Treatment of  Flexor Hallucis Longus Tendinopathy:

The flexor hallucis longus tendon flexes the big toe and assists in plantarflexion of the ankle. It passes posterior to the medial malleolus, and runs between the two sesamoid bones to insert into the base of the distal phalanx of the big toe.

Causes:

• Flexor hallucis longus tendinopathy may occur secondary to overuse, a stenosing tenosynovitis, pseuocyst or tendon tear.
• A common cause is overuse in a ballet dancer, as dancers repetitively go from flat foot stance to the en pointe position, when extreme plantarflexion is required. Wearing shoes that are too big and require the athlete to ‘toe-grip’ may also result in flexor hallucis longus tendinopathy.
• This condition is often associated with posterior impingement syndrome as the flexor hallucis tendon lies in a fibro-osseous tunnel between the lateral and medial tubercles of the posterior process of the talus.
• Enlargement or medial displacement of the os trigonum puts pressure on the flexor hallucis longus at the point where the tendon changes direction from a vertical course dorsal to the talus to a horizontal course beneath the talus.
• This can cause tendon thickening and may result in ‘triggering’ of the tendon, when partial tearing and subsequent healing of the tendon produce excessive scar tissue.

Clinical Features:

• Pain on toe-off or forefoot weight-bearing (e.g. rising in ballet), maximal over the posteromedial aspect of the calcaneus around the sustentaculum tali.
• Pain may be aggravated by resisted flexion of the first toe or stretch into full dorsiflexion of the hallux.
• In more severe cases, there may be ‘triggering’ of the first toe, both with rising onto the balls of the foot (e.g. in ballet) and in lowering from this position. Triggering occurs when the foot is placed in plantarflexion and the athlete, unable to flex the hallux, but then with forcible active contraction of the flexor hallucis longus, is able to extend the interphalangeal or metatarsophalangeal joints of the toe. A snap or pop occurs in the posteromedial aspect of the ankle when this happens. Subsequent passive flexion or extension of the interphalangeal joint produces a painless snap posterior to the medial malleolus.

Diagnosis of Flexor Hallucis Longus Tendinopathy:

MRI or ultrasound may both reveal pathology. The characteristic MRI sign is abrupt fluid cut-off in the tendon sheath; excessive fluid is found loculated around a normal-appearing tendon proximal to the fibro-osseous canal.

Treatment of Flexor Hallucis Longus Tendinopathy:

In the acute phase, treatment may include:

• Ice
• Avoidance of activities that stress the flexor hallucis longus tendon (e.g. dancer working at the barre but not rising en pointe)
• Flexor hallucis longus strength and stretching exercises
• Soft tissue therapy proximally in the muscle belly
• Correction of subtalar joint hypomobility with manual mobilization
• Control of excessive pronation during toe-off with tape or orthoses-this may be helpful but is difficult to achieve in dancers.

Prevention of  Flexor Hallucis Longus Tendinopathy:

Prevention of recurrences should focus on a reduction in the amount of hip turnout, thus ensuring that the weight is directly over the hip, avoidance of hard floors, and using firm, well-fitting pointe shoes, so that the foot is well supported and no additional strain is placed on the tendon. Technique correction is important in ballet dancers with this condition as it is thought to arise not only from excessive ankle eversion or inversion with pointe work but also from proximal weakness, such as poor trunk control. Surgical  should be considered when persistent synovitis or triggering prevents dancing en pointe. Surgery involves exploration of the tendon and release of the tendon sheath.