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Talar fracture- Talar neck fracture fixation using Stryker Variax implants

    Overview

    Learn the Talar fracture: Talar neck fracture fixation using Stryker Variax implants surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Talar fracture: Talar neck fracture fixation using Stryker Variax implants surgical procedure.
    The case presented is a left open Hawkins III fracture of the talar neck.
    This 30 year old male sustained an open fracture dislocation of the left talus when crashing his motorcycle. His initial management was according to ATLS guidelines through the Resuscitation area of the MTC Emergency Department. He was noted to also have multiple rib fractures but no lung injury and an off ended closed right detail radius fracture.
    Initial management included lavage and reduction of the dislocation under entonox and application of a backslap cast. His wrist was also manipulated and placed into a temporary cast.
    He was taken to the operating theatre within 2 hours of presentation. There his wound was debrided, the fracture was debrided of contaminants including road grit and after wound closure a bridging delta External Fixator was applied.
    The reduction was adequate but imperfect and in order to allow for earlier mobilisation and anatomic reduction Open Reduction and Rigid stabilisation was required.
    A second CT scan (after the initial resuscitation scan) was obtained with the external fixator in Situ. This was to determine with more detail the nature of the injury and to plan operative intervention. A syndesmosis injury was also diagnosed at this stage. Gas can be seen in the soft tissues.
    The lateral wound was clean and dry by 4 days. The external fixator allowed the wound to be inspected without a cast being in place. The patient developed a pyrexia secondary to his chest injury at day 4 and so surgery was delayed until day 6 when he was apyrexial and his chest had improved.
    Plans were made for definitive fixation though this was delayed for further 48 hours due to a pyrexia secondary to chest infection. Definitive surgery was conducted at day 6.


    Indications

    INDICATIONS
    Talar neck fractures are relatively rare but very significant injuries. The mechanism varies from simple falls to very high energy injuries with multiple associated and potentially distracting injuries. In the presence of an appropriate mechanism and a swollen painful ankle, care should be taken to look closely at the plain radiographs.
    SYMPTOMS & EXAMINATION
    In the presence of an appropriate mechanism care should be taken to exclude a talar neck fracture. The signs are those of pain and swelling. A careful history should be sought from paramedics of deformity at the scene requiring a reduction and then splintage as this will raise suspicion.
    IMAGING
    Focus should be made on the talar neck on the lateral radiograph but also on the AP image where small fragments of bone around the medial (more often) or lateral sides of the talus should raise concern. CT scans are mandatory if a talar neck fracture is suspected.
    The classic classification used is that of Hawkins in his 1970 paper, though this was usefully amended in 1978 by Canale with the addition of a fourth group.
    Hawkins 1 fractures are those with no or minimal displacement
    Hawkins 2 fractures include displacement of the fracture and the subtalar joint
    Hawkins 3 fractures are defined as those where there is in addition to the subtalar displacement, displacement of the ankle joint
    Hawkins 4 added by Canale is as for a 3 but also has displacement of the talus head form the talo-navicular joint
    The classification matters as it gives good prognosis in that the rates of avascular necrosis increase with the severity of each grade.
    ALTERNATIVE OPERATIVE TREATMENT
    The fracture if minimally displaced may be stabilised with screws either posterior-anterior (my preference) or anterior-posterior. Care must be taken not to shorten either column and thereby displace the farcture. Most ofetn I open the fracture at the site of maximum comminution in order to anatomically reduce the fracture – as I did in this case which was more complex due to the dislocation and the open wound.
    NON-OPERATIVE MANAGEMENT
    Hawkins 1 fractures may be managed expectantly but close serial radiographs must be taken to ensure there is no displacement. I keep patients in a cast for 2 weeks and then if they are compliant will start range of movement exercises under the care of the physiotherapists but I keep the patients non-weight bearing for 6 weeks. If compliance is an issue then a cast is used for longer. Hawkins 2-4 fractures require operative treatment generally.
    This was not an option for an open talus fracture dislocation.
    CONTRAINDICATIONS
    The presence of more urgent fractures and other injuries may delay treatment as it did in this case but generally there are no formal contraindications to reduction and fixation of these injuries. In this case the definitive surgery was delayed whilst the patient was pyrexial to reduce the risk of infection at the operative site.

    Setup

    The patient was positioned supine with sandbags under the ipsilateral hip to allow easy access to the lateral aspect of the rearfoot. If a medial approach was also required (which I did not expect in this case) then the sandbags would be removed and the leg allowed to naturally rotate outwards allowing access medially
    General anaesthesia employed, although a spinal epidural could have been used, with the history of chest sepsis the anaesthetists were keen to avoid the risks of epidural sepsis.
    A radiographer and standard image intensifier was employed throughout to ensure reduction and appropriate hardware positioning.
    Prophylactic antibiotics are used though this patient was on antibiotics for his chest infection and so these were augmented with gentamicin given intravenously.
    Thigh tourniquet was applied and inflated to 300mmHg after limb elevation
    The external fixator was prepared with chlorhexidine along with the limb and left in situ to provide stability and to potentially aid reduction. The delta construct for the external fixator uses a minimum of two Schantz pins in the tibia and one pin in each of the calcaneus and the medial ray of the foot. No pins should be placed in the talus as 75% of its surface is articular.

    Operation – 1

    A spanning delta external fixator had been applied 6 days earlier. Pins had been positioned in the calcaneus and the base of the first metatarsal and two further Schantz pins into the tibia. This is the most simple and stable frame and we use this type of shape to stabilise ankle and rearfoot fractures when there has been a dislocation, almost routinely whilst awaiting for soft tissues to settle. The use of a cast to do this makes subsequent soft tissue inspection difficult. With this frame on we could inspect the traumatic lateral wound and time the second stage accurately.
    Once the limb and frame had been prepped the distal clamps of the external fixator were loosened to allow the hindfoot to be maniplutaed during the reduction and fixation of the talus fracture. It was expected that the external fixator would be retained once the fractures had been reduced as a “stable splint”.

    Viewed from the lateral side – the lateral traumatic wound had been extended, skin edges were excised and the joints debrided, lavaged copiously and then closed with interrupted nylon stitches six days earlier. With the Delta External Fixator on we were able to directly observe the limb for signs of swelling reduction and so time our intervention once we were happy that the tension of the skin was satisfactory.

    A separate approach was selected rather than extend the traumatic wound, to access the lateral talar neck. The incision is in line with the 4th metatarsal and is limited posteriorly by the skin bridge toward the traumatic wound. The orientation of the trauma wound does not lend itself to extension and I was concerned that a sharp angle would be required.
    Both wounds in fact risk damage to the dorsal branch of the superficial peroneal nerve which courses antero-laterally at the ankle joint and into the foot towards the 4th toe. Plantarflexion of the ankle and the 4th toe whilst inverting the hindfoot can render this nerve visible (as was described by Michael Stephens in year 2000) but in this case the swelling and presence of the external fixator made this action impossible.
    The sural nerve also gives a dorsal branch on occasions at the level of the neck of the talus. This nerve is usually easily seen in the subcataneous fat. If damaged an an area of anaesthesia over the dorsum of the foot towards the 4th and 5th toes can result.
    Division of either of these cutaneous nerves will not cause undue concern (though it is inelegant) but traction or crushing of either of the cutaneous nerves can lead to allodynia with a poor subsequent outcome.
    The wound was carefully marked out from the base of the 4th metatarsal directly posteriorly as far as the peroneal tendons

    After sharp incision of the skin, scissors are used to cut through the subcutaneous fat in order to protect against inadvertant damage to the superficial peroneal nerve or the dorsal branch of the sural nerve. Under the fat the fascia over the muscle belly of Extensor Digitorum Brevis (EDB) is located. This fascia is cut with a knife in line of the incision. The muscle belly itself is reflected interiorly by releasing its bony origin from the dorsum of the calcaneus to gain access to the lateral aspect of the neck of the talus and the sinus tarsi.

    The muscle belly of EDB is seen in the plantar aspect of the wound here. A self retaining retractor is positioned with the teeth in deep to avoid pressure on the vulnerable skin edges. The sinus tarsi is now easily visualised.

    In the sinus tarsi the lateral talar neck fracture comminution is located and the fragment explored as this will be used to also gauge and guide reduction anatomically of the neck fracture. Care must be taken not to pull the wall fragment off its soft tissue attachments and thus devitalising it.
    Dissection within the sinus is kept to a minimum as the sinus tarsi artery (a branch of the anterior tibial artery) courses through the sinus to anastamose with the medial artery (the tarsal canal artery – a branch of the posterior tibial artery) in the sinus tarsi. The lateral artery comes into the sinus dorsally and so care is taken not to dissect deep at this level. The lateral comminution at the time of the fracture being sustained may already have damaged this delicate anastamosis but we do not want to cause a second injury or further compromise the fragile blood supply to the talus.

    The fragment is small and care is taken to rotate it correctly whilst respecting the soft tissue attachment which was a tenuous pice of periosteum. The reduction of the fragment is held with forceps prior to stabilisation with a temporary 1.4mm k-wire. I use a small wire so that the fragment does not get split whilst introducing it. I am careful that the fragment does not spin with the wire by holding it with the forceps whilst the wire is introduced.

    Because of the lateral comminution there is a risk that if the length of the lateral wall is not maintained that the fracture will become displaced into abduction or valgus. For this reason rather than use two screws along the length of the talus a plate is selected for the lateral wall. Plates, such as the Stryker Variax talar neck plate, are now manufactured specifically for this purpose and have the advantage of being well precontoured and also locking, thus reducing the risk of malreduction.
    A 1.4mm wire holds the lateral comminuted fragment and a plate is rested in situ to check its situation in terms of shape and apposition to the lateral neck. The plate is the Stryker Talar Neck plate from the Stryker Variax set.

    The plate is temporarily stabilised with a K-wire and its position as well as the reduction of the fracture is checked with the image intensifier.

    Oblique AP intensifier view is taken to check the reduction of the neck fracture and plate position. The situation of the plate is adequate without any evidence that it will impinge and its contour appears correct. However, the head of the talus remains in varus. This would lead to shortening of the medial column and a subsequent probable cavus foot deformity. This element of mal-union is very poorly tolerated.
    The plate contour is correct and I decided to therefore reduce the fracture by bringing the head to the plate.

    The plate is attached proximally to the body with locking screws – care is taken to protect the soft tissues and an image intensifier is used again to ensure screws are correctly situated. There is an option to vary the orientation of the locking screws through a 30degree arc – ie 15degrees either side of neutral. The guide must be well seated in the locking hole to use the variable angle guide appropriately. Drill with care so as not to penetrate the mostly articular cortex of the talus.

    Care is taken to select appropriate length screws to ensure that the articular surface of the talar dome is not penetrated. The longest screw that will not cause damage to the articular surface is selected as this will provide maximum stability.

    A locking screw is used to secure the plate to the body of the talus proximally. The plate remains stabilised with a guide wire to avoid displacement in rotation of the plate as the screw is engaged with the plates locking threads.

    Distal fixation to the talus head is with the use of a non-locking screw, in effect lagging the head to the plate and thereby achieving reduction. Once again careful length of screw selection is made subtracting 3mm from the maximum screw length as the bone will move towards the plate.

    A non locking screw is used to allow the varus to be corrected at the fracture site by reducing the head onto the plate. Note the non locking screws are gold in colour and have no threads on their neck.

    The reduction is again checked with the image intensifier in the oblique AP view. The medial wall of talus is now reduced. It can be seen that the screws are orientated correctly and are the right length so that no penetration of the articular has occurred.

    Image intensifier is used also to further check on the lateral view particularly to look for extension or flexion of the neck and to examine for screws penetrating articular areas.

    Residual screws are positioned and the non locking screw which was used to ‘lag’ the head onto the plate is also replaced with a locking screw to secure fixation 1. I use the Image Intesifier quite liberally to make sure that the screws are correct in length and orientation.

    This small plate is not robust enough on its own in my opinion to stabilise this veryu unstable fracture and a supplemental long screw is also needed. Given the lateral “column” of the talus has been stabilised I now plan to position a screw along the medial “column”.
    A further open medial approach would cause a significant risk to the talus blood supply and we dont need to visualise the medial side of the fracture. With this in mind a percutaneous screw is used. For me I prefer to introduce this from the posterior side so as not to violate the chondral surface of the head of the talus at the talo-navicular joint.
    An assistant is needed to elevate the limb in this case to gain access. but were there no medial Ex Fix in situ the patient may have been positioned in “sloppy” lateral position with the affected limb uppermost and this would obviate the need for elevating the limb to do this part of the procedure.
    A guide wire for a 5mm Asnis cannulated Stryker screw is introduced from a postero-lateral to antero-medial direction to provide stable fixation to the medial column of the talus. I do not require compression herte but just beam stregth and so a fully threaded screw is used. Compression would again risk moving the talus into varus at the fracture site despite the lateral locking plate.

    The approach to position the guide wire and subsequent screw is through a small stab incision just lateral to the achilles tendon so that the sural nerve is well protected. The talus is accessed at the lateral tubercle just lateral to the sulcus for the flexor hallucis longus tendon. The length is measured with care again using an image intensifier to ascertain the correct length and orientation. The limb is elevated to get this fixation in. An assistant is required.

    A fully threaded screw is used, as compression of the medial column is to be avoided, otherwise there is a risk that the fracture is mal-reduced into varus.

    Intensifier view is again used to check that the fracture is well reduced. The screw is positioned down the length of the talus into the center of the head. Note there is no varus on this image.

    Closure: the deep layer is closed with interrupted sutures.

    And the skin is closed without tension with interrupted nylon skin sutures.

    Turning now to the ankle joint. On an AP Image intensifier view it is apparent that the talus reduction and hardware is satisfactory but the medial clear space is wide and the syndesmosis is open 1. No fibula fracture has been identified. This is therefore a soft tissue syndesmosis injury with my assumption that at the time of the talus dislocation laterally, the anterior inferior tibio-fibular (AITFL) and probably also the posterior inferior tibio-fibular ligaments have been torn.
    There are several options now including:
    open repair of these ligaments which I am reluctant to perform as this will involve reopening the closed traumatic wound and causing yet further damage to these vulnerable soft tissues and perhaps also to the blood supply laterally
    screw fixation of the syndesmosis with 4 cortical fully threaded screws
    endobutton (Tightrope by Arthrex) suture button technique for stabilisation.
    This latter option is selected as I prefer to allow some flexibility in the syndesmosis is what is already a severely compromised ankle articulation and is very likely to lead to a degree of stiffness in any event. for this reason I prefer in this situation not to use screw fixation.

    Operation – 2

    The syndesmosis is reduced with pressure from my thumb. The use of a large compression clamp is not recommended as in my opinion, this can cause over tightening of the syndesmosis and easy lead to malposition of the fibula in the transverse plane ie: positioning the fibula either anteriorly (most frequently) or posteriorly in the incisura.
    At the level of the syndesmosis a Tightrope guide wire is introduced. Care is taken to ensure that this is parallel with the joint line and that it is positioned along the intermalleolar axis. The tightrope should be positioned within the incisura ie: at the level of the inferior tibio-fibula joint and not above it as this can result in springing of the fibula at the level of its articulation with the talus distally. Image intensifier is used to check position and reduction of the medial clear space.
    In a less complex situation I usually use two Tightropes with a small lateral plate as per our paper (Storey P, Gadd R, Blundell CM and Davies MB. Complications of suture button ankle syndesmosis stabilisation with modifications of surgical technique; Foot and Ankle International 2012 Sep;33(9):717-21) but again for reasons of access and soft tissue preservation here I accept a single Tightrope

    The wire and subsequently the tightrope should lie along the intermalleolar axis to anatomically reduce the syndesmosis ie: to avoid transverse mal-reduction. This means that in the sagittal plane the guide (& tightrope) should be angled superiorly relative to the lateral face of the Fibula as is well demonstrated by this picture.

    The cannulated drill is passed over the wire using image intensifier to check clear passage and correct orientation.

    Image intensifier to ensure correct placement. Note the medial clear space is better reduced on the mortice view though until the tightrope itself is positioned and tightened the fibula-tibia overlap remains wide (it should be >4mm)

    The Tightrope is passed down the drill hole using the carrier needle whilst keeping a little tension on the fibre wire so that the endobutton is orientated along the access of the drill hole and does not snag whilst being passed.

    The tightrope is pulled tight making sure the medial endobutton is sitting on the bone first. This is done through a small medial incision. This incision is made just as the needle pentrates the skin on the medial side and scissors used to open this space and clear a small area of soft tissue prior to passage of the endobutton itself.

    The endobutton must not have soft tissue between it and the medial tibia or later the tightness will be lost and the fixation will fail. This technique is described in “Complications of suture button ankle stabilisation with modifications of surgical technique FAI 2012 Sep;33(9):717-21 Storey, Gadd, Blundell and Davies.” see evidence section.
    The medial clear space is well reduced. Looking at the syndesmosis on image intensifier we can see that there is now correct overlap of the tibia by the fibula on a mortice view. This obviates need to explore or repair the deltoid as it was felt that further exploration medially would further risk damage to the talus blood supply which includes the deep deltoid vessel.

    Carrier sutures are removed cutting one end of each of the white and blue sutures and pulling through, note that all firewire needs to be cut with scalpel blade rather than scissors.

    The skin wounds for the posterior screw and the Tightrope endobutton are closed with a single nylon suture each.
    The bars for the mono-lateral external fixator are reattached once again, checking with image intensifeir to ensure in AP and lateral images that the ankle and subtalar joints are perfectly aligned. The External fixator is maintained in situ for soft tissue management whilst the wound heals as the alternative of a plaster cast is suboptimal in my opinion – see post operative care.

    The surgical and traumatic wounds are dressed with paraffin gauze, dressing gauze, wool and crepe. We dress the External Fixator pin sites with Chlorhexadine soaked gauze squares.

    The dressed limb with external fixator in situ is now stable and these dressings are left untouched for 5 days pending a wound inspection. The patient is allowed home as soon as comfortable and safe with mobilisation non-weight bearing.

    Post Operative

    Analgesia
    Observation of neurovascular status
    Wound inspection at 5 days
    Mobilise non-weight bearing
    Thromboprophylaxis as risk assessed
    Removal of external fixator at 2 weeks providing traumatic and surgical wounds healing
    Begin Non-weight bearing range of motion exercises at 2 weeks in compliant case such as this under the guidance of physiotherapy
    Weight bearing however is delayed until at least 8 weeks with the expectant appearance of Hawkins sign on plain radiographs, which will indicate the absence of talar AVN and has been proven to be an accurate predictor of talar AVN though not a good predictor of ankle function see “The prognostic value of the Hawkins sign and diagnostic value of MRI after talar neck fractures, Chen H et al”.

    Recommended Reading

    Coltart WD. Aviator’s astragalus.
    J Bone Joint Surg. 1952;
    34B:545–66.
    This is a classic and historic paper in which a large series of ‘Aviator’s astragalus’ being in modern parlance fractures of the talus are reviewed.
    Hawkins LG. Fractures of the neck of the talus. J Bone Joint Surg.
    1970; 52A:991–1002.
    This is the original paper in which Hawkins outlines his classification into three types for fractures of the talar neck

    Stephens MM and Kelly PM. Fourth Toe Flexion Sign: A New Clinical Sign for Identification of the Superficial Peroneal Nerve. Foot and Ankle Int 2000; 21(10), 860
    The authors concisely describe the sign in awake volunteers and they inject the superficial branch of the nerve with local anaesthetic to confirm the sensory distribution. A very useful clinical sign.
    Canale ST, Kelly FB. Fractures of
    the neck of talus. Long-term evaluation of seventy-one cases. J Bone Joint Surg. 1978;
    60A:143–56.
    In this review of a cohort of cases Canale adds the type 4 fractures to Hawkins original classification. The rates of avascular necrosis are also stated here. Treatment by way of fusions for AVN are recommended but removal of the avascular talus gives poor outcomes functionally.
    Vallier HA, Nork SE, Barei DP, et al. Talar neck fractures: results and outcomes. J Bone Joint Surg.
    2004; 86A:1616–24.
    A modern review of 102 fractures reviews the rates and risks of AVN of the talus.
    Storey P, Gadd R, Blundell CM and Davies MB. Complications of suture button ankle syndesmosis stabilisation with modifications of surgical technique; Foot and Ankle International 2012 Sep;33(9):717-21
    A review of 102 cases from the authors unit discusses complications in ankle fractures including hardware issues and some tips with experience on how to avoid them.

    Chen H, Liu W, Deng L and Song W. The prognostic value of the hawkins sign and diagnostic value of MRI after talar neck fractures. Foot and Ankle Int; 2014 Dec;35(12):1255-61
    A comparison study in which cases where Hawkins sign was absent subsequently underwent MRI. The authors demonstrate that Hawkins sign and MRI have good agreement when Hawkins is positive. The Hawkins sign was a reliable predictor excluding the possibility of AVN. It did not have predictive value on the ankle function in low-energy fractures and may predict better ankle function in high-energy fractures.

    Chen H, Liu W, Deng L and Song W. The prognostic value of the hawkins sign and diagnostic value of MRI after talar neck fractures. Foot and Ankle Int; 2014 Dec;35(12):1255-61
    A comparison study in which cases where Hawkins sign was absent subsequently underwent MRI. The authors demonstrate that Hawkins sign and MRI have good agreement when Hawkins is positive. The Hawkins sign was a reliable predictor excluding the possibility of AVN. It did not have predictive value on the ankle function in low-energy fractures and may predict better ankle function in high-energy fractures.

    Reference

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