Flexor hallucis longus tendinitis is an injury seen more often in athletes, dancers, and gymnasts who are doing repetitive motions using the flexor hallucis longus tendon. The flexor hallucis longus tendon is the tendon that allows you to rise up on your toes. When you are doing this motion repetitively and overusing that tendon, it tends to get injured.

The patient typically will present with pain that’s over the — either over the inside of the foot (in back of the — behind the small bone in the inside of the ankle, the medial malleolus), they can have some pain behind that area, they can have pain underneath their first metatarsal in the foot, or a little bit distal to that. And often they’ll have pain when they’re trying to go up on their toes. For athletes, it’s more common with any kind of running activity will exacerbate that.

Physical examination. When doing a physical exam for foot and ankle pain in general, we do the normal test of muscle strength for the foot and ankle muscles. We do a sensory exam and test the reflexes in the lower extremities. A provocative maneuver specifically for FHL tendinitis involves testing the tendon under — when it is taut versus when it is released. So that’s called a Tomasen test, this is just specific for FHL tendinitis. And so you’ll have the patient flex their foot—and when you’re trying to—also flex their big toe, and usually they’ll have restricted range of motion. And pain most often elicits that. That’s considered a positive Tomasen test. This usually, when you allow the patient to release the foot and to now plantarflex and point the foot, then they’ll have better range of motion of the big toe. So this occurs because when you are putting the foot into dorsiflexion, you’re really making that tendon taut.

As the tendon passes underneath, it passes through a tunnel called the tarsal tunnel, similar to the carpal tunnel in the wrist. As it passes through that tunnel time and time and time again, it sometimes can start to fray. When it starts to fray, patients can also feel a kind of locking or catching of the tendon that’s also usually painful because as a result, when it starts to fray, the tendon gets swollen, it gets irritated, and inflamed, their fluid builds up around that area. And the patient feels that swelling and feels the pain.

Treatment for FHL tendinitis is to relieve the pressure off of that tendon. And first really is to protect that area, to rest the feet if at all possible, and to use good anti-inflammatories. And those can be anywhere from natural anti-inflammatories such as ice after any kind of activity, to oral anti-inflammatories. Also, we now have image-guided injections, where, using the ultrasound machine, we can nicely localize that FHL tendon as it passes through the tunnel going underneath — in the ankle.

And with the ultrasound, you can see the foot in real-time so that the patient can go through those motions. After visualizing the tendon, you can put a little bit of medication, including steroid and anesthetic, right around the tendon to reduce the inflammation. Usually that’s good to reduce the pain, also reduce the inflammation in that area. And then, in combination with the modification of activities, plus doing good exercises, are usually sufficient to allow the tendinitis to heal.

Dr. Ana Bracilovic is a physiatrist at the Princeton Spine and Joint Center, where she has more than a decade of experience specializing in the diagnosis and non-surgical treatment of spine, joint, and muscle pain.