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Tibialis anterior transfer in Talipes Equinovarus

    Overview

    Learn the Tibialis anterior transfer in Talipes Equinovarus surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Tibialis anterior transfer in Talipes Equinovarus surgical procedure.
    Relative overactivity of the hindfoot invertors (tibialis anterior and posterior) compared to the evertors (peroneus longus and brevis) is common in congenital talipes equinovarus (Clubfoot ) as well as in neuromuscular conditions such as spina bifida and cerebral palsy.
    In the ambulant child this results in supination deformity which over time this can become rigid, with calluses and pressure areas over the lateral border of the foot as the hind foot drifts into varus.
    Tendon transfer is a useful intervention, providing the foot retains a good passive range of movement with dorsiflexion and eversion at least past neutral. Transfer of tibialis anterior from its anatomical insertion to the 1st metatarsal and medial cuneiform into the lateral cuneiform is a well recognised and reliable procedure to correct a flexible supination deformity. It is rarely indicted before age 2.5 years and furthermore the ossification centre of the lateral cuneiform should have appeared before surgery is considered. There is no upper age limit providing the foot remains supple although most surgeries for CTEV take place between 3 and 5 years.
    The technique described here involves passing sutures through the sole of the foot and securing them over a button that is later removed. Authors have described securing the suture to the plantar fascia and in older children bone anchors or bio-absorbable interference screws are suitable alternatives.
    Surgery is performed as a daycare or overnight stay. Cast immobilisation is required for 6 weeks during which time there should be restricted weight bearing.
    Results are reliable providing the indictions are adhered to. In CTEV tibialis anterior usually has grade 5 power. This is a phasic transfer, which means the muscle is still acting to produce dorsiflexion in swing phase. Given this power is retained and function improved in more than 90% of cases. In neurological conditions outcome may be poorer since muscle power may be sub optimal already. It is rarely advisable to use a tibialis anterior transfer as a static stabiliser. If muscle power is less than MRC grade 4 it is generally preferable to use an orthotic (AFO) or (if functional) tibialis posterior transfer to the dorsum of the foot.
    Readers will also find the following OrthOracle surgical techniques of interest:
    Posteromedial release for clubfoot in Spina Bifida
    Tibialis posterior transfer (through interosseous membrane )for foot drop
    Tibialis posterior transfer (for foot drop)
    Gastrocnemius recession
    Achilles tendon lengthening: open

    Indications

    INDICATIONS
    The most frequent indication for total transfer of tibialis anterior to the lateral cuneiform is weakness and correctible deformity post Ponseti treatment of congenital talipes equinovarus (CTEV). In CTEV the invertors, tibialis posterior and tibialis anterior, are frequently more powerful than the evertors. This results in supination of the forefoot. In more severe cases patients will have a tendency to walk on the lateral border of the foot. The skin under the lateral rays is thickened and the bones become hypertrophied over a number of years. The hind foot will eventually follow into varus.
    Recurrence of deformity post Ponseti is usually due to lack of compliance with abduction bracing (boots and bar) which is typically utilised at night time up to age 4 years. Morcuende (2006) showed that relapse occured in 88% of feet where children were non compliant with bracing compared to 1% when boots and bar were utilised.
    The principles of tendon transfer dictate that the joints across which the tendons move must be mobile. If the foot is stiff (frequently the case following open release of CTEV) tendon transfer will not work.
    Either a split or total transfer of tibialis anterior is also indicated in neurological feet. This may be as part of the Equinovarus deformity scenario (syndromic clubfoot) or as an isolated problem due to muscle imbalance.
    SYMPTOMS & EXAMINATION
    Young children usually do not complain of pain but supination of the forefoot will cause uneven shoewear. Parents often notice that the feet ‘turn inwards’ and that patients are clumsy and tend to trip easily. The clinician will note that the foot progression angle is often internal. The forefoot will often be in adduction and the heel in varus. The skin under the 1st MTPJ is often soft since relatively little weight has been put through it. Conversely, there may be calluses under 5th ray. In older children and adolescents the foot deformity is often more rigid and may become painful.
    Look at the position of the firs ray. This should not be plantar flexed. If it is this would suggest relative over activity of Tibialis posterior relative to Tibialis anterior. In such circumstances tibialis anterior should not be transferred.
    It is important to determine whether there is a full passive range of hind and mid foot movement. Check the range of subtalar inversion and eversion. In addition the ankle must dorsiflex past neutral.
    Check power and voluntary control in tibialis anterior. Any transferred muscle will inevitably loose some power (typically 1 MRC grade). Grade 4 MRC power is a prerequisite for transfer (active movement against gravity and resistance). Patients with neuromuscular conditions may have weakness and/or poor control.
    IMAGING
    Imaging is usually not necessary although AP and lateral radiographs can be helpful to determine whether there is ossification of the lateral cuneiform (which is necessary for tibialis anterior transfer).
    If there is doubt as to whether the ankle is truly dorsiflexing rather than spurious dorsiflexion due to mid foot break/rocker bottom foot, a lateral radiograph taken with the foot in maximum dorsiflexion can be helpful.
    ALTERNATIVE OPERATIVE TREATMENT
    If the foot does not dorsiflex past neutral and if the heel is in varus serial casting in younger children (less than 6 years) will often restore sufficient movement to allow tibialis anterior transfer. If despite casting there is insufficient dorsiflexion tendoachilles lengthening or gastrocnemius lengthening can be performed in conjunction with tendon transfer.
    Split transfer of tibialis anterior can also be used to rebalance the foot. This operation is more popular in neuromuscular feet, particularly cerebral palsy where muscle balancing is more unpredictable. The lateral limb of tibialis anterior is transferred either to the peroneus tertius, brevis or cuboid. The medial limb remains attached to the 1st metatarsal. This operation is technically more difficult than total transfer of tibialis anterior.
    NON-OPERATIVE MANAGEMENT
    Serial casting can improve range of movement prior to tendon transfer. In neuromuscular feet with muscle imbalance or weakness the foot can be controlled in an AFO (ankle foot orthosis).
    CONTRAINDICATIONS
    There is no role for transfer of a non functional muscle. Most tendon transfers will loose some power (often one MRC grade) when transferred. This is not usually an issue in CTEV where the relatively over powerful tibialis anterior is in part driving the deformity. However, it is important to determine power in the muscle in neuromuscular conditions such as spina bifida.
    Tendon transfer is contraindicated if the foot deformity is rigid. In these circumstances osteotomy of foot fusion is more reliable although such surgery may need to be deferred until the child is older (generally at least 8 years old).
    Morcuende J. Congenital idiopathic clubfoot: prevention of late deformity and disability by conservative treatment with the Ponseti technique. Pediatr Ann. 2006.

    Setup

    Surgery is performed under general anaesthesia.
    Patient is supine and tourniquet is utilised. A single dose of intravenous antibiotic (Flucloxacillin) is administered before the tourniquet is inflated.

    Operation – 1

    Patient is placed in supine position with tourniquet on thigh and a sandbag under the contralateral to allow access to the medial hind foot if necessary.
    This patient is 4 years old and has low level Spina Bifida. He has good power in tibialis anterior indicating that the L5 neurological level is intact.
    Notice the feet are in equinus with forefoot supination. He had previous Ponseti casting for CVTE as an infant followed by achilles tenotomy. He is independently mobile with MRC grade 4 quadriceps power.
    The patient is supine with thigh tourniquet.

    It is mandatory to have ankle dorsiflexion past neutral if the transferred tendon is to be sufficiently powerful to dorsiflex the foot. If the hind foot is tight, a period of serial casting may allow adequate dorsiflexion.
    Alternatively, formal hind foot release and/or Achilles tendon lengthening can be undertaken at the same time as the tibialis anterior tendon transfer.
    If access is required to the hind foot this is best achieved by placing a sandbag or large bag of fluid behind the opposite hip as shown here.

    A bloodless field is preferable. For younger children this is best achieved by using an Esmarch bandage.

    Make an incision in line with the tibialis anteroir tendon insertion insertion approximately 3cm long.Tibialis anterior tendon is the most medial of the extensor tendons. It descends to insert at the base of the first metatarsal and medial cuneiform.
    Mark an incision in line with the tendon insertion approximately 3cm long. Ensure that the distal extent of the incision reaches the medial aspect of the metatarsal base.
    Medial maleollus marked (M). It can be helpful to mark out the tibialis anterior tendon prior to surgery by getting the patient to actively dorsiflex the ankle.

    The skin and subcutaneous fat are incised with a size 15 scalpel. There may be one or two subcutaneous veins that require coagulation.
    The saphenous nerve may run in the subcutaneous tissues close to the insertion of tibialis anterior.
    The bursa over tibialis anterior is then identified.

    Both the tibialis anterior sheath and its bursa need to be opened with a size 15 blade or sharp tenotomy scissors.The tibialis anterior tendon runs within a sheath that extends down from the level of the inferior extensor retinaculum to the talonavicular joint.
    A synovial bursa then runs from the distal extent of the sheath to the insertion of the tendon.

    Place a mosquito clip or tenotomy scissors under the tendon.Tibialis anterior tendon is often made of 2 separate bundles. Place a mosquito clip or tenotomy scissors under both to ensure that the correct tendon has been isolated.
    If the surgeon is too lateral it is possible to pick up extensor hallucis longus by mistake.
    By pulling on the tendon its action can be confirmed visually.

    Release tendon from the bone using a sharp size 15 bladeTibialis anterior attaches to the base of the 1st metatarsal and the medial cuneiform. It “wraps” around the bone.
    Trace the tendon as far around the side of the bone as possible to achieve maximum length. The tendon will be felt and seen inserting into the bone. Release using a sharp size 15 blade. Avoid damage to the growth plate at the base of the 1st metatarsalby placing a mosquito forcep or tenotomy scissor between the tendon and the bone.
    Cut onto the mosquito to avoid damage to other structures.

    Pick up the end of the tendon with mosquito or small kocher clamp. It will be noted that there are several vinculae that attach to and tether the tendon to the tendon sheath.

    Release any tethers around the tendon once released and then insert a “whip stitch”The tendon is put under tension by applying force through the mosquito forcep that is holding the tip of the tendon.
    Small Langenbeck retractors are placed under the skin so that the tendon can be identified running up to the extensor retinaculum. The tendon sheath and bursa are split using scissors all the way up to the lower edge of the extensor retinaculum. Any adhesions/vinculae are divided to ensue that the tendon can glide and move freely.

    Hold the released tendon under tension using a pair of mosquito forceps. A whip stitch is inserted using 0 or 1 vicryl.

    To insert a whip stitch take approximately 5 passes, half the thickness of the tendon, distal to proximal. Then continue from proximal to distal taking passes through the opposite half of the tendon as shown.

    Once the whip stitch has been inserted and tightened the distal end of the tendon should be inspected and any loose tissue should be carefully trimmed.If the end of the tendon is too bulky it will not slide freely into its prepared tunnel in the cuneiform. Leave suture ends long to allow threading into straight needles.

    Insert a white hypodermic needle into approximate site of 3rd (lateral) cuneiform, and check position with Image intensifier.The next step is to prepare the insertion site for the transferred tendon.
    For a complete transfer this should be the lateral cuneiform. This lies at the base of the 3rd metatarsal. Insert a white hypodermic needle in the approximate position.

    An image intensifier ‘C’ arm is then draped and advanced to check the position.

    Identify 3rd cuneiform with image intensifier and check hypodermic needle placement.Ensure correct placement with image intensifier.
    The cuneiforms are mostly cartilaginous in young children. On average the ossific centre is 9mm diameter at 2 years and 11mm at 3 years. At 2 years age there may not be enough ossified bone to create a drill hole but by 3 years this is usually possible.

    Without removing the needle mark a 2-3cm longitudinal incision in line with the extensor tendons.Without removing the needle mark a 2-3cm longitudinal incision in line with the extensor tendons.

    After incising the skin the extensor tendons will be visible. The needle may need repositioning before retracting any tendon that has been transgressed.

    The tunnel in the cuneiform is prepared using hand held Paton Burrs, starting with the smallest of the 3 burrs, a 3.5 mm one.The aim is to create the tunnel in the bone. However, it is impossible to determine the joints between the mid tarsal joints. Inevitably there is a risk that the tunnel may pass into one of the joints. Whilst not ideal this does not appear to result in any long term pain nor functional deficit in this age group.

    Create a tunnel starting with the smallest 3.5mm burr. The whole depth of the cuneiform needs to be breached. This is safer done with a hand burr rather than a drill.
    The tip of the burr will be felt on the sole of the foot when it has passed through the full thickness of the bone. Patons burrs are unlikely to damage the soft tissues on the sole as opposed to peer instruments. Remember that this operation is generally performed in young children when the cuneiform is mostly cartilage. This is softer than bone and easier to pass the burr through.
    Direct the burr 5 degrees posteriorly and 20 degrees medially to avoid damage to neurovascular structures on the sole of the foot.

    It is very important to pass the burr all the way through the cuneiform bone otherwise the transferred tendon will not slide fully into the prepared tunnel.Increase the burr sizes sequentially in doing so from 3.5mm to 4.5mm to 5.0mm.Sometimes the diameter of the tunnel needs to be increased a little by pivoting the burr as it is passed through the bone. This will only become obvious once the surgeon has attempted to pass the tendon. If it is tight, retrieve it and increase the diameter of the tunnel before passing it again.

    Having created a bone tunnel in the lateral cuneiform a subcutaneous passage has to be developed to transfer the tendon from the medial side of the foot to the mid foot.It is crucial that the tendon is transferred superficial to the other extensor tendons.
    Bowstringing does not occur since the tendon is still beneath the extensor retinaculum at the ankle.
    Develop a spacious path across the foot by spreading scissors or a mosquito type clip in the subcutaneous tissues.

    Pass a tendon passer or mosquito from the lateral wound to the medial wound to retrieve to suture ends attached to the tibialis anterior tendon.

    It is crucial to ensure that the tendon passes easily from medial foot to lateral foot with no restriction. This will only be achieved by thoroughly freeing up the tissues and dividing any adhesions right up to the extensor retinaculum.
    Ensure that the tendon is running freely and in a straight line. A Langenback retractor is used to directly visualise the tendon and see that it is passing in a straight line with no ‘kinks’ or tethers.

    With the tendon in position dorsally thread both ends of the whip stitch suture onto straight needles

    Operation – 2

    Both needles should be passed simultaneously through the bone tunnel in the cuneiform, to exit in the sole of the footBoth needles should be passed simultaneously through the bone tunnel in the cuneiform. if they are passed one at a time there is a risk that the suture material of the first is penetrated by the second needle.

    The needles are passed through to exit in the sole of the foot. The needles should be approximately 5mm apart and roughly in the middle of the foot.
    The surgeon should be between the medial and lateral plantar nerves if the exit point is central.

    Pull the sutures through the foot and apply point-pressure dorsally to advance the tibialis anterior tendon into the tunnel prepared in the cuneiform.The tendon should glide easily into the tunnel without having to apply much pressure to the sutures.

    Observe the tendon itself slide into the tunnel.
    It is important to to ensure that it hasn’t become stuck in soft tissues and the ensure the tunnel is large enough to accommodate it.
    Generally it is possible to advance the tendon to the point that the whip stitch is entirely within the tunnel.
    The tunnel should allow the tendon to glide into it without impediment. ‘Snagging’ of the tendon within the tunnel will mean that the tendon is not under sufficient tension and may result in weak dorsiflexion.

    Sutures need to be tied over a button but this needs considerable padding to stop pressure necrosis.
    I find that a scrub brush sponge cut in half gives adequate thickness. On top of this is added a diathermy scratch pad. In the past we have used standard tailors buttons although formal ‘surgical’ buttons can now be purchased.

    An assistant forces the foot into maximal dorsiflexion and eversion and the sutures are tied over a plantar button that overlies protective foam paddingSutures are passed through the sponges, scratch pad and button using the straight needles. An assistant forces the foot into maximal dorsiflexion and eversion while the sutures are tensioned. This allows maximal tension in the transferred tendon.

    Significant force has to be applied to the sutures to maintain tension through the tendon. Observe how the sponges are compressed.
    The assistant maintains dorsiflexion until the sutures have been tied over the button, to avoid over-tightening the transfer.

    Check sufficient tension has been applied to the transfer so the foot will lie in a neutral position and the transferred tendon will feel taught under the skin and may even be visible (A).If there is insufficient tension the suture should be untied and tightened. Check that the tendon has advanced into the bone tunnel and is not stuck. If it is stuck back it out and increase the diameter with the burrs.

    Augment stability with suture through tendon and periosteum.For extra security a 0 vicryl suture is passed through the tendon and secured to the periosteum over the adjacent cuneiform.

    The tourniquet is released and haemostats secured. Wounds closed with 2/0 vicryl fat stitch and subcuticular 3/0 or 4/0 monocryl.
    0.25% chirocaine or marcaine.

    A full below knee plaster of Paris cast is applied.A full below knee plaster of Paris cast is applied with foot dorsiflexed and abducted/everted. This should be well padded.

    In younger children it is a good idea to extend the cast up above the knee with the knee flexed at 90 degrees. This relaxes tension through gastrocnemius and also makes it difficult for uncooperative patients to weight bear. Older more cooperative children (>4yrs) may be treated with below knee cast.

    A soft-cast above knee extension is ideal since it can be removed after 3-4 weeks without disturbing the below knee part of the cast which needs to be maintained for 6 weeks in total.

    Post Operative

    The foot is elevated in the immediate post operative period to avoid swelling. Patients do not require post operative antibiotics as a routine. The majority of cases will stay over night but if done early, some will be managed as day cases.
    Patients are not allowed to weight bear for 6 weeks. Unless there are concerns over possible wound infection the cast should not be removed until the 6 week point. If the cast is removed early the suture may rupture and the tendon retract. If the wound has to be viewed or the cast changed (for example in spina bifida where there are concerns over pressure sores) this should be done by the operating surgeon with an assistant. The assistant ensures that the foot is kept strictly dorsiflexed throughout the cast change to stop excessive tension through the tendon.
    After 6 weeks the cast can be removed in the outpatient department. The suture will often have failed and the button found to be loose within the cast. If not, it is easily cut with scissors. Patients are then allowed to fully weight bear. Splintage is generally not necessary except in certain neuromuscular cases where there is weakness around the foot and ankle. Most patients will not require physiotherapy.

    Recommended Reading

    Prospective studies have shown that in idiopathic CTEV tibialis anterior tendon transfer effectively restores the eversion to inversion strength balance (pre operatively patients have significantly worse eversion to inversion strength ratio) (Kelly Grey et al 2014 CORR). Long term studies suggest that in idiopathic CTEV treated by Ponseti regime when tibialis anterior transfer is performed further relapses are avoided (Dietz 2006, Morcuende 2006).
    In a study by Holt (2015), 25 patients undergoing tibialis anterior tendon transfer were followed until average age 47 years. No patients required further surgery and function was comparable to patients who had undergone Ponseti treatment without requiring tendon transfer.
    Tibialis anterior transfer can also been utilised as part of a more extensive soft tissue release for stiff relapsed club foot. In this setting results are not as gratifying with failure rates as high as 50% (Lampasi 2010). This emphasises the importance of having a passively correctable supple foot. This is usually the case for CTEV treated by Ponseti manipulations. By comparison, feet having had previous extensile posteromedial release are often much more stiff and in this scenario the results of tibialis anterior transfer are much less likely to be effective.

    Grey K et al. Is tibialis anterior tendon transfer effective for recurrent clubfoot? Clinics Orthopaedic Relatability Res. 2014
    Holt JB. Long term results of tibialis anterior tendon transfer for relapsed idiopathic clubfoot treated with the Ponseti method: a follow up of thirty seven to fifty five years. J Bone Joint Surg (Am). 2015.
    Dietz FR. Treatment of a recurrent clubfoot deformity after initial correction with the Ponseti technique. Instr Course Lect. 2006.
    Morcuende J. Congenital idiopathic clubfoot: prevention of late deformity and disability by conservative treatment with the Ponseti technique. Pediatr Ann. 2006.
    Lampasi M, Bettuzzi C, Palmonari M, Donzelli O. Transfer of the tendon of tibialis anterior in relapsed congenital clubfoot. J Bone Joint Surg (B). Published Online 1st feb 2010; 92-B:2.
    Lullo B et al. Split tibialis anterior transfer to the Peroneus brevis or Tertius for the treatment of various foot deformities in children with static encephalopathy: a retrospective case series. Am Acad Orthopaedic Surgeons. 2020.

    Reference

    • orthoracle.com

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