A 44-year-old man with right ankle pain and weakness

Issue: November 2015

ByBrian R. Waterman, MD

ByVeasna T. Srey, DPM

ByMarina J. Rodriguez, MD

A 44-year-old male Army service member presented to the emergency department with acute onset of right ankle pain and weakness during a game of kickball. He described inadvertently catching his foot on the ground while attempting to strike the ball, which resulted in a fixed plantarflexion and audible pop. Afterward, he noted immediate onset of severe pain, swelling, and inability to lift his ankle or bear weight without assistance. He denied any antecedent ankle pain or prior injuries, and his medical history was only significant for well-controlled hypertension. The patient had no history of prodromal symptoms.

On physical examination, his ankle demonstrated increased resting plantarflexion compared with his contralateral side. There was a soft tissue prominence about the proximal anterior aspect of his ankle with moderate edema and exquisite tenderness to palpation present throughout the entire course. He had two out of five motor strength for ankle dorsiflexion with recruitment of his great and lesser toe extension, and five out of five strength during resisted ankle plantarflexion. He was able to actively plantar and dorsiflex his great toe against resistance, and he exhibited foot drop on attempted of ambulation. He demonstrated no neurosensory deficits, and his foot was well-perfused with brisk capillary refill and palpable dorsalis pedis pulse.

Plain film radiographs of the foot and ankle revealed soft tissue edema without evidence of osseous injury. Further evaluation with MRI of the ankle was obtained (Figure 1).

What’s your diagnosis?

MRI studies of sagittal T2-weighted images demonstrating injury.

See answer on next page.

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Atraumatic tibialis anterior tendon rupture

The patient’s history, physical examination and MRI findings are consistent with disruption of the tibialis anterior (TA) tendon with proximal retraction. TA tendon rupture is a rare injury with limited published literature discussing repair techniques or clinical outcomes after repair or reconstruction. Coursing from the proximal lateral tibia and interosseous membrane to its insertion on the plantar and medial aspect of cuneiform and base of the first metatarsal, the TA functions as the primary dorsiflexor of the ankle, with secondary contributions from the extensor hallucis longus and extensor digitorum longus. With these structures intact, patients retain the ability active dorsiflexion the ankle and foot after heel strike during normal early to middle gait cycle.

However, with untreated TA dysfunction, this action can be notably weaker than the normal extremity and ultimately, the development of compensatory claw or hammer toe deformities. Traumatic ruptures to the TA tendon are often associated with a direct laceration or blunt force trauma with combined osseous or further soft tissue injury. Atraumatic ruptures are sustained after an eccentric load to a plantar flexed foot in a younger population. Conversely, attritional ruptures are more frequently seen in older individuals and can be associated with a history of diabetes, local corticosteroid injections, prior fluoroquinolone use or inflammatory arthropathies. Physical exam findings supportive of rupture include loss of normal contour of the ankle, use of extensor hallucis longus for dorsiflexion of the ankle and pseudotumor at the anterior ankle. Ambulation occurs with a high-step gait to permit foot clearance during the swing phase in absence of active dorsiflexion. Traumatic ruptures can occur anywhere along the length of the tendon, although atraumatic ruptures frequently are associated with a prodrome of anterior ankle pain and typically occur close to the insertion site on the medial cuneiform.

Discussion and management

In older, low-demand individuals or in patients with partial tendon ruptures, nonoperative management with an ankle-foot orthosis can be successful. Operative repair or reconstruction is advocated for in a younger population due to better overall patient satisfaction and objective ankle scores. Nonoperative management is associated with gait disturbance, lesser toe deformity, equinus contracture, functional weakness with ankle dorsiflexion and pain from the retracted tendon stump.

This intraoperative photograph demonstrates the tibialis anterior rupture (left is proximal and right is distal).

This intraoperative photograph demonstrates the tibialis anterior tendon after tenodesis to the medial cuneiform (left is distal and right is proximal).

Images: Rodriguez MJ

Operative techniques range from primary repair or tenodesis to reconstruction with interpositional grafting or formal tendon transfers. Primary repair is recommended when the injury occurred within 3 months of presentation. If ruptured midsubstance, acute, end-to-end tendon repair can be performed with a high-tensile, nonabsorbable suture. If the rupture occurs more distally, the proximal end can be tenodesed back to its anatomic insertion using variety of fixation constructions, including suture anchors or interference screw fixation. If tendon length is insufficient after debridement of non-healthy tendon and will not allow for primary repair without excessive tension or extreme dorsiflexion (e.g., greater than 20°), the gap may be bridged with autograft tendon; usually with the extensor digitorum longus, Achilles or plantaris tendon. Alternatively, a sliding tendon lengthening technique has been well described. As an adjunct, these procedures may be combined with tendo-Achilles lengthening to restore optimal balance between the flexor and extensor musculature about the ankle, particularly when intraoperative Silverskiold test reveals less than 5° of dorsiflexion.

Postoperative clinical image confirms full, active dorsiflexion of the ankle at 10-week follow-up.

Postoperative care often entails cast immobilization and protected weight-bearing for 4 weeks, followed by transition to a hinged CAM walker with discontinuation of crutch use. Formal physical therapy is initiated at approximately 4 weeks to 6 weeks with full active and passive dorsiflexion and limited forcible plantarflexion. An ankle foot orthosis may be discontinued when full plantar flexion was achieved, and return to running and full physical activity at 4 months to 6 months postoperatively.

Postoperative AP, weight-bearing radiograph of the foot after tibialis anterior tenodesis is shown.

Individuals with delayed presentation or attritional tibialis anterior injuries may warrant more complex clinical management and prolonged rehabilitation. Due to poor tissue quality associated with chronic tears or underlying tendinopathy, these patients may require tendon transfers to recover adequate dorsiflexion strength, most commonly with adjacent transfer to the extensor halluces longus (EHL) or to a lesser extent, the second or third slip of the extensor digitorum longus. For EHL transfers, the distal EHL is sutured to the extensor hallucis brevis to mitigate loss of great toe extension. Other authors have also suggested the use of the posterior tibialis tendon as an alternative transfer. Due to small sample sizes in available studies, there is little comparative data to discern relative differences in clinical outcomes by treatment choice or timing of reconstruction. However, most patients report satisfactory clinical outcomes and most return to regular activities with full dorsiflexion strength.

In the current case, the tendon rupture occurred just proximal to its footprint on the medial cuneiform (Figure 2), leaving a frayed and non-viable residual distal stump. Accordingly, the proximal tendon was subsequently delivered into a 7-mm tunnel in the medial cuneiform and fixed using a 6.25 x 15-mm biocomposite tenodesis screw (Figure 3). The patient was immobilized in a splint followed by a short leg cast for a total of 4 weeks. After cast immobilization, the patient was transitioned to a hinged CAM walker and began a physical therapy protocol of full active dorsiflexion and progressive plantarflexion. The CAM walker was discontinued and the patient was transitioned to a custom hinged ankle foot orthosis.

At 10 weeks postoperatively, he is pain-free and has regained full range of motion at the ankle symmetric to his uninjured side. In addition, he has full strength with active dorsiflexion (Figure 4) and radiographs are featured (Figure 5). With full range of motion and strength, the patient was cleared to begin a return to run program and will progress out of the AFO with resumption of full unrestricted activity at approximately 16 weeks postoperatively.

References:
Christman-Skieller C, et al. Am J Orthop (Belle Mead NJ). 2015;44(4):E94-99.
Ellington JK, et al. Foot Ankle Int. 2010;doi:10.3113/FAI.2010.0412.
Gwynne-Jones D, et al. Foot Ankle Int. 2009;doi:10.3113/FAI.2009.0758.
Sammarco JV, et al. J Bone Joint Surg Am. 2009;doi:10.2106/JBJS.G.01386.
Negrine JP. Foot Ankle Clin. 2007;12(4):569-572.
Otte S, et al. Arch Orthop Trauma Surg. 2002;122(3):188-190.
Wiesel SW. Operative techniques in orthopaedic surgery. Lippincott Williams & Wilkins. 2012.

For more information:
Marina J. Rodriguez, MD; Veasna T. Srey, DPM; and Brian R. Waterman, MD, can be reached at Department of Orthopaedic Surgery and Rehabilitation, William Beaumont Army Medical Center, 5005 North Piedras St., El Paso, TX 79920; Rodriguez’s email: rodrimar8@gmail.com. Srey’s email: veasna.t.srey.mil@mail.mil. Waterman’s email: brian.r.waterman@gmail.com.

Disclosures: Rodriguez and Srey report no relevant financial disclosures; Waterman reports he is a committee member of AANA and SOMOS, is on the editorial board for Arthroscopy and receives honoraria from AANA and royalties from Elsevier.