DEFINITION

Tibialis anterior rupture may present as an acute injury or as a chronic painless foot drop. The diagnosis is often delayed.

Recommended treatment is surgical for active patients and nonsurgical for low-demand patients. Surgical options include direct repair and reconstruction.

 

 

ANATOMY

 

The tibialis anterior muscle originates from the lateral tibial condyle and interosseous membrane.

 

 

Its insertion is the medial side of the medial cuneiform and the inferomedial base of the first metatarsal. The musculotendinous junction is at the junction of the middle and distal thirds of the tibia.

 

The tendon courses within a synovial sheath from the musculotendinous junction to its insertion,2 deep to the extensor retinaculum of the ankle and foot.

 

Innervation is the deep peroneal nerve.

 

The tibialis anterior muscle controls deceleration of the foot after heel strike and dorsiflexes the ankle.

 

PATHOGENESIS

 

Younger individuals with healthy tibialis anterior tendons rarely suffer spontaneous rupture; instead, their mechanism of injury is laceration from penetrating trauma or distal tibia fracture.

 

Spontaneous ruptures typically occur in older individuals with degenerative tendinopathy of the tibialis anterior tendon. Minor trauma may be associated with these ruptures, with a mechanism of plantarflexion-eversion.

Ruptures typically occur within 3 cm of the tendon's insertion on the medial cuneiform.1

 

NATURAL HISTORY

 

The natural history of tibialis anterior rupture is inferred from studies documenting the results of nonoperatively treated patients. These patients will ambulate with a slap foot gait and sometimes have difficulty negotiating uneven terrain. Most patients are functional; however, they may require a brace.

 

Nonoperatively treated patients tend to be older and lower demand. The natural history for younger, more active patients may indicate less desirable results.

 

Definite conclusions regarding the natural history of tibialis anterior ruptures are limited due to the low number of reported cases in the literature and lack of natural history studies.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Physical examination methods include the following:

 

Examining for swelling. The examiner should palpate along the course of the tibialis anterior muscle-tendon. Swelling with discontinuity of the tendon indicates a tendon rupture. An anterior ankle mass may be the presenting complaint.

 

Gait disturbance. The examiner should observe the patient ambulating, looking for slap foot gait or foot drop. Chronic ruptures may present with minimal gait disturbance; the patient may have difficulty ambulating only when on uneven surfaces. Inability to heel walk indicates tibialis anterior dysfunction. The patient may need to hyperflex the hip and knee to clear the foot during the swing phase of gait because the ankle does not dorsiflex adequately.

 

Muscle strength is evaluated with manual motor testing. No contraction or weak ankle dorsiflexion suggests tibialis anterior dysfunction. Patients will substitute the toe extensors for the tibialis anterior during ankle dorsiflexion, exhibiting toe hyperextension when asked to dorsiflex the ankle.

 

The examiner should note any heel cord tightness. Subacute and chronic injuries often present with heel cord contractures because the major antagonist to ankle plantarflexion is forfeited with tibialis anterior tendon rupture. As a rule, at least 10 degrees of ankle dorsiflexion must be present for a tibialis anterior repair or reconstruction, and thus surgical management may require adding Achilles tendon or gastrocnemius lengthening.

 

The examiner should completely assess the involved extremity to rule out other diagnoses. The most common errors in diagnosis are as follows:

 

 

Lumbar radiculopathy: presents with diminished sensation, positive straight-leg raise test

 

Peroneal nerve palsy: affects the toe extensors and peroneal musculature in addition to the tibialis anterior. Preservation of extensor hallucis longus (EHL) and toe extensor function will distinguish tibialis anterior

rupture from peroneal nerve palsy.1

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Imaging studies are generally not required in the evaluation of tibialis anterior tendon ruptures because the diagnosis is usually simple to make on clinical examination alone.

 

Radiographs are nondiagnostic and rarely required in the evaluation of tibialis anterior tendon ruptures. Radiographs are, however, useful to assess associated injures (tibial fractures).

 

 

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Magnetic resonance imaging (MRI) may be useful in chronic cases where patients do not recall a history of

trauma.1 MRI demonstrates lack of continuity in the tibialis anterior and signal change in the tendon, particularly with preexisting tendinopathy. Because the tibialis anterior tendon courses from lateral to medial across the anterior ankle and retracts with rupture, occasionally, it is difficult to assess.

 

If there is uncertainty in the diagnosis, electrodiagnostic studies may identify common peroneal palsy or lumbar radiculopathy.

 

DIFFERENTIAL DIAGNOSIS

Peroneal nerve palsy Lumbar radiculopathy

Rarely, a peripheral neuropathy may present as isolated tibialis anterior tendon dysfunction.

 

NONOPERATIVE MANAGEMENT

 

Low-demand patients may be treated with an ankle-foot orthosis (AFO).

 

SURGICAL MANAGEMENT

 

Direct repair of the tendon is occasionally possible, but delay in diagnosis may preclude direct repair due to muscle contracture.

 

A sliding tibialis anterior tendon grafting technique has been described to gain tendon length to allow repair, and allograft tendon transfers have been proposed in the absence of tibialis anterior myofibrosis.

 

 

 

FIG 1 • Extensor hallucis longus (EHL) transfer to medial cuneiform. The proximal end of the tibialis anterior tendon is tenodesed to the EHL. Distally, the extensor hallucis brevis (EHB) is tenodesed to the EHL distal end to preserve hallux interphalangeal joint extension.

 

 

Our preferred reconstruction for tendons that cannot be directly repaired is to augment the repair with the adjacent, native EHL tendon (FIG 1).

 

Indications for allograft tendon reconstruction

 

 

 

Advanced tibialis anterior tendon degeneration Tibialis anterior muscle excursion preserved

 

Minimal to no myofibrosis

 

Allograft reconstruction for a muscle that has no excursion, that is, is scarred, will result in a no more than a tenodesis without function.

 

Preoperative Planning

 

Imaging studies are reviewed when available to appreciate the extent of preexisting tendinopathy and to potentially identify the approximate site of the rupture.

 

The surgeon should prepare for Achilles tendon lengthening or gastrocnemius-soleus recession to achieve adequate (at least 10 degrees) dorsiflexion.

 

Positioning

 

The patient is positioned supine. A bump may be placed under the ipsilateral hip, but this is typically not necessary because access is required only to the anteromedial ankle.

 

Approach

 

An anterior approach is made directly over the course of the tibialis anterior tendon.

 

As has been learned from total ankle arthroplasty and open reduction and internal fixation of tibial pilon fractures, careful soft tissue handling is essential.

 

 

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TECHNIQUES

• Extensor Hallucis Longus Transfer to Medial Cuneiform

Exposure

Perform gastrocnemius recession or Achilles tendon lengthening if indicated.

Use an anterior approach with an incision over the course of the tibialis anterior tendon (TECH FIG 1). Divide the superior and inferior extensor retinaculum and tibialis anterior sheath.

Isolate the remnant of the tibialis anterior tendon. Occasionally, direct repair is possible, rarely by advancing the residual tendon to bone, but instead to the residual tendon stump on the medial cuneiform. If inadequate tendon is available or muscle excursion is poor, proceed with EHL transfer.

Extensor Hallucis Longus Transfer

Expose the EHL tendon. Proximally, the EHL is in a separate sheath adjacent to the tibialis anterior.

Through a separate 3- to 5 -cm incision over the distal EHL immediately proximal to the first metatarsophalangeal joint, divide the EHL tendon distally. Leave enough distal stump to suture to the adjacent tendon of the extensor hallucis brevis. Place a whipstitch consisting of no. 2 nonabsorbable suture in the free end of the EHL.

 

 

 

TECH FIG 1 • A. Anterior approach over tibialis anterior. B. The tendon sheath is opened, exposing the torn retracted end of the tibialis anterior. The sheath is carefully preserved for later repair.

 

 

 

TECH FIG 2 • A. The EHL tendon is harvested by dividing it at the level of the metatarsophalangeal joint.

B. The EHL tendon sheath is entered proximally. The EHL tendon is passed into the tibialis anterior sheath and pulled distally.

 

 

Pass the EHL under the skin bridge and through the tibialis anterior sheath proximally. The EHL will now occupy the previous sheath for the tibialis anterior (TECH FIG 2).

 

Drill a vertical hole in the medial cuneiform for attachment of the EHL. Sequentially drill using 2.5-, 3.5-, and 4.5-mm drill bits. Enlarge the hole with a curette as needed to allow graft passage. Leave enough periosteum to provide additional points of attachment for suturing the graft in place.

Fixation

 

Secure the graft with the ankle in 10 degrees of dorsiflexion (TECH FIG 3A-D).

 

 

 

TECH FIG 3 • A. A drill hole is placed from dorsal to plantar at the midpoint of the medial cuneiform.

(continued)

 

 

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TECH FIG 3 • (continued) B. The drill hole is sequentially enlarged. C. Fixation using a biotenodesis screw (Arthrex, Inc., Naples, FL). The graft is also looped around the medial cuneiform and sutured to itself and surrounding soft tissue. D. Proximally, the EHL is tenodesed to the tibialis anterior stump. E. The EHL stump is sutured to the extensor hallucis brevis.

 

 

Pass the EHL graft from dorsal to plantar. Fixation may be accomplished with an interference screw or by

looping the graft around the medial cuneiform and suturing it to surrounding periosteum and back on itself. The EHL tendon may be further anchored to the residual distal fibers of the torn tibialis anterior tendon.

 

The transferred EHL tendon serves to bridge the gap created by the tibialis tendon rupture. However, the relative strength of the EHL muscle is far less than that of the tibialis anterior muscle. Therefore, in the absence of myofibrosis of the tibialis anterior, we recommend sewing the residual tibialis anterior tendon stump to the transferred EHL tendon under some tension.

 

Attach the distal EHL stump to the extensor hallucis brevis, and we recommend dorsiflexing the hallux about 10 to 15 degrees to compensate for anticipated stretching of this tendon transfer postoperatively (TECH FIG 3E).

Completion

 

Close the tibialis anterior tendon sheath, superior extensor retinaculum, and wound in layers (TECH FIG 4).

 

Place a splint or bivalved cast with the ankle in 10 degrees of dorsiflexion. Avoid plantarflexion, as this places tension on the wound edges and tendon transfer.

 

 

 

TECH FIG 4 • The tibialis anterior sheath is closed.

• Allograft Tendon Reconstruction

Assess for Equinus Contracture

 

 

Delay in diagnosis and treatment of a tibialis anterior tendon rupture may lead to an equinus contracture. Allograft tibialis anterior tendon reconstruction typically restores satisfactory dorsiflexion.

 

 

If no equinus contracture, then the Achilles tendon should not be lengthened. However, it may not restore full physiologic function.

 

Cannot overcome an equinus contracture

 

With an equinus contracture, consider judicious tendo Achilles tendon lengthening or gastrocnemius-soleus recession.

 

If equinus indeed present, Achilles lengthening or gastrocnemius-soleus recession should be performed prior to allograft tibialis anterior tendon reconstruction.

 

Although a utilitarian midline anterior approach to the ankle may be used, repair/reconstruction of distal tibialis anterior tendon avulsion is facilitated if the incision is directed medially toward the physiologic course of the tibialis anterior tendon.

 

This is important in allograft tendon reconstruction where exposure of the residual distal tendon and first cuneiform is important for securing the distal allograft.

 

 

Create a longitudinal incision directly over the physiologic course of tibialis anterior tendon (TECH FIG 5A). Protect the superficial peroneal nerve that courses superficial to the extensor retinaculum.

 

 

Expose the extensor retinaculum (TECH FIG 5B). Divide the extensor retinaculum.

 

The retinaculum may be divided directly over the ruptured tibialis tendon to expose the ruptured tibialis anterior tendon (TECH FIG 5C).

 

 

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TECH FIG 5 • A. Longitudinal incision directly over physiologic course of the tibialis anterior tendon. B. Expose the extensor retinaculum. C. Longitudinal incision in the extensor retinaculum to expose the tendon rupture.

Assessing the Ruptured Tibialis Anterior Tendon

 

 

Often, patients with tibialis anterior tendon ruptures do not present immediately after acute rupture. Proximal tendon

 

The proximal end of the tendon is typically retracted.

 

The example case demonstrates a subacute rupture with a bulbous proximal end of the tendon (TECH FIG 6A,B).

 

To consider allograft reconstruction, the proximal tendon and muscle must have some excursion.

 

 

 

TECH FIG 6 • A. Proximal tendon identified. B. Characteristic findings of a subacute rupture. C. The proximal tendon (and muscle) must have excursion for an allograft tendon reconstruction to restore dynamic ankle dorsiflexion. D. Release of proximal tendon adhesions. E. Adhesions released within the tibialis anterior tendon sheath deep to the proximal extensor retinaculum. F. Limited residual distal tendon is this patient with tibialis anterior tendon avulsion injury. G. After proximal tendon mobilization, the tendon ends can be approximated, but the poor quality of residual distal tendon is not conducive to direct repair.

 

 

 

Place distally directed tension on the proximal tendon to assess excursion (TECH FIG 6C). Applying careful tension for several minutes typically restores some excursion.

 

Lack of excursion does not necessarily indicate muscle fibrosis; limited excursion may be due to adhesions within the sheath from lack of motion.

 

Release adhesions with blunt-tipped scissors advanced between the proximal tendon and its tendon sheath (TECH FIG 6D,E).

 

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Distal tendon

 

 

The distal tendon, with its attachment to the base of the first metatarsal, is static without excursion. In the example case, the tibialis tendon ruptured from its distal attachment.

 

Minimal residual tendon attachment remains (TECH FIG 6F).

 

Although the proximal and residual distal tendon ends may be approximated after proximal tendon and muscle mobilization, the lack of satisfactory distal tendon quality eliminates the option of direct repair (TECH FIG 6G).

Reconstruction

 

The allograft tibialis tendon should be pretensioned.

 

 

Preserve the residual distal native tendon to be used in the distal allograft reconstruction. Assess the planned course of the allograft tendon (TECH FIG 7A).

 

It should course to the plantar medial aspect of the first cuneiform.

 

Place suture anchors in the medial aspect of the first cuneiform.

 

Consider fluoroscopic guidance to optimize anchor positioning (TECH FIG 7B).

 

Anchor the allograft tendon distally.

 

 

Suture anchors to the medial aspect of the first cuneiform (TECH FIG 7C). Suture the residual distal native tendon to the allograft tendon (TECH FIG 7D).

 

A tendon weave may be considered.

 

In this example case, the residual native tendon was more conducive to a side-to-side repair.

 

 

 

TECH FIG 7 • A. Assessing course of allograft tendon with planned distal reattachment. B. Suture anchors placed in medial aspect of first cuneiform. C. Anchoring allograft to medial first cuneiform. D. Securing residual distal native tendon to anchored allograft tendon. E. Confirming satisfactory distal allograft tendon attachment.

 

 

Confirm that the distal attachment is satisfactory.

 

By applying tension to the attached allograft tendon, ankle dorsiflexion should be possible (TECH FIG 7E).

Proximal Allograft Tendon Attachment

 

 

Support the ankle in neutral position (TECH FIG 8A). Weave the allograft into the proximal native tendon.

 

Carefully create the first longitudinal slit in the distal aspect of the native proximal tendon.

 

Create the slit sharply with a scalpel and avoid unnecessary injury to the tendon.

 

This initial slit should be no more than 1 cm in length affording optimal contact between tendons.

 

 

Pass the proximal end of the allograft tendon through the distal proximal native tendon. Place proximally directed tension on the allograft.

 

Place distally directed tension on the proximal native tension.

 

Because the tendon reconstruction is intended to be dynamic and function physiologically, excessive overtensioning is typically not indicated.

 

However, because some stretch of the allograft and more proximal native tendon/muscle excursion is anticipated, slightly greater than physiologic tension should be considered.

 

 

Secure the allograft to the native proximal tendon with nonabsorbable suture (TECH FIG 8B). Weave the allograft tendon through the native tendon for a second time.

 

Perform the second longitudinal slit in the native tendon approximately 2 cm proximal from the first slit.

 

To avoid the two slits in the tendon becoming confluent, create the second slit at 90 degrees from the first.

 

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TECH FIG 8 • Weaving allograft tendon to the proximal native tendon. A. Ankle held in neutral dorsiflexion. B. After first pass of allograft tendon through native tendon, tension applied to tendons and tendons secured with suture. C. Second weave created by passing scalpel blade through tendon at 90 degrees from initial weave in the direction intended for the allograft to be passed. D. Scalpel blade pushed back through slit in native tendon with a hemostat clamp. E. Allograft tendon pulled through the native tendon with the hemostat clamp.

 

 

The slit in the native tendon is performed sharply with a scalpel blade passed through the native tendon from the same direction intended for the allograft tendon to be passed.

 

Once the tip of the scalpel blade has passed through the tendon, fasten a hemostat clamp to the scalpel's tip and push the scalpel blade back out of tendon so that the hemostat is safely passed through the same slit in the tendon without compromising the tendon (TECH FIG 8C,D).

 

 

Pull the allograft tendon through the slit in the native tendon (TECH FIG 8E). Tension the two tendon ends and suture as described for the first weave earlier.

 

A third weave and possibly a fourth weave are created to optimally secure the allograft to the native tendon.

 

 

Each slit is spaced at least 2 cm from the previous slit. Each slit is created at 90 degrees from the previous slit.

Completion

 

The excess allograft tendon is excised.

 

 

Reinforce the distal and proximal allograft attachments to the native tendon with absorbable suture. Ensure that the tendon is intact and competent with ankle motion.

 

Close the retinaculum over the reconstructed tendon (TECH FIG 9A-D).

 

Avoid a suture capturing the tendon reconstruction.

 

Routine skin closure; consider using a drain.

 

Consider temporary chemical weakening of the gastrocnemius muscle.

 

Although the tibialis anterior tendon reconstruction is healing and muscle function is restored, its antagonist, the gastrocnemius muscle, may be temporarily weakened with botulinum toxin injection (TECH FIG 9E).

 

Botulinum toxin injection to the gastrocnemius muscle for this purpose may be expensive and should be preauthorized prior to surgery (TECH FIG 9F).

 

Gastrocnemius weakness after botulinum toxin injection typically persists for 3 to 6 months, ideal for recovery of the tibialis anterior tendon reconstruction.

 

Because botulinum toxin has some potential side effects, the plan to inject botulinum toxin to the gastrocnemius muscle must be discussed with the patient as part of the informed consent process.

 

Splint or cast with ankle in slight dorsiflexion.

 

 

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TECH FIG 9 • Closing extensor retinaculum. A. After tendon reconstruction complete, begin closing extensor retinaculum proximally. B. Care to avoid trapping the tendon reconstruction in the retinacular closure. C.

Important to completely close retinaculum over full length of tendon reconstruction. D. Note that tendon

reconstruction well contained within retinaculum. E,F. Temporary chemical gastrocnemius weakening. E. Botulinum injection into gastrocnemius muscle (the antagonist to the tibialis anterior) may help protect the reconstruction during the 6 months of rehabilitation. F. Botulinum toxin is expensive and should be preapproved before surgery.

 

 

Misdiagnosis ▪ Perform a complete history and physical examination to rule out conditions that

may mimic tibialis anterior rupture.

Failure to ▪ Note ankle dorsiflexion as part of the preoperative evaluation and perform Achilles

address heel tendon lengthening or gastrocnemius recession as indicated. cord

tightness

Inadequate

EHL graft length

• Expose and divide the distal end of the EHL at the metatarsophalangeal joint level.

Wound

breakdown

• Carefully close the tibialis anterior sheath, superior extensor retinaculum, and

subcutaneous tissue before skin closure. Immobilization in at least 5 degrees of dorsiflexion is important to avoid tension on the wound edges.

Graft failure

• Secure fixation with proper use of an interference screw and adequate graft length

  to suture back on itself and surrounding tissues.

• Postoperative immobilization

• Avoidance of early aggressive rehabilitation

PEARLS AND PITFALLS

 

 

POSTOPERATIVE CARE

 

EHL transfer

 

 

A short-leg cast is worn for 6 weeks, followed by an AFO for an additional 6 weeks.

 

Allograft tendon reconstruction

 

 

Two to 3 weeks

 

 

Wound check and suture removal

 

 

Sturdy posterior splint with ankle in slight dorsiflexion Two to 6 weeks

 

Reliable patient should perform intermittent gentle passive ankle range of motion.

 

 

Three or four times a day ankle removed from splint to perform passive ankle/hindfoot range of motion

 

No active ankle dorsiflexion unless physical therapist (PT) supervision available to perform active-assisted dorsiflexion

 

Touchdown weight bearing

 

 

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Unreliable patient probably best casted in slight ankle dorsiflexion Six to 10 weeks

 

Cam boot

 

Weight bearing as tolerated in cam boot

 

Physical therapy with active-assisted ankle dorsiflexion for first 2 weeks and gradually progressing to active dorsiflexion over second 2 weeks

 

Ten to 14 weeks

 

 

 

Continue physical therapy and progress to active dorsiflexion. Hinged AFO with a plantarflexion stop during day.

 

Still use splint or boot with ankle in neutral position while sleeping.

 

Fourteen to 24 weeks

 

 

Gradual return to activities of daily living without splint

 

Continue physical therapy to develop program to return to full activities by 6 months.

OUTCOMES

Sammarco et al5 presented a series of 18 patients with acute and chronic tibialis anterior tendon ruptures managed with direct repair or interpositional graft. There was significant improvement in the average hindfoot score. The authors concluded that surgical repair of a ruptured tibialis anterior tendon can be beneficial regardless of age, sex, medical comorbidities, or delay in diagnosis.

Ouzounian and Anderson4 reported on seven patients with tibialis anterior rupture treated with a variety of surgical reconstructive techniques. All patients had an increase in strength and function.

Markarian et al3 failed to show a significant difference between operative and nonoperatively treated groups. The lack of statistical significance was possibly due to the bimodal age distribution in the study, with older, more sedentary patients receiving nonoperative treatment.

The literature is scarce regarding the results and complications of surgical reconstruction of the tibialis anterior tendon due to the rarity of this injury.

 

 

COMPLICATIONS

Intraoperative graft complications Neuroma

Wound dehiscence Infection

 

Graft failure

 

 

REFERENCES

1. Coughlin MJ. Disorders of tendons. In: Coughlin MJ, Mann RA, eds. Surgery of the Foot and Ankle, ed 7. St. Louis: Mosby, 1999: 790-795.

    

    

2. Cracchiolo A. Anterior tibial tendon disorders. In: Nunley JA, Pfeffer GB, Sanders RW, et al, eds. Advanced Reconstruction Foot and Ankle. Rosemont, IL: American Academy of Orthopaedic Surgery, 2003:173-177.

    

    

3. Markarian GG, Kelikian AS, Brage M, et al. Anterior tibialis tendon ruptures: an outcome analysis of operative vs. nonoperative treatment. Foot Ankle Int 1998;19:792-802.

    

    

4. Ouzounian TJ, Anderson R. Anterior tibial tendon rupture. Foot Ankle Int 1995;16:406-410.

    

    

5. Sammarco VJ, Sammarco GJ, Henning C, et al. Surgical repair of acute and chronic tibialis anterior tendon ruptures. J Bone Joint Surg Am 2009;91(2):325-332.