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Calcaneal fracture fixation – Internal fixation of sustentaculum tali fracture (Acutrak screws)

    Overview

    Learn the Calcaneal fracture fixation : Internal fixation of sustentaculum tali fracture (Acutrak screws) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Calcaneal fracture fixation : Internal fixation of sustentaculum tali fracture (Acutrak screws) surgical procedure.
    When describing intra-articular calcaneal fractures where the primary fracture lines involve the posterior facet, the sustentaculum tali is often quoted as the “constant” fragment. This is because, although the sustentaculum tali often detaches from the body of the calcaneus, it seldom displaces due to its strong ligamentous attachment to the medial malleolus (via the deltoid ligament), the navicular (via the spring ligament) and the talus (medial talocalcaneal ligament). In reconstructing these injuries, fixation focuses on re-attaching the body of the calcaneus onto this stable, constant fragment of the sustentaculum tali.
    Considering the range of calcaneal fractures, displaced, isolated fractures of the sustentaculum tali are very rare. Although not obviously intra-articular fractures, they can be regarded as such because the middle facet of the subtalar joint is always effected in the injury and also, in some individuals, there is a confluence between the middle and anterior facets of the subtalar joint.
    The other significant anatomic structure that can be effected by a fractured sustentaculum tali is the tendon of flexor hallucis longus. Acutely, the tendon can become interposed between the fracture fragments. This can prevent fracture union and can lead to a chronically painful tenosynovitis. It is also thought that the FHL tendon is at risk of rupture if it frets against the callus from the healing fracture line, particularly if the fracture is managed non-operatively. Other complications following fractures of the sustentaculum tali include non-union and chronic tarsal tunnel syndrome.
    In this case, a middle aged male, wearing fully protective clothing and footwear, was involved in a road traffic accident, sliding his motorcycle at speed. At the moment of collision, the forces were probably transmitted through the “peg” of the motorbike pedal and into his right midfoot. There were no other injuries sustained. The surgery for fixation is recorded 12 days post-injury.

    Indications

    Indications
    Acute fracture-subluxation of the sustentaculum tali. The pathoanatomy of the injury can only be fully established by CT scanning.
    Demographics
    The classic patient is a male with a mean age of 32 years. Invariably sustentaculum tali fractures occur as a result of high energy trauma usually from road traffic accidents or falls from a height.
    Symptoms & Examination
    Acute pain and swelling in the medial aspect of the hindfoot are cardinal features. The patient struggles to bear body weight through the effected limb. A significant proportion of sustentaculum tali fractures (20%) will have contralateral foot injuries and/or injuries to the upper limbs or axial skeleton. On the ipsilateral foot, fracturing of the head and neck of the talus, navicular and cuboid frequently occur and should be looked for.
    Examination often reveals swelling, but acutely may demonstrate deformity associated with subluxation of neighbouring joints. Careful examination of the soft tissue envelope is mandatory and expeditious management of any open injuries undertaken. The neurovascular supply of the foot needs assessment, and the . The classic D-shaped ecchymosis associated with calcaneal fractures in patients presenting a few days post injury (see later photographs).
    Investigation
    Plain radiographs are helpful in assessing the foot especially with the presence of deformity but are usually unhelpful in diagnosing an isolated fracture of the sustentaculum tali, unless a high quality axial view of the calcaneus is obtained (see operative section). In my opinion, all high energy trauma involving the foot warrants urgent CT assessment.
    Operative alternatives
    There are no alternative operative procedures other than internal fixation.
    Anecdotally, some simple fracture patterns or those with minimal displacement, can be managed by careful percutaneous application of a partially-threaded lag screw from the lateral aspect of the calcaneus. This is best achieved by placing the patient in a full lateral position (injured side up) on the operating table. However, managing these fractures in this manner is the exception rather than the rule. In my experience, deciding whether to adopt this approach is governed by the appearances on the CT scan. It is important to have sufficient bone stock in the sustentacular fragment to accommodate the whole thread length of a partially-threaded cannulated screw.
    Non-operative intervention
    Treatment with cast or walker boot immobilisation can be considered in lower demand or medically-unfit patients or those with minimally displaced fractures. There is the concern of late FHL rupture with attrition of the tendon against fracture callus. There is no literature that discusses the outcomes of managing cases in this manner.
    Contraindications
    In very comminuted fractures, reconstruction may not be possible.

    Setup

    The patient is positioned supine on the operating table and may benefit from a sandbag placed under the contralateral buttock so that the foot is as flat to the operating table as possible (see operative photographs). This allows optimal access for a medial approach to the hindfoot. In addition, the leg must be manoeuvrable to permit fluoroscopic evaluation. Fluoroscopy should be available with an image intensifier and a trained radiographer.
    Appropriate antibiotics are administered and a thigh tourniquet and exclusion drape are applied. The limb is prepared with Chlorhexidine from toes to tourniquet.

    Operation

    Pre-operative imaging and planning
    Coronal CT scan showing the fracture of the sustentaculum tali(1). There is a small degree of comminution but note the dislocated middle facet.

    On the sagittal CT sections, it is clear that the inferior articular surface of the talus has no reciprocal articulating surface with the sustentaculum tali because the fracture is displaced.

    An additional fracture line is seen in the medial aspect of the head of the talus but the fracture fragments are minimally displaced. Pre-operatively I decided that there was no benefit in fixing the fracture within the head of the talus as it was small and minimally displaced.

    Positioning the patient on the table allowing for a medial hind foot approachThe operated limb is placed into an appropriate degree of external rotation.
    Positioning of the patient on the operating table to allow a medial approach to the hindfoot. Note that the sandbag under the contralateral buttock has achieved this positioning on the table.

    Note the characteristic D-shaped ecchymosis on the plantar aspect of the sole of the midfoot. This is often seen in calcaneal fractures and it represents haemorrhage into the central compartment of the foot adjacent to the calcaneal tuberosity. This central compartment lies deep to the plantar aponeurosis and, moving from superficial to deep, contains the muscle belly of flexor digitorum brevis in the first layer, the bellies of quadratus plantae and the lumbricals as well as the tendons of flexor digitorum longus in the second layer, the adductor hallucis muscle belly in the third layer and in the deepest layer, the plantar interossei.

    Assessing the limb for previous surgical scars that govern surgical approach.
    With an existing medial surgical scar following previous trauma, I was concerned that this would compromise the planned surgical approach.

    The skin is marked from the tip of the medial malleolus to the navicular tubercleThankfully, the scar was ideally positioned and extended from the tip of the medial malleolus [A] and extended distally inferior to the navicular tubercle [B]. This approach would be exactly the same approach required to excise a medial talo-calcaneal coalition and if extended proximally, would be suitable to fix a fractured medial malleolus.

    The skin and subcutaneous fat are incisedThe skin is incised and staying in line with the skin incision, the subcutaneous fat is incised.

    Once the subcutaneous fat is reflected, the sheath and tendon of tibialis posterior are revealed Once the subcutaneous fat is reflected, the sheath and tendon of tibialis posterior are revealed [A].

    By incising the fascia immediately inferior to the tibialis posterior tendon, the tendon of the flexor digitorum longus is easily identified By incising the fascia immediately inferior to the tibialis posterior tendon, the tendon of the flexor digitorum longus is easily identified [A].
    It is important to mobilise both of these tendons to allow access and manipulate the sustentaculum tali fragment which lies deep to them. Of course, with a displaced fracture fragment, the normal anatomy is disorganised and knowledge of where to look for the fragment is paramount.

    The tendon of tibialis posterior is mobilised inferiorly with Langenbeck retractors revealing the displaced sustentaculum tali fragment.Usually by reflecting the tendon of tibialis posterior inferiorly with Langenbeck retractors, the displaced sustentaculum tali fragment becomes visible as is the case here. It is clear from this photograph, that the articular surface of the middle facet is malorientated and facing the surgeon [A]. Note the lack of fracture haematoma given the length of time post-injury.

    The axial calcaneal view, clearly demonstrating discontinuity of the medial wall (A).

    This ball and spike tool is very useful for reducing fracture fragments with your non-dominant hand whilst applying a temporary K-wire across the fracture fragments in your other hand.
    My tip is to use one with a broad handle as some of the narrower all-metal tools are uncomfortable in the heel of your hand!.

    The sustentaculum tali fragment is mobilised, removing debris such as fracture haematoma and small comminuted fragments. Temporary K-wire stabilisation.The sustentaculum tali fragment is mobilised, removing debris such as fracture haematoma and small comminuted fragments.
    The sustentaculum tali fragment is then manipulated with the ball and spike tool so that the joint of the middle facet is reduced [A]. This is a straightforward manoeuvre. Essentially, you know when the fracture is reduced when you can see that the middle facet becomes congruent. This remains a truism even in the presence of comminution. This is confirmed on fluoroscopy. Once reduced, the fragment is temporarily held with a K-wire. In this instance, the reduction wire is the definitive 1.4mm guide wire for the Acumed Acutrak 2 headless compression screw.
    The orientation of the K-wire is difficult to photograph but, given that you can see where the middle facet lies, the wire should not violate this joint and should engage the lateral calcaneus in the bone forming the inferior boundary of the sinus tarsi. This can be checked with fluoroscopy. Equally, it is important that the wire does not travel inferior to the sustentaculum tali because this could transfix the flexor hallucis longus tendon.

    Fluoroscopic assessment of the fracture reduction includes an axial view of the calcaneus.The key fluoroscopic views needed to guide fixation are a true lateral of the hindfoot together with an axial view of the calcaneus. This latter view is achieved by orientating the foot vertically and the toes held to make the ankle as plantigrade as possible. By dorsiflexing the toes, this helps remove them from the image. The X-ray generator is under the operating table and aligned approximately at 45 degrees to the sole of the foot. The draped image detector should be as close to the foot as possible.

    Drilling and preparation for application of a cannulated screwThis sustentaculum tali fragment has enough room to cater for two fixation screws. A second 1.4mm guide wire was placed across the fracture. This helps to prevent any rotation of the fracture fragment generated by the torque from over-drilling the wires and from screw placement.
    The wires can be measured with the depth gauge, but given that the longest Acutrak 2 Standard screw lengths are 34mm, these were selected. It is useful to pass the guide wires beyond the selected screw lengths to prevent the guide wires being removed by over-drilling.
    The Acutrak 2 Standard screws have a diameter of 4.0mm at the tip of the screw and 4.1mm at the “head” end of the headless screw.
    The initial drilling over the guide wire proceeds with the 3.1mm drill bit to the required depth.

    The profile for the headless end of the screw is then drilled with the 4.1mm profile drill bit. This is sunk to the clearly demarcated junction between the drill bit and shaft.

    This image shows the Acutrak 2 Standard screw seated in its screwdriver and the clear but subtle taper. It is important to drill and pass one screw at a time in order to maintain stability of the fracture fragments.

    This clearly shows the 2 screws in situ together with the tendons of tibialis posterior [A] and flexor digitorum longus [B]. The articular surface of the middle facet appears congruent.

    Final imaging of the fixationLateral fluoroscopic image demonstrating the screw positioning of the reduced fracture of the sustentaculum tali.

    This is the axial image obtained. It demonstrates the reduction of the fracture by showing the clear normal curve of the medial wall of the calcaneus. It also shows the positioning of the screws and that they lie extra-articularly.

    Test for stability of the fracture fixation with subtalar motion.I like to test the integrity of my fracture fixation. Here I am demonstrating inverting the hindfoot at the subtalar joint. I can feel for and visualise any compromise of my fixation. I do this by viewing the subtalar motion and palpating the fragment during this motion. In fragile bone, I may be less rigorous in testing my fixation, although I may consider using a locked plate as an alternative method of fixation.

    Here I am demonstrating everting the hindfoot at the subtalar joint.

    Skin closureSubcutaneous fat is closed with 2/0 vicryl and skin with 3/0 monocryl. The wound is dressed and plaster of Paris slabs are applied to immobilise the wound.

    Post Operative

    The patient is placed in a below the knee back slab for the first two weeks after surgery. At two weeks, the wounds are inspected. At this stage, I am keen to mobilise a stable intra-articular fracture, so a removable lightweight, focussed-rigidity cast is applied. This allows the physiotherapists to demonstrate ankle and subtalar range-of-motion exercises. Weight bearing is not permitted for the first six weeks after surgery and in my practice, rivaroxaban is prescribed for this duration to prevent thrombo-embolic events.
    At six weeks, the patient can commence weight bearing in a walker boot which can be removed for sleeping. Ankle and subtalar range-of-motion exercises are encouraged.
    At twelve weeks, the foot is assessed radiographically with radiographic views in both lateral and axial planes before abandoning further immobilisation. At this stage, the patient can be discharged to the further care of the physiotherapy team.

    Recommended Reading

    Fractures of the sustentaculum tali: Injury characteristics and surgical technique for reduction. GJ Della Rocca, SE Nork, DP Barei, LA Taitsman, SK Benirschke. Foot Ankle Int 30(11): 1037-1041; 2009.
    This retrospective case series of the management of 19 fractures remains the gold standard paper representing a world expert’s opinion and describes the characteristics and surgical treatment of this injury. It does not comment on the outcome of the injury.
    Treatment for displaced sustentaculum tali fractures. ME Al-Ashab, AS Elgazzar. The Foot 35:70-74; 2018.
    This retrospective series of 10 fractures recorded good functional outcome scores in isolated fractures of the sustentaculum tali. However, these scores were significantly reduced in fractures associated with other ipsilateral foot and ankle fractures.
    Technical tip: Percutaneous fixation of sustentacular fractures of the calcaneus. SJ Lawrence, LE Loutzenhiser. Foot Ankle Int 28(4): 524-5; 2007.
    This short paper elegantly describes the percutaneous method of fixing these fractures from a lateral approach but acknowledges that in order to do so, the fracture should not be comminuted. Equally, there should be sufficient bone stock to accommodate all of the threads of a partially-threaded cannulated screw.

    Reference

    • orthoracle.com

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