suture  70  used in the apparatus can be made from any material which is suitable for this purpose, whether absorbable or non-absorbable, provided it is sufficiently strong. A number 5-strength braided polyester (FIBERWIRE®) suture is preferred. This is a non-absorbable suture which knots easily without slipping. The second suture  74  can be made from any material which is suitable for this purpose, and preferably should be at least 0-strength. 
         [0088]    The pull through needle  72  can be of any dimensions, provided it is long enough to span the clavicle  12  or the coracoid process  14  of the shoulder  10 . The needle  72  is preferably about 100 mm in length. The needle&#39;s body can either be straight or curved. The needle&#39;s tip can be either “taper cut” or “cutting.” 
         [0089]    In the present embodiment, leading and trailing edges of the button  50  are substantially symmetrical, although it will be appreciated that this is not a requirement of the present invention. Specifically, the leading edge  56  (illustrated in  FIG. 15 ) of the button  50  should be blunt and should have a width sufficient to reduce the possibility that the leading edge  56  of the button  50  follows the second or pull-through suture  74  through the intact skin or to catch or skewer any soft tissue structures between the bone and the skin, as will be described in detail hereinafter. 
         [0090]      FIG. 15  also illustrates a bone screw  68  as part of the implant apparatus. The bone screw  68  is used for engaging the washer  60  with the coracoid process  14  ( FIG. 16   f ). As discussed below in detail and with reference to  FIG. 14   b , the bone screw  68  has an arcuate undersurface  69  for defining the movement of the washer  60  between the coracoid process  14  and the arcuate undersurface  69 . 
         [0000]    
       
         
               
             
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Apparatus/Button of FIGS. 12 and 15 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Button 50 overall dimensions: 
                 10.0 mm (length) × 3.5 mm (width) × 1.5 
               
               
                   
                 mm (thickness) 
               
               
                 Basic shape: 
                 Oblong in plan shape, with chamfered or 
               
               
                   
                 rounded corners and edges - this reduces 
               
               
                   
                 the chance of the button 10 being 
               
               
                   
                 palpated under the skin and, in addition, 
               
               
                   
                 eases the passage of the button 50 
               
               
                   
                 through a drill hole as will be explained 
               
               
                   
                 hereinafter. 
               
               
                 Button 50 material: 
                 Preferable titanium or stainless steel 
               
               
                 Button apertures 52, 54: 
                 Two apertures 52, 54 (oblong in plan 
               
               
                   
                 shape) 
               
               
                 Aperture 52, 54 dimensions: 
                 2 mm height × 3 mm length (oblong with 
               
               
                   
                 chamfered edges), preferably 1 mm 
               
               
                   
                 distance between first and second 
               
               
                   
                 apertures 
               
               
                 Suture 70 (first suture): 
                 Number 5 strength braided polyester 
               
               
                   
                 suture, looped twice through the first and 
               
               
                   
                 second apertures 52, 54 of the button 50 
               
               
                   
                 and each of the four apertures 64 (64a, 
               
               
                   
                 64b, 64c, 64d) of the washer, leaving the 
               
               
                   
                 two free ends of suture 70 free for tying 
               
               
                   
                 adjacent the undersurface of the washer 
               
               
                   
                 60. 
               
               
                 Pull-through needle 72: 
                 100 mm long straight, or curved, needle 
               
               
                   
                 72 with pull-through, or second suture 74 
               
               
                   
                 attached. 
               
               
                 Pull-through suture 74: 
                 Minimum 0-strength suture 74 looped 
               
               
                   
                 through the aperture 52 of the button 50, 
               
               
                   
                 the second suture 74 being secured to the 
               
               
                   
                 needle 72. 
               
               
                   
               
             
          
         
       
     
         [0091]    The following sets out the procedure, as shown in  FIGS. 16   a - 16   f , to be followed for Rockwood Type III dislocations. Surgeons skilled in the art will appreciate the modifications that might be needed in addressing Rockwood Type II and IV-VI dislocations. 
       Set-Up 
       [0092]    The patient is positioned in a “deck-chair” position on the operating table (not shown). A sandbag (not shown) can be placed under the scapula to ease access to the shoulder region. A longitudinal or horizontal incision of about 5 cm is made on the skin, at the front of the shoulder, overlying the coracoid process  14  and the clavicle  12 . The clavicle  12  and the superior surface of the coracoid process  14  are exposed by blunt dissection. As explained in detail below, if the clavicle hole  80  is to be drilled ( FIG. 16   a ) from above and substantially downwardly through the clavicle  12 , it will also be necessary to retract the skin about the clavicle  12 , in order to expose the superior surface  33  of the clavicle  12 . 
       Instrumentation 
       [0093]    A 3.5 mm drill bit is required for drilling a hole  80  through the clavicle  12 . A 2.5 mm drill bit is required for drilling a hole  82  into the base of the coracoid process  14  of the scapula ( FIG. 16   a ). It is not necessary that the drill holes  80 ,  82  be aligned with each other. In addition, it is not necessary, when the coracoclavicular interspace is reduced to normal, that the longitudinal axes of the respective drill holes  80 ,  82  be co-linear or even substantially parallel with each other. 
       Button Placement 
       [0094]    As illustrated in  FIG. 16   b , the long straight needle  72  with pull-through, second suture  74  is passed upwards through the 3.5 mm drill hole  80  in the clavicle  12  and can be passed through the intact skin on the superior aspect of the clavicle  12  or through the open surgical wound. In  FIG. 16   c , the pull-through suture  74 , which engages the first aperture  52  (not shown) of the button  50 , can now advance the button  50 , substantially longitudinally through the drill hole  80 . Engagement of the second suture  74  in the aperture  52  (not shown) ensures that the second suture  74  is located adjacent the longitudinal mid-line of the button  50  so that the second suture  74  stays central in the first aperture  52 . 
         [0095]    In  FIG. 16   d , once the button  50  has exited the superior surface  33  of the clavicle  12 , the angle of traction on the pull-through, or second, suture  74  is changed and counter-traction is exerted on the first suture  70 , in order to flip (pivot) the button  50  and engage the button  50  against the superior surface  33  of the clavicle  12 . Once the button  50  is anchored, the pull-through, or second, suture  74  can be cut and removed ( FIGS. 16   d  and  16   e ). In  FIG. 16   f , the screw  68  containing the washer  60  is inserted into the 2.5 mm drill hole  82  ( FIG. 16   e ) in the base of the coracoid process  14  of the scapula. Before the washer  60 /bone screw  68  is fully seated into the drill hole  82 , the acromioclavicular joint  34  is reduced by downward manual pressure on the lateral end  20  of the clavicle  12  ( FIGS. 16   e  and  16   f ). 
         [0096]    The two trailing ends of the first suture  70  ( FIG. 16   e ) are pulled to approximate the desired distance between the button  50  and the washer  60 , and hence reduce the interval between the clavicle  12  and the coracoid process  14 . The first suture  70  is then secured to itself with a knot, tied tight by hand. The free ends of the first suture  70  can then be cut approximately 1 cm long, to avoid knot slippage. The screw  68  can then be fully seated into the drill hole  82  in the coracoid process  14  to maximize suture tension, or may be advanced or retracted accordingly to fine tune the suture tension, according to the surgeon&#39;s preference. 
         [0097]    The volume between the arcuate undersurface  69  of the bone screw  68  and the coracoid process  14  defines the maximum flexibility of the washer  60  therebetween. The designed flexibility is helpful in increasing the tolerance for non-aligned drill holes and the like. 
       Post-Operative Management 
       [0098]    Following wound closure, the shoulder should be placed in a shoulder immobilizer for three weeks. Gentle range of motion exercises can begin after three weeks. Full range exercises can be allowed after six weeks. 
       Implant Removal 
       [0099]    Routine removal of the first suture anchor-suture-second suture anchor construct is not required. If, for any reason, it needs to be removed, this can be performed simply by re-opening the surgical incision, cutting the first suture  70  as it loops through the button  50  and removing the button  50 . The screw  68  and washer  60  can be removed easily using the screwdriver. 
         [0100]    It is noted that the above description and drawings are exemplary and illustrate preferred embodiments that achieve the objects, features and advantages of the present invention. It is not intended that the present invention be limited to the illustrated embodiments. Any modification of the present invention which comes within the spirit and scope of the following claims should be considered part of the present invention.