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LARS ligament reconstruction stabilisation acromioclavicular joint

    Overview

    Learn the LARS ligament reconstruction stabilisation acromioclavicular joint surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the LARS ligament reconstruction stabilisation acromioclavicular joint surgical procedure.
    The LARS ligament technique is one of many described to reconstruct the coracoclavicular ligaments of the shoulder for a dislocated or subluxed acromioclavicular joint. This is an open technique passing the artificial ligament underneath the coracoid and securing it to the distal clavicle through drilled tunnels at 90 degrees to each other and secured using interference screws. The LARS ligament is made of PET (polyethylene terephthalate) and for ACJ come sin two sizes, LAC20 with strength 1000N and the LAC30 with strength 1500N. It can be used for repair and reconstruction of the acute AC joint dislocation or for stabilisation of the more chronic injury by providing a scaffold for natural tissue ingrowth. Like other sub-coracoid techniques it removes the need to drill holes into the coracoid process which are sometimes narrow and carry with them a risk of fracture. The fixation using interference screws is strong and reduces the risk of attritional wear notching the clavicle seen in some cases when an artificial ligament is looped around the clavicle.
    Author : Mark Crowther FRCS (Tr & Orth)
    Institution: The Avon Orthopaedic centre , Bristol, UK.
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    Indications

    INDICATIONS
    The indication for reconstruction and stabilisation of an injured acromioclavicular(AC) joint is usually one of the variations of AC joint subluxation or dislocation. The absolute indications are very small in number and the relative indications for surgical treatment of such an injury can be debated long and hard by shoulder surgeons and traumatologists. The vast majority of injured acromioclavicular joints can be treated non-operatively with a conservative regime in the first instance. If however a patient is significantly disabled with pain and a mobile distal clavicle then surgical intervention can be considered but in my practice this would usually be as a delayed procedure rather than an acute operation. The majority of cases would be widely displaced dislocations, so called Grade 5 in the Rockwood classification with over 100% displacement of clavicle in relation to acromion. Further indications could be 100% displacement with a Grade 3 or posterior displacement through the trapezius muscle, the so called Grade 4 injury.
    SYMPTOMS & EXAMINATION
    The majority of the patients will have fallen from a height landing with a direct blow on to the point of their shoulder. They may hear a pop or a click and they present with pain over the top of the shoulder. There will also be swelling and perhaps bruising present and they may well be aware of a deformity which can be noticed early. Later presentation or at review several weeks down the line may reveal symptoms of pain around the back of the shoulder, indistinct neurological symptoms down the arm which can be described as a dragging or lame sensation. On clinical examination acutely both shoulders should be exposed to assess for symmetry. Inspecting from behind the patient it is important to look at the position of the scapula and scapula thoracic movement through range of motion which may be limited in the acutely painful phase. Integrity of the skin should be noted, as often if a patient has had a direct blow to the shoulder, the skin may be contused or there may be superficial abrasions. Such superficial damage to the skin may preclude early surgical intervention.
    Careful neurological examination of the upper limb is important and findings should be documented carefully. Range of motion should be assessed. There may be obvious deformity at the acromioclavicular joint and even in the early stages following injury, relative stability or indeed mobility of the distal clavicle in relation to the acromion can be assessed. In the presence of obvious deformity it is important not to miss any occult injuries in the shoulder and it is important to ascertain that the glenohumeral joint is enlocated. Also assessment of the rotator cuff status should be performed. Often the acute injury can be treated conservatively with rest in a broad arm sling supporting the elbow, which in some cases can relatively reduce the acromion to the distal clavicle. Some authors have advocated a strapping over the top of the shoulder to reduce the lateral clavicle but often in the acute phase this is not well tolerated by patients. With suitable oral analgesia and application of ice packs to the injured shoulder, symptoms will settle over the first couple of weeks. Further clinical examination to reassess symptoms and clinical findings as documented should be repeated in the initial few weeks. Whilst some patients can tolerate conservative management and do extremely well without surgical intervention, delayed symptoms are often described as a generalised weakness in the shoulder girdle, difficulty loading the shoulder and hence lifting anything heavier than minor domestic articles with the unpleasant sensation of a highly mobile distal clavicle which exaggerates obvious deformity in the shoulder, particularly with cross body adduction of the effected arm.
    IMAGING
    Plain x-rays should always be performed and in my practice 3 views (AP, lateral and axillary views) are mandatory. X-rays are important to assess the overall displacement and hence severity of injury and can also pick up fractures around lateral clavicle or indeed around the scapula coracoid or acromial processes. Often plain x-rays are sufficient to aid decision making in the management of such injuries and can be performed as comparison studies with the opposite shoulder holding a weight in each arm to pull the shoulder down. This can exaggerate any injury to the superior suspensory apparatus around the acromioclavicular joint. Widening of the acromioclavicular joint or displacement of the distal clavicle then indicates damage to the coracoclavicular and acromioclavicular ligaments. If there is concern that there may be a fracture, then CT scan with 3D reconstructions is very useful. If an occult soft tissue injury is suspected, then a plain MRI scan is also indicated. Rarely is examination under anaesthetic or screening with image intensifier required.
    ALTERNATIVE OPERATIVE TREATMENT
    There have been numerous surgical techniques described for the treatment of a dislocated acromioclavicular joint. Historically a Bosworth screw between the distal clavicle and the coracoid process perhaps supplemented with transarticular K-wires was used but this often resulted in the screw breakage or wire migration. The Weaver-Dunn procedure released the coracoacromial ligament from the under surface of the acromion, leaving it attached to the coracoid and fixed into the end of the distal clavicle. This procedure could be supplemented with subcoracoid suture tapes. Techniques have also been described using autologous tendon grafts such as hamstrings or palmaris longus. Tendons would be passed beneath the coracoid and then wrapped around the distal clavicle reconstructing the coracoclavicular ligaments. Some surgeons have advocated the use of a hook plate with screw fixation to the lateral clavicle with the plate hook extension dipping beneath the acromion. This technique has been successful and is still used extensively in some units but does require the need for removal of the plate to avoid painful erosion of the acromion or even fracture in an unreliable patient with poor follow up compliance. More recently artificial ligaments have been developed and there has been several reports of success using the Surgilig, now known as Lock Down. This artificial ligament has looped ends, one being a soft and the other a hard. The ligament is passed beneath the coracoid and then the hard loop passed through the soft loop and pulled down to wrap around the coracoid. The hard loop is then passed behind the clavicle and fixed with a anterior to posterior screw, sometimes using a washer. Further techniques have been developed using heavy suture material between buttons passed through drill holes in both coracoid and clavicle, resulting in metal buttons sitting beneath the coracoid and on top of the clavicle. Arthrex tightrope is one example. In this technique, I describe use of the LARS (Ligament Augmentation and Reconstruction System). LARS ligaments (Corin, UK) have been developed since the early 1990’s. Such LARS ligaments have been used for reconstruction in numerous anatomical sites but particularly for ACL reconstruction in the knee. The LARS ligament is made from PET (polyethylene terephthalate) and this provides a scaffold for natural tissue ingrowth.
    NON-OPERATIVE MANAGEMENT
    Broad arm sling immobilisation supporting the elbow, which can lift the acromion of the scapula to reduce the acromioclavicular joint is necessary for the first couple of weeks. The patient is allowed under arm hygiene and is encouraged to mobilise elbow, wrist and hand. Gentle glenohumeral joint pendular exercises are encouraged but elevation of the arm above shoulder height is limited for the first 4 weeks and usually too uncomfortable to be possible during this time. Application of cold ice packs can help for symptomatic relief, as well as regular oral analgesia or anti-inflammatory medication. Between 3 and 4 weeks following injury the sling can be removed and with time the injured shoulder tends to settle down and the distal clavicle can stabilise within scar tissue. Outpatient physiotherapy guidance is very useful to regain range of motion with assisted exercises initially. Once range of motion has returned to near normal, then strengthening exercises can be instigated. It is important to concentrate on scapulothoracic position and strengthening of the periscapular muscles, as well as overall shoulder movement.
    CONTRAINDICATIONS
    As with all surgical procedures, the patient’s general medical fitness should be assessed. They should be fully counselled as to the nature of surgery, the post-operative immobilisation and graduated rehabilitation process. A relative contraindication to surgical fixation with the LARS ligament would be inability to comply with a post-operative regime. Given the subcoracoid nature of the reconstruction, a fracture of the coracoid process would be a contraindication to this surgical intervention.

    Setup

    LARS ligament reconstruction of the dislocated acromioclavicular joint is performed under general anaesthetic and depending on the anaesthetist’s experience and preference, an interscalene nerve block can be performed. I prefer to perform surgery in the sitting position with the feet at the anaesthetic machine so that the surgeons have full access in front and behind the shoulder and this also allows safe positioning of the image intensifier for intra-operative x-ray screening. Intravenous antibiotics are administered by the anaesthetist and during surgery we use intermittent calf compression to reduce the risk of thromboembolic disease. Under anaesthetic the shoulder is further examined with a passive range of motion and assessment of the mobility of the distal clavicle and stability of the glenohumeral joint. It is advisable to perform a social wash prior to formal skin preparation. The bony anatomical landmarks are marked out with a skin marking pen. The skin preparation is started with the hand using Chlorhexidine solution. The whole arm is prepared so that it is freely mobile during surgery. The adhesive surgical drapes are applied as shown.

    Operation – 1

    Plain AP x-ray confirming Grade 5 dislocation acromioclavicular joint with >100% displacement of distal clavicle with respect to the acromion.

    Patient placed into sitting position on operating table with head secured to the head ring attachment and arm resting on a narrow arm board attachment.

    With adduction of the arm across the patient’s body, the mobile deformity of the distal clavicle dislocation is obvious.

    The skin is marked to show the bony anatomical landmarks. Coracoid process (Co), clavicle (Cl) and acromion (Ac).

    The mini-strap skin incision is marked from the coracoid process anteriorly to cross the distal clavicle.

    Posterior aspect of the proposed incision is seen behind the distal clavicle in front of the spine of the scapula.

    Following skin preparation the adhesive drapes are applied, ensuring adequate access to the shoulder. Keep the arm draped free so that it can be mobilised during the operation particularly to elevate the elbow to help reduce the AC joint.

    The skin is incised and the superficial soft tissues are dissected down to the clavipectoral fascia overlying the acromioclavicular joint and deltoid.

    The coracoid process is palpated as indicated by position of the forceps in this picture. Cutting diathermy is then used to incise the clavicle periosteum along the length of the clavicle and then into an L-shape, splitting deltoid towards the coracoid.

    The soft tissues are elevated anteriorly away from the clavicle and deltoid is split down to be able to identify the top surface of the coracoid process as indicated again by the position of the forceps in this image.

    The LARS ligament AC joint set (Corin, UK) is neatly assembled with the necessary instruments.

    The Corin LARS ligament ACJ set contains a specific sub-coracoid passing instrument. This consists of a cannulated curved metal hook from which a looped wire can be passed by advancing the button on the blue handle. The other parts of the instrument are the trocar and sheath which can pass down through the silver metal attachment on the neck of the introducer to approximate the open end of the cannulated hook. The wire can then be passed up through the sheath to facilitate passage through the soft tissues.

    The cannulated passer is passed underneath the coracoid process from medial to lateral. It is essential at this stage to stay close to bone with the tip of the passser as any deviation away from the coracoid medially puts the brachial plexus and subclavian vessels at risk. The brachial plexus surrounds the subclavian artery with the vein more medial all running from medial to lateral. With gentle pressure, the passer can be advanced beneath the coracoid.

    Rotating the passer hook the tip is brought to the lateral edge of the coracoid and advanced to penetrate the soft tissues laterally.

    Rotating even further brings the mouth of the passer underneath the lateral border of the coracoid. Then advancing the plunger reveals the looped wire within the cannulated hook.

    This image shows how the trocar and sheath can be positioned to facilitate passage of the wire.

    Once the trocar has been removed then the wire can be passed into the body of the sheath and the sheath can then be retracted. This can facilitate passage of the wire through the soft tissues.

    This is the LAC20 size LARS ligament. Each end is tapered and has a pair of thin tails. It has 4mm diameter and passes through a 3.5mm tunnel for use with a 4.7mm interference screw.
    The larger LAC30 ligament can be used for AC joints, has 5mm diameter for a 4.5mm tunnel and 5.2mm interference screw.

    The pair of tails from one end of the artificial ligament is then passed through the loop of wire.

    The plunger is then withdrawn so that the wire is pulled down bringing the tails of the ligament to the mouth of the cannulated passer.

    Reversing the position of the cannulated passer by rotating it medially allows the tails of the ligament to be pulled from lateral to medial underneath the coracoid process.

    The ligament can then be pulled into its position slung underneath the coracoid process. A gentle tug on both limbs of the artificial LARS ligament confirms that the position is correct beneath the coracoid.

    In this case I have chosen to use the LAC20 ligament which has a diameter of 4mm. The 3.5mm drill is used to create the tunnel through which the compressible 4mm LAC20 ligament passes easily. This picture shows the position of the medial drill hole going from anterosuperior diagonally across the clavicle to come out on the posteroinferior surface.

    It is now necessary to pass the medial end of the ligament behind the clavicle and this is best achieved by passing the cannulated passing device from posterior to anterior behind the clavicle. In a chronic case the area under the clavicle is usually full of thick scar tissue which needs careful dissection to release the clavicle and allow safe passage of the instrument. This dissection relatively freshens the soft tissues to facilitate natural tissue ingrowth of the LARS ligament scaffold.

    The wire loop has been advanced and the medial pair of ligament suture tails is placed through the wire loop.

    Operation – 2

    Retraction of the wire loop and reversal of the position of the cannulated passer brings the medial limb of the ligament underneath and behind the clavicle.

    A free standing wire loop is then passed into the medial tunnel drill hole from anterior.

    The wire is then passed out through the tunnel at the back of the clavicle.

    The tail sutures are passed into the wire loop.

    Pulling the wire through brings the medial end of the ligament through the drill hole and passing out through the anterior mouth of the tunnel.

    This shows the position of the lateral tunnel. Once again using the 3.5 drill and drill guide this is positioned posterosuperior to anteroinferior at 90 degrees to the medial tunnel.

    The tip of the drill penetrates the anteroinferior surface of the lateral clavicle.

    Again the free standing wire loop is placed through the tunnel this time from posterior to anterior and the tails of the lateral limb of the ligament are passed into the loop.

    Pulling on the wire then brings the lateral ligament through the drilled tunnel.

    The ligament is pulled through the lateral tunnel.

    With both limbs of the ligament through their respective tunnels, they can be pulled tight to reduce the lateral clavicle to the acromion. This can be facilitated by lifting the elbow on the freely draped arm. In a chronic case if there is not good reduction of the distal clavicle to the acromial facet of the acromioclavicular joint then the distal clavicle articular facet can be resected using an oscillating saw or bone nibbler. The medial limb of the ligament is pulled tight and the blunt ended pin from the LARS ligament set is then placed within the drilled tunnel.

    The blunt ended pin is passed into the tunnel next to the medial limb of the ligament until it is felt protruding through the posteroinferior exit of the tunnel.

    Take the 4.7 x 15mm titanium cannulated screw and screwdriver. For the LAC20 ligament this is the only size screw available.

    This is the 4.7mm x 15mm screw with the screwdriver.
    For the LAC30 ligament, 5.2mm titanium screws are used and available in lengths 15, 20 and 30mm.

    The screw is placed over the blunt ended wire and then keeping tension on the limb of the ligament, the screw is advanced into the tunnel, compressing the ligament with a tight interference fit.

    The screw is advanced until the head is flush with the clavicle bone surface.

    Once the medial limb of the ligament is securely fixed then final reduction of the lateral clavicle can be achieved by elevating the ipsilateral elbow to bring the acromion close to the clavicle, then pulling on the lateral limb of the ligament to ensure that the lateral clavicle articular facet is brought down to the acromion. The blunt ended pin is then placed into the lateral drill tunnel and a second interference screw is placed over the pin into the drill tunnel.

    Prior to insertion of the second interference screw, the position of the first screw and the reduction of the lateral clavicle to the acromion can be checked with the image intensifier with the C arm brought in from the contralateral side of the patient. Once the position is accepted then with continued tension on the lateral limb of the ligament the second screw can be advanced until it is fully seated within the bone.

    Image intensifier showing reduction of lateral clavicle to the acromion and the orthogonal position of the interference screws. The lateral screw tip appears prominent beneath the clavicle but this is well clear of the neurovascular structures that run medial to the coracoid process.

    Second image with the intensifier tilted to confirm reduction and position of the screws.

    With both interference screws seated down to the bone and reduction confirmed then the redundant limbs of the ligament can be cut with a scalpel blade, flush with the bone.

    In most instances I prefer to reinforce this fixation by a second passage of the ligament beneath the coracoid. Taking the cannulated passer once again from medial to lateral the tails of the medial ligament are then passed from lateral to medial beneath the coracoid

    This shows the crossover position of the medial limb of the ligament in front of the clavicle after second sub-coracoid passage.
    In revision cases or for high risk patients the lateral limb of ligament could now be passed laterally and shuttled through a vertical superior to inferior tunnel in the acromion to reconstruct the acromioclavicular ligaments.

    The medial limb can then be tied with a simple knot to the lateral ligament reinforcing the fixation with a figure of eight.

    The ends of the ligament are then cut with a scalpel blade.

    Operation – 3

    Final position of the ligament reconstruction.

    Thorough washout and haemostasis is confirmed. The L-shaped incision into the clavicle periosteum and the reflected deltoid is then repaired with interrupted heavy vicryl stitches.

    Good water tight closure is achieved repairing deltoid back to the clavicle periosteum.

    Continuous vicryl suture to repair superficial fascia and fat.

    Subcuticular 3/0 Monocryl is used to close the skin as this gives a good cosmetic result.

    Paper suture Steristrips are applied to the wound.

    Simple adhesive dressing is applied.

    Second view of the simple dressing. Arm is then placed in a broad arm sling supporting the elbow

    Post Operative

    The vast majority of these operations are performed as a day case. Patients are allowed under arm hygiene and encouraged to mobilise their elbow wrist and hands. Sling is advised to be used for at least 3 weeks and then can be weaned off as comfort allows. Early post-operative physiotherapy should concentrate on posture and scapula setting. Active assisted forward elevation to 90 degrees and external rotation is allowed in the first 3 weeks as comfort dictates. Once the sling has been removed then exercises should progress from active assisted to full active range of motion as comfort allows. Check x-rays of the shoulder should be performed at 2 weeks when the wound is checked and again at 4 weeks when range of motion has started to increase and the sling has been discarded. Then gradually increase range of motion and start strengthening at approximately 8 weeks. Final x-rays at 4 months and return to full activities including sport at that stage if able.

    Recommended Reading

    LARS ligament for ACJ – surgical technique. Prof L. Funk www.shoulderdoc.co.uk/article/1208
    LARS Ligament Reconstruction for acromioclavicular joint dislocations – a clinical study. Quin T, Nicolleti S, Fourie B, Funk L. www.shoulderdoc.co.uk/news/view/1341
    Clinical and radiological results after coracoclavicular ligament reconstruction for Type III acromioclavicular joint dislocation using three different techniques. A retrospective study. Vascellari A, Schiavetti S, Battistella G, Rebuzzi E and Coletti N. Joints. 2015 Apr-Jun;3(2):54-61
    Controversies relating to the management of acromioclavicular joint dislocations. Modi C, Beazley J, Zywiel M, Lawrence T, Veillette C. Bone Joint J 2013;95-B:1595-1602
    Treatment of acute grade III acromioclavicular dislocation: a lack of evidence. Ceccarelli E, Alviti F, Miulli F, Padua R. J Orthopaedic Traumatol. 2008 Jun;9(2):105-8

    Reference

    • orthoracle.com

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