Anterior Tibialis Transfer for Residual Clubfoot Deformity

 

 

 

 

DEFINITION

The incidence of residual deformity in congenital clubfoot ranges from 26.6% to 50%, regardless of the initial treatment provided.2

The disparity in the reported incidence is due to varying severity of clubfoot deformity, different methods of treatment, and, in part, differing definitions of residual deformity.

Residual deformities include isolated equinus, cavus, metatarsus adductus, hindfoot varus, forefoot supination, and combinations of the above.

Dynamic forefoot adduction and supination can be observed after clubfoot treatment with or without soft tissue releases.

Dynamic forefoot supination deformity results from muscle imbalance. Anatomic imbalances can be due to primary absence or weakness of the anterior tibialis or peroneal muscles or as a result of neurologic abnormalities in the central nervous system or the peroneal nerve. Functional muscle imbalance can result from residual medial displacement of the navicular on the head of the talus. In this case, because its insertion is medially displaced, the anterior tibialis becomes a forefoot supinator instead of a dorsiflexor (FIG 1).

 

 

 

FIG 1 • Normal foot versus supinated foot. Medial subluxation of the navicular, the medial cuneiform, and the first metatarsal results in supination deformity as the line of pull of the tibialis anterior tendon directs the foot into supination instead of dorsiflexion.

 

 

The aim of treatment is to correct any fixed deformity and to rebalance the muscles of the foot, thereby correcting dynamic deformity and improving foot alignment.

 

ANATOMY

 

The anterior tibialis muscle originates from the upper two-thirds of the tibia.

 

The anterior tibialis tendon fibers rotate 90 degrees from the musculotendinous junction to its insertion on the medial cuneiform and first metatarsal.

 

 

Medial rotation begins proximally, so the most medial muscle fibers proximally rotate to the posterior surface of the tendon near the midpoint and continue to rotate so that their final insertion is as the distal-lateral fibers on the first metatarsal.

 

Meanwhile, the most lateral muscle fibers proximally rotate to the anterior surface at the midpoint and

continue distally to insert on the cuneiform as the proximal-medial fibers (FIG 2).4

 

 

 

FIG 2 • Anatomy of the tibialis anterior muscle-tendon. The anterior tibialis tendon fibers rotate 90 degrees from their musculotendinous junction to their insertion on the medial cuneiform and the first metatarsal such that the proximal-medial insertional fibers on the cuneiform begin as the lateral fibers at the musculotendinous junction (see window).

 

 

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The anterior tibialis muscle is active in two important stages of the gait cycle; it concentrically fires during the initiation of swing phase and keeps the foot dorsiflexed during early swing phase and then it relaxes. The anterior tibialis muscle then fires eccentrically as the foot is lowered to the floor from heel strike to foot flat in stance phase.

 

As a dorsiflexor, the anterior tibialis muscle opposes gravity and the strong gastrocsoleus complex. Importantly, the anterior tibialis muscle may also be a supinator of the forefoot in the face of peroneal longus weakness or medial displacement of the insertion.

 

There are important bony abnormalities associated with residual clubfoot deformity.

 

 

The subtalar joint may have an absent anterior facet and small, narrow medial and posterior facets, resulting in restricted subtalar motion. In this setting, the calcaneus does not slide fully into valgus with casting such that the navicular remains medially displaced.

 

The navicular itself is wedge-shaped and is medially displaced along with the cuneiforms and metatarsals.10 With medial displacement of its insertion, the biomechanical advantage favors the action of the anterior tibialis

muscle as a strong supinator over its role as a dorsiflexor ( FIG 3).

 

PATHOGENESIS

 

The cause of residual clubfoot deformity may be incomplete correction or recurrence of deformity as part of the natural history of the resistant clubfoot.

 

Electromyographic and magnetic resonance imaging (MRI) studies have demonstrated that the peroneal muscle group can be absent, smaller, and relatively weaker, thus increasing the supinator action of the tibialis anterior muscle.1, 3

 

Medial subluxation of the navicular is considered an important factor influencing both the appearance of the foot and the lateral rotation of the ankle.9

 

In addition to the bony abnormalities associated with clubfeet, anatomic variations from the customary insertion of the anterior tibialis muscle into adjacent areas of the first metatarsal and medial cuneiform occur in 10% of pathologic specimens.

 

 

In these variants, the distal anterior tibialis muscle inserts more medially than normal, optimizing the force vector for supination.8

 

 

 

FIG 3 • Bony abnormalities associated with residual clubfoot deformity. The navicular is wedge-shaped and is medially displaced along with the cuneiforms and metatarsals.

 

 

 

FIG 4 • Hindfoot varus. When untreated, residual deformity may become stiff. When fixed inversion deformity is combined with residual equinus deformity, hindfoot varus occurs.

 

NATURAL HISTORY

 

Residual deformities are usually encountered within the first year after initial treatment and generally before the age of 5 years, even in congenital clubfeet that had been fully corrected since the first month of life.

 

Residual forefoot adduction and supination are common deformities after nonoperative treatment and can also be seen after initial operative repair. They can result from undercorrection at the time of the primary

intervention.13

 

Correction of resistant congenital clubfoot often requires more than one surgery, not because of a “failed initial intervention,” but because the dynamic muscle imbalances may not be fully manifest at the time of the initial intervention. Thus, the need for an additional operation can be perceived as part of the natural history of

congenital clubfoot.12

 

If left untreated, the dynamic deformity may become stiff and the foot tends to invert.

 

 

When inversion deformity is combined with residual equinus deformity, hindfoot varus may recur (FIG 4).

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Residual deformity is more likely in patients who have clubfoot as a result of myelomeningocele or other neuromuscular syndromes and genetic disorders such as Larsen syndrome. Therefore, it is important to consider neurologic causes, such as tethered cord, when confronted with residual deformity.

 

Recurrent deformity may be found in children with only four toes on the affected foot, as these individuals may have absence of the peroneal muscle group (similar to that seen in fibular hemimelia), thus leaving them prone to recurrence.

 

Recurrent deformity may be suspected prior to treatment in newborns with curled toes and no active toe dorsiflexion when scratching the plantar aspect of the foot. In those infants that have been treated with the Ponseti method, later recurrence may be heralded by scratching the bottom of the foot that leads to more supination than dorsiflexion.

 

One of the first clinical signs of recurrence is a dynamic inversion of the foot with slight equinus. Equinus may be difficult to quantify, as midfoot breech will often accommodate and hide the hindfoot equinus (FIG 5).

 

Residual deformity most frequently occurs in severe or atypical cases, which are often associated with a small calf size. These children may also have short, fat feet with a deep plantar crease that extends from the medial border

 

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to the lateral border of the foot and a shortened first ray. These findings are consistent with severe or atypical clubfeet (often termed complex clubfoot) that have a propensity for residual deformity.

 

 

 

FIG 5 • Examination findings of residual supination and equinus deformity. A. Forefoot supination. B. Hindfoot equinus. C. Anterior view combined forefoot supination and hindfoot equinovarus. D. Posterior view combined forefoot supination and hindfoot equinovarus.

 

 

In maximum pronation or maximum supination, the navicular-medial malleolar distance is decreased compared to the normal foot. In fact, the medial malleolus can be difficult to delineate because it is in contact with the navicular. The navicular malleolar distance demonstrates the extent of medial subluxation.

 

It is important to examine gait when possible.

 

 

During examination of gait, the clinician should identify whether the tibialis anterior is a dynamic supinator; this is best observed in swing phase when no antagonist muscles contract.

 

This finding will confirm the appropriateness of surgery.

 

The strength of the tibialis anterior is tested. With dynamic supination deformity, the supinator action of the anterior tibialis muscle will overpower the dorsiflexor action, thus demonstrating the appropriateness of surgery. In addition, good power is needed for a successful transfer.

 

The clinician should evaluate for other deformities, such as equinus, cavus, varus, adductus, and tibial torsion.

 

Range of motion of the ankle is examined. Transfer will work only as long as there is no fixed contracture of the ankle or heel cord.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Anteroposterior (AP) and lateral radiographs may be helpful to study and quantify various deformities.

 

AP radiographs will demonstrate medial deviation of the metatarsals, which can indicate residual medial displacement of navicular, which is yet to ossify (FIG 6).

 

 

On an AP radiograph of normal feet, the line drawn through the long axis of the talus should point to the first metatarsal, whereas the line drawn through the long axis of the calcaneus should point toward the fourth metatarsal.

 

 

In clubfeet, these lines become more parallel, depicting “stacking” of the talus and calcaneus.

 

Forced maximum dorsiflexion lateral radiographs may reveal hindfoot equinus with midfoot breech.

 

 

Stacking of the metatarsals on the lateral radiograph identifies the presence of residual forefoot supination (a decreased talocalcaneal angle).

 

 

Ultrasound evaluation of the foot is not done routinely. However, experimental studies have demonstrated that this technique is capable of documenting the location of the navicular in relationship to the head of the talus. The navicular is subluxated plantarward and medially on the head of the talus.

 

Similarly, MRI can be performed to completely identify the relationships of the cartilaginous bones and the size and presence of the lateral leg muscles.

 

 

This technology is rarely clinically used, as orthopaedists are aware of the classic deformities that are associated with recurrence and the increased risk of general anesthesia for a childhood MRI scan may not be justified.

 

 

DIFFERENTIAL DIAGNOSIS

Residual deformities in clubfoot may be due to unrecognized tarsal coalitions or other conditions in syndromic clubfoot, severe, or complex clubfeet.

Unexpected and rapid recurrent deformity in children with previously corrected feet and with known myelomeningocele may be a result of continued neurologic involvement, such as tethering of the spinal cord.

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FIG 6 • Weight-bearing AP and lateral radiographs of feet shown in FIG 5. A. The long axes of the talus and calcaneus are somewhat parallel rather than divergent. The metatarsals appear adducted in relation to the talus. B,C. The long axis of the talus and calcaneus appear somewhat parallel rather than divergent on

 

 

the lateral view of the right foot. The axes of the talus and the first metatarsal do not form a straight line, as opposed to a normal foot. This degree of divergence from this linear alignment represents intrinsic deformity of the clubfoot. The metatarsals are stacked on the weight-bearing lateral views.

 

 

NONOPERATIVE MANAGEMENT

 

Treatment of residual deformity depends on the location, severity, and age of the child.

 

Recasting and repeat tenotomy may be considered in children younger than 18 months of age who have residual deformity.

 

 

Most residual deformities at this age can be treated by manipulation, followed by application of a toe-to-groin plaster cast with the feet in a fully corrected position for 2 weeks. Most of these patients have residual equinus that requires progressive dorsiflexion at each casting session.

 

After 2 weeks, the casts are removed and reapplied.

 

Usually, three casting sessions are required, for a total of 6 weeks.

 

Thereafter, abduction bracing is reinstituted. Several different abduction orthosis are commercially available and if one system is not well accepted, another maybe better tolerated.

 

In larger children, ankle-foot orthoses (AFOs) may also be used to prevent recurrence.

 

Physiotherapy may also be used in patients with residual deformity. The therapist must be familiar with techniques to manipulate residual forefoot adductus and stretch the posterior contracture without producing or accentuating midfoot breech. In older children and in patients with midfoot breech, it can be difficult to effectively stretch any hindfoot equinus contracture.

 

With residual equinus contracture, abduction bracing is difficult.

 

 

Unbraceable posterior contracture can then lead to recurrent metatarsus adduction and forefoot supination. Thus, a repeat percutaneous heel cord tenotomy and casting may be required.

 

SURGICAL MANAGEMENT

 

In children more than 2 to 3 years of age, and who failed conservative measures to correct deformity, it may be preferable to correct any residual deformity using soft tissue lengthenings or transfers with or without bony procedures.

 

As the anterior tibialis acts as a supinator, lateral transfer of the anterior tibialis tendon is often necessary to correct dynamic supination deformity.

 

The optimal age for lateral transfer of the anterior tibialis tendon varies from case to case. Important factors are the rapidity of recurrence, the strength of the anterior tibialis muscle, the presence of fixed forefoot deformity, or the presence of concurrent equinus deformity or cavus and the desired location to transfer the tendon.

 

 

Ponseti advocated transferring the tendon completely into the lateral cuneiform as such the surgery should be performed after the lateral cuneiform ossification center appears (2 to 4 years of age). Although some surgeons have successfully transferred tendons into cartilage anlage, this chapter outlines transfer of the tendon into the ossified cuneiform.

 

Alternatively, some surgeons have advocated transfer of the anterior tibialis tendon into the peroneus tertius, half of the peroneus brevis, or occasionally into metatarsals. In general, insertion of the tendon along an axis drawn along the third metatarsal will promote foot dorsiflexion.

 

The split anterior tibialis tendon transfer (SPLATT) of Hoffer et al6 is rarely used in idiopathic clubfeet but is an excellent method for correcting dynamic supination deformity as a result of spasticity associated with disorders such as cerebral palsy. This method may have some use in children with mild, flexible forefoot supination who require surgery for other deformity.

 

Preoperative Planning for Transfer into the Lateral Cuneiform

 

Feet with residual deformity should be extensively evaluated by clinical and radiographic assessment before surgical planning. Each foot should be treated individually, as no single treatment plan is appropriate for all feet.

 

 

Associated deformities must be identified. For example, an anterior tibialis transfer will function poorly in the face of a fixed equinus contracture. In this case, it will be necessary to correct equinus deformity with a heel cord tenotomy or lengthening or posterior release.

 

Residual varus deformity may indicate the need for an opening wedge or sliding calcaneal osteotomy.

 

Persistent metatarsus adductus may necessitate midfoot osteotomies in order for the lateral border of the foot to be reduced.

 

 

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Anterior tibialis tendon transfer does not correct restricted subtalar motion.

 

 

It is important to confirm that the ossific nucleus of the lateral cuneiform is present in order to place the anterior tibialis tendon into an appropriate anchor site.

 

Positioning

 

The patient is placed in the supine position on a standard operating table or the legs draped over a hand table.

 

 

Either positioning is done in a way to ensure good fluoroscopic images.

 

A well-padded, thigh-high tourniquet should be placed before preparing and draping the patient.

 

Approach

 

A medial incision is based over the insertion of the anterior tibialis tendon.

 

From this incision, the surgeon may be able to perform an opening wedge osteotomy of the medial cuneiform if indicated.

 

 

Once the anterior tibialis tendon is detached, a lateral incision is based over the lateral cuneiform. Fluoroscopic imaging can assist in planning this incision.

 

The lateral incision may need to be longer and more laterally based should the surgeon decide to perform a cuboid closing wedge osteotomy at the same time.

 

TECHNIQUES

• Full Anterior Tibialis Tendon Transfer to the Lateral Cuneiform5, 11

Approach

A 4-cm long dorsal-medial longitudinal skin incision is made over the course of the anterior tibialis tendon from the inferior margin of the ankle retinaculum (the superior limb of the inferior extensor retinaculum) to its palpable distal insertion based over the medial cuneiform (TECH FIG 1).

Dissection is carried down through subcutaneous tissues and the inferior limb of the inferior extensor

 

retinaculum to expose the tendon sheath.

 

The anterior tibialis tendon sheath is incised sharply and opened as far distally as possible and then proximally to just short of the ankle retinaculum.

 

A hemostat is placed under the anterior tibialis tendon to help expose the insertion.

 

This broad extensive insertion is detached as far distally as possible to gain maximum length of tendon for the transfer.

 

It is critical to obtain as much length as possible.

 

 

 

TECH FIG 1 • A. Two incisions are made. B. The medial incision is made over the course of the tibialis anterior tendon. The surgeon frees the tendon from its broad insertion as far distally as possible and proceeds proximally as far as the ankle retinaculum.

 

Transferring the Tendon

 

Once the tendon is freed and detached distally, a strong absorbable suture (eg, 1-0 Vicryl) is woven in a Bunnell-type fashion through the anterior tibialis tendon.

 

Care is taken to weave the suture in a fashion that does not lead to a bulbous end, thus making the tendon difficult to deliver to the lateral wound and subsequently pass into the lateral cuneiform.

 

Occasionally, the loose ends of the tendon insertion are trimmed or incorporated with a 3-0 absorbable suture to facilitate passage and anchoring.

 

By pulling on the suture, the tendon is gently pulled distally while the soft tissue attachments to the tendon are freed up to, but not beyond, the ankle retinaculum.

 

 

To avoid bowstringing of the tendon, it is important not to release the ankle retinaculum. A dorsal-lateral longitudinal incision, 1.5 to 2 cm long, is made over the lateral cuneiform.

 

The lateral cuneiform is identified just proximal to the base of the third metatarsal.

 

 

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Dissection is carried down through subcutaneous tissues to the toe extensors.

 

To expose the lateral cuneiform, the toe extensors are retracted medially and the extensor digitorum

brevis muscle is retracted laterally.

 

A cruciate periosteal incision is made directly over the lateral cuneiform, carefully avoiding the adjacent joint articulations.

 

In young children, a Keith needle is used to fluoroscopically locate the center of the ossific nucleus.

 

In older children, a small periosteal elevator is used to elevate the periosteal flaps off the lateral cuneiform.

 

Occasionally, these flaps may be sutured into the transferred tendon, thus supplementing fixation. In young children, however, it may be difficult and futile to elevate perichondrium from the predominantly cartilaginous bone.

 

A blunt hemostat is then passed from the lateral incision over the lateral cuneiform and under the extensor tendons to the point where the anterior tibialis tendon passes beneath the ankle retinaculum.

 

Use the hemostat to develop a tract for the transfer of the anterior tibialis tendon.

 

The hemostat is passed into this same tract into the medial wound to grasp the suture ends and bring the anterior tibialis tendon into the lateral wound (TECH FIG 2).

 

Ensure that the available length of the tendon will reach the proposed transfer site into the lateral cuneiform.

Attaching the Transferred Tendon

 

A drill bit is selected to be slightly larger than the diameter of the sutured anterior tibialis tendon end.

 

Once the bit is selected, make a hole directly in the center of the lateral cuneiform, drilling just through the plantar aspect of the bone (dorsal to plantar while aiming for the arch of the foot).

 

The suture ends of the tendon are threaded onto Keith needles (TECH FIG 3A).

 

While the foot is maximally dorsiflexed and everted, the suture needles are passed through the lateral cuneiform drill hole and out through the plantar aspect of the foot, guiding the tendon through the drill hole.

 

 

 

TECH FIG 2 • The freed anterior tibialis tendon is brought into the lateral wound.

 

 

The tendon is confirmed to easily and reproducibly slide into its new insertion.

 

This is a critical step: Be certain that the tendon reliably enters the anchoring hole after the skin is closed when the foot is dorsiflexed and when the suture is tensioned. Smooth passage of the tendon into the third cuneiform may be facilitated by a drop or two of sterile mineral oil.

 

The suture needles on the plantar aspect of the foot are passed through a nonadhesive dressing (eg, Adaptic) and a sterile felt pad.

 

At this time, it is advisable to irrigate and close all other associated wounds, leaving the lateral recipient wound for last.

 

This way, the surgeon can ensure that the anterior tibialis is in the intended position just before dressing and cast application.

 

The periosteum of the lateral cuneiform is sutured with two interrupted absorbable sutures to the transferred anterior tibialis tendon while it is pulled into the recipient site (TECH FIG 3B).

 

The lateral wound is irrigated and closed in layers while the foot is held in a dorsiflexed position, thus ensuring that the anterior tibialis remains in the hole and the continuity of the periosteal sutures is preserved.

 

Sterile dressings are applied while an assistant simultaneously maintains the foot dorsiflexed with tension on the suture.

 

The distal foot and ankle portion of a toe-to-groin cast is applied while ensuring that the suture ends of the tendon are in tension.

 

In the past, we have tied the button over the felt underneath the cast. However, a high rate of pressure

sores has led us to consider alternative fixation.

 

After the cast is hardened, the suture is tied over a button on the exterior of the plantar aspect of the cast (TECH FIG 3C).

 

 

To prevent plantar pressure sores, make sure the plaster is sufficiently hardened. Commercially available suture anchors can also be used to facilitate fixation of the tendon.

 

Some surgeons will perform the exact procedure except transfer the whole tendon into the cuboid. These surgeons choose this

 

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insertion site if the foot has a concurrent fixed forefoot deformity and mild hindfoot varus that they choose not to correct.

 

 

 

TECH FIG 3 • A. The suture ends of the tibialis anterior tendon are threaded onto Keith needles and passed into the drill hole through the plantar aspect of the foot. The tendon is guided into the drill hole. B. While the foot is maximally dorsiflexed and everted, the tendon is secured. The periosteum of the third cuneiform is sutured with interrupted nonabsorbable sutures into the transferred tibialis anterior tendon. C. The cast is molded and hardened with the foot in dorsiflexion and eversion and with the suture ends under

appropriate tension. The suture is tied over a button on the exterior of the hardened cast to prevent plantar pressure sores.

 

 

We prefer to correct the fixed deformity and transfer the anterior tibialis into the lateral cuneiform, as we fear overcorrection from the more lateral insertion into the cuboid.

 

Some surgeons add a third incision at the anterior distal tibia directly over the anterior tibialis tendon and just lateral to the tibial crest. The tendon can be easily palpated. The tendon sheath is incised here and the freed distal tendon end is pulled with a hemostat into this incision. From this incision, the freed distal tendon end is eventually pulled into the lateral incision for attachment.

• Split Anterior Tibialis Tendon Transfer

  Approach

   

  A 4-cm long dorsal-medial skin incision is made over the course of the anterior tibialis tendon from the inferior margin of the ankle retinaculum (the superior limb of the inferior extensor retinaculum) to its palpable distal insertion based over the medial cuneiform.

   

  Dissection is carried down through subcutaneous tissues and the inferior limb of the inferior extensor retinaculum to expose the tendon sheath.

   

  The anterior tibialis tendon sheath is incised sharply and opened as far distally as possible and then proximally to just short of the ankle retinaculum.

   

  The lateral half of the anterior tibialis tendon insertion is detached as far distally as possible to gain maximum length of tendon for the transfer.

   

  A strong absorbable suture (eg, 1-0 Vicryl) is woven in a Bunnell-type fashion through the lateral half of the anterior tibialis tendon.

  Transferring the Tendon

   

  The suture is grasped and pulled, allowing the lateral tendon to be gently dissected proximally but not beyond the ankle retinaculum.

   

  To avoid bowstringing of the tendon, it is important not to release the ankle retinaculum.

   

  A dorsal-lateral longitudinal incision, 1.5 to 2 cm long, is made over the cuboid in line with the fourth metatarsal axis.

   

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  Dissection is carried down through subcutaneous tissues to the toe extensors. To expose the cuboid, the toe extensors are retracted medially.

   

  A cruciate periosteal incision is made directly over the cuboid, carefully avoiding the adjacent joint articulations.

   

  An appropriate drill hole is then made in the cuboid, drilling dorsal to plantar in line with the fourth metatarsal axis and through the plantar aspect of the bone.

   

  A blunt hemostat is then passed from the incision over the cuboid under the extensor tendons to the point where the split anterior tibialis tendon passes beneath the ankle retinaculum.

   

  Use the hemostat to develop a tract for the transfer of the anterior tibialis tendon.

   

  The hemostat is passed into this same tract into the medial wound to grasp the suture ends and bring the split anterior tibialis tendon into the lateral wound.

   

  The suture ends of the tendon are threaded onto Keith needles.

  Fixation of the Tendon to Bone

   

  While the foot is maximally dorsiflexed and everted, the suture needles are passed through the cuboid drill hole and out through the plantar aspect of the foot, guiding the tendon through the drill hole.

  The tendon is confirmed to easily and reproducibly slide into its new insertion.

  The suture needles are passed through a nonadhesive dressing (eg, Adaptic) and a sterile felt pad.

  The periosteum of the cuboid is sutured with two interrupted absorbable sutures to the transferred split anterior tibialis tendon.

  The wounds are irrigated and closed in layers.

  Sterile dressings are applied while ensuring that the felt pad is flush with the plantar skin and the suture ends of the tendon are at hand.

  Alternative fixation may include use of suture anchor into the cuboid or transfer of the lateral half of the tendon into half of the peroneus brevis tendon or the peroneus tertius tendon prior to its insertion into base

  of the fifth metatarsal.9

  With the standard technique described earlier, the most medial muscle fibers proximally are the ones attached to the laterally transferred split tendon, resulting in a proximal crossing over as the split tendon is laterally transferred.

  Fennell and Phillips4 suggest releasing the proximal medial insertion on the cuneiform instead of the distal lateral insertion on the first metatarsal to avoid this proximal crossing over, allowing for a more direct line of pull of the muscle on the transferred tendon.

   

  PEARLS AND PITFALLS
  	Indications ▪ Anterior tibialis transfer will work only as long as there is no fixed contracture. Flexibility of the foot is the main condition for a successful surgical result because the surgical procedure is based on the dynamic muscle imbalance of the forefoot.     Positioning ▪ Use of a tourniquet at 200-250 mm Hg will allow easier surgery.     Tendon ▪ Too short a tendon can make transfer difficult, so the surgeon should obtain as harvest much length as possible.     Tendon ▪ It may be difficult to locate the lateral cuneiform in small children. Therefore, fixation intraoperative fluoroscopy should be available.

  • Bowstringing and weakness by inadvertently cutting the extensor retinaculum should be avoided.

  • The surgeon should attach a suture to the released tendon to allow ease of handling and passing. This will also keep the tendon from fraying as it exits the donor site.

  • An absorbable suture is used to hold the tendon as it usually dissolves and weakens by 6 weeks.

  • Alternative forms of fixation may be considered in older children with large bones, such as a suture anchor (FIG 7).

  • Overcorrection can be avoided with insertion of the full tendon transfer along the third metatarsal axis. For the split tendon transfer, the optimal site for insertion to

   

  obtain maximal dorsiflexion in biomechanical studies is along the fourth metatarsal axis.7

   

  Wound closure

  • All wounds are closed except the recipient site to be sure that the transferred tendon stays in the tunnel. Also, the foot is kept in maximum dorsiflexion during final wound closure and casting. A well-trained assistant is paramount.

 

Cast management

• Pressure sores on the bottom of the foot can result from too much tension on the button. Therefore, it should be placed on the exterior of the cast.

• Swelling and pressure sores may result if extensive and lengthy procedures are done. In these cases, prophylactic dorsal splitting of the cast in the operating room is important.

 

 

 

 

FIG 7 • Intraoperative photo of lateral (recipient) wound. Alternative forms of fixation may be considered in older children with large bones, such as a suture anchor.

 

 

 

 

POSTOPERATIVE CARE

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In patients younger than 5 years of age and those who may be noncompliant, a toe-to-groin bent-knee cast is maintained with the patient non-weight bearing for about 6 weeks.

 

 

At 6 weeks, the button and suture are removed and the patient is allowed to begin walking.

 

In older children, a short-leg cast for an initial 6 weeks is maintained.

 

 

At 6 weeks, the button is removed and patient is placed in a short-leg walking cast for an additional 3 weeks to ensure healing and to avoid tendon rupture.

 

Clinical and radiographic assessment of outcomes is performed at the end of healing. Plain radiographs

(standing AP and lateral foot radiographs) are usually sufficient. Computed tomography (CT) examination may be obtained if indicated (FIG 8).

 

A nighttime stretching AFO is often recommended for use in those children with residual Achilles contracture that required reduction. This may be needed for a year or so.

 

OUTCOMES

 

Successful surgery will be noted by correction of the supination deformity and conversion of the anterior tibialis into the primary dorsiflexor of the foot. Clinical examination of the foot during active dorsiflexion demonstrates the new insertion site of the anterior tibialis tendon.

 

Twenty-seven previously treated clubfeet in 25 patients were retrospectively evaluated after tibialis anterior

tendon transfer to correct residual dynamic supination deformity.1 All showed active contraction of the transferred tibialis anterior tendon. There was no case of overcorrection.

 

 

 

FIG 8 • Postoperative clinical photograph of patient in FIG 5. Foot alignment is restored after full-thickness anterior tibialis tendon transfer in the right foot. The left foot is shown as comparison.

 

 

Clinical and radiographic improvement in both forefoot adduction and supination was demonstrated in 71 cases of residual dynamic congenital clubfoot deformity treated by full and split anterior tendon transfer,

with an increase in the eversion strength of the tibialis anterior muscle.8

 

Farsetti et al2 confirmed the findings of multiple studies, demonstrating that transfer of the anterior tibial tendon to the lateral cuneiform underneath the extensor retinaculum corrects and stabilizes relapsing clubfeet by restoring normal function of foot dorsiflexion-eversion. In their two series of patients reviewed at the end of skeletal growth, none of the operated patients had further relapse.

COMPLICATIONS

Undercorrection Cast sores Wound infection

Loosening of the transferred tendon Rupture of the transferred tendon

Bowstring at the anterior ankle joint resulting in weakness and a cosmetic deformity Loss of dorsiflexion force

Overcorrection

 

 

REFERENCES

1. Ezra E, Hayek S, Gilai AN, et al. Tibialis anterior tendon transfer for residual dynamic supination deformity in treated clubfeet. J Pediatr Orthop B 2000;9:207-211.

    

    

2. Farsetti P, Caterini R, Mancini F, et al. Anterior tibial tendon transfer in relapsing congenital clubfoot. J Pediatr Orthop 2006;26:83-90.

    

    

3. Feldbrin A, Gilai AN, Ezra E, et al. Muscle imbalances in the etiology of idiopathic clubfoot: an EMG study. J Bone Joint Surg Br 1995;77(4): 596-601.

    

    

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