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Ankle fracture – Fibula pro-tibia fixation technique with Stryker Variax plate

    Overview

    Professional Guidelines Included
    Learn the Ankle fracture : Fibula pro-tibia fixation technique with Stryker Variax plate 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 : Fibula pro-tibia fixation technique with Stryker Variax plate surgical procedure.
    The management of unstable ankle fractures in the elderly is both controversial and evolving. The importance of early ambulation in this patient group, for the same reasons as in a hip fracture patient, is being increasingly recognised.
    Fracture-dislocations in osteoporotic bone are increasingly common with an ageing population and in order to allow early ambulation fixation techniques need to be employed which provide a higher degree of stability than is required in a younger patient cohort.
    With a fibula fracture the traditional technique of fixation with a 1/3 tubular plate may not allow an adequate hold on soft bone, in particular if early mobilisation is going to be aimed for. The tibia however provides an excellent “internal strut” to bolster the fibulas’ stability and the use of screws which pass from the fibula and into the tibia has been termed “fibula pro-tibia fixation”. It was originally described for fixation in the context of tibial non-unions by DeOrio and Ware (Foot Ankle Int: March 24(3) 2003. Salvage technique for treatment of peri-plafond tibial fractures: the modified fibula-pro-tibia procedure). Its use in management of the acute ankle fracture has yet to be formally published in the Orthopaedic literature, though is a technique that we have found of significant merit at the Northern General Hospital in Sheffield.

    Indications

    INDICATIONS
    In elderly patients or those with poor bone quality stabilisation of the lateral side with a traditional plate and screw construct may provide inadequate fixation. Experience has shown that rehabilitating patients in this group with early weight bearing is beneficial to outcome. Strong fixation is necessary to permit this.
    This fixation will reduce the motion between the fibula and the tibia which normally permits external rotation of the fibula with ankle joint dorsiflexion which will in turn restrict ankle joint dorsiflexion in the same way as it will for screw fixation of ankle joint diastasis injuries. The number of screws used here and the lower level of patient demand means that the screws do not break. We have not seen this failure in more than 65 cases fixed this way. However it must be accepted that there will be reduction in ankle joint dorsiflexion in the long term. Generally this is not recognised as a problem in this cohort of patients but it is wise to warn patients that the ankle will be stiffer in dorsiflexion permanently after this injury and fixation. Alternative methods of fixation are discussed below.
    SYMPTOMS & EXAMINATION
    Patients have a history of osteoporosis and usually have a low energy injury such as this case where the patient simply missed a few steps. Presentation is with a swollen and often dislocated ankle. Open injuries in this group are not uncommon often with a curved medial open wound which may be hemi-circumferential. These need urgent stabilisation and usually in my unit we stage surgical management with the initial application of a mono-lateral external fixator and after skin cover is achieved definitive fixation.
    IMAGING
    Plain radiographs, AP and Lateral, are a basic requirement but in more complex situations we use CT scans. These may be carried out after temporary stabilisation with an external fixator, whilst repeating the well rehearsed mantra of “SPAN-SCAN-PLAN”.
    ALTERNATIVE OPERATIVE TREATMENT
    The main alternative used once bone fragility is recognised is the use of an Intra-medullary hindfoot fusion nail. However this method sacrifices both the ankle the subtalar joint and because of this requires removal of hardware in the more ambulant patient in whom either the nail or fixation will break or the joints become painful. A recent presentation at BOFAS Congress (Edinburgh Annual Congress November 2018) from our institution where over a 5 year period we have recorded 65 cases managed with this technique and compared 27 of these that were matched to 27 hindfoot nailings in a similarly co-morbid group of patients. This highlighted the increased complication rate in those who had received an intra-medullary nail compared to Fibula Pro-Tibia fixation.
    NON-OPERATIVE MANAGEMENT
    Prolonged cast usage with the requirement for non-weight bearing in unstable fractures results in a high complication rate due to immobility. A study from Oxford (Close Contact Casting vs Surgery for Initial Treatment of Unstable Ankle Fractures in Older Adults: A Randomized Clinical Trial. JAMA, 2016 Oct 11;316(14):1455-1463, Willet K, et al) regarding the use of close contact casting suggested that this was a successful treatment in the elderly with displaced fractures but the idea has not gained traction widely and is not employed at our institution.
    CONTRAINDICATIONS
    Those who remain unfit for surgery or refuse this treatment will require cast treatment. Instances of active pulmonary infective disease or unstable cardiac disease (either of which may in fact be the cause of the fall and fracture exactly as for fractured hips) may pose too much risk to justify operative intervention. We use fibula nails and as discussed intra-medullary nails if the lateral skin is too fragile for an incision.
    Intra-medullary fixation of the Fibula is a technique detailed elsewhere on OrthOracle https://www.orthoracle.com/library/lateral-malleolar-fixation-using-acumed-fibula-rod-system/

    Setup

    We use a laminar flow theatre environment for all fracture surgery. Ideally an assistant is available also. The patient is positioned supine, a thigh tourniquet is applied but increasingly we do not inflate this unless we encounter excessive bleeding intra-operatively.
    A sandbag is used to rotate the limb internally to gain good and clear access to the lateral ankle. A sterile bolster is handy too to elevate the limb and allow free passage of the drills and screws. The radiographers are notified before hand so the image intensifier is already in theatre and ready before the skin is prepared.

    Operation – 1

    This case is of an elderly lady who sustained a supination external rotation fracture (Type IV – ie with a posterior malleolus component also) when she fell down a few steps in her home. The fracture could also be considered as a Weber B oblique fibula fracture with an associated displaced transverse medial malleolar fracture and a posterior fracture, the so called classical “Trimalleolar Fracture”.

    The fracture was displaced at presentation and early reduction was achieved in the emergency department under sedation and with the application of a Plaster of Paris backslab.

    In Sheffield we carry out CT scans in situations where there has been a dislocation with involvement of the posterior malleolus in order to ascertain clearly the magnitude and extent of the posterior fracture. This also follows BOAST (British Orthopaedic Association Standards for Trauma) guidelines which recommend CT scans in more complex ankle fractures (https://www.boa.ac.uk/wp-content/uploads/2016/09/BOAST-12-Ankle-Fractures.pdf).
    In this case the posterior fracture was a Haraguchi Type 3 with a thin shell of fracture posteriorly which we decided to treat this element indirectly by stabilising the fibula and medial fracture.

    The initial incision is marked out in line with the fibula and anteriorly curved a little distally to avoid branches of the sural nerve. The incision will need to be at least 10cms proximal to the fracture to allow an adequate plate and a tension free exposure.

    Skin and fat are incised and usually subcutaneous bruising is well seen. I do not put self retaining retractors at the skin edges which are often vulnerable to pressure injury. Fine tooth (Addisons’) forceps are employed to avoid crushing the skin edges.

    Deep to the fat a window of injury is often seen where the fibula has ripped the soft tissues open. I utilise this area to gain exposure of the fracture as the injury has already done this dissection for you and we do not want to create a “second hit” to this area. The “window” is extended distally and proximally with minimal or no periosteal stripping required. This technique is commonly applied for foot and ankle fractures where soft tissue cover is scarce.

    Now self retaining retractors can be deployed but making sure that, 1: that the blades are deep to the skin edges and 2: that they are not under great tension – the minimum that is needed to see what you are doing.
    The fracture is now adequately exposed.

    Using Rongeurs, the fracture site is cleared of any bone debris and organised haematoma, which might hamper anatomic reduction of the fracture.

    I find a small curette a great tool for cleaning the fracture ends and ensuring there is no infolded periosteum which will delay healing. One can see that I am rotating the foot out to open up the fracture site so that I can see clearly the bone ends.

    Next Tenaculum forceps are used to reduce the fracture. The supinated foot is rotated internally (ie in the opposite direction to our pronation external rotation force), to reduce the fracture. Tenaculum forceps damage the periosteum less than Crocodile tooth forceps but if the bone is so soft that the pointed ends just go through the bone then these may be needed.
    An independent lag screw could easily be employed here and in stronger bone I would use this, however in this case (as is usual with fibula pro-tibia cases) the bone is so soft that inter-fragmentary compression is not realistic with a screw.

    An image intensifier view is used to check anatomic reduction – seen here with a well reduced ankle joint mortice (A)

    In order to select the appropriate length of Stryker VariAx Locking plate a disposable ruler is used to measure the plate length. The plates are separately packed sterile and clearly labelled both by number of holes but also by plate length in millimetres. In this case a plate close to 100mm is selected. The 5 hole lateral locking plate is 101mm in length.
    The Stryker VariAx lateral fibula locking plate has a nice contour to it, the distal spoon shape fits the fibula metaphysis well and it has multiple clustered locking options. Screws are 3.5mm diameter and are either locking or non-locking. There is a 15 degree variable angle allowed by the locking guide and hole geometry in any direction – this is therefore a 30 degree arc of locking from side to side.

    This plate is termed a “5 hole plate” as the distal 5 holes are in fact common to all the plates (Lengths vary from 3 hole which is 77mm long to 12 hole at 185mm long). It is this slightly confusing hole terminology which makes me prefer to select on the basis of the plate length.

    The plate is bent to take out the precontoured shape, as I wish to ensure this plate butresses the fibula toward the mortice.

    The plate is applied and if not well held then wire holding pins can be used.

    The drill guide with Yellow marks is the correct one for the 3.5 mm screws. It has a fluted end which snaps into the plate and allows a 30 degree total arc of variable angle drilling. The drill selected also has a yellow colour code and is 2.6mm in diameter.

    Screw depth is checked with the depth gauge and care taken that these screws are unicortical distally to avoid damage to the ankle joint. The image intensifier can be used as an additional check, as sometimes the bone is so soft it is hard to be sure that the medial cortex has not been breached.

    An appropriate length 3.5mm locking screw is selected. These are also sterile packed.

    I prefer to put the distal and very proximal screws in first for two reasons. The first is that this keeps the bone out to length and maintains the reduction as I proceed with the other screws. The second is that this way I know that the plate is lying centrally on the bone all the way along. This is especially important to define before fixation through the plate has commenced. It is key that the long, transfixing screws sit both in the plate and also have good purchase upon the tibia. This is not aided by inappropriate seating of the plate.

    All distal locking points are required in this osteoporotic bone .

    Now we begin to use the tibia to provide additional fixation. The number of these long screws required, which are akin to a diastasis screw, is determined by the quality of the bone. I tend to use 3 or more.
    The drill must be positioned transversely in alignment with the inter-malleolar axis so that these screws do not “skirt off ” the back of the tibia. The drilling hand is therefore dropped a little posteriorly whist making these holes. A sterile bolster, to raise the ankle above the operating level, is often helpful to give space for this manoeuvre.

    This image shows the first screw well positioned. I like to use the longest screw that I can but don’t want them to be palpable medially. This would risk injury to the tibial nerve posteriorly and the saphenous nerve anteriorly.

    Three screws are used. The distal two are orientated a little more posteriorly hence they look “short” on the AP image here but are in fact in the medial cortex of the tibia. This provides a very strong construct.

    Closure is tension free with vicryl absorbable sutures deep and monocryl absorbable interupted sutures to skin.

    I prefer interrupted skin closure as I feel that this allows any haematoma that may form to leak onto dressings rather than form a potential clot and source of sepsis or wound breakdown. This is just my personal preferenec in foot and ankle trauma practice.

    Operation – 2

    Attention is turned to the medial side. The fracture site is palpable and is the centre of my skin incision.

    A short (5cm) straight or hockey stick incision is used after marking the skin. A small anterior abrasion from the fall is seen here (A).

    A direct incision is straight down to the fracture site and the talus can be clearly seen here once the fracture site is opened. Again fracture ends are curetted to ensure debris and especially the periosteum is not in the fracture site, as on the medial side it so often is.

    I reduce the fracture with a small dental hook and use a wire from the Asnis III cannulated 4mm screw set to complete and hold the reduction. Often the reduction is guided by the contour of the articular surface that can be either felt or inspected directly anteriorly by elevating the soft tissues a little more anteriorly. The image intensifier is useful of course to guide this reduction too.
    This fragment is too small for a pair of cannulated parallel screws (which is my preferred technique) so here only one screw is used. The 1.4mm guide wire tip is treaded so it doesn’t tend to come out after drilling. The guide wire is aimed posteriorly and laterally but care taken to ensure the joint is avoided. Subsequently only the displaced fragment needs drilling and not the whole screw site(due to the softness of the bone). A 2.7mm diameter drill is used. A 5mm screw can be used if the fragment will take it. The Stryker Asnis III screws have a well contoured head which avoids screw head prominence.

    This image shows correct wire orientation and fracture reduction.

    An extraction measure gives appropriate screw length. I aim to guide the screw to the posterior cortex of the tibia as the metaphyseal medulla is often very osteoporotic.

    Whilst placing the screw rotation of the fragment is prevented by holding it with the dental hook. A washer has been used here to help hold the fragment and gain some compression if possible.

    The fracture is reduced and stable on the AP image intensifier views.

    Likewise the fracture is reduced and stable on the lateral image intensifier views. The tangential aim of the long pro-tibia screws can be well appreciated on this true lateral image.
    In the elderly oetoporotic fracture this technique generally reduces the posterior fracture as can be seen here and the ProTibia screws provide excellent stability. However the loss of rotation between the fibula and tibia will restrict dorsiflexion in the long term. In the higher demand patient with stronger bone and where this functional loss will be more noticeable then preservation of motion will be more achievable and in these circumstances I will carry out fixation of the posterior malleolus separately with a postero-lateral approach as has been documented on OrthOracle by my colleague Mark Davies also from Sheffield.
    https://www.orthoracle.com/library/postero-lateral-fixation-pronation-external-rotation-ankle-fracture/

    The medial wound is closed in the same manner as the lateral wound, with vicryl sutures deep and interrupted monocryl sutures for skin.

    Wounds are dressed with paraffin soaked gauze. This is non adherent and bacteriostatic. The abrasion is similarly dressed.

    A well padded plaster back slab and ‘U’ splint is applied with the ankle in a neutral position.

    Standing view X-rays are required at the 12 week stage.

    Post Operative

    The patient has had surgery to facilitate mobility. With this in mind the cast is changed at 48 hours to a weight bearing synthetic cast. Weight bearing is pragmatic. I advise that the limb is elevated to hip height as much as possible for the first 2 weeks to assist the wounds in healing well and to minimise swelling. Allowing the patient to weight bear to mobilise will allow her to get out of institutional care and home as soon as possible.
    Thromboprophylaxis is as per department guidelines after risk assessment – in this ladys’ case 2 weeks of Rivaroxaban were used (an oral clotting Factor Xa inhibitor).
    The wound is inspected in outpatients at 2 weeks and a new weight bearing cast applied for a further 4 weeks.
    The cast is removed and a walker boot applied at 6 weeks (usually radiographs are taken at this point often to reassure the patient that all is well) and the patient then advised to use the boot only as pain and swelling dictate.
    Free mobilisation is encouraged and the patient discharged if we have satisfactory images at 12 weeks (an AP standing Xray at 12 weeks is shown here).
    This fixation has by definition reduced the motion between the fibula and the tibia which normally permits external rotation of the fibula with ankle joint dorsiflexion. This reduction of this motion will in turn reduce ankle joint dorsiflexion in the same way it will with screw fixation of ankle joint diastasis injuries. The number of screws used here coupled with the lower level of demand means that these screws tend not to break. We have not seen screw breakage yet in more than 65 cases fixed this way. However it must be accepted that there will be reduction in ankle joint dorsiflexion in the long term. Generally this is not recognised as a problem in this cohort of patients but it is wise to warn patients that the ankle will be stiffer in dorsiflexion permanently after this injury and fixation.

    Recommended Reading

    Musculoskeletal Imaging Free Access, Simplified Diagnostic Algorithm for Lauge-Hansen Classification of Ankle Injuries, H Okanobo, B Khurana, S Sheehan and S Ledbetter. Online publication Mar 5 2012https://doi.org/10.1148/rg.322115017
    The original Lauge Hansen classification was published in 1950 and is still available to read. It was based on cadaver experiments. This article however is easy to read and understand. It is aimed at radiologists. The online version also includes videos to help understand this important classification system.
    BOAST 12. BOA Standards for Trauma – Guidelines for the management of ankle fractures
    This British Orthopaedic Association publication from August 2016 sets the standards for care and imaging for ankle fractures and is both useful as an audit tool but also to encourage all to best practice.
    Pathoanatomy of posterior malleolar fractures of the ankle. J Bone Joint Surgery Am. 2006 May;88(5): 1085-92. Haraguchi N, Haruvama H, Toga H and Kato F.
    The seminal reference for posterior malleolus fractures. This study gave a greater understanding of the shape and incidence of these fractures in 57 consecutive cases. The recommendation that CT scanning was recommended has taken a long time to seep into the orthopaedic trauma mindset however.

    Reference

    • orthoracle.com

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