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Ankle fracture- Lateral malleolar fixation using Acumed Fibula Rod System

    Overview

    Learn the Ankle fracture: Lateral malleolar fixation using Acumed Fibula Rod System surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Ankle fracture: Lateral malleolar fixation using Acumed Fibula Rod System surgical procedure.
    Most ankle fractures are stable meaning that, under physiological load, the key stabilising structures of the ankle joint remain sufficiently able to perform their function. Therefore, stable ankle fractures are, by and large, managed non-operatively. In the remainder, stability can be conferred to various structures by a variety of methods. Factors that govern the choice of fixation range from available resources and surgical preference to factors determined by the pathology facing the surgeon. These factors are often influenced not only by the quality of the bone such as the degree of comminution or osteoporosis, but also by the effects of the injury to the soft tissue envelope. The Acumed Fibula Rod System (FRS) offers the surgeon an additional, proven treatment option with advantages over open techniques for those with poor quality bone and soft tissue envelope.
    When a bone breaks, the skin is subjected to large strains and the dermo-epidermal junction shears giving rise to fracture blister formation. This occurs most frequently in anatomic sites where a bone lies subcutaneously and is more pre-disposed in any co-morbidity that impedes wound healing. Blisters can be clear or haemorrhagic with the latter indicating more severe injury to the dermis. The definitive management of fracture blisters with regards timing of surgery and whether to aspirate, incise through or leave well alone is not clear from the literature.
    In an era of an ageing population, surgeons face difficult decisions about how to confer stability to the skeleton with appropriate rigid internal fixation. This case illustrates the various dilemmas facing surgeons in making and performing surgical treatment plans in an elderly patient with a poor soft tissue envelope. The case features the decision-making steps in using the Acumed Fibula Rod System (FRS) as the definitive treatment option for a fracture of the lateral malleolus in a patient with poor quality bone and significant compromise to the soft tissue envelope.


    Indications

    Indications
    There are key objectives in managing an unstable ankle fracture in an elderly patient with poor bone quality and a poor quality soft tissue envelope. The patient needs a stable ankle that will allow the soft tissues to heal and will permit the patient to bear weight whilst this process occurs.
    Symptoms & Examination
    Patients present with pain and swelling. In an unstable ankle fracture, the patient is unable to bear weight. In an overt ankle fracture-dislocation, the patient will have an obvious deformity of the ankle. The soft tissue envelope may be compromised either with an open wound (usually located medially) or skin blanching and blistering. Manipulation and reduction of a clear fracture-dislocation and application of back slab cast is mandated to provide temporary immobilisation.
    In the presence of an open wound, urgent wound toilet, administration of appropriate antibiotics, and sterile dressings should be applied. The tetanus toxoid status of the patient should be noted and appropriately acted upon. Any blisters should also be dressed with non-adhesive dressings. Manipulation and reduction of the fracture should then be performed and a temporary cast applied whilst plans are made for urgent debridement and temporary external fixation in an operating theatre.
    Specific management of the fracture blisters remains controversial. Some authors prefer to leave the blisters intact and acting as a biological dressing with concerns about incising skin through the blistered areas provided that the skeleton is stabilised. Blisters are then left to resolve prior to planning any surgical procedure. Others suggest that the blisters can be disregarded as they are only a manifestation of the degree of trauma to the skin and the skeletal instability. These authors suggest incising through the skin and blisters to achieve skeletal stability as soon as possible.
    Investigation
    Plain radiographic assessment should be the initial mode of imaging. Two standard orthogonal views should be taken. My personal view, and that of my colleagues in Sheffield, is that a CT scan is mandated in the following three ankle fracture scenarios:
    Any history of dislocation
    Suspected syndesmotic injury
    Evidence of posterior plafond involvement
    A CT is particularly helpful in demonstrating the pathoanatomy of the fracture. This aids in planning surgical approach and methods of fixation. MRI may be of limited benefit but can help in assessing concurrent ligamentous injuries.
    Operative alternatives
    In the situation where an ankle fracture occurs in an elderly patient, with probable osteopenia or osteoporosis, with significant wound healing co-morbidities and any compromise to the soft tissue envelope, the surgical strategy to stabilise the fracture is challenging. Open reduction with standard non-locking fixation is likely to achieve poor hold from the screws in the bone. Definitive treatment with a monolateral external fixator can be considered but it does not permit the patient to bear weight. Fine wire circular fixators would have a role to play but are not well tolerated. With locking plates and screws, solid fixation can be achieved in soft bone but, unless these plates can be safely inserted through minimal incisions, then applying them through poor soft tissues can be risky as there is a significant risk of wound complications. This latter issue may thwart tibia-pro-fibula fixation too (a robust technique involving placing multiple screws across from fibula to tibia to stabilise the ankle). Lastly, applying a tibio-talo-calcaneal fusion nail through the sole of the foot and into the tibia provides a stable construct but hold within the calcaneus can be tenuous in poor quality bone. Not infrequently these nails, or at least, their locking apparatus need further surgery for metalwork removal.
    Contraindications
    Be very aware of the red, swollen and unstable foot with little pain. This presentation should raise the suspicion of a neuropathic foot undergoing a Charcot process. Diabetics with ankle fractures should be managed as if they do not have diabetes but, as a rule of thumb, they should have a prolonged period of post-operative immobilisation. There is some evidence in the literature supporting the use of the fibula nail in treating diabetic patients with unstable ankle fractures.
    Non-operative intervention
    In the presence of an anatomic reduction of the ankle fracture with a moulded cast, this may be considered as a treatment.

    Setup

    The patient is placed on an operating table capable of allowing easy access of intra-operative fluoroscopic imaging. To a certain extent, the patient is positioned according to two factors: firstly, surgeon preference and secondly, as determined by the fracture pattern that needs treating. In the following case, the patient was positioned supine to allow easy access to the medial and lateral malleoli. A thigh tourniquet was applied and the lower limb was isolated from the tourniquet by an exclusion drape. The principle reason for the tourniquet is to allow a bloodless field when opening the medial side of the ankle. Ordinarily, a tourniquet is not required solely for insertion of a fibular nail.
    Appropriate antibiotics were administered intravenously prior to the tourniquet being inflated. An image intensifier is necessary for use throughout the procedure.

    Operation – 1

    A 75 year old female slipped on ice and fell awkwardly sustaining a closed left ankle fracture dislocation. Key features of her past medical history included seronegative arthropathy and osteoporosis.

    The ankle was manipulated into a temporary back slab plaster of Paris cast prior to any plain imaging. At the time of the attempted reduction, the skin was noted to be of poor quality, but intact nonetheless. The attending doctors could feel that it was a difficult fracture to control in the cast and the malreduction was accepted. Plans were made for urgent definitive treatment in the operating theatre.

    The temporary external fixator is removed.At the time of planned definitive fixation, the soft tissue envelope was noted to be blistered laterally over the distal diaphyseal aspect of the fibula and at the antero-medial aspect of the distal tibia. A mono-lateral external fixator was applied using fixation pins to the medial face of the tibial shaft, proximally and distally, and one fixation pin in the medial aspect of the calcaneal body and the base of the first metatarsal respectively. These intra-operative photographs are taken at the time of planned removal of fixator and definitive fixation.

    All blisters appeared to be filled with serous fluid.
    A CT scan was performed to clarify the pathoanatomy of the fracture. It revealed comminution of the distal fibula, a small rim of posterior malleolus fracturing and a significant sized medial malleolar fracture fragment.

    12 days after application of the fixator, the lateral blisters had dried completely. Medially one blister [A] still contained a little serous fluid but the all of the others had settled demonstrating the benefits of stabilising the skeleton and the soft tissues with the external fixator.

    Image intensification films taken at the end of the initial procedure to apply the external fixator demonstrate the comminuted appearance of the distal fibula but also suggested that the medial malleolus fracture fragment was well reduced. Given that the soft tissues were known the be blistered medially, the initial plan for definitive fixation was for percutaneous fixation of the medial malleolus especially as it appeared to be full reduced on the fluoroscopic images taken at the time of application of the external fixator.
    In the 12 days after application of the external fixator, the reduction of the medial malleolus was lost meaning that an alternative method of definitive fixation was required. It is useful to remember that patients with ankle fractures kept in a temporary external fixator may well lose the reduction in very unstable fracture patterns, especially if patients have born weight through their temporary fixators or have bone quality incapable of supporting the fixation pins.

    The fixator pins are curetted to clean the pin tracks.The fixator is removed and the leg is prepared with a suitable agent (in this case alcoholic chlorhexidine). The fragile blisters are often removed in this process. It is good practice to curette the pin site wounds and flush them with saline.

    The medial malleolus is marked on the skin and the incision planned to lie midway between its anterior and posterior boundaries.In this case, given the known comminution of the fibula, my decision was to fix the medial malleolus first as the CT had given sufficient indication that the medial malleolus fracture was not comminuted. When faced with a choice between fixing two areas of fracture that are inter-related by injury, I feel that it is always easier to fix the simplest fracture pattern first. Quite often, this has the advantage of reducing or improving the position of the other fractures.
    The skin is marked with a marker pen. Note the proximity of the blisters to the skin incision.

    The leg is elevated on a pack of towels and the boundaries of the tip of the lateral malleolus are marked with a pen. The skin incision is marked longitudinally from the tip of the malleolus distally. With the medial malleolus fracture fixed, attention is then turned towards the lateral malleolus. The leg is elevated on a pack of sterile towels to improve all round access the the ankle and to help with obtaining fluoroscopic imaging.
    The tip of the distal fibula is palpated and its boundaries marked on the skin with a pen with the continuous line. The hatched line is the intended 1-2cm long skin incision for commencing the insertion of the fibula nail.
    Note the pigmented appearances of the healed lateral blisters [A] overlying the subcutaneous border of the fibula diaphysis.

    The skin and subcutaneous tissues are incised enough to introduce the 1.6mm guide wire for the fibula rod system.The skin and subcutaneous tissues are incised and the tip of the fibula is located using the 1.6mm guide wire provided on the Acumed FRS set. There are two reasons why this part of the procedure might provide some technical challenges. Firstly, if the incision is incorrectly placed, the soft tissues can hinder locating the entry point. Secondly, in soft bone the sharp tip of the guide wire can easily enter the fibula without the surgeon being aware. In young, hard bone, this lack of proprioceptive feedback is not an issue.

    The skin is incised and the deep structures are divided in line with the incision.The skin is incised and the deep tissues divided in line with the incision. The shear forces to the soft tissues have often dissected down to the bone.
    The fracture is then distracted to examine the contents of the fracture gap. Almost invariably, there is some interposition of sheared periosteum in the fracture gap. This will block anatomic reduction and is best removed. In this case, the 12 day delay in definitive fracture fixation had allowed the fracture haematoma to start to mature. This haematoma was semi-solid and preventing anatomic reduction, thus it was also removed.

    The fracture is distracted, haematoma and bone fragments are excised and the periosteum reflected from the fracture site.Once the fracture gap is cleared, the fracture is reduced. In this instance, the fracture line coursed in two directions and the reduction was held with three wires: one anterior wire lying out of the usual fracture plane and the two more familiar parallel wires. The reduction and wire positioning is confirmed on image intensifier.

    The fracture is reduced and held with two guide wires.Once content with the reduction and wire positioning, using tissue protecting drill sleeves, the wires are over-drilled.

    After over-drilling, two part-threaded cannulated screws are inserted with washers. A third stabilises an atypical anterior fracture line extension.In each case, a partially-threaded cannulated screw and washer is inserted, gaining sequential compression across the fracture site.

    The position o the screws is checked with fluoroscopy.The image intensifier confirms anatomic reduction and optimal screw positioning.

    The wire is placed at the tip of the fibula in both views and this is confirmed fluoroscopically.Other than the fixation of the medial malleolus, no concerted efforts are made to anatomically reduce the fibula fracture in this case. This is because applying reduction forceps to soft comminuted bone will only further crush the bone and will also further injure the soft tissue envelope. If performing this operation on harder bone, then prior reduction will aid in positioning the guide wire.
    As in any intramedullary nailing procedure, the entry point position is checked in two, orthogonal planes on an image intensifier before advancing the wire.

    The guide wire can then introduced into the distal fibular fragment and then into the shaft of the fibula.Once the entry point has been established, the guide wire can be advanced on power into the shaft of the fibula. Note that the wire is introduced by deliberately keeping the hand piece of the drill close to the lateral border of the foot.

    The position of the wire should be checked to lie in the medullary canal of the fibula shaft using fluoroscopy.The guide wire is advanced and the position is checked in two planes with fluoroscopy. In soft bone, there is no feedback from the instrumentation mandating the careful scrutiny of the intra-operative imaging as the wire can easily pierce the fragile cortices of the proximal fibula.

    Using a soft tissue protector, the distastes 4cm of the fibula is then drilled with the 6.1mm drill.Making sure to protect the soft tissues with the drill sleeve, the distal 4cm of the fibula is then prepared using the cannulated 6.1mm drill over the guide wire.

    The full length of the flutes need to enter the fibula.The full length of the flutes on the 6.1mm drill need to be introduced into the fibula creating the 4cm entry track. This track caters for the diameter of the metaphyseal component of the fibula nail common to both the 3.0mm and 3.6mm nail sizes. These two dimensions relate to the diameter of the diaphyseal portion of the fibula nail. In the vast majority of cases, the smaller diameter nail is used.


    The next step is to prepare the fibula diaphysis. For each diaphyseal diameter, the Acumed FRS offers three different nail lengths (110mm, 145mm, 180mm) dependent upon the required working length of the nail for the fracture pattern. Remember that the working length of any nail transmits load from one main fracture fragment to the other. In this case the nail spans a multifragmentary fracture relying heavily on the friction between the nail and the fibula diaphysis and the distal locking screws for stability, thus increasing its working length.
    The T-handled reamer comes in two sizes (3.1mm and 3.7mm) to prepare for either diaphyseal nail diameter.

    The T-handled reamer is not cannulated. It has a blunt tip and flutes to fashion the endosteum.

    The T-handled reamer is then introduced through the entry hole and across the fracture site.The T-handle is carefully introduced into the entry hole and guided across the fracture site. In soft bone, there is little proprioceptive feedback so it is recommended to check that it passes into the proximal fragment using the image intensifier. The depth to which it inserted can be ascertained by reading from the black etching markers seen on the reamer.

    The appropriate sized nail is selected and mounted onto its jig.The appropriate sized fibula nail is then selected [A]. The nail has an inbuilt anatomic curve reflecting the relative valgus orientation of the axis of the distal fibula metaphysis relative to the anatomical axis of the fibula diaphysis. In this case a 3.0mm x 145mm nail has been selected for implantation.
    The nail is then attached to the base plate [B] by the locking bolt [C] making sure that the apex of the curve of the nail is pointing away from the targeting guide [D]. The targeting guide is then attached to the base plate [B] by another bolt [E]. All bolts are tightened.

    You can be certain of the correct alignment of the fibula nail into the base plate by making sure that the two black lines etched into the base plate and the nail are aligned.

    Operation – 2

    The targeting sleeves for the nail need to be checked for alignment of locking screws.The anterior-posterior targeting guide [A] is then attached to the base plate with another bolt that is tightened. Using the drill sleeves, the A-P screw targeting guide should allow easy passage of the drills through the two A-P holes in the fibula nail.

    Using the black targeting guide, the same checks can be made for targeting the two lateral to medial locking screws. Note that with the sleeve touching the cortical bone, the drill can be used to measure the appropriate screw lengths by reading off the depth gauge [A].

    The fibula nail can then be introduced across the fracture site.The fibula nail can then be introduced into the prepared fibula canal. It is a good idea to introduce the nail relatively externally rotated into the fibula as, once the metaphysis is locked into the nail using the A-P screws, an internal rotation manoeuvre can reduce the fracture. Similarly, after application of the A-P screws, gentle traction can then be applied to alter the length of the fibula.

    Screen the nail during introduction and do not strike it to ease its passage.It is useful to screen the nail as it is inserted. At no point should there be the need to strike the insertion jig in order to pass the nail.

    Determine the correct depth of the nail fluoroscopically and then apply the AP targeting jig. Incise the skin.It is easy to appreciate when the nail is sufficiently seated by using the image intensifier as the junction between the base plate and the nail is clearly defined. Using the drill sleeves through the A-P targeting guide, the skin can be appropriately incised to allow passage of the drill sleeves to engage the anterior cortex of the distal fibula. The A-P locking screws can be drilled, measured and then passed.

    Drill and measure the AP screws and check their position on the intensifier.The image intensifier is then used to verify the screw positioning. On the lateral view, it is important to ensure that these screws are not too long as their tips could impinge on the peroneal tendons.
    Once the two A-P screws are seated some internal rotation can be applied to the distal fragment to aid reduction.

    Apply the lateral locking screws through the jig.The lateral locking screws can then be inserted using the black targeting guide and by adhering to the same steps as the A-P screw placement. The key difference here is to make sure that at least 3 cortices are engaged by the screws.

    Check final fracture reduction and fixation using fluoroscopy.Final images are taken in both planes making sure to identify the proximal tip of the fibula. Note that the most distal lateral-medial screw has failed to engage with the soft comminuted lateral cortex of the fibula. In spite of both lateral-medial screws not lying perfectly parallel to the mortise, the reduction of the ankle is good with the fibula lying out-to-length and in the correct rotational alignment.

    The final lateral views show the lateral-medial screws lie within the distal metaphysis of the tibia.

    Dissemble the jig from the nail.The jig is dissembled from the nail using the black nut.

    Closure of skin. Apply plaster of Paris temporary cast.On the lateral side, for each of the three wounds, only the skin is closed with 3/0 monocryl.

    On the medial side, the deep tissues are closed with 2/0 vicryl and the skin is closed with 3/0 monocryl.
    Jelonet dressings are applied to all wounds and blisters areas remembering to dress the previous pin sites. Surgical gauze, wool and crepe dressings are applied. No plaster of Paris was used in this case as it was intending to allow this elderly lady to commence weight bearing with immediate effect using a walking boot. In my opinion, not allowing an elderly patient to bear weight immediately is deleterious to their recovery.

    Post Operative

    In the elderly patient, weight bearing has to be permitted immediately, at the very least to allow transfers. To give confidence and rest the soft tissues, I find that fitting an off-the-shelf walking boot suits most patients. However, these boots often have a significant built-up sole that can affect the balance of patients when walking. Equally, in patients with unusually large or small soft tissue coverage, these boots may not fit well. If the boot is not well tolerated, a well fitted weight bearing light weight cast is an excellent alternative.
    The soft tissues should be inspected regularly and dressed whilst the wounds are still moist. If the patient is able to bear weight, then the physiotherapists can help with assessing the need for any walking aids such as frames. With weight bearing, there is no need for thromboprophylaxis.
    I tend to keep the boot in place for 6 weeks and then assess the fracture for union on plain radiographs. In severe fragility fractures, if the fibula remains tender at 6 weeks post-operatively, then I would maintain the boot for a further 6 weeks.

    Recommended Reading

    The treatment of unstable fractures of the ankle using the Acumed fibular nail. Bugler KE, Watson CD, Hardie AR et al. J Bone joint Surg 2012; 94B: 1107- 1112.
    This is a retrospective review of over 100 patients that had been treated with the Acumed FRS. This group of patients were found to have a high number of co-morbidities and a significantly higher mortality rate compared to a cohort of patients with a similar fracture pattern. It documents the evolution of the surgical technique in response to complications arising from loss of reduction owing to the lack of lateral buttressing. The authors conclude that use of both A-P locking screws as well as lateral locking screws give the most favourable results with the latter screws conferring most stability to the construct.
    A prospective randomised controlled trial of the fibular nail versus standard open reduction and internal fixation for fixation of ankle fractures in elderly patients. White TO, Bugler, KE, Appleton P et al. Bone Joint J 2016; 98B: 1248-1252.
    This prospective RCT studied patients over the age of 65 with co-morbidities treated by standard methods of open reduction and internal fixation compared with the closed reduction techniques and the Acumed FRS nail. The primary outcome measures were the results of functional scores where no difference between the groups was observed. However, the secondary outcomes detailed that there significantly fewer complications when using the fibula nail than with ORIF and that this had significant cost benefits from employing this fixation method.
    Fluoroscopy-guided reduction and fibula nail fixation to manage unstable ankle fractures in patients with diabetes. Ashman BD, Kong C, Wing KJ et al. Bone Joint J 2016; 98B: 1197-1201.
    This decade long study looked at a small cohort of diabetic patients who presented with unstable ankle fractures managed by fibula nail fixation. The study showed low rates of wound complications and re-operation rates suggesting that the technique is an appropriate surgical management strategy.
    Biomechanical comparison of intramedullary fibular nail versus plate and screw fixation. Smith G, Mackenzie SP, Wallace RJ, White TO 2017;38(12): 1394-1399.
    This cadaveric study simulated supination-external rotation fracture patterns stabilised using either a fibular nail or lag screw and non-locked 1/3 tubular neutralisation plate and screws. A supination force was applied with the metalwork in place and the ankles were taken to failure. The failure in the plating group occurred by the metalwork pulling out of the bone whereas the failure of the ankle occurred with greater forces through the whole lateral ligament complex rather than through the fracture site or through the fibula nail.
    A biomechanical comparison study of a modern fibular nail and distal fibular locking plate in AO/OTA 44C2 ankle fractures. Switaj PJ, Fuchs D, Alshouli M et al. J Orthop Surg Res 2016; 11: 100.
    In another cadaveric study simulating a high fibula fracture with a bone defect treated either with a bridging locking plate or a fibula nail, each specimen was tested to failure by applying external rotation. Compared to the locking plate, the fibula nail had lower external rotation stiffness as would be expected given the nail has no proximal locking. Remarkably, the syndesmosis was largely maintained within anatomic parameters.

    Reference

    • orthoracle.com

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