The flexor hallucis longus tendon originates from the calf muscle and courses along the instep of the ankle and foot, assisting with flexion of the big toe and maintenance of the medial longitudinal arch. This tendon can become irritated and inflamed due to a combination of its location and function as well as poor loading strategies or biomechanical deficits.
Flexor hallucis longus tendinopathy is caused by overuse of the flexor hallucis longus tendon. Repetitive use of the flexor hallucis longus muscle and, therefore, the flexor hallucis longus tendon can cause microscopic tears within the tendon. The failure to repair these microscopic tears within the tendon is termed tendinopathy.
Can commonly be misdiagnosed as Achilles tendinopathy or posterior impingement due to the location of pain.
This injury is common in runners and ballet dancers with repeated pushing off the foot & toes. This injury can be further worsened with everting or rolling out the foot, often in young dancers who have improper form when performing the ”turnout” manoeuvre.