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Tibialis Posterior Reconstruction for pes planus

    Overview

    Learn the Tibialis Posterior Reconstruction for pes planus surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Tibialis Posterior Reconstruction for pes planus surgical procedure.
    The operation described using a Flexor Digitorum Longus(FDL) transfer, spring ligament plication and medialising calcaneal osteotomy is the classic reconstruction for a grade 2 (flexible ) flat foot due to Tibialis Posterior dysfunction.
    Tibialis Posterior dysfunction is typically a condition of middle age and onwards in which conservative management with orthotics and physiotherapy is usually the first line of management and often successful (in approximately two thirds of cases).
    Surgical correction of the flexible flat foot using the FDL transfer with calcaneal osteotomy (and other procedures) results in high patient satisfaction rates and symptomatic relief but with a slightly lower incidence of maintained correction of the pes planus deformity. A proportion of patients, though improved, still require the use of a corrective orthotic.

    Indications

    INDICATIONS
    Grade 2 Tibialis Posterior tendonitis which has failed conservative management.
    SYMPTOMS & EXAMINATION
    Patients present usually with unilateral symptoms which in the main progress along the same lines though with a variable timeline. The causes are various and include recurrent overuse such as seen in a runner , as part of an an acute inflammatory arthropathy or most commonly are due to chronic degenerative change of the tendon. Pain is felt fairly precisely behind the medial malleolus and on occasion radiating down to the tendons’ insertion into the Navicular. Pain is felt on weight bearing , possibly just on excercise ,but will progress sometimes to pain at rest. If deformity ensues then postero-lateral hindfoot pain classically occurs with pain at the tip of the Fibula due to the valgus heel abutting the soft tissues at the Fibula tip. Whilst the deformity remains flexible these symptoms may be reduced by mechanically offloading the tendon (with orthotics and intelligent shoewear choices) .If progression to arthritic change occurs in the subtalar then ankle joints symptoms from these joints may dominate the clinical picture.
    On examination in mild cases there will be little to find. The tendon is in most cases discreetly tender but if swelling (of the tendon and associated subcutaneous oedema) is particularly severe then it may be difficult to identify the tendon itself. The degree of medial longitudinal arch reduction will vary from none to a severe planovalgus collapse. Until a fixed deformity ensues the planovalgus foot may not be obvious unless the patient is weight-bearing. It should be appreciated that the deformity is multi-planar and comprises a reduction of the height of the medial longitudinal arch ,hindfoot valgus and abduction of the forefoot due to midfoot pronation.
    A key test to do in assessing the plano-valgus foot and ankle is the single heel rise test , observing the patient from behind and noting whether the hindfoot moves appropriately into varus or remains in valgus. This differentiates a grade 1 tendinopathy in the Johnson and Strom classification (see below) which will likely respond to a more minor surgical intervention if this becomes required .
    Also important to examine specifically is whether the Achilles is tight or not. This is assessed with the foot aligned in its “anatomical position” ( a longitudinal axis between the 2nd and 3rd toes is in line with the Patella) with the ankle in neutral and the knee extended. It should be noted whether it is it possible to dorsiflex the ankle easily beyond neutral in the saggital plane or not. If not then a tight Achilles tendon is diagnosed which may be a contributing factor in the deformity and may also require correction at the time of surgery. The foot sitting in a plano-valgus position will allow the Achilles to shorten and become tight over time but in some cases the Achilles tightness may be part of the primary problem rather than a secondary effect.
    It should be remembered that there are many causes of a unilateral planovalgus foot (including Lisfranc arthritis , Charcot midfoot collapse , arthritis of the triple complex and previous Calcaneal fracture ) and other diagnoses must always be considered.
    The grading system of Johnson & Strom is most often used in describing the extent of the deformity and also is used in decision making on which intervention may be used most appropriately. Stage 1 is defined by tenosynovitis of the tendon with minimal deformity or weakness of the tendon and the single heel raise test is largely normal. This is likely to respond to conservative measures or a tendon sparing procedure ( debridement). A stage 2 tendon produces the classic pes planus deformity due to its elongation and reduction in power. A single heel rise will not be possible but the subtalar joint is mobile. This is the type of tendon requiring the reconstruction described in this section if conservative management fails. In stage 3 arthritis has occurred and the valgus deformity is fixed .Surgical treatment now requires a triple fusion. In stage 4 the ankle is also in Valgus and if surgical treatment is required this is a true pantalar fusion.
    INVESTIGATION.
    Plain X-Ray: Weight-bearing films can be used to document the structural deformity if one exists but are not required to make the diagnosis.
    MRI:The investigation of choice for Tibialis posterior tendinosis which most objectively defines both the extent of the disease process and also the existence of intercurrent arthritic change.
    Ultrasound:In patients with paratenon inflammation only this can be used very effectively to both diagnose and infiltrate local anaesthetic and steroid into the appropriate layer.
    NON-OPERATIVE ALTERNATIVES.
    The first line management of most patients is initially non-operative with activity modification and non steroidal anti-infammatory medications.
    An off the shelf semi-rigid functional foot orthotic or custom made rigid orthotic device and activity modification is a starting point. Physiotherapy modalities including theraputic ultrasound and a graded rehab program are appropriate. Occasionally a few weeks immobilisation and strict non-weight bearing in a cast will be of benefit especially for the acutely swollen and painful tendon.
    A tall and appropriately designed post-operative boot is helpful for a number of weeks and beyond this the use of a more normal pair of boots that sit well above the ankle(for example hiking boots) , controlling hindfoot movement , help.
    OPERATIVE ALTERNATIVES (or adjuncts).
    Cobb (Split Tibialis anterior) tendon transfer.
    Flexor Hallucis Longus tendon transfer
    Cotton (medial column osteotomy )or similar
    Lateral column lengthening.
    Triple Fusion :Should be given consideration in the more elderly as an alternative to tendon transfer even in the absence of arthritic change.
    CONTRAINDICATIONS.
    The usual ones of poor vascularity , poor soft tissue quality ,smoking and immunosuppressive treatments that would need optimising pre surgery.

    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 , for the initial stage which is the calcaneal osteotomy.
    Large , rolled up sterile towels behind the ankle to improve access for cuts.
    For the medial approach side support on operated side and large sandbag under contra-lateral buttock to produce a good degree of external rotation.

    Operation

    The flexor digitorum longus transfer is preceded by a medialising calcaneal osteotomy in every case. See separate technique for this.
    A long skin incision is required. This extends a good hand’s breadth above the ankle (running just behind the subcutaneous border) to well distal to the Tibialis Posterior insertion (at the Navicular), almost to the first metatarsal base.

    Full thickness skin flaps are raised to reveal the underlying deep fascia. In this layer are the Saphenous nerve and vein anteriorly.The Tibialis posterior sits within a sheath immediately behind the medial malleolus.

    The sheath is sharp dissected and widely opened above the malleolus to expose the Tibialis posterior tendon(1) as well as beneath the malleolus(3). A sling of sheath at the malleolus is left intact(2) to prevent subluxation of the transferred tendon/new composite tendon.

    The whole tendon is exposed down to its insertion (1) and then all surfaces of the tendon need to be inspected. The last 5cm or so of tendon in this case are clearly degenerate (2). The portion of the Tibialis posterior that sits beneath the the sling of fascia at the malleolus also needs to be inspected which is done by moving the ankle and hindfoot to reveal it.
    A debridement of patently unhealthy tissue should occur. How exactly to proceed is a matter of judgment. The tendon can be very degenerate with multiple longitudinal tears and significant sections of poor tissue which are best completely excised. Less severe degeneration may be addressed by selectively placed longitudinal incisions through unhealthy areas or repairs with running Vicryl sutures. Salvaging as much Tibialis posterior as is sensible whilst then subsequently during the operation ensuring it is re-tensioned appropriately with the Flexor Digitorum Longus (FDL) transfer tenodesed through it is often most appropriate.
    The plantar aspect of Tibialis posterior insertion also needs to be defined in preparation for persuing the FDL tendon to the knot of Henry. This involves mobilising the Abductor Hallucis muscle belly(3) and as later one proceeds more distall the Flexor Hallucis Brevis.
    Once an assessment has been made of the tendon an initial dissection can proceed distally.

    The Flexor Digitorum Longus (2) is identified immediately posterior to the Tibialis posterior tendon (1) above the medial malleolus. It may occupy a separate sheath or share the Tib posts’ sheath. Distal to the malleolus(3) the FDL lies beneath a discreet fascial layer and its location is not immediately obvious.
    The FDL is best identified distally by passing a McDonalds (or Watson-Cheyne) along its course having identified it proximally, as here.

    The FDL tendon (2) now exposed beneath the malleolus after sharp dissecting onto the McDonalds, passed along its sheath from proximal.

    The FDL needs to traced into the sole of the foot (to the knot of Henry, where it crosses the Flexor Hallucis tendon) to harvest enough length for the transfer. Closely adherent soft tissues and small vessels are encountered on the way plantar-wards. Careful dissection should be used with fine tenotomy scissors and Bipolar diathermy (1). Dissection should proceed along the superior aspect of the FDL. The neuro-vascular structures lie not far from the plantar aspect of the tendon and need not be approached.
    The soft tissue space is dissected between the under-surface of the Tibialis posterior ,1st metatarsal and the FDL tendon, always remaining dorsal to the surface of the FDL tendon (2). One will encounter short leashes of vessels in this space which will need to be diathermied whilst progressing inwards towards the crossing point of the Flexor Hallucis Longus and FDL tendons.

    The “Knot of Henry” ,where the FHL tendon(3) crosses over the FDL tendon(2). Once this point is reached enough tendon can be harvested for the transfer.
    The Abductor Hallucis muscle has been further freed .

    There may also be interdigitations between the FDL(2) and FHL (3) at the knot of Henry and if present these will need to be divided or they will prevent the FDL being mobilisable.
    If the dissection is continued distally in this line the insertion of Tibialis Anterior into the base of the 1st metatarsal will be encountered .

    The Flexor digitorum (1) can be pulled to confirm that one has the correct tendon. Maximum length is gained by plantar flexing all the toes(and ankle) before harvesting.The knife cut should be under direct vision and from plantar to dorsal ,starting from directly upon the tendon.

    The FDL tendon(1) harvested and ready to be prepared for transfer to the Tibialis Posterior insertion (2).
    This is a good time to assess the tightness of the Achilles tendon (which should be done in all cases). Any heel valgus and mid/forefoot deformity is passively corrected to align the foot & ankle complex anatomically (2nd toe/metatarsal in line with the patella). In this position Achilles tightness will be revealed as an inability to get the ankle to neutral or beyond. If at this stage there is significant Achilles tightness revealed (a lack of neutral alignment by 15-20 degrees ) then an open Z lengthening of the Achilles should be considered. The Achilles can be exposed by posterior dissection through this exposure , keeping above the deep fascia which overlies the neuro-vascular bundle whilst maintaining a full thickness skin/fat flap.
    Lesser degrees of Achilles tightness can be dealt with by a triple cut to the Achilles at the end of the procedure.
    In cases displaying a significant degree of sag at the Navicular-cuneiform articulation (especially with a degree of associated degenerative change) this is the stage to consider exposing these articulations for a corrective & repositioning fusion prior to the tendon transfer. An alternate procedure is to plicate and tighten the Spring ligament as shown in the next stage.

    Deep to the Tibialis posterior(1) and FDL tendons(3) is a deep and thick fibrous layer of tissue ,the Spring ligament (4,6 & extending proximal to point 5). This plays a key role in the formation and support of the Medial longitudinal arch. It forms a tough sheet of tissue across the plantar-medial aspects of the Talus, Navicular and Calcaneum. It should be inspected as tears in its structure contribute to the deformity. If a tear is present it should be excised back to healthy tissue and repaired under appropriate (& tight ) tension. If a tear is not present (which is more usually the case) then as shown here an ellipse of the ligament is excised ,revealing the plantar aspect of the Talar head(5). 2 or 3 tough and braided non-absorbable sutures (such as 2 Fibre-wire) are locked into the distal flap (6) taking a narrow cuff of tissue. Both ends of each suture are then under-sewn beneath a much wider cuff of proximal Spring ligament tissue. The foot is then placed into supination and the sutures tied off sequentially once all have been placed . The Knots must not be prominent as they will directly underlie the tendons. A further oversew of the resulting double breasted ligament tissue is advisable using a running 1 Vicryl suture.
    In this case an intermediate portion of the Tibilais Posterior has required excision. Proximal (1) and distal (2) ends are visible. These will be recruited for the reconstruction with the FDL(3) tendon being routed through them before being implanted under appropriate tension into the Navicular.

    If using the Arthrex Bio-tenodesis implant the diameter of the FDL tendon is next sized with the Arthrex paddle and the Bio-tenodesis screw of closest size chosen accordingly. This is often a 5.5 mm screw which is 10mm long. The same sized cannulated drill is chosen(or 1mm larger) and drilled to 2mm deeper than the implant.
    A hole is drilled into the navicular(3) , into which the FDL tendon will be anchored. This is drilled with a 5.5 or 6.5 mm Arthrex drill to a depth of 12mm(Marked on drill).
    The FDL is offered up to the mouth of the drilled hole , pulled to an appropriate (tight)tension and its proximal end marked at the proximal extent of the hole(1).10 mm of tendon are marked(2) which is the amount needed to anchor with the Bio-tenodesis screw. Any excess tendon is removed.
    A decision needs to be made , prior to anchoring the FDL transfer , what to do with the Tibialis posterior. This depends upon state of the tendon as well as the surgeons preference ( and belief system). If the Tibialis posterior is still in a good state (despite tendinosis and being lengthened) I will preserve it , following a debridement.
    The FDL may be routed through the retained Tibialis Posterior , prior to anchoring it ,which will have the effect of retensioning the Tibialis posterior appropriately. If the Tibialis Posterior is significantly lengthened consider a Z shortening reconstruction of the debrided Tibialis Posterior which then incorporates the FDL tenodesis.

    A suture to allow controlled traction on the end of the FDL tendon is as an initial step sewn into the tendon end(2). The cannulated Bio-tenodesis screw(1) is introduced on the cannulated screwdriver onto the marked distal end of the FDL tendon.
    The screwdriver and screw are attached to the tendon by a suture ,looped around the FDL tendon end and passed through the centre of the screwdriver. This step of “lassoing” the distal end of the FDL prior to encouraging it into the drilled tunnel is not specifically shown but this point of attachment can be seen marked 3. As the screw is tightened into its tunnel the tendon(and its marked end,4) is also drawn in due to the interference fit.
    In this case the Tibialis Posterior has obviously not been retained .There are other equally valid ways of anchoring the FDL transfer into the Navicular. In particular if an adequate tendon insertion of the Tibialis posterior exists this can be used. A plantar based tunnel can also be used, in particular one which allows the FDL to be routed from plantar to dorsal and then anchored back onto itself.

    Once the Bio-tenodesis screw is fully home the suture ends can be tied over the end of the screw(1).Note how the marked end of the Flexor digitorum tendon has now disappeared into the tunnel.
    As a final step one should make sure that with the foot in neutral(Tibial crest aligned with 2/3 toe) the ankle goes at least to neutral.
    If the Achilles is over-tight perform a triple cut.
    My own preference is to leave the foot with a tendency towards supination at the end of the operation (that is to say an “over-tight ” transfer). It should be able to rest in neutral though . The transfer usually stretches out a bit during the early weight-bearing stages to an optimal position and is thus still able to provide good correction as opposed to becoming over-lengthened.

    A saggital T1 MRI showing clearly the very thickened distal Tibialis posterior tendon

    An Axial MRI showing some slight thickening above the level of the medial malleolus and higher signal associated with the Tibialis posterior.

    A few slices more distally , closer towards its insertion into the Navicular , the tendon and sheath are grossly thickened and degenerate.

    Post Operative

    1-2 night stay
    2 weeks in back-slab
    dressing changes at 1 & 2 weeks
    Complete cast between weeks 2 to 6 & non-weight bear
    Check X-ray at 6 week stage .
    Into long post-operative boot and gradual increase in weight-bearing at this stage .
    Add an “off the shelf” supportive , semi-rigid 3/4 length orthotic , for the next 3 months.
    Physio to work on ankle range and ankle and subtalar balance and strengthening regime from
    9 weeks or so.
    May be comfortable enough to make transition into stiff soled walking boot by 12 weeks.
    Remain in this for all weight bearing for a further 6 weeks as a minimum. Orthotics may be required in some be required in the longer term . A full functional recovery will not unusually take 6 months.

    Recommended Reading

    Complex reconstruction for the treatment of dorsolateral peritalar subluxation of the foot
    J Bone Joint Surg. 81-A. 1999 :11; 1545-1560
    B C Toolan , B J Sangeorzan , S T Hansen.
    All patients had grade 2 Tibialis posterior tendinosis.
    All patients underwent a tri-cortical bone block distraction fusion of the calcaneo-cuboid joint . All underwent an FDL transfer through the distal Tibialis posterior tendon from plantar to dorsal. All underwent a triple cut of the Achilles tendon. No spring ligament work was undertaken but 27 patients also required 1st TMT joint fusion , 4 naviculo-cuneiform fusion and 2 underwent both .
    36 patients (& 41 operations) were treated of which 88% were painfree or less painful than pre-op.
    There was high patient satisfaction rates with the outcome 33 of the 36 willing to undergoe the operation again if the same circumstances presented.
    That said 20% non-union at Calcaneo-cuboid joint ,32% sural nerve complications and 71% required secondary surgery.
    Correction of moderate and severe acquired flexible flatfoot with medialising calcaneal osteotomy and flexor diditorum longus transfer.
    J Bone Joint Surg ,2006 .88A:1726-1734
    A.M.Vora ,T.R.Tudor , B.G.Parks ,L.C.Schon
    Cadaveric study, 7 pairs of limbs. Different levels of deformity created. Severe deformity may require additional operative procedures.
    Dysfunction of the tendon of Tibialis Posterior.
    J Bone Joint Surg (br) 2004;86-B:939-46
    H.J.Trnka
    A good Review Article
    Arthrodesis techniques in the management of stage 2 and 3 acquired adult flatfoot deformity.
    J Bone Joint Surg 2005.87-A; 8:1866-1876.
    J.E.Johnson , J.r.Yu.
    An excellent and well illustrated and referenced review article on the role of fusions (and osteotomies) in flat foot reconstructions after Tibialis posterior failure.
    Calcaneal osteotomy and transfer of the tendon of flexor digitorum longus for stage 2 dysfunction of Tibialis posterior.
    J Bone Joint Surg 2002.84-B;54-58.
    J.T.Wacker ,M.S.Hennessy, T.S.Saxby.
    51 patients with grade 2 dysfunction prospectively enrolled.
    44 reviewed at a mean 51 months follow up. 43 Excellent or good outcome regarding pain & function using AOFAS score. Only 36 scored in the same categories for deformity correction. 2 Failures resulting in Calcaneo-cuboid fusion.
    The objective alignment assessed clinically was only “Fair” in 25% of patients.
    On technical points the transfer of FDL described was from plantar to dorsal navicular , then suturing the tendon back onto itself. The Tibialis posterior was radically excised and not tenodesed . The spring ligament was not tightened/plicated.
    No orthotics were proscribed in the post-operative period.

    Reference

    • orthoracle.com

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