//

Calcaneo-navicular Coalition takedown

    Overview

    Learn the Calcaneo-navicular Coalition takedown surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Calcaneo-navicular Coalition takedown surgical procedure.
    As with all coalitions the main indication for operation in a Talo-Calcaneal coalition is for pain relief. Improved joint mobility may result though this is far less predictable , especially in the adult patient, and is not an indication for operation.
    The classical features of a unilateral plano-valgus foot and a fixed subtalar joint are by no means invariably present. Some patients may demonstrate apparent subtalar mobility on examination due to compensatory ankle mobility.
    The question in adults with Tarsal coalitions is always whether to perform a simple take-down rather than to proceed directly to fusion surgery and this is a decision made with the patient fully aware of the implications of both surgical paths.

    Indications

    INDICATIONS.
    -As with all coalitions the main indication for operation is for pain relief .
    -Improved joint mobility may result though this is far less predictable , especially in the adult patient, and is not an indication for operation.
    SYMPTOMS AND EXAMINATION.
    The commonest presentation of the condition is with lateral hindfoot pain. This can occur in a previously asymptomatic adult (though it will have been longstanding) or there may be a long history of manageable symptoms which have deteriorated. On rare occasions the coalition presents co-incidentally following an ankle sprain or other unrelated injury which has failed to settle. A proportion of patients will also have associated spurring of the talo-navicular joint, which can be discreetly symptomatic. If so they will suffer dorso-medial midfoot pain and probably be locally tender here. This requires an additional approach to debride the talo-navicular joint.
    The classical features of a unilateral plano-valgus foot and subtalar stiffness are by no means invariably present. Some patients have a normally aligned hindfoot and apparently mobile Subtalar joint. The latter on accurate examination can be seen to be due to compensatory ankle mobility. Coalitions may on occasion present bilaterally.
    It is often difficult clinically to make an assessment of the presence of arthritis given the inherent stiffness in many coalitions .
    The question in adults with Tarsal coalitions is always whether to perform a simple take-down rather than to proceed directly to fusion surgery. My own preference has always been to preserve the joints initially in the absence of degenerative change and especially in the absence of any deformity of note. This is less successful in percentage terms than opting primarily to fuse (Subtalar or Triple) but is quicker to recover from and will not have the likely deteriorating effect upon the ankle observed in the longer term after fusion surgery.
    The long-term outcome of leaving asymptomatic coalitions untreated in terms of their relative risk of developing secondary arthritic change is not known. If the coalition is associated with significant stiffness that this may occur ultimately is a logical assumption (and of course arthritis is present in some at presentation). It is difficult to argue for surgically treating coalitions if they are not symptomatic.
    Though classically coalitions present from late childhood into adolescence they can first become symptomatic far later into adult life, when minor symptoms become less tolerable.
    INVESTIGATION.
    Coalitions are detectable by their direct appearance on imaging and an educated guess can be made about their presence if spurring (and sometimes dysmorphism) of the Talo-navicular joint is seen.
    A purely bony coalition can be seen with an oblique or lateral hindfoot X-Ray as can any relevant Talo-navicular pathology.
    A more objective and comprehensive assessment of all relevant joints, alignments and pathologies is more routinely made however with MRI, occasionally CT or both. Coalitions may be purely fibrous, purely bony or more often a mix.
    NON-OPERATIVE MANAGEMENT.
    In the adult an attempt at conservative management is appropriate in many patients. The nature of this may be a period in a post-operative boot , the use of an orthotic or an intra-coalition injection (or all three). One paper in the literature review of this section suggests that conservative management is highly successful in the symptomatic adult but I have never found it so.
    ALTERNATE/ADDITIONAL OPERATIVE MANAGEMENT.
    -In Adults the first question if operative treatment is required is whether there is significant inter-current arthritic change present or not. If so joint fusing surgery may be a better choice. Whether a triple fusion or simply subtalar fusion depends on the nature of the deformity and degenerative change.
    -In the presence of significant hindfoot valgus additional procedures may be considered at the time of surgery to improve the hindfoot position during joint sparing surgery. In the adult an examples would be a medialising Calcaneal osteotomy . In the child or adolescent the addition of an arthroresis implant into the sinus tarsi.
    -It there is inter-current dorsal spurring of the talo-navicular joint and the patient also localises discomfort to this area this joint should be debrided also.
    The approach described is used for access to the medial side of the subtalar joint
    The most common reasons for this are either as part of correcting a severely valgus & degenerate subtalar joint or takedown of a Talo-calcaneal tarsal coalition.

    Setup

    GA or Regional anaesthetic
    Thigh tourniquet
    Femoral & Sciatic nerve block for post-operative pain relief
    Peri-operative antibiotics
    LMW Heparin prophylaxis in appropriately aged patients.
    Supine position , sandbag under contra-lateral buttock

    Operation

    The skin incision runs from the tip of the fibula along a line running to the base of the fourth metatarsal(1,1). The Sural nerve can be encountered in the inferior part of the wound , in the vicinity of the peroneal tendons. It is most predictably located (and should be located to avoid inadvertent injury) usually just posterior to the peroneal tendons at the level of the Fibula tip. On occasion it may however sit just anterior to the tendons also .The nerve must be handled gently & only dissected enough to allow its protection. Neuromas or nerve dysfunction which not infrequently result from nerve injury produce symptoms and hypersensitivity in an awkward area.
    The Extensor Digitorum Brevis (EDBr) (2) belly is immediately deep to the incision in its mid-point and should be defined.
    On occasion a second dorsally placed incision is required if the Talo-navicular joint has symptomatic spurring and also requires debridement.

    If fat is excised carefully from the area of the origin of the EDBr muscle belly then one gains access to the sinus tarsi region of the Subtalar joint . This is an easy landmark from which to direct dissection forwards along the anterior process of the calcaneus and to the coalition.

    The origin of the Extensor Digitorum Brevis (1) is carefully reflected en masse off the Calcaneus , to expose its anterior process. Inferiorly the peroneal tendons are visible (2).
    Some advocate sewing of this muscle into the resected coalition to reduce the chance of re-fibrosis or ossification but I’m not sure the evidence for this is much. It can be slightly disfiguring to the lateral aspect of the foot to do this.

    The initial exposure once the EDBr is reflected is of the Calcaneo-cuboid joint (1). Further sub-periosteal stripping is required to follow the anterior Calcaneal process in a superior & medial direction towards the coalition.

    The anterior process has been exposed (1) and rather than finishing discreetly it runs on into the Navicular. The extent of this “bridging” by the coalition is variable.
    The coalition can be fairly mobile and predominantly fibrous (in which case the abnormal area is easy to identify by virtue of its relative mobility) or as in this case a dense , complete bony bar. These can be more difficult to decide on how much to resect and where to start and finish the resection. It is key that a complete and generous resection of the abnormal tissue is undertaken.

    A Calcaneo-Navicular bar may need to be persued far across to the medial aspect of the mid-foot. A Homans’ retractor placed deeply into the dorsal aspect of the wound ,after a wider sub-periosteal dissection, aids this. A medium sized Wests’ retractor is also key but should be both placed well beneath the skin edges as well as frequently relaxed to minimise the chance of skin damage.

    An appropriately sized osteotome should be selected and the direction of travel informed by the pre-op CT imaging. Care needs to be taken superiorly with the inferior aspect of the Talar head and neck. It is entirely appropriate to dissect the soft tissues from the inferior aspect of the distal Talus to help in its definition.
    In excising the coalition the direction of the osteotomes’ travel will be by definition distal and inferior to the Talus.

    A ¾ cm width of bone to be removed (1) in this case. The inferior aspect of the talar neck is seen superiorly (2). This is a discreet anatomical structure with a different orientation to the coalition.

    A good section of bone needs removing . This is best done progressively with a completely bony bar as is shown here with further bone to be excised in the deep aspect of the wound.

    A large and complete bony coalition such as this will require resection right across to the medial aspect of the foot. The deepest aspect of this resection should be performed with care , bearing in mind that the neuro-vascular bundle sits at a level just beneath the Sustentaculum Tali medially. After adequate resection there should be visible mobility at the resected interface and also Subtalar joint. Bone wax may be used on the raw bone surfaces. Some advocate the placing of a fat graft or sewing of the EDBr into the gap but based on no great evidence.
    Re-growth of the coalition is a recognised complication of “take-down” surgery for any coalition.
    The aim is to reduce the chance of re-fibrosis/ossification across the interface.

    An Axial CT of a bony Calcaneo-Navicular bar.

    An oblique lateral x-ray of a different patient but again with a complete bony coalition .

    It is more usual that an MRI is required to diagnose the coalition. Here a combined bony & fibrous coalition is seen, with oedema especially effecting the lateral navicular (1)

    The combined bony & fibrous nature of this calcaneonavicular coalition is best demonstrated with this T1 image.

    Post Operative

    After take down of a coalition the first two weeks are spent in a lightweight cast , limited weight bearing
    After two weeks into long post-operative boot and commence weight bearing using crutches.
    Usually by the end of 3 weeks post op it is comfortable to weight-bear just in the boot without the need for crutches.
    From 2 weeks , once out of cast , active and passive ankle & Subtalar range of movement exercises are started .This should be under physiotherapy supervision.
    The main objective of surgery is pain relief. On occasion increased Subtalar range that is achieved on table can be maintained , but only with an active program of joint mobilisation and only if this is not at the expense of pain returning.
    Routine post-operative imaging is not required. Coalitions often require either CT or MRI to diagnose and in an improved patient this is not justified post-operatively. The time to consider imaging is if in doubt about the resection (its level or adequacy) when on-table. If patients are not improved post-operatively then imaging is required. This may be anywhere from earliest 6-12 weeks. An MRI initially is preferred as bone oedema is not uncommon and will settle with adequate off-loading of the area (post-operative boot and crutches).
    Of greatest 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/shoewear.
    Any exudate from the wound which is allowed prolonged contact with the wound will further excacerbate any skin breakdown . Dressing changes may therefore need to be frequent if such a complication ensues.
    Once out of cast I advise another month of daytime dressings when in shoes and also nocturnal dressings whilst any of the wound remains unhealed
    Showering & bathing is from when out of cast.

    Recommended Reading

    Tarsal coalitions in the adult population :Does treatment differ from the adolescent ?
    Foot Ankle Clin 2012 (jun) 17 (2): 195-204 .Thorpe SW, Wukich DK
    The authors management protocol is detailed. 3 months of conservative treatment initially followed by joint sparing surgery as an initial route in the absence of significant intercurrent arthritic change is advocated. Resection is more likely to be successful in Calcaneonavicular coalitions than Talocalcaneal coalitions in the authors experience
    For patients requiring fusion if the hindfoot is neutral alignment an in-situ subtalar fusion and if valgus deformation then a Triple fusion possibly with additional calcaneal osteotomy.
    Tarsal coalition in adults.
    Foot Ankle Int 2000 ;21(8):669-72.
    Varner KE, Michelson JD.
    32 feet with 18 talocalacaneal ,14 calcaneonavicular coalitions & 1 naviculocuneiform coalition reported. Approximately 2/3rds showed decreased subtalar movement and a similar proportion had a neutral hindfoot. Conservative management was used comprising casting , analgesia & activity modification .
    5 patients proceeded to operative management (onecoalition resection and 4 subtalar fusions)
    Long term functional outcomes of resected tarsal coalitions.
    Foot Ankle Int 2013:34(10):1370-5
    Khoshbin A, Law PW, Caspi L, Wright JG.
    Mean age at surgery 12 years and at follow up 27 years
    19 calcaneonavicular coalitions reviewed and 13 Talocalcaneal coalitions .No significant difference with respect to outcome and no effect on outcome relating either to extent of coalition or degree of hindfoot valgus.
    Calcaneonavicular coalition :Treatment by excision and fat graft.
    J Paediatric Orthop.2009 :29(5);418-26.
    Mubarak SJ et al
    Review of a paediatric cohort treated operatively with a minimum of 12 month follow up .
    Most patients had returned to sporting activity , in 3/4 of patients the subtalar joint was demonstrably more mobile and in 5% the coalition regrew requiring re-excision .

    Reference

    • orthoracle.com

    Tags:

    You might be interested in

    Dark mode powered by Night Eye