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Pilon fracture- C-type fixed using Smith and Nephew EVOS small fragment system

    Overview

    Learn the Pilon fracture: C-type fixed using Smith and Nephew EVOS small fragment system surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Pilon fracture: C-type fixed using Smith and Nephew EVOS small fragment system surgical procedure.
    The operative fixation of pilon (pestle) fractures was first described by Ruedi and Allgower in 1968. They advocated surgical fixation with a four stage approach. Firstly restoration of fibula length, secondly reconstruction of the joint surface, thirdly bone grating to the metaphysis and fourthly a medial buttress plate. They also provided a classification with 3 types, Type 1 with no joint displacement, type 2 with articular displacement and type 3 with significant articular comminution.
    The majority of the injuries reported by Ruedi and Allogower occurred after skiing accidents, in contrast to this most injuries seen in less mountainous regions occur after high energy injuries involving axial loads to the ankle such as falls from significant height or road traffic accidents. The classification has been further refined by Topliss and Atkins who described the commonly seen articular fragments and patterns of injury.
    Current management of high energy pilon fractures normally involves a staged approach with initial placement of an external fixator to resuscitate the soft tissues and restore overall limb alignment followed by definitive fixation once the soft tissues have recovered sufficiently.
    Readers will also find of use the following operative techniques on OrthOracle dealing with pilon fractures:
    C-Type Pilon Fracture – Open Reduction and Internal Fixation with Stryker AxSOS 3 Periarticular Plating System
    Internal fixation of distal tibial Pilon fracture using Stryker AxSOS 3Ti plate.

    Indications

    INDICATIONS
    Most pilon fractures will be managed surgically. The aim of surgery is to reconstruct, as far as possible, the articular surface and to restore the overall joint and limb alignment.
    SYMPTOMS & EXAMINATION
    These are high energy injuries and often occur in polytraumatised patients in which case priority should be given to life threatening injuries and the management of long bone fractures prior to definitive fixation of the pilon fracture. Assessment of the injured limb will include checking for signs of vascular injury, compartment syndrome and open wounds.
    In most centres a staged approach is taken to high energy c-type pilon fractures. The first stage involves placement of a spanning external fixator across the ankle joint. This allows restoration of the overall limb alignment (which will facilitate later surgery) and by stabilising the fracture helps to resuscitate the soft tissues. After the external fixator is applied a CT scan of the fracture is obtained. Delaying the scan until after the ex-fix gives more information as many fragments are dis-impacted following the external fixation and overall fracture morphology is easier to appreciate. Following the scan the definitive surgery can be planned, leading to the useful mantra”span, scan and plan”.
    The timing of surgery is dictated by the condition of the soft tissues. The staged approach was first advocated by Sirkin et al (see results, below) who found that by adopting a staged approach with delay of definitive open reduction and internal fixation until the soft tissues had settled resulted in a reduction in soft tissue complications with only 1 of 29 patients with closed pilon fractures in their cohort developing a deep infection. This means that often patients will wait for 1-2 weeks, occasionally longer, before the skin has recovered sufficiently for safe definitive surgery. A small number of patients will have severe soft tissue injuries that are not amenable to the incisions needed for internal fixation or fracture patterns with long proximal extension difficult to span with plates and should be considered for definitive stabilisation with a ring fixator.
    IMAGING
    Several classification systems exist. The AO/OTA system divides distal tibia fractures into 3 types, type a fractures are extra-articular. In terms of managing extra-articular fractures the most useful distinction to make is between an AO/OTA B type (partial articular fracture) where part of the joint surface remains attached to the tibia, these fractures require stabilisation with a buttress plate with a direct approach, and AO/OTA C type (complete articular) fractures which have complete dissociation of the joint surface and often require multiple approaches.
    C type injuries with simple splits and no articular step or gap may be fixed with lag screws to compress the joint surface and a single plate to fix the joint to the tibial shaft. The plate is generally applied on the side of the initial displacement (eg medial plate if initial displacement in varus). Most c type fractures will have articular displacement (ie steps and/or gaps). My approach to these fractures is to use multiple approaches and plates, the overall strategy is to convert the c type fracture to a B type (often with a posterior plate to fix the posterior component) and then to reduce the remaining joint onto this fragment. The chosen surgical approach will depend on where the main fragments are and whether a central fragment needs to be addressed via a fracture window. Each surgical approach should be planned to come directly to the relevant fracture fragment with minimal soft tissue stripping.
    The Topliss and Atkins classification helps to identify the main articular fragments. From their series they identified 6 articular fragments: anterior, posterior, medial, anterolateral, posterolateral and die-punch. Furthermore two fracture ‘families’ were described, sagittal and coronal, based on the plane of the primary fracture line. Understanding this helps to understand the surgical approach(es) required to address the main articular fragments and also how fixation must be applied to stabilise the fracture.
    When assessing these injuries I will study the plain films to understand the primary deforming force (valgus/varus or anterior/posterior) to guide my primary approach (eg anterolateral plate for values deformity). I will then study the X-ray and CT to distinguish between a B-type and C-type – this may be obvious but there can be an undisplaced split only visible on CT indicating that the joint is completely separated. I will then study the articular fragments and plan how to approach and stabilise each of these.
    ALTERNATIVE OPERATIVE TREATMENT
    For high energy C-type pilon fractures the main treatment choices are between internal fixation, often with multiple incisions, or ring fixators. There is currently a multi-centre RCT of frame vs internal fixation for pilon fractures which may help to guide our treatment decisions in the future. In my opinion these injuries should be managed in centres capable of reconstruction with both frames and internal fixation. Open fractures, those with very long proximal fracture extensions or with severely injured soft tissues unlikely to recover in time for open surgical reconstruction (obviously a subjective measure) should be offered fixation with a frame. Conversely fractures very close to the joint (ie within 10mm) when fixed with frames are likely to result in intra-articular wires and should be fixed internally. Clearly most fractures fall between these extremes and the consent process should involve a discussion of the risks and benefits of both frames and internal fixation.

    Setup

    For anterior approaches the patient is positioned supine on a table with a radiolucent end. Many c-type fractures will require approaches to the posterior component of the fracture, either posteromedially or posterolaterally, and my preference is to fix these with the patient in a prone position even if it means the patient must be turned during the operation or even if the fixation has to be performed in two stages.
    For anterolateral approaches it is helpful to have a ‘sandbag’ placed under the ipsilateral buttock to provide slight internal rotation of the limb. The limb should be elevated, either with a fixator or with a radiolucent bump, to allow good AP and lateral imaging without the need to move the leg. The patient should be given antibiotic prophylaxis according to local protocol. A TED stocking and flowtron boot should be applied to the contralateral limb assuming there are no contraindications. I do not use a tourniquet for these cases, the soft tissues are already severely injured in most cases and adding a further ischaemic insult for minimal gain seems counterintuitive.

    Operation – 1

    The plain radiographs confirm that this is a C-type pilon with complete articular involvement. on the AP view it can be seen that the main deforming force is valgus suggesting that the main plate in our construct should be on the lateral side to control this deformity. The medial side has failed in tension and will likely require compression. On the lateral view it can be seen that there is a large central fragment (1.), this fragment shows significant depression and rotation and will need direct reduction to restore the joint anatomy. The posterior fragment is multifragmentary and displaced.

    The coronal views of the CT scan demonstrate large anterolateral and medial fragments.

    The axial CT allows the fracture to be classified according to Topliss and Atkins.
    This shows anterolateral (1.), anterior (2.), medial (3.), central (4.) and posterolateral (5.) fragments. The operative plan needs to consider each of these fragments. The posterior fragment will require a posterior approach and separate plate. The central fragment will be reduced via the window between antero-lateral and anterior fragments, this can be approached with an anterolateral incision directly over the fracture through which the anterior and anterolateral fragments can then be fixed. The medial fragment will need a separate approach and, as noted above, compression plating.

    The sagittal CT confirms the position of the central fragment (1.) and illustrates the discplacement of the posterior portion (2.).

    Owing to the high energy mechanism and persistent significant swelling, a staged approach was taken to the reconstruction.
    An initial spanning external fixator had been applied at the referring hospital to restore overall alignment and resuscitate the soft tissues.
    Our first operation at approximately 2 weeks post-injury involved a posterolateral approach. The posterior fragment was reduced, paying attention to correcting the extension these fragments tend to lie in.
    A Smith and Nephew EVOS posterior distal tibial plate was used with distal unicortical locking screws. These were positioned so as not to impede the later anterior reconstruction. Proximally bicortical cortical screws were used.
    Readers should refer to Mark Davis postero-lateral approach for ankle fracture fixation to gain familiarity with this part of the technique
    Postero-lateral plating of pronation-external rotation ankle fracture (posterior malleolar fixation)

    Following fixation of the posterior fragment the patient was left in the spanning external fixator.
    The fixator had been adapted from our standard delta frame with a Denham pin placed in the proximal tibia and medial and lateral longtitudonal rods (see below) to allow the patient to be positioned prone for the posterior fixation with the ex-fix in situ (otherwise the anterior pins of the delta frame prevent prone positioning) – this aids fracture reduction.
    Following posterior fixation the soft tissues were rested for a further 5 days before the anterior reconstruction was performed.

    The patient is positioned supine with the external fixator left in place to provide joint distraction. The proximal tibial Denham pin can be seen (1.).
    Once the soft tissues had settled sufficiently (wrinkle sign present- this is a return of the skin creases as the swelling subsides) anterior fixation was performed.

    Start with an anterolateral approach to address the antero-lateral, anterior and central fragments.The fracture window between the anterolateral and anterior fragments is identified with a needle (1., the split between the anterior and anterolateral fragments can be developed to allow access to the central fragment), the incision will be directly over this fracture window to minimise soft tissue stripping.

    Fracture window between anterior and anterolateral fragments (7.)

    A needle is positioned in the fracture window and this is confirmed on X-ray (1.), assisting correct location for the antero-lateral approach.

    A direct, longitudinal skin incision is made and careful dissection performed on to the underlying fascia. Carefully look for and avoid the superficial peroneal nerve.The superficial peroneal nerve lies above the fascia and is normally found in the proximal part of the wound (1.). It does not need to be fully dissected out but should be mobilised and protected. There is considerable variation in the course of the SPN. In most patients it traverses the lateral compartment of the leg before piercing the crural fascia and becoming subcutaneous, crossing the fibula approximately 12cm proximal to the tip of the distal fibula and the dividing into two terminal branches approximately 4cm above the ankle joint. This approach is based on a direct approach to the fracture with minimal soft tissue disruption rather than a true internervous approach and as such is not extensile per se. The plate will be applied with a MIPPO technique and extensive dissection of the metaphyseal component of the fracture is neither needed nor desirable and therefore proximal extension should not be required.

    The fascia and then extensor retinaculum are then divided and the underlying long extensors exposed.

    A plane is now developed between the long extensors directly down to the fracture window (1.).The ankle joint and talus are exposed distally (2.). Throughout the approach care is taken to avoid undermining the skin edges and excessive soft tissue stripping from bone.

    The anterolateral ((1.) and anterior (2.) fragments can now be seen with the talar dome visible (3.).
    The central fragment (4.) lies behind the anterior fragment.

    The window between the anterolateral and anterior fragments is gently mobilised and deep to them is found the depressed, central fragment.The central fragment is accessed via the fracture window, 2 k-wires (1.) have been placed under image control to use as ‘joysticks’ to aid reduction. The fracture is gently mobilised with the joysticks and a McDonald elevator.

    Tke k-wires are used to reduce the central fragment (1.) onto the previously fixed posterior fragment (2.).Reduction is assessed by direct inspection of the joint surface (although given its domed morphology complete visualisation is not possible) and use of the image intensifier. Once a satisfactory reduction is obtained the wires are advanced to provisionally hold the fragment. Reduction is often difficult to achieve, it is important to clear out haematoma and early callus with irrigation and judicious use of the elevator. If an anatomical reduction is not achieved at the first attempt then it should be taken down and the steps repeated. In some cases articular fragments will be missing or non-reconstructable and a balanced decision as to the relative risks of a more extensive dissection versus the risk of sub-optimal joint reconstruction must be reached

    The anterolateral fragment is now reduced with the help of a ball-tipped spike (1.), this is then held with further k-wires.We have now built the central, anterior and anterolateral fragments on to the previously fixed posterior fragment. Fixing the posterior fragment effectively turned an AO/OTA C-type fracture into a B-type onto which the rest of the joint surface can be built. This is my general approach in pilon fractures when both posterior and anterior approaches are needed.

    A lag screw is inserted anteriorly to fix the central fragment to the posterior tibia.I use a 3.5mm cortical screw with over-drilling of the near fragment to achieve inter-fragmentary compression of the main articular fragments. Cannulated screws are not needed. I drill first with a 2.5mm drill bit via the 3.5mm guide to ensure accurate screw placement and then overdrive the near fragment with a 3.5mm drill bit.

    The anterior to posterior lag screw is inserted under image guidance with a lateral view to check the reduction and ensure the joint is not penetrated.I have used a small fragment cortical screw from the EVOS set in lag mode. Countersinking is not normally needed, the screw will sit down in the cancellous bone sufficiently for the plate to sit over it. It would be entirely reasonable to use a partially threaded cancellous screw here.

    For this reconstruction I am using the Smith and Nephew EVOS small fragment set.
    This has well laid out instrumentation with a range of retractors (1.) and reduction clamps (2.). There are screw size options in 3.5mm (orange tray, 3) or 2.7mm (blue tray,4) .

    The plates (1.) shown are for the distal tibia and fibula, they have options for posterior, medial, anterior and anterolateral distal tibia in addition to standard small fragment plates.
    The plates are sided with a range of length options although as noted above fractures with very long proximal extensions may not be adequately spanned by a plate and in this situation I prefer to use a ring fixator. The peri-articular plates have options for partial articular buttress plates or complete articular plates. Screws are loaded on the trays (2) and colour coded orange for 3.5mm and blue for 2.7mm the same as the instruments.

    Here I am using an anterolateral complete articular plate, the length is chosen to give a long span and good overlap with the posterior plate.
    The plate has holes for variable angle locking screws in the articular segment (1.), the most distal row of screws are 2.7mm to allow a very distal position if required. Proximally 3.5mm locking or cortical screws can be used.

    The EVOS anterolateral complete articular plate is inserted by sliding it through the incision under the muscles but over periosteum.It is then provisionally held it with k-wires and the position checked proximally and distally with imaging.

    The first screw through the plate is inserted just proximal to the apex of the anterolateral fragment (1.)this is a cortical screw engaging 2 cortices, the intention is that this will buttress the plate and aid fracture reduction as the screw is tightened.

    The plate is now seated on the bone.
    The anterolateral, anterior and central fragments have now been reduced onto the posterior fragment. Before further fixation is performed the medial fragment should be reduced- this will allow any adjustments to the lateral reduction to be made to allow the medial articular fragment to be adequately reduced.

    Operation – 2

    A direct medial approach is performed after fixation of the anterolateral fragment, again centred on the fracture.The long saphenous vein is formed from the dorsal venous plexus of the foot, it course over the anterior aspect of the medial malleolus and then ascends over the medial aspect of the tibia. The saphenous nerve descends posterior to the vein before dividing into anterior and posterior branches approximately 3 cm above the tip of the medial malleolus. The long saphenous vein and nerve may be encountered in the wound, if so they should be mobilised and protected.

    Firstly I attempted reduction with clamps and digital reduction.
    This however failed to achieve a satisfactory reduction. I therefore extended the incision distally, further anterior dissection allowed visualisation then mobilisation of the anterior shoulder of the medial malleolus.

    The periosteum is gently cleared from the fracture ends to assist in visualisation of the medial malleolar fracture. The anterior “shoulder” of the medial malleolus is a good way to guide alignment of the medial fracture.It was then possible to achieve a satisfactory reduction which was then held with a large tenaculum reduction forcep(1.).

    The medial fracture once reduced is stabilised with bone holding forceps.This plate is part of the EVOS mini fragment set (in this case 2.7mm), as with the larger plates it can be used with cortical or locking screws. The medial soft tissues are unforgiving and the plate should be low profile to avoid irritation and soft tissue problems.
    I have positioned the plate and provisionally held it with k-wires while the position is checked on image intensifier.

    A low profile 2.7mm Evos plate is contoured distally around the tip of the medial malleolus plate and fixed.This will allow a screw to be passed through the plate and across the fracture. The proximal end of the plate should not be contoured- here it will be used to buttress the fragment.

    The proximal end is secured first, the distal k-wire ensures the plate remains is place distally.
    This is achieved with three 2.7mm cortical screws (2mm drill bit). The screws should engage 2 cortices. As they are tightened the plate will bend to the bone, this will pre-load the plate and help it to buttress the fragment.

    After proximal fixation a screw is inserted in the distal segment.
    This is placed through the plate, the near side is over drilled (2.7mm drill bit) to allow further compression as the screw is tightened. I have used a cortical screw and attempted to achieve bi-cortical fixation with this screw.

    Check AP image showing adequate medial reduction, the distal screw is engaging 2 cortices (1.).

    The main articular fragments have now been reduced and the lateral fixation can be completed.
    In the distal segment locking screws are used to give a fixed angle construct and increase pull out strength in a short segment.
    The distal locking screws on the EVOS plate are variable angle, a conical drill guide is used (1.). Provided the drill hole remains in the trajectory of the cone the locking screw will engage and lock into the plate.
    This allows some freedom in screw positioning and is useful for very distal fractures that conventional locking may struggle to stabilise or for capturing fracture fragments with specific screws.
    The distal screws are 2.7mm (2mm drill bit). Screw positions are selected to capture each individual fragment. Generally a minimum of 4 screws would be used in the distal segment.

    .Proximal fixation is now completed
    The EVOS plate allows either locking or cortical fixation in each proximal screw hole. In patients with normal bone quality locking screws are not required in the proximal segment. The screw holes are first identified with the image intensifier. An incision is made over the screw hole and scissors used to dissect down the plate.

    Here a ‘screw-in’ drill guide (1) has been positioned in the screw hole to aid drilling.
    The drill guide can be used for cortical or looking screws. A hole is drilled for a 3.5mm cortical screw (2.5mm drill bit). The screws should engage both cortices.

    A total of 3-4 cortical screws are used in the proximal segment. The screws are tightened under image control.
    The fibula fracture rarely requires fixation. This is an axial load injury rather than a rotational ankle fracture. Fibula fixation does not aid joint reduction or help to stabilise the ankle joint. In some instances fixation of the fibula may help to stabilise the lateral column and fixation should be considered in these situations.

    Final check images are taken.
    The articular reduction and overall alignment are checked as well as screw position and lengths.

    Final lateral images are checked.

    Wound closure is performed in a layered fashion.I use interrupted sutures for each layer with nylon to skin. Non-adherent dressings should be used.

    Post Operative

    I generally splint the ankle in a backslab to maintain a neutral position and to overcome the tendency for the ankle to adopt an equinus position. The wounds are checked at 2 weeks and at that point the patient is transferred to an aircast boot and foot and ankle exercises are commenced with physiotherapy. Graduated weight bearing is commenced from 4-6 weeks. VTE prophylaxis with low-molecular weight heparin should be given until the patient is weight bearing (maximum 6 weeks).

    Recommended Reading

    Sirkin, Michael; Sanders, Roy*; DiPasquale, Thomas*; Herscovici, Dolfi Jr.
    A Staged Protocol for Soft Tissue Management in the Treatment of Complex Pilon Fractures
    Journal of Orthopaedic Trauma: February 1999 – Volume 13 – Issue 2 – p 78-84
    This paper popularised the staged approach to c-type pilon fractures. Their protocol involved early (within 24 hrs ) fixation of the fibula to restore length and application of a spanning external fixator followed by definitive internal fixation of the distal tibia once the soft tissues had settled. They reported results in 29 closed fractures, with only one case of deep infection and in 17 open fractures with 2 cases of deep infection, one of which resulted in a below knee amputation.

    Topliss CJ, Jackson M, Atkins RM. Anatomy of pilon fractures of the distal tibia. J Bone Joint Surg Br. 2005 May;87(5):692-7.
    This paper describes the anatomy of pilon fractures with respect to the common articular fragments and fracture patterns. They reported on 1267 fractures, identifying 6 main articular fragments (anterolateral, anterior, medial, posterior, posterolateral and die-punch) together with 2 fracture families, coronal and sagittal.

    Assal M1, Ray A, Stern R. Strategies for surgical approaches in open reduction internal fixation of pilon fractures. J Orthop Trauma. 2015 Feb;29(2):69-79.
    A comprehensive review of the different surgical approaches that can be employed to fix pilon fractures and the indications for their use with anatomical drawings.
    Esposito JG van der Vliet QMJ, Heng M, Potter J, Cronin PK, Harris MB, Weaver MJ. Does surgical approach influence the risk of post-operative infection following surgical treatment of tibial pilon fractures? J Orthop Trauma. 2019 Sep 30.
    In this study the authors assessed infection rates following ORIF of 590 pilon fractures and the relation to the surgical approach. Most fractures were fixed with medial (54%) or anterolateral (25%) approaches. The overall deep infection was high at 19% however there was no correlation with the chosen surgical approach although smoking and the need for soft tissue coverage were risk factors for deep infection.

    Esposito JG van der Vliet QMJ, Heng M, Potter J, Cronin PK, Harris MB, Weaver MJ. Does surgical approach influence the risk of post-operative infection following surgical treatment of tibial pilon fractures? J Orthop Trauma. 2019 Sep 30.
    In this study the authors assessed infection rates following ORIF of 590 pilon fractures and the relation to the surgical approach. Most fractures were fixed with medial (54%) or anterolateral (25%) approaches. The overall deep infection was high at 19% however there was no correlation with the chosen surgical approach although smoking and the need for soft tissue coverage were risk factors for deep infection.

    Spitler CA1, Hulick RM, Weldy J, Howell K, Bergin PF, Graves ML.What are the Risk Factors for Deep Infection in AO/OTA 43C Pilon Fractures? J Orthop Trauma. 2019 Dec 20
    Another recent study assessing infection rates after C-type pilon fractures. This paper reviewed 150 fractures over a five year period. Overall deep infection rate was 16.7%. Risks factors for deep infection were segmental bone loss and open fractures requiring soft tissue coverage.

    Kurylo, John C; Datta, Neil; Iskander, Kendra N; Tornetta, Paul III Does the Fibula Need to be Fixed in Complex Pilon Fractures?
    Journal of Orthopaedic Trauma: September 2015 – Volume 29 – Issue 9 – p 424-427
    This group reviewed 111 complex pilon fractures with metadiaphyseal dissociation. They identified 3 groups, those who had fibula fixation, those who did not and those in whom the fibula was intact. There was no difference in final alignment between the 3 groups although those who had the fibula fixed required more subsequent metalwork removal. They concluded that fibula fixation is not an essential step in pilon reconstruction.
    This group reviewed 111 complex pilon fractures with metadiaphyseal dissociation. They identified 3 groups, those who had fibula fixation, those who did not and those in whom the fibula was intact. There was no difference in final alignment between the 3 groups although those who had the fibula fixed required more subsequent metalwork removal. They concluded that fibula fixation is not an essential step in pilon reconstruction.

    Reference

    • orthoracle.com

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