Guidelines for the Treatment of Tibialis Anterior Tendon Ruptures

Tendon ruptures of the tibialis anterior are uncommon. That makes it tough to study and come up with treatment guidelines. Should surgery be done to repair or reconstruct the tendon? Will it heal with nonoperative care? How do the results between these two treatment approaches compare?

The tibialis anterior is the muscle along the front of the lower leg that dorsiflexes the foot. Dorsiflexion means the tendon pulls the ankle up toward the face. The tibialis anterior can tear partially or rupture fully as a result of trauma or degeneration. Or it can rupture without any external trauma or for some unknown reason. In some cases, the patient steps wrong, twists the ankle, and overstretches the tendon to the breaking point.

Trauma includes lacerations (cuts) or blunt trauma of some sort. Degenerative causes usually affect men over the age of 45. Other risk factors for tendon rupture include taking steroids or having gout, diabetes, or inflammatory joint disease such as arthritis.

At the time of the degenerative-related injury, the ankle is in a plantar flexed (toes pointed down) position. The large calf muscle (gastrocnemius) is contracted and overpowers the much smaller and weaker tibialis anterior tendon that was trying to pull the foot and ankle back toward a neutral position.

This is the first report of a large series of patients who had surgery to repair this injury. Results for early and delayed surgical treatment are reported and compared to the results reported in other published studies.

Surgery is suggested in order to restore a normal gait (walking) pattern. Surgery may also be done to avoid a foot deformity. Conservative (nonoperative) care is more likely for older, inactive adults or when treatment has been delayed for three months or more.

Delays can occur because the problem isn't obvious. Other muscles and tendons take over for the damaged tibialis anterior. Motion appears normal but symptoms eventually develop. Patients report ankle weakness. There may be a visible mass that can be felt along the front of the ankle. This is where the ruptured tendon has pulled back and bunched up. The weakness can result in changes in the way the person walks.

In this study, 19 adults between the ages of 21 and 78 had surgery to repair or reconstruct a fully ruptured tibialis anterior tendon. Most of the group (16 patients) had no known trauma (atraumatic). Some of the patients had been treated at the time of the injury but ended up with an infection, failed wound healing, and in two cases, failure to repair the lacerated tendon before closing the wound.

Before the operation, an exam was performed. Strength and range-of-motion were measured and recorded. And the American Orthopaedic Foot and Ankle Society (AOFAS) score was calculated. The AOFAS rating system looks at pain, function, and alignment.

Gait pattern was also evaluated. Most of the patients were unsteady and walked with a limp. Many of them had a foot slap gait pattern. Without the strength of the tibialis anterior to pull the ankle up, the foot slaps with a noticeable sound when the foot hits the floor. Some patients end up compensating by picking the foot up higher to avoid tripping. This gait pattern is referred to as a steppage gait.

The surgical procedure performed was determined at the time of the operation. While the patient was anesthetized, the surgeon evaluated foot and ankle motion. In some cases, it was necessary to perform a partial release of the gastrocnemius muscle. This step was needed to restore proper tension and balance between the tibialis anterior (front of the leg) and gastrocnemius (back of the leg).

If the torn tibialis anterior was visible and could be pulled back down, it was repaired by reattaching it to the bone. If it could be brought back down but not far enough to restore normal function, then a tendon graft was used to make up the length. A tendon graft is taken from some other tendon in the foot or ankle and used to reconstruct the tibialis anterior. The tendon graft is called interpositional as it help bridge the gap between the end of the ruptured tendon and the bone.

Everyone was put in a short-leg cast to immobilize the ankle in a neutral (zero degrees of dorsiflexion) position. The cast was kept on for a month to six weeks. Weight-bearing was allowed after the first three weeks. Patients were progressed from a cast to a hinged-ankle boot. Motion was restricted somewhat until the boot was no longer needed.

Using before and after AOFAS scores, the authors found great improvement in 18 of the 19 patients. Strength, motion and function were much better. They could all walk without a limp. Results were not dependent on age, sex, or general health.

There were a few complications such as failure of the wound to close and heal, infection, and scar tissue holding the tendon down. Most of these problems occurred in patients who had delayed surgical treatment. Early operative care seemed to have fewer postoperative problems. One patient had an infected wound and severe pain that made walking difficult. The surgeons suggested an ankle fusion as the next step, but the patient said, No, thanks.

The authors say that most of the time, a careful clinical exam can make an early diagnosis of tibialis anterior tendon rupture. If there is any question at all, an MRI can help show the area and amount of damage.

MRI results help the surgeon plan the surgical reconstruction. Tendons available for grafting will also be seen on the MRI. Whether or not a tendon graft is needed won't be determined by MRIs. The surgeon makes that decision at the time of the actual procedure.

Early surgical repair is advised. Nonsurgical treatment doesn't work well -- especially for younger or more active patients. If a delay does occur, surgical repair or reconstruction is still an option. Patients may be warned about the increased risk of problems or complications when treatment has been delayed.

Results of this study show positive outcomes. The results are tolerated well by patients. The surgery holds up well if the muscles are balanced properly and ankle rehab is done to strengthen the muscles. Even with rehab, there may be some permanent loss of strength with easy muscle fatigue. These changes aren't easily seen with manual muscle testing. Patients who try walking on their heels may notice some difficulty. But since this is not a typical motion needed for daily activity, it's not a major problem.

Reference: 

V. Sammarco, MD, et al. Surgical Repair of Acute and Chronic Tibialis Anterior Tendon Ruptures. In The Journal of Bone and Joint Surgery. February 2009. Vol. 91. No. 2. Pp. 325-332.

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