The Flexor hallucis Longus is a tendon that originates in the back of your leg and connects onto the fibula. It comes down behind the inner ankle wrapping under the shelf on the heel bone called the sustentaculum tali, moves under the arch, and connects onto the tip of the big toe. Its purpose is to plantar flex the big toe, pointing downward, and supinates the foot, lifting the arch up.

Symptom for Flexor Hallucis Longus

When you get up from sitting and begin to walk, pain will occur most of the time at the point when you are pushing off and the foot is behind your body. The pain will be most intense just behind the big toe joint and back to just below the ankle. At this point the tendon turns up under and then behind the ankle where some additional discomfort can occur. When you push the front of the foot upwards with your knee locked and then push the big toe upwards, you will feel the tendon protruding through the plantar fascia tendon.

Cause of Flexor Hallucis Longus

The primary cause is tight calves which will cause the heel bone along with the sustentaculum tali to rotate inwards called pronation. As this occurs, tension is placed on the flexor Hallucis Longus tendon and when the big toe is then asked to bend upwards at push off, the tension is more than what it can handle. Seldom do we see any tears but often inflammation.

Treatment of Flexor Hallucis Longus

The first step is to get on a stretching program for the calves. Putting a 1/4 inch to 1/2 inch heel lift in both shoes will take the tension off the Flexor Hallucis longus temporarily while the stretching takes hold. Then a shoe with a stiff bottom and forefoot rocker will reduce the need for the big toe to bend upwards taking the stress off the tendon. If necessary a rocker bottom can be added to a pair of shoes to add more relief to the tendon. Finally, putting either an over-the-counter arch support or custom foot orthosis, where the apex of the arch support is back under the navicular bone, in your shoes. Since most over-the-counter arch supports don’t come this way, best to have a pedorthist fit you in the arch supports so that they can be modified properly.