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Achilles tendon and posterior ankle release for severe ankle equinus contracture

    Overview

    Learn the Achilles tendon and posterior ankle release for severe ankle equinus contracture surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Achilles tendon and posterior ankle release for severe ankle equinus contracture surgical procedure.
    Severe equinus contracture at the ankle, with associated contracture of the long flexors and joint capsules, can be the end point of a wide variety of congenital, developmental and acquired neurological conditions as well the result of acute, but recovered, vascular compromise to the limb.
    In general with ankle and hindfoot deformity one can never go far wrong adhering to Paul Cookes mantra “place a balanced foot squarely beneath the tibia in the coronal and sagittal planes”. These are the sort of patients however where this advice needs on occasion to be tempered as the examples at the start of the operation technique illustrate. A significant ankle equinus can be highly functional in a short and undeveloped limb and neurological patients with a crouch type gait and proximal muscle weakness may be dependent for ambulation upon the relatively powerful but contracted achilles and gastrocsoleus complex.
    The decision about what might be achieved with soft tissue correction and what more appropriate for corrective fusion surgery is often a multi-faceted one. The issue is not simply having the surgical ability to correct the deformity. The subsequent function and also stability afforded if an extensive soft tissue release is chosen, over fusion surgeries which require a longer recovery period, needs to be weighed up. In patients with spasticity and multi-level lower limb contractures deciding what will respond to extensive soft-tissue releases can be difficult. It is often a team decision with key insights from other members into the patients potential future function and current ability at the heart of this.
    Other associated techniques which may be usefully read in conjunction with this are https://www.orthoracle.com/library/gastrocnemius-recession/
    https://www.orthoracle.com/library/achilles-tendon-lengthening-open/ and https://www.orthoracle.com/library/tibialis-posterior-transfer-interosseous-membrane-foot-drop/.




    Indications

    INDICATIONS
    The indications for an open achilles and associated posterior tendon lengthening and capsular releases include:
    -Severe, fixed and isolated equinus that has not responded to appropriate non-operative management.
    -Achilles tendon contracture in association with contracture of other long flexors of the foot and ankle.
    The objectives of surgery should also be considered and in particular not simply the correction of deformity but also the subsequent function. It may be the case that intercurrent tendon transfers are indicated to optimise function or, though technically correctable by soft tissue releases, a more robust solution will be afforded by mutli-level fusion surgery.
    HISTORY
    Many patients will have undergone multidisciplinary management in a neuro-rehabilitation unit. Patients with this type of deformity may well be neurologically challenged at various levels of both the musculoskeletal system and also more centrally and a comprehensive history needs to be sought.
    This restriction maybe in the use of a standing frame or of balance during the stance phase of gait. It is often helpful to gain information from the patients’ neuro-rehabilitation team about their specific restrictions and the realistic functional expectations.It is helpful to know the correctability and function that has been achieved following interventions such as serial casting and botulinum injections.
    EXAMINATION
    Examination should be performed ideally, with the patient lying, standing and walking. Any fixed deformity in pelvis, hips, knees should be documented, as should flexibility of these joints. Muscle power in hips, knees ankle and core should be assessed. Equinus contracture in the ankle is examined, both with the knee flexed and extended in order to determine whether the equinus is related to an achilles or is an isolated gastrocnemius contracture. The degree of equinus deformity should be documented carefully for both.
    Ankle, hindfoot, midfoot and toe deformity, and specifically their correctability, should be assessed, as should muscle power and tone, and in particular spasticity, in each muscle group.
    A thorough vascular examination of the limb should be made as well as assessment of the state of the soft tissue envelope in the area undergoing the acute correction. Significant traction upon vessels and soft tissues undergoing large corrections can result in significant complications and

    IMAGING/INVESTIGATION
    Radiographs of the foot and ankle should be routinely performed, and in multi-planar deformity cross-sectional imaging may be required to clarify the location of ankle or hindfoot/midfoot deformity.
    In the presence of a severe deformity that will be acutely corrected, or any equivocation about the vascular state of the limb, vascular opinion and investigation should be sought.
    ALTERNATIVE OPERATIVE TREATMENT
    In patients with a mild fixed equinus(<15 degrees) who fail non-operative management a “Hoke” triple cut lengthening will usually suffice. Here using posteriorly based stab incisions, whereby the distal and proximal cuts are through the medial 50% of the tendon and the middle cut through the lateral 50% of the tendon, firm controlled dorsiflexion of the Achilles produces a palpable and instantaneous “giving” of the tight tendon, which stretches sufficiently to allow correction.
    In larger deformities, or where there is contracture of the posterior capsule and long flexors, this will not allow adequate correction, and the triple cut will have compromised a formal open lengthening.
    In compliant and robust patients Ilizarov and Taylor Spatial frames can play a role in the correction of these significant deformities.
    NON-OPERATIVE MANAGEMENT
    In patients with established equinus contracture, again passive physiotherapy stretches and splinting can be helpful. Serial casting after stretching and manipulation can be helpful, this can be performed in association with botox injections into the gastrocnemius or soleus and gastrocnemius, depending on whether the silverskiold test indicates an isolated gastrocnemius contracture.
    CONTRAINDICATIONS:
    Whilst achilles release can be very effective in correcting ankle equinus, a full assessment of joint flexibility and proximal muscle power, control and spasticity should undertaken before deciding to proceed. Patients who have significant proximal weakness, spasticity or restricted knee and hip movement can be at risk of decompensating following isolated achilles release. An example of this is a patient suffering from cerebral palsy, with a crouch gait, weak and poorly controlled gluteals and quadriceps, fixed flexion deformities of hips or knees. These patients rely on their relatively powerful achilles(gastroc-soleus) to stand and initiate gait. In these patients isolated release of the Achilles can have a dramatically detrimental effect on their ability to stand and walk.
    Other contraindications to isolated achilles tendon lengthening include active infection, cellulitis, peripheral vascular disease, and severe ankle arthritis (patients with ankle arthritis may be better served with an ankle arthrodesis in association with achilles release).
    COMPLICATIONS
    Complications of open achilles lengthening include triceps-surae weakness, rupture, recurrent equinus contracture, residual deformity, anterior ankle impingement, infection, wound breakdown, thrombo-embolic disease and sural nerve injury.

    Setup

    Operation – 1


    This image shows a significant ankle equinus associated with some mild clawing of the toes. The calf musculature is wasted in this patient with a mild cerebral palsy.


    From the posterior aspect significant atrophy of the calf and foot musculature is evident as well as an associated lack of development of the normal size of the limb. It is also evident that this is predominantly a uniplanar deformity.
    Given the relatively short right below knee segment, the ankle equinus has functional advantage in terms of effectively increasing the length of this part of the limb, and making of use in bipedal gait.


    A more severe and almost a complete ankle equinus is evident. There is from this view probably a hindfoot varus as well as an associated forefoot adductus.

    From the posterior aspect is evidence how significant the hindfoot varus and associated midfoot supination is.
    It is also evident that there is significant shortening of the effected right lower limb compared to the left. Once again the effect of correcting this deformity would be to unmask the significantly shorter below knee segment on the right side.
    There is evidence of significant achilles scar and reference back to the previous image shows clear evidence of bilateral postero-medial hindfoot scars. This is a patient with previously operated CTEV.

    This is a patient with severe ankle equinus, midfoot plantaris and significant flexion deformity of all the toes, combined with a tight plantar fascia. The deformity is very largely in the sagittal plane only.
    The patient’s deformities are also in fact are bilateral, having suffered a significant brain stem bleed which left the patient significantly and multiply neurologically challenged.
    Previous responses to botulinum had been encouraging though temporising only.
    The patient’s bilateral foot positions were preventing use of a tilt table as some degree of slow neurological improvement occurred. He was expected to continue as, a non-ambulator.
    Foot cleansing was also a problem given the significant toe deformities.

    The skin incision is placed midway between the posterior aspect of the tendon achilles and the posterior aspect of the medial malleolus.
    A long incision used and blunt dissection through the fat layer is used, avoiding undermining the skin edges, until the deep fascia is identified.

    There is widespread fatty infiltration of the anatomical layers in this patient and the deep fascia (A) is not a particularly well defined structure.
    Immediately beneath the fascia, which has been already opened, is the neurovascular bundle and this is indicated by the McDonalds.


    The soft tissue posterior (and superficial to the deep fascia) has been dissected to reveal the achilles tendon, which has also been invested in deeply adherent and contracted fat layer which is not often seen outside the context of a significant posterior contracture or trauma.

    Immediately deep to the neurovascular bundle is the flexor hallucis longus (FHL) tendon. This is identified here again with the McDonalds gently retracting the neurovascular bundle.


    The appearances of the previous steps are relatively atypical and the following few images are a clearer representation of the regional anatomy.
    A similarly placed skin incision has been opened and the fat layer is being dissected directly in line with the skin incision using tenotomy scissors.

    Once the fat layer has been part scissors dissected and part swab dissected, the underlying deep fascial layer is evident. This runs transversely across the posterior aspect of the ankle and evident deep too it are the vessels and nerve, seen quite clearly, as is usual, through the deep fascia.

    The deep fascia is opened carefully initially by gently lifting it up with a pair of fine forceps and making a small nick with a pair of tenotomy scissors (this step is not shown).
    This then allows access immediately beneath the deep fascia for a gentle scissors opening to allow mobilisation of the neurovascular bundle away from the deep fascia. Another alternate (or additional) manoeuvre is to place the McDonalds directly beneath the deep fascia and free it by gentle medio-lateral movement.
    The next step is then to divide the deep fascia carefully and under direct vision. This is shown here with a sharp knife dissection onto the McDonalds which is leading the direction of the knife dissection.

    Once the deep fascia has been opened under direct vision the neurovascular bundle is seen beneath.
    The cut edges of the deep fascia are labelled A in this photograph.
    It is important that the neurovascular bundle is mobilised adequately and this is always done under direct vision, throughout the extent of the incision. It should be wherever possible moved by indirect traction upon it through neighbouring soft tissues, handled carefully with non-toothed forceps, and the use of vascular sloops.


    The neurovascular bundle does not simply fall off the back of the FHL tendon (marked A).
    To get the degree of mobility of the bundle seen here some fine tenotomy scissors dissection will have been required superiorly. Small transverse vessels may need to be diathermised using bipolar diathermy, and this should be performed as far away from the main vessels as possible. Larger traversing branches may need to be tied with fine 2.0 vicryl.
    It is worth assessing the neurovascular bundle before deciding whether to mobilise it posteriorly (as shown here) or to take it anteriorly. This will be determined by the location of the small vessels coming off these main vessels and whether they are predominantly anterior or posterior in their distribution.
    The flexor digitorum longus and the tibialis posterior both sit anterior to the FHL tendon, sometimes in a shared sheath.

    This is a return to the case being demonstrated.
    The neurovascular bundle (A) has been allowed to sit back in its previous position and the exploration has continued superior and anterior to this to locate the tibialis posterior (B) tendon (possibly sitting with the flexor digitorum longus tendon) in its own fibrous sheath which sits immediately posterior to the posterior subcutaneous border of the tibia.

    With some of the anatomy now identified the first tendon lengthening can occur. Here there has been a long Z-lengthening of the achilles tendon, utilising the entirety of its longitudinal length has been performed. A midline longitudinal incision has been made which has been exited superiorly, laterally and inferiorly medially.
    The foot is then placed into dorsiflexion. As can be seen when looking at the cut end of the lateral slip of the tendon there has been significant lengthening (point A to point B).

    Placing the foot into as much dorsiflexion as possible it is evident that the ankle equinus is starting to correct (if one references from the plantar fat pad of the calcaneus to the longitudinal axis of the tibia).
    There is still a significant midfoot plantaris and flexion of the toes evident.

    With the neurovascular bundle moved posteriorly the FHL tendon is accessible. In this case it is being divided transversely. The patient is a non-ambulator. It would be more normal to perform a long Z-lengthening of the tendon. There may well be adhesions surrounding the tendon which need to be divided to allow it to move adequately.


    The common sheath (A) shared by the tibialis posterior (C) and the flexor digitorum longus (B) has been longitudinally opened here, anterior to the neurovascular bundle and just behind the posterior subcutaneous border of the tibia.
    The FDL tendon has been divided and has separated spontaneously as can be seen. The tibialis posterior tendon will be similarly divided, or more normally Z-lengthened.

    A further subtle improvement in the ankle/hindfoot equinus is seen and also some improvement in the position of the midfoot.
    It is not especially evident from this picture but the foot is not yet in a functional enough position, neither from the ankle/hindfoot nor from the midfoot.
    Consideration needs now to be given to further sequential releases. In the first instance the posterior ankle capsule should be elevated and divided.

    The Z-lengthened tibialis posterior is seen in the superior/anterior portion of the wound as is the gap within the FDL tendon.
    The neurovascular bundle has been further mobilised by careful tenotomy scissors dissection and the use of bipolar diathermy to coagulate small vessels coming from the vessel main branches. All bipolar diathermy is carried out away from both the vessels and the underlying posterior tibial nerve and its branches. On occasion small 2.0 vicryl ties are used for larger vessels. It is important to be meticulous in the technique of mobilising the neurovascular bundle. Nerve injury and hematoma formation of both complications it can be largely avoided. For a more comprehensive description of the surgical anatomy of the posterior tibial nerve the technique of tarsal tunnel decompression should be read on OrthOracle at https://www.orthoracle.com/library/tarsal-tunnel-decompression/.
    The mobilisation of the neurovascular bundle has a purpose and this is to gain adequate access to the posterior aspect of the tibia. It is useful during this dissection to identify the target, which is the posterior aspect of the ankle joint, by plantar flexing and dorsiflexing the foot and looking for the point of posterior movement which will be were the capsule needs to be elevated off the posterior aspect of the joint and potentially off the posterior aspect of the talus also.

    With two vascular sloops passed around the neurovascular bundle the posterior aspect of the ankle joint can be accessed. Here it has been opened already and a McDonalds retractor is within it. It is then progressively released from the posterior aspect of the tibia in the first instance. This is done carefully and under direct vision. There can be vessels in this capsular layer and the deeper placed synnovial tissue within the ankle and these need to be carefully diathermised also.
    It is important that the capsule is released across the whole width of the tibia and this must be carefully traced to the lateral aspect of the tibia also. A large round nosed periosteal elevator (not shown) is also a useful instrument to strip this posterior capsule. Stripping may not be adequate and the capsule will probably need to be divided transversely also once it has been dissected free of the neighbouring structures.

    Here the capsule has been stripped superiorly from the posterior aspect of the tibia (A) and also divided transversely (B) effecting adequate dorsiflexion from the ankle to just beyond neutral.

    Referencing from the plantar surface of the calcaneum it is evident that dorsiflexion beyond neutral has now been achieved.
    There is however still a fairly marked midfoot plantaris still evident and visible is the tight plantar fascia which is evident at the apex of the medial longitudinal arch, plantar aspect (A).
    The toes are also still relatively plantar flexed(B) despite release of the FHL and FDL tendons already.

    A longitudinal incision is made over the tight plantar fascia in its middle aspect (A). This is divided under direct vision and can be seen to have significantly improved both midfoot and toe position.
    There may still be some capsular release required from the plantar aspect of the first MTPJ.

    Operation – 2


    It is worth comparing the corrected foot with the pre-operative starting point.

    This is a patient who suffered a traumatic knee dislocation with associated transection of the popliteal nerves and vessels.
    Evident here is the proximal surgical scar used for the re-vascularisation of the limb.
    The nature of this deformity has been again a complete equinus with associated hindfoot varus. These deformities were only partially correctible but the patient was an adolescent who had not reached skeletal maturity. Given this I opted for soft tissue releases rather than corrective and stabilising fusion surgery.

    The hindfoot position is more evident here, as are the lack of toe deformities. The long lateral scar was used for fasciotomies and also the vascular reconstruction.

    The appearance at three months post-procedure. The posteromedial scar is well healed and the foot is plantigrade.
    The mark from an AFO (A) is evident. There is little active muscle function in the below knee segment.

    Post Operative

    4-6 weeks in below knee cast post-operatively. The plaster should be applied with the ankle in plantigrade whilst in the operating room, the sound side to side repair will tolerate the slight tension that the achilles should be under. The ankle should not be placed in equinus, as this tends to lead to incomplete correction, excessive dorsiflexion will lead to lengthening of the achilles and unnecessary weakness.
    Dressing changes at 1 & 2 weeks and then as required depending upon wound healing.
    Long pneumatic boot or a custom Ankle-Foot-Orthosis(AFO) to follow after 6 weeks, until 12 weeks. Those with neurological weakness or spasicity, are likely to continue to wear an AFO.
    Of upmost importance through-out the post-operative period is that the wound is looked after. Wound infection and small areas of breakdown occur easily in a freshly healed wound that is allowed to rub on socks/shoe-wear after a patient is out of cast.
    Any exudate from the wound which is allowed prolonged contact with the wound will further exacerbate any skin breakdown . Dressing changes may therefore need to be frequent if such a complication ensues.
    Once out of cast I routinely advise another month of daytime dressings when in shoes and also nocturnal dressings whilst any of the wound remains unhealed
    Showering & bathing is allowed from when out of cast
    Commence range of motion exercises and non-weight bear and strengthening regime if appropriate from when out of cast.

    Recommended Reading

    1. JBJS Br. 1988 May;70(3):472-5.
    Graham HK, Fixsen JA.
    Lengthening of the calcaneal tendo Achilles in spastic diplegia by the White slide technique. A long term review.
    This study followed 35 patients with spastic hemiplegia for 14-20 years and concluded that it was a simple technique with low complications, recurrence rates and satisfactory outcomes over the long term.

    2. FAI 2005 Dec;26(12):1017-20
    Lee WC1, Ko HS.
    Achilles tendon lengthening by triple resection in adult.
    25 ankles with spastic paralysis, percutaneous triple cut achilles tenotomy(hoke) followed up for 1 year. They concluded that there was a risk of achilles rupture in more severely equinus corrections (>30deg), there was an 8% incidence of residual deformity The study suggests that the Hoke tenotomy may have limitations when used for more severe equinus deformities.
    3. FAI 2008 Mar:29(3):325-8.
    Redfern JC1, Thordarson DB.
    Achilles tendon lengthening/posterior tibial tenotomy with immediate weightbearing for patients with significant comorbidities.
    This study followed 13 ankles in 10 patients who underwent achilles lengthening, with tibialis posterior tenotomy, all of the patients had significant comorbidities, the equinus was corrected from a mean of 26 degrees to 1 degree and an improvement in ambulatory status. The study shows that achilles release is effective in correcting ankle equinus, early weight bearing is well tolerated, and was effective in improving ambulatory status.
    4. FAI 2013 Sep:34(9):1233-7
    Sung KH1, Chung CY, Lee KM, Lee SY, Park MS.
    Anterior ankle impingement after tendo achilles lengthening for long standing equinus deformity in residual poliomyelitis
    27 patients with longstanding equinus deformity of the ankle underwent achilles tendon lengthening, there was a 88% incidence of radiographic anterior ankle impingement, most of which were symptomatic, the impingement was significantly worse in those with more severe equinus deformities. The study suggests that further surgery may be required to address ankle impingement following achilles release for long standing equinus, certain in the poliomyelitis group.
    5. JBJS 2013 Aug21;95(16): 1489-56 95
    Firth GB1, McMullan M, Chin T, Ma F, Selber P, Eizenberg N, Wolfe R, Graham HK.
    Lengthening of the gastrocnemius-soleus complex: an anatomical and biomechanical study in human cadavers.
    A cadaveric study comparing 6 different triceps-surae and achilles lengthening procedures, they found that releasing the Triceps surae at deifferent levels bestowed different mechanical and anatomical characteristics whilst a number of the more proximal procedures such as the Baker, Strayer and Vulpius were more stable releases, the z lengthening of the achilles provided a more powerful correction of equinus.
    6. . J Foot Ankle Surg. 2013 Feb;52(1):42-4
    Blackmon JA, Atsas S Clarkson MJ, Fox JN, Daney BT,Dodson SC, Lambert HW
    Locating the sural nerve during Achilles tendon repair: a cadaveric study with clinical applications.
    This was an anatomical study of 107 cadaveric leg dissections, aiming to estimate the intersection point where the sural nerve crosses the lateral border of the Achilles tendon, and is at high risk from iatrogenic injury. In most cases, the sural nerve crossed the lateral border of the Achilles tendon 8 to 10 cm proximal to the superior border of the calcaneal tuberosity. The relevance of this study is that the location of the sural nerve can, in most cases be reliably predicted, and in open achilles lengthening is directly within the surgical field and therefore can be identified and protected.

    Reference

    • orthoracle.com

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