Anterior Tibial Tendon Tears

Courtesy: NIcholas Strasser MD
Vanderbilt Unviersity, Nashville, Tennessee, US

 

Overview and Background

• Anterior tibial tendon ruptures are rare and not well documented.

• Treatment strategies can be tricky due to the limited literature.

• The speaker has experience with external ankle bracing, which is used in rehabilitation.

Anatomy Review

• The anterior tibial tendon originates from the lateral tibia and runs under the extensor retinaculum.

• It inserts into the medial cuneiform and base of the first metatarsal.

• Innervated by the deep fibular (peroneal) nerve.

• Blood supply includes the anterior tibial artery (proximal) and medial tarsal artery (distal).

• The rupture often occurs in a “watershed” area with less vascular supply.

Function of the Tendon

• Main function is during about 1/3 of the gait cycle.

• In swing phase: helps dorsiflex the foot for toe clearance.

• In stance phase: eccentrically lowers the foot to the ground during heel strike.

• Provides dorsiflexion and inversion.

• Dysfunction may mimic foot drop and lead to tripping or foot slapping.

Pathophysiology and Biomechanics

• Ruptures often occur in tendons with pre-existing tendinopathy.

• Tendon behaves like a spring during gait, storing and releasing energy.

• Muscle fibers don’t change length as much—tendon stretch accounts for motion.

Epidemiology and Presentation

• Much less common than Achilles tendon ruptures.

• Typical patient: active male in 60s–70s, sometimes linked to sports like pickleball.

• Common patient remarks:

  • “My foot slaps when I walk.”

  • “I trip over my foot.”

  • “It’s weak, not painful.”

  • “Feels unstable.”

  • “I catch my toe when barefoot.”

Clinical Diagnosis

• Often misdiagnosed as an ankle sprain.

• Important to test ankle dorsiflexion in all “ankle sprain” patients.

• Must check contralateral side for comparison.

• EHL (extensor hallucis longus) may compensate, masking the rupture.

• Gait may show compensatory big toe lift (steppage gait).

Imaging

• MRI is useful—look for distal rupture signs (e.g., “Slytherin sign” or snake-head shape).

• May show associated arthritis or osteophytes irritating the tendon.

Treatment Options

• Non-operative treatment:

  • Best for elderly or non-surgical candidates.

  • Use of drop foot braces can be surprisingly effective.

  • No need to operate on all patients.

  • Concern exists about delaying surgery: may lead to muscle atrophy or worsen function.

• Surgical repair:

  • Preferred for acute traumatic ruptures.

  • Timing and patient selection are key.

  • Tendon transfers may be needed in some cases.

• Key Points Summary:

  Early Repair (<6 weeks):

  • Not always ideal — tendon may be too diseased to heal well.

  • Even early, tendon reapproximation can be difficult.

  • Standard approach: Anteromedial incision; repair with a Krackow stitch technique.

  • If the tendon quality is good, early repair is reasonable.

  Techniques for Primary Repair:

  • Insertional ruptures can use:

    • Suture anchors

    • Teno-deses screws

    • Endobuttons (looped through the medial cuneiform)

  • Goal: regain tendon length — often challenging.

  Outcomes & Expectations:

  • Only small case series available; no large comparative studies.

  • Patients generally do well but rarely regain full strength.

  • Residual weakness common — especially in toe extension (EHL still firing).

  • Important to counsel patients pre-op: “never quite normal”.

  Case Example (Traumatic Laceration):

  • Female in her 50s with ATT laceration and retraction.

  • Successful acute repair after separate incision for proximal stump.

  • Also repaired EHL, EDL.

  • Result: functional recovery, but minor imbalance/clawing of toes — typical due to altered length-tension relationship.

  If You Can’t Reapproximate Tendon:

  • Z-lengthening or free sliding tendon graft using the patient’s own tendon.

  • Maintains native anatomy and avoids donor site morbidity.

  • Downside: altered tendon biomechanics.

  • Gait analysis: good function but not symmetrical — about 50% dorsiflexion compared to the unaffected side.

  Chronic Cases: Tendon Transfer Options:

  • Most use EHL or EDL transfers.

  • EHL transfer:

    • In-phase transfer.

    • Weak (ATT provides ~80% of dorsiflexion strength).

    • Risks: big toe droop.

    • May require IP joint fusion to stabilize toe.

    • Fixation methods: interference screw, drill hole + loop back.

    • Set repair in 10° dorsiflexion.

    • Often combined with gastrocnemius recession to reduce posterior tension.

  • EDL transfer:

    • Weaves EDL into ATT.

    • Distal slips tenodesed to EDB.

    • Rarely used; mostly case reports.

  Allograft/Autograft Reconstruction:

  • Often used when:

    • Large gaps or chronic ruptures.

    • Extensor tendons not available.

  • Needs viable ATT muscle for function.

    • Consider MRI of proximal leg to evaluate muscle quality.

    • Similar approach to rotator cuff tear evaluation.

  • May also achieve tenodesis effect (passive support) even with minimal muscle contraction.

    Surgical Technique Overview:

    1. Graft Options:

    • Allografts are usually preferred due to availability and avoidance of donor site morbidity.

    • Hamstring autografts may be used in revisions or when allografts aren’t viable.

    2. Graft Fixation Strategy:

    • Use of Pulvertaft weave and distal bio-tenodesis for strong fixation.

    • If using a longer graft (allograft/autograft), a drill hole in the medial cuneiform can help anchor it.

    3. Graft Material:

    • Preference for Arthrex FlexBand Twist (5mm x 30mm).

      • Benefits: strong suture-holding capacity, spring-like behavior, durable under tension.

    4. Incision and Tissue Management:

    • Two-incision approach:

      • Distal incision to identify and tag the ATT stump.

      • Proximal incision above the extensor retinaculum, preserving overlying soft tissue to reduce wound complications.

    • Avoid disruption of the extensor retinaculum, which improves healing and lowers morbidity.

    5. Surgical Steps:

    • Secure graft distally into medial cuneiform.

    • Attach native ATT to graft at distal end.

    • Pass graft under retinaculum to proximal ATT stump.

    • Max dorsiflex the ankle and tension graft proximally before fixation.

    • Reinforce with tendon-to-tendon suture repair, potentially with a Z-lengthening if tension is too high.

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    Post-Op Rehab Protocol:

    0–4 Weeks:

    • Splint or cast in maximum dorsiflexion.

    • Emphasis on no plantar flexion or stretch—staff instructed not to let foot hang.

    4–8 Weeks:

    • Transition to a CAM boot.

    • Begin passive dorsiflexion, active plantarflexion, progressive weight-bearing.

    8+ Weeks:

    • Transition to brace or similar:

      • Can be locked in dorsiflexion.

      • Avoids limb length discrepancy.

    • Continue physical therapy to regain strength and function.

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    Clinical Outcomes:

    • Early results show good dorsiflexion strength return.

    • Incisions heal well; tendon glides appropriately.

    • Avoids drawbacks of autografts (donor site issues), while achieving strong functional restoration.