Introduction

The anterior tibial tendon is the primary dorsiflexor of the ankle. It has two main functions during the gait cycle. It contracts concentrically during the swing phase of gait to help clear the floor. At heel strike, the tibialis anterior eccentrically contracts to prevent foot slap.

Clinical Presentation

Two classic presentations for tibialis anterior tendon ruptures exist. The first is in young patients in their 20's and 30's who experience a sudden eccentric load to the ankle (Slide 1). This most commonly occurs when plantarflexion is forced against a maximally contracting tibialis anterior. These patients present early following injury due to acute pain and swelling.

Slide 1

The second presentation is in patients between 50 and 70 years of age (Slide 2). These patients typically do not recall any episode of trauma and present with a painless foot drop. The average delay to diagnosis is 10 weeks.

Slide 2

Underlying etiologies for tibialis anterior rupture include a tibia fracture, laceration, inflammatory arthritis, gout, steroid injections, impingement from underlying osteophytes, and diabetes.

Location of Rupture

The most common site of tibialis anterior rupture is 2 to 3 cm proximal to its insertion. A tibialis anterior rupture can also occur more proximally under the edge of the extensor retinaculum or as a result of tendon attrition from underlying dorsal midfoot osteophytes.

Clinical Examination

Physical examination reveals a visible or palpable lump over the anterior aspect of the ankle. This is the proximal stump of the tendon entrapped under the extensor retinaculum. However, excessive swelling may mask this lump.

Patients typically have weak dorsiflexion on manual muscle strength testing. However, the amount of weakness may be deceiving, as patients can recruit the extensor digitorum longus and extensor hallucis longus as secondary dorsiflexors of the ankle. Inability to heel walk is usually indicative of a tibialis anterior tendon rupture.

Treatment

Young patients who have an acute tibialis anterior tendon rupture should undergo primary repair of the ruptured tendon (Slide 3). In very distal ruptures, the tendon can be inserted into bone.

Slide 3

Markarian and colleagues¹ and Ouzounian and Anderson² recommend nonoperative treatment of a tibialis anterior tendon rupture in elderly patients with low activity levels. The investigators reported no significant difference between operative and nonoperative treatment. Also, patients experienced minimal disability with conservative care.

For treatment of chronic or late tibialis anterior tendon ruptures, the surgical alternatives include direct repair, reinsertion into the navicular bone, anterior tibial tendon sliding graft, extensor hallucis longus tendon transfer into the cuneiform, extensor digitorum longus transfer, and peroneus brevis free graft.

References

1. Markarian GG, Kelikian AS, Brage M, Trainor T, Dias L. Anterior tibialis tendon ruptures: an outcome analysis of operative versus nonoperative treatment. Foot Ankle Int. 1998; 19:792-802.
    
2. Ouzounian TJ, Anderson R. Anterior tibial tendon rupture. Foot Ankle Int. 1995; 16:406-410.