Attritional Rupture of Tibialis Anterior Tendon
(Anterior Tibial Tendon Attritional Rupture)
Attritional rupture of tibialis anterior is an uncommon injury that typically affects individuals over the age 60 and older. The tibialis anterior muscle and tendon are primarily responsible for lifting the foot up towards the shin (or preventing the foot from flopping downwards). Tearing the tendon results in pain, local swelling, and difficulty with walking. Patients may even develop a dropfoot. Treatment options include doing nothing, using an ankle-foot orthosis (AFO), or surgery. Selecting an option will depend on the patient’s preferences and lifestyle.
The tibialis anterior muscle and tendon is the primary flexor of the foot upwards towards the shin (dorsiflexion). Attritional rupture of tibialis anterior tendon occurs when the patient develops weakening of the tendon similar to how a rope can fray over time. Patients may have symptoms of tibialis anterior tendonitis prior to the tendon actually rupturing. The injury tendons to occur in older individuals who are still active. It is often precipitated by a minor trauma. Symptoms are often subtle which can delay an accurate diagnosis. Often the main symptoms are a swelling in the front of the ankle (where the tendon has retracted); some mild-moderate discomfort in this area; and a sense of weakness in the foot. The condition is caused by the tearing of the tibialis anterior tendon from wear and tear. The loss of muscle attachment causes the weakness and partial dropfoot (two other tendons can still help left the foot up) and difficulty in walking. Any pain from the injury normally subsides in a few days and the patient may only notice weakness flexing the foot towards the shin.
Physical exam may reveal a mass in the front of the ankle or slightly above the bony prominence on the inside of the ankle depending on where the tendon has retracted. The patient is able to walk on their toes but will have difficulty walking on their heels.
Gout, steroid injections, rheumatoid arthritis, and diabetes have all been identified as risk factors for the an attritional rupture of tibialis anterior, though most patients will not have any of these conditions.
Plain x-rays of the foot and ankle are usually unremarkable as the injury is to the tendon of the tibialis anterior muscle
Magnetic resonance imaging (MRI) can be useful for surgical planning. It allows for differentiation of a complete versus partial tear; identifies the exact location of the tear; and shows how far the tendon has retracted.
Treatment depends on the patient’s desired level of activity. In sedentary older individuals an ankle-foot orthosis (AFO) functions well and is generally the suggested approach.
For younger and/or more active patients surgical intervention is recommended. Surgery may include a direct repair of the ruptured tendon, or the use of a tendon graft if the gap caused by the rupture is too great. Possible tendon grafts include a tendon taken from the patient (autograft) or from a cadaver (allograft). The exact surgery depends on the size of gap and location of the tear. Surgery normally has a good functional result.
June 18th, 2020