Tibialis Anterior (TA) Tendon Rupture: Management, Classification, TA Repair & EHL Transfer

Epidemiology & Anatomy

1. At its insertion into the medial cuneiform (Fig. 88.59 in Campbell's)
2. Beneath the superomedial limb of the inferior extensor retinaculum - this zone is relatively avascular and is associated with attritional ruptures

• Attritional/spontaneous - in patients >45 years with predisposing conditions (inflammatory arthritis, steroid injections, diabetes)
• Acute traumatic - forceful dorsiflexion of an acutely plantarflexed foot against resistance (soccer, American football)

Classification of TA Rupture

A. Chronicity (Ouzounian/Clinical Classification)

B. Gap Size After Debridement (Vosoughi et al. 2019 - Treatment Algorithm)

C. Aetiology

• Traumatic (laceration, acute overload)
• Atraumatic/Spontaneous (attritional, degenerative - more common)

Diagnosis (Campbell's)

• Presenting complaint: weakness of dorsiflexion and (to lesser degree) anterior ankle pain
• Physical exam can be misleading: extrinsic toe extensors compensate for dorsiflexion, masking the degree of deficit
• Palpable tendon defect may be absent in chronic cases (scar healing in continuity with lengthening)
• Chronic ruptures: contracture of long toe extensors causing toe clawing
• Beischer et al. test for distal tendinosis: ankle plantarflexed + hindfoot everted + midfoot abducted/pronated to passively stretch TA - sensitivity 90%, specificity 95%

Treatment

Non-operative

• Reserved for low-demand patients or those with surgical contraindications
• Short leg brace with 90-degree downstop for 3-6 months
• NSAIDs + immobilization for tenosynovitis (removable walking cast, 6 weeks total)
• Note: in more active patients, surgical management of both acute and chronic ruptures showed better outcomes than non-operative management

Surgical Techniques (Campbell's)

Technique 88.18: Synovectomy of the Anterior Tibial Tendon

• Incision begins just distal to the ankle joint, courses medially and posteriorly to the anterior tibial tendon (does not cross the ankle joint)
• Open sheath, excise synovium; one or both limbs of the inferior extensor retinaculum can be preserved
• Postoperative: cast 4-6 weeks; compressive ankle corset for additional 4-6 weeks

Technique 88.19: Debridement and Repair of Distal Anterior Tibial Tendon (Grundy et al.)

1. Supine positioning, thigh tourniquet; curvilinear incision over TA tendon
2. Open tendon sheath, examine for tendinosis and split tears
3. Excise degenerated tendon, exostosis of medial cuneiform, and midfoot osteophytes
4. If >50% of normal tendon remains: repair longitudinal split with No. 0 Ethibond; Bio-Corkscrew FT suture anchor with No. 2 FiberWire at medial cuneiform insertion
5. If <50% of normal tendon remains: augment with EHL transfer (see EHL Transfer steps below)

EHL Transfer Technique (Augmentation - within Technique 88.19)

1. Make a second longitudinal incision over the dorsolateral aspect of the 1st MTP joint
2. Identify extensor hallucis brevis (EHB) and extensor hallucis longus (EHL); scrape their surfaces with No. 15 blade to facilitate adhesion
3. Suture EHL to EHB with No. 0 PDS and No. 0 Vicryl, with hallux IP joint held in 20 degrees of dorsiflexion
4. Identify EHL tendon proximally and transect it immediately proximal to the EHB tenodesis site
5. Pull EHL tendon into proximal wound; tag cut end with Krackow suture
6. Close the distal incision
7. Drill a 4.5-mm hole in the medial cuneiform from dorsal to plantar
8. Pass EHL tendon through the split in the remaining anterior tibial tendon, then through the drill hole from plantar to dorsal
9. Secure EHL tendon with a 5.5-mm Bio-Interference screw under firm (not maximal) tension, ankle held in plantigrade position

Fig. 88.62: A) Ruptured anterior tibial tendon, B) EHL anastomosed to EHB before transection, C) EHL passed through drill hole in cuneiform, D) Close-up of the transfers

Technique 88.20: Repair of Complete Rupture of the Anterior Tibial Tendon

1. Incise the inferomedial band of inferior extensor retinaculum
2. Advance the tendon as far distally as possible
3. Drill a hole in the medial cuneiform from dorsal to plantar (enlarge incrementally to 0.635-2.5 cm)
4. Pass tendon through the hole with a Bunnell weave of No. 0 nonabsorbable suture on free straight needles; pull tendon into hole while dorsiflexing ankle 20-30 degrees; suture tendon edge to adjacent periosteum and deep fascia

1. Incise the superomedial limb of inferior extensor retinaculum
2. If tendon cannot be advanced: make a second small incision (2-3 cm) anteromedially above the ankle to retrieve the proximal stump
3. Pass a long curved clamp along the tendon proximal-to-distal; use a rubber urinary catheter sutured to tendon to pull it distally if needed
4. If tendon cannot reach medial cuneiform: use navicular as the bony insertion instead

• Interpositional graft sources (preferred order): plantaris, extensor digitorum, peroneus tertius, Achilles; semitendinosus allograft
• Fold grafts 2-3 times to match TA tendon diameter
• Repair extensor retinaculum to prevent bowstringing

Technique 88.21: Minimally Invasive Tendon Reconstruction with Semitendinosus Autograft (Michels et al.)

• If 5 degrees of dorsiflexion cannot be achieved preoperatively: perform gastrocnemius recession first
• Harvest semitendinosus with a tendon stripper (as in ACL reconstruction)
• Small longitudinal incision above superior extensor retinaculum, leaving extensor retinaculum intact (minimizes adhesions, decreases recovery time)
• Evidence shows this results in minimal disturbance of the extensor retinaculum, decreasing recovery time, adhesions, and wound problems

Postoperative Care Summary

Evidence Summary (Campbell's Systematic Review)

• Direct repair, turn-down tibialis anterior flap, semitendinosus autograft, EDL autograft, plantaris autograft - all showed better outcomes than EHL autograft reconstruction techniques
• Allograft vs. autograft reconstruction: both achieved good patient-reported outcomes and both graft types remained intact in comparison studies
• Key principle: when TA muscle shows fatty infiltration on MRI, free tendon graft is not useful - EHL transfer is preferred in this scenario

Miller's Review Key Points (Orthopaedic Board Summary)

• Tenosynovitis: uncommon; seen in inflammatory arthritis; NSAIDs + walking cast/boot; corticosteroid injections may provide relief but increase risk of tendon rupture
• Complete ruptures: rare, mainly older patients; commonly missed diagnosis (presents as painless anterior ankle mass; foot drop subtle due to toe extensor recruitment)
• Primary repair generally improves functional results regardless of age
• Tendon grafting augmentation if adequate excursion and healthy muscle
• Interpositional graft required in delayed cases
• Consider adding gastrocnemius recession/Achilles lengthening to take tension off the TA reconstruction

Note on Hoppenfield