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Triple Fusion

    Overview

    Learn the Triple Fusion surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Triple Fusion surgical procedure.
    The Triple fusion is a versatile and successful intervention for treating both significant deformity as well as arthritic symptoms. The joints fused in this operation are the subtalar, talo-navicular and calcaneo-cuboid.
    It is key that joint preparation is correctly done and that hind-foot and mid-foot alignment is restored. A CT or MRI is required in the majority of cases pre-operatively to adequately define the bone stock and level of deformity and identify all associated degenerative change.
    Though the approaches used and techniques employed in the operation have changed little over the last thirty years a significant assistance to those performing has has been the development over the last ten to fifteen years of large and compressive staples and locking plates to fix the midfoot joints. This technique demonstrates the use of an Orthosolutions cannulated large fragment screw to fix the subtalar joint and Wright Charlotte staples for the midfoot joints.
    Functionality for most activities of daily living is little effected after a triple fusion but in the longer term arthritis is likely to occur in the neighbouring joints.


    Indications

    INDICATIONS.
    The following list is not entirely comprehensive but covers the commoner indications for a triple fusion.
    -Symptomatic degenerative change effecting joints of the triple complex (subtalar, calcaneocuboid & Taonavicular)
    –Tarsal coalition with associated significant degenerative change
    –Peri-talar subluxation or dislocation (post traumatic or secondary to neuro-arthropathy)
    -Salvage operation after a failed Tibialis Posterior tendon reconstruction
    -Primary operation for Grade 2 Tibialis posterior deficiency in the elderly patient
    -Salvage operation after Calcaneal fracture
    -Flexible, unstable and uncontrolled ( though not necessarily arthritic ) deformity in a Neuro-muscular patient
    SYMPTOMS & EXAMINATION
    Pain will be the overriding presenting complaint. This is most likely to be felt in the lateral hindfoot region , the dorsal mid-foot and occasionally medial hindfoot. If a deformity is associated with the degenerative change then this may produce additional areas of pain on loading the foot related to the weight-bearing profile of the foot. In the presence of significant hindfoot deformity it is not unusual to get proximally located pain as an abnormal foot position will alter the lower limbs mechanical axis and its loading pattern. Pain initially will be on weight-bearing but may progress to be present at rest and night pain also. A characteristic of subtalar pain is that it is often worse on uneven ground.
    The Triple joint complex also contributes to composite foot and ankle dorsiflexion and plantarflexion. If the subtalar, talonavicular and calcaneocuboid joints are stiff this will reduce this total range. Having examined the individual joints to assess their mobility and presence of pain it is important to assess the alignment of ankle to hindfoot and hindfoot to midfoot.
    If deformity is present an assessment of its location and degree should be made as well as whether fixed or flexible. A severe but flexible deformity needing surgery will be easily corrected whereas if fixed the differential removal of bone from joint surfaces may be required to allow correction. A simple initial mantra for success, which covers many different situations (not only the triple complex), is to ensure that the foot (or a plantar grade surface as with orthotic management of a fixed deformity) is placed squarely beneath the Tibia in both the frontal and sagittal planes.
    With a severely valgus and fixed subtalar deformity consideration should be given to the use of an additional medial hindfoot approach (through the bed of Tibialis posterior) to access the subtalar joint and remove bone under direct vision which is more straightforward than trying to remove large amounts of bone through a lateral approach. A bone block can of course also be employed into the lateral aspect of the joint. After a severe planovalgus hindfoot deformity has been corrected an assessment of the Achilles should be made. This may be overly tight and require lengthening. The varus subtalar deformity, approached laterally provides little challenge if differential amounts of bone require removing from the lateral surfaces of the subtalar joint.
    The overall alignment of the whole lower limb needs also to be considered. In general terms more proximal deformity should be corrected first as the hindfoot will aligned to the position of the tibia, so this should sit correctly.
    With a Triple fusion the hindfoot should be fused in neutral or slight valgus, the midfoot rotated so that the foot is fully plantar grade and aligned also so that the axis of the 2nd and 3rd metatarsals is in line with the Patella. Intra-operatively the alignment is not the only consideration and in particular the bone to bone contact of surfaces to be arthrodesed should be optimised.
    INVESTIGATION.
    CT/MRI: The delineation of the location of bony deformity and assessment of significantly arthritic joints is arguably easier done with a CT scan than MRI. If there is the possibility of an active bony infection in the neuropathically collapsed foot then MRI has obvious advantages as it will have with the detection of early
    ALTERNATIVES TO OPERATION
    Activity modification ,analgesics ,corrective or supportive orthotics and shoewear modifications.
    ALTERNATIVE OPERATIVE TREATMENT
    -Isolated fusions: Each of the joints in the complex may be fused in isolation if more appropriate. It should be remembered of course that they work as a functional unit and fusing one will reduce the range of movement through the remaining joints. The time to recovery is not
    –Bone Block fusion: In the presence of significant deformity direct intra-articular correction through the prepared joints may not provide enough correction in which case tri-cortical graft should be used. This would be most often employed for a deformity post calcaneal fracture , that compromises talar inclination as well as resulting in Hindfoot valgus.
    –Subtalar arthroscopy: For milder and isolated subtalar arthritis
    CONTRAINDICATIONS TO OPERATION
    The usual ones of poor vascularity , poor soft tissue envelope , active smoking .Optimising these factors is required as is any relevant medical treatments such as steroids and other immunomodulating medications which may effect healing.

    Setup

    GA or regional anaesthesia
    Femoral & sciatic blocks for post-operative pain relief
    Laminar flow , peri-operative antibiotics , 2-4 weeks of post operative LMW Heparin
    Thigh tourniquet and Flowtron on contra-lateral calf
    Ankle positioned into neutral using sandbags & side supports
    Large , rolled up sterile towels behind the ankle to improve access for cuts.

    Operation – 1

    This whole of the lower limb mechanical alignment should be assessed and proximal deformity dealt with before the triple complex is fused.
    Here the osteoarthritic valgus knee should knee should be realigned before correcting the fixed and valgus hindfoot with a triple fusion.

    The initial skin incision for the subtalar joint runs from the base of the fourth metatarsal(2) to posterior to the tip of the fibula (1).
    It may need extension to a point a little more posterior to the Fibula tip.

    The fat should be blunt dissected in the line of the skin incision to allow avoidance, if present in the operative field, of the sural nerve, which sits in the line of the peroneal tendons. It will usually run the length of the wound.
    Both the peroneal sheath(2), which is inferior in the wound, and the extensor digitorum brevis(1) are quickly identified once dissecting through the fat. The location of its muscle belly is marked in yellow.

    Both the peroneal sheath(1), which is inferior in the wound, and the extensor digitorum brevis(EdBr, 2) are quickly identified once dissecting through the fat.Fine tenotomy scissors are used. The sural nerve should be very gently handled if being mobilised. It is not always found in this relatively narrow field.
    It also needs to be carefully and deliberately avoided during wound closure.
    Even careful handling of the nerve may result in a degree of post-operative paraesthesia.

    The subtalar joint is accessed by sharp dissection through the EdBr muscle(1), in the line of its fibres. This takes you directly onto the antero-lateral calcaneus.The skin edges should be carefully treated through-out. Retractors should be placed deep to the fat and not between skin and fat layers, which delaminates the cutaneous blood vessels from the skin.

    A Wests’ retractor (1) is useful to assist in the reflection of the muscle off the calacaneus.

    Deeper dissection through EdBr and reflection of it deeply exposes the calcaneo-cuboid joint.A good view of the calcaneo-cuboid joint. Calcaneus (1) and cuboid (2).

    A large blunt nosed periosteal elevator is required for the next step.

    A large round-nosed periosteal elevator is run along the lateral wall of the calcaneus (1), beneath the peroneal tendons and their sheath and superiorly and proximally the calacaneo-fibular ligament(a well defined vertical band of soft tissue in the bed of the peroneal tendons)It should be inserted as far as the posterior aspect of the calcaneus with a levering/ stripping action . The aim is to mobilise the deeper soft tissue envelope to allow the easy insertion of a Trethowans’ or Homans’ type retractor.
    With such a retractor inserted deeply to the postero-lateral aspect of the calcaneus the soft tissues can be elevated off the bone to assist with adequate visualisation of the posterior facet of the subtalar joint.

    Once cuboid(1) and calcaneus(2) are exposed the sinus tarsi is identified by following the anterior process of the calcaneus proximally and superiorly and its contents excised.Its contained soft tissue is removed with a bone nibbler (3) and by sharp dissection. This clearance should continue into the depth of the joint, including the inferior surface of the talar neck and head, to allow their identification.
    Care must be exercised to identify the medial aspect of the subtalar joint and not dissect beyond it.

    With some of the sinus tarsi soft tissue removed (1) the approach into the joint can be better appreciated.
    The anterior process of Calcaneus is marked 3, and the calcaneo-cuboid joint 2.
    The dissection is now progressed sub-periosteally in posterior , superior and medial directions.
    This is aided by the insertion of a laminar spreader into the sinus tarsi and the Homans’ retractor deeply placed along the lateral margin of the calcaneus to elevate the peroneal tendons and associated soft tissues from the postero-lateral aspect of the Calcaneus.

    Once the main contents of the sinus tarsi have been resected (2) and soft tissue released from the lateral calcaneus, it should be possible to identify the posterior facet (1), middle facet leading onto the anterior facet (3) and the inferior surface of talar neck (4) and talar head.

    The subtalar joint now fully exposed. The posterior facet (3, mostly devoid of cartilage), the anterior process (5), the peroneal tendons (1), and the lower part of the talar body, the lateral process (4). The calcaneo-fibular ligament (2) needs to be elevated off the calcaneus by placing a Homans’ retractor or similar between it and the posterior facet to gain adequate exposure to the posterior part of the joint.
    For wider joint exposure a laminar spreader is usefully inserted between anterior process and talar neck.

    The subtalar joint surfaces are prepared with a high speed burr and Lambotts osteotomes, being careful to resect back to the subchondral bone evenly from both articulating surfaces and leave a joint that has good bone to bone contact.In achieving this one should also pay particular attention to the margins of the joint, in particular the medial aspect, to ensure no “proud” edges are left.
    With each case the exposure should be sufficient to visualise across to the medial wall anatomy. Posterior facet(3), middle facet of subtalar joint(2) leading onto anterior facet and reciprocal surface of talus(1) leading to under surface of talar head.
    With a fixed valgus deformity more bone may need to be removed/prepared from along the whole medial wall to allow the hindfoot to correct. Any unprepared edge will prevent reduction. Bone can be removed predominantly from the superior (talar) aspect of the joint. With more significant deformity one may wish simply to break up this talar ledge with controlled use of the Hibs osteotome , potentially leaving the morcellised bone in situ. It should be recalled that the neurovascular bundle runs along the medial wall of the calcaneum and therefore resection per se is avoided from this area and the use of the osteotome must be very controlled.
    Back cutting spinal rongeurs of various sizes (used under direct vision) are also helpful for removal of bone from this area. On occasion this technique may not allow sufficient correction. If this occurs (or if the deformity is particularly severe and it is anticipated this may occur)then a medial approach through the bed of Tibialis posterior (see tarsal coalition operations) can be used to directly approach the medial wall by which means it is easier and safer to more radically resect bone. Alternatively an “opening wedge” bone block is placed through the standard lateral exposure into the subtalar joint to effect the correction.
    Correction of hindfoot varus involves may involve removal of more bone from the lateral aspect of the joint and so access is not an issue.
    It is of course possible that simply mobilising the subtalar joint and standard (non-differential ) preparation of the joint surfaces will allow deformity correction.

    In most cases it is a useful additional manoeuvre once the subtalar joint has been prepared to discreetly remove the both the highest point of the calcaneal anterior process (1) as well as the under surface of talar head (2).
    This bone is preserved for use as bone graft at the end if required.
    This additional resection avoids the impingement and compromise of reduction of the talo-navicular joint which can occur upon compressing talus onto calcaneum during the final fixation of the subtalar joint.

    The calcaneo-cuboid joint is prepared second of the three joints using a McDonalds (3) and small laminar spreader to lever open the joint.This is done with a 5mm high speed burr in the main. The joint is deep and the full depth needs to be prepared or it won’t compress.
    The bone is soft relatively speaking and it is easy to over-resect so care should be taken.

    The 5mm burr in use. The joint is saddle shaped and it should be kept congruent. It is relatively deep and one should take time to ensure the medial aspect is seen and prepared. The bone is also often soft and easy to over-resect so care should be taken not to be too vigorous.

    To expose the talo-navicular joint a skin incision is made in the line of tibialis anterior tendon (1) running from just distal to the ankle to the level of the navicular tuberosity.A little blunt dissection in the same line through the superficial fat takes one to the extensor retinaculum(2) which is sharp dissected open

    Once the extensor retinaculum is opened and tibialis anterior retracted there is another dense layer of fat, with vessels running transversely which require cauterisation.Dissect directly immediately beneath the tendon (1) to avoid the main neuro-vascular bundle

    Once on the deeper fat layer the talo-navicular joint is immediately deep and subperiosteal dissection should extend proximally to the talar neck and distally to the navicular-cuneiform joint. Before preparation of the joint is commenced be sure you have the correct joint. The navicular-cuneiform joint can be confused with the talo-navicular joint if exposure is limited.
    Also dissect enough proximally to expose the talar neck (which will need to be done prior to fixation anyway) to be sure one is in the correct location.
    1 Talar osteophyte
    2 Navicular osteophyte
    3 Tibialis anterior
    4 Talar neck.

    To prepare the talonavicular joint remove any dorsal osteophytes. The joint will be fairly tight and access difficult which is improved by levering it open with a McDonalds’ and small laminar spreader.
    Care should be taken both to clear all articulating surfaces, in particular not leaving the far medial or lateral margins proud which is easily done. It is important not to remove too much bone from either joint surface, which will also effecting the fit of the surfaces.

    The 5 mm high speed burr being used to prepare the joint. One should aim to keep the surfaces congruent.

    A guide wire is placed from the talar neck (1) across the subtalar joint. It should be angled from the midpoint of the talar neck towards the midpoint of the posterior facet.A finger placed laterally into the sinus tarsi(2) is a useful point to aim behind.
    Care should be taken to ensure that the subtalar joint is both in a reduced position(2nd ray in line with patella and heel beneath the Tibia) and held there as the wire is advanced.

    The point of guide-wire entry on the talar neck should not be too far proximal(1). If it is impingement of the screw head upon the anterior tibia may occur.
    The ankle should be dorsiflexed with the guide wire in situ and screened with a lateral x ray to ensure this does not occur.
    In choosing the point of entry on the talar neck for the guide-wire consideration also should be given to leaving adequate position for the later placement of at least two fairly evenly spaced staples, ideally either side of it.

    Guide wire position is checked with image intensifier and then length confirmed with a gauge. By angling the guide wire postero-laterally it should eventually pass out of the lateral wall of the calcaneus (becoming palpable) and this can then be withdrawn(1) back into the bone. This potentially allows screw length to be estimated without using X-ray ( but it’s necessary to check with a lateral X-Ray prior to overdrilling the wire).
    Once the subtalar joint has been temporarily reduced and held with the k-wire an assessment should be made of the ease of reduction and bone to bone contact of all 3 joints. Some fine adjustment to the prepared surfaces may need to be made to improve this.
    There is always a balance to be struck between bone to bone contact and the alignment required. Both are of equal importance.

    Operation – 2

    A large fragment and long partially threaded screw is inserted over the guide wire after over-drilling with the cannulated drill has occurred.It is an idea to not over-drill the entire length of the guide-wire to ensure some good distal bone remains, helping adequate thread bite of the screw thread. The calcaneal position is controlled by hand during screw insertion (2).
    A partially threaded screw of appropriate diameter (6.5 -8mm) is used. A longer partial thread gives better purchase than a short partial thread. In a smaller patient start with the smaller diameter but depending on compression generated /bone purchase the larger diameter may be required.
    Consideration should also be given to using a washer to ensure the head does not sink too deep beneath the bone of the talar neck if the bone is soft.
    Once the screw is seated home not only should the image intensifier be used for a lateral check image but a visual assessment of the bone to bone contact across the joint and stability of fixation made.
    Some osteophytes and bone swarf from burring will have been saved during joint preparation and can be used if fixation is robust but there are gaps in the bone to bone contact
    An alternative approach for fixation is to route a screw percutaneously from the inferior and posterior aspect of the calcaneus superiorly to the talar neck. This produces a scar on the weight-bearing surface of the heel which can be more prone to local problems of irritation and slow healing but this approach has its uses.

    The large fragment titanium screw and washer (2) with an appropriate amount of talar neck visible distally(1). The joint line is marked as is the navicular (3).

    It is key that the mid-foot is held in an anatomical and functional position as the fixation is applied to the talo-navicular joint.A compressive staple is the ideal fixation for the talo-navicular joint.
    Certainly two staples will be required and if space allows then three.
    When severe deformity is being corrected a useful step is to temporarily hold the reduced talo-navicular joint with K-wires prior to fixation.
    Here the Wright Charlotte staple drill guide is shown being set to a 15 mm width staple, the minimum for this joint.
    The staples are sized by both the depth of the “legs” as well as the distance between them. The first question is to decide upon the width of the staple (either 13, 15, 20 or 25 mm). The drill guide is then set to this dimension. Care should be taken to be accurate when setting this width as the guide allows widths to be selected that do not exist (22 mm).
    One should aim if possible for at least one 20mm width staple across this joint. This also allows a depth of 2omm to be chosen for the staple. The 15mm width staple only comes as a maximum 15mm depth.

    The Wright drill is used to pre-drill for the Charlotte staple. A 20x 20 and 15 x15 mm combination of staple implants are often used.It is important to position the holes so that they sit comfortably in good bone stock.

    The second drill hole is made, 2, with the first drill, 1, remaining in-situ to ensure an accurately positioned second hole is drilled.
    The depth of the holes are then checked using the depth gauge.

    The Wright Charlotte staple is inserted using an artery clip to manoeuvre it into position on the talonavicular joint.Prior to insertion the depth should be measured and a staple of appropriate depth used.

    The Wright Charlotte staple is impacted across the joint using a specific impactor, followed which the expanding pliers are placed into the widest point of the Charlotte staple and its tips opened to compress the staple.

    The expanding pliers are placed into the widest point of the Charlotte staple and its tips opened, thus expanding the mid point of the staple and bringing the legs of the staple together , producing compression. The tips need to be fully engaged within the staple of they will slip out during this step.
    My suggestion is that all the staples (2 or 3) are first placed before any compression is applied. Once the staples are expanded the room on the dorsal aspect of the joint is reduced and it becomes more difficult to apply the subsequent staples.

    A second staple also producing compression across the joint. There is still some gap visible dorsally which will be grafted with bone saved from the preceding joint preparation.
    The navicular-cuneiform joint is marked.

    The final joint to be fixed is the calcaneo-cuboid joint which is also fixed with Charlotte staples(1) using the same technique.
    Large 20mm or even 25 mm diameter and depth staples can be used here.

    The Charlotte staple being expanded to produce compression across calcaneus(1) and cuboid(2).Two staples are used here though three can be accommodated in larger feet.

    An acute flat foot in an insensate diabetic patient, due to a subtalar dislocation.
    This is an urgent indication for corrective triple fusion before plantar ulceration occurs through the head of the talus which has now become a directly weight-bearing plantar surface, 1

    Pre and post operative xrays of triple fusion with Wright Charlotte staples and Orthosolutions titanium cannulated screws.
    This case is one of a plano-valgus foot collapse through the triple complex with pre-operative subluxation of the talo-navicular joint (seen best in the top right X-ray) .

    Gross subtalar degenerative change and loss of calcaneal height leading to a dorsiflexed talus in a patient with an untreated calcaneal fracture.
    The patient presented with a broad heel, lateral hindfoot impingement and anterior ankle impingement with severe subtalar pain.

    The coronal CT demonstrates how grossly widened the calcaneus is with lateral extrusion of its lateral wall.
    There is very little calcaneal height and the lateral calcaneus should not articulate anywhere near the fibula tip (1).

    Following a radical debridement of the lateral calcaneal wall and insertion of a laterally based tri-cortical iliac crest graft the heel height and talar inclination is restored.

    Post Operative

    2 weeks in back-slab cast.
    DVT prophylaxis for 2-6 weeks.
    Dressing changes at 1 & 2 weeks
    Complete cast between weeks 2 to 6 & non-weight bear
    Check X-ray at 6 & 12 week stage and subsequently if equivocal.
    Into long post-operative boot and gradual increase in weight-bearing at this stage as symptoms allow .
    A further X-ray and clinical assessment is required at the 12 week stage.
    It is not unusual for X-Rays not to show full union of all joints at this stage. How to regard this depends upon symptoms.
    A patient who has responded to increased weight bearing by getting increasing pain by the 12 week stage may require a CT assessment .Dealing with this scenario it is important to be clear of the location of any pain .Heel pain can occur simply due to plantar fascitis as most patients walk with a shorter step between week 6 and 12 which will load the soft tissues of the heel proportionally more than normal.If pain is from the calf a DVT should be considered even at this stage. If clinically the fusion mass appears to be the source of pain then weight-bearing should be reduced for a further 4-6 weeks (using post-operative boot & crutches) and the use of an external bone stimulator such as an Exogen unit (Bioventis) should be considered. 4-6 weekly assessments are then required until pain and imaging improves.

    Most patients however will be comfortable enough to make transition into stiff soled walking boot by 12 weeks with an appropriate X-Ray and minimal symptoms
    They should remain in this for all weight bearing for a further 6 weeks minimum.
    Add an “off the shelf” supportive , semi-rigid 3/4 length orthotic , is also used for the next 3 months in all shoewear.

    Recommended Reading

    Clinical outcome after primary triple arthrodesis.
    J Bone Joint Surg.2000.82-A.1;47-57.
    R.F.Pell, M.S.Myerson, L.W.Schon.
    111 patients followed up for an average of 5.7 years. Modern fixation technique with screws used. No Charcot, revision or infected cases were included.
    Only 3 non-unions reported. A high correlation between alignment & outcome and a poor correlation between the progressive arthritic change in the same foot and outcome . The incidence of arthritis increased from 7% pre-operatively to 60% post-operatively (predominantly ankle).
    Triple arthrodesis using internal fixation in treatment of adult foot disorders.
    Clinical Orthopaedics and related research.1993.294; 299-307
    B J Sangeorzan, D Smith, R Veith, S.T.Hansen
    44 feet fused using screw fixation in a varied group of neuro-muscular , post-traumatic and primary arthritic patients.
    2 non-unions . 40 feet with a good or fair result and 4 classified as failure( the non-unions and two varus deformities).
    A physical activity score was also used (AIMS) indicating little restriction in the main re the activities of daily living.
    Triple Arthrodesis: Twenty five and forty-four year average follow-up of the same patients.
    J Bone Joint Surg.1999.81-A;1391-1402.
    C I Saltzmann, MJ Fehrle, RR Cooper, EC Spencer, IV Ponsetti.
    67 feet of which approximately 70% had a neurological or neuromuscular condition . “Historical”means of internal fixation with initial review performed in 1974 and at 25 years post op.
    Perhaps unsurprisingly non-union found in almost 20%.
    Pain was present in 45% of feet at 25 years and 55% at 44 years
    Progressive arthritic changes noted in 70 % of ankles 80% of Naviculo-cuneiform and 70% of tarso-metatarsal articulations by 25 years.
    Isolated Subtalar Arthrodesis.
    J Bone Joint Surg.2000.82-A;613-624
    M.E.Easley, H.Trnka,L.C.Shon,M.S.Myerson
    148 patients followed up for mean of 51 months
    86% primary union rate reported and 71 % union after revision subtalar fusion .
    Subgroups identified within this study with an increased incidence of non-union were smokers (46% of the group) , previous failed fusions, subtalar fusions using structural graft and subtalar fusions beneath ankles that were already fused.

    Lambrinudi triple arthrodesis for correction of severe rigid foot drop.
    J Bone Joint Surg.1984.66-B;66-70.
    SC Tang, JCY Leong, LCS HSU
    Worth a read for the technique (though not optimally described).

    Reference

    • orthoracle.com

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