The Flexor Hallucis Longus Tendon

The flexor hallucis longus (FHL) is a deep posterior leg muscle whose tendon travels through a fibro-osseous tunnel on the posterior aspect of the talus, then under the foot to insert at the base of the great toe’s distal phalanx. Its function is powerful plantarflexion of the hallux and secondary ankle plantarflexion — critically important for the push-off phase of gait and for the extreme plantarflexion required in dance and gymnastics.

FHL pathology encompasses a spectrum from simple tendinopathy to stenosing tenosynovitis (the tendon sheath constricting the tendon) to “trigger toe” (a nodule or partial tear causing the toe to catch and snap) to complete tendon rupture.

Why Dancers and Gymnasts Are Most Affected

Classical ballet dancers spend hours daily in extreme plantarflexion on pointe or demi-pointe, repeatedly loading the FHL through its narrowest anatomical passage — the fibro-osseous groove on the posterior talus. This creates predictable FHL tenosynovitis in a high proportion of serious dancers, which is why the condition carries the informal name “dancer’s tendinitis.”

Gymnasts performing arabesques, back walkovers, and other extreme plantarflexion skills face similar loading patterns. Long-distance runners, soccer players, and other athletes who perform high volumes of push-off also develop FHL pathology, though less commonly than the extreme plantarflexion sports.

Symptoms of FHL Tendinopathy

FHL tendinopathy presents with posterior ankle pain localized medial to the Achilles tendon — importantly, in the posteromedial ankle rather than the posterior midline (which suggests Achilles pathology) or posterolateral (which suggests peroneal or os trigonum issues). Pain worsens with push-off, rising onto tiptoe, and the extreme plantarflexion positions of dance and gymnastics.

Stenosing Tenosynovitis

When the FHL tendon sheath becomes constricted (stenosed), the tendon cannot glide freely through its tunnel. The patient may note that the great toe becomes transiently locked in a flexed position and then suddenly snaps straight — this is the pathognomonic “trigger toe” sign. Passive dorsiflexion of the hallux with the ankle held in neutral reproduces the catching sensation or pain.

Diagnosis

The clinical examination is usually sufficient for diagnosis. The Flexion-Extension test (passively flexing and extending the hallux while palpating the posteromedial ankle) can demonstrate crepitus, reduced glide, or the trigger sign. MRI confirms the diagnosis and reveals the extent of tendinopathy, sheath effusion, or partial tears. Ultrasound is useful for dynamic assessment of tendon gliding and can be performed in-office.

Conservative Treatment

Initial management includes relative rest from the aggravating extreme plantarflexion demands, NSAIDs, and physical therapy focusing on eccentric FHL loading, stretching of the flexor compartment, and gradual return to plantarflexion demands. Corticosteroid injection into the FHL sheath can reduce synovial inflammation and sheath swelling, providing relief in many cases. Most cases of FHL tendinopathy resolve with 6–12 weeks of conservative management.

Surgical Treatment

Stenosing tenosynovitis that fails conservative treatment, persistent trigger toe, and FHL tears confirmed on MRI are indications for surgery. Endoscopic FHL tendon sheath release (tenoscopy) is the preferred approach — two small portals allow endoscopic visualization and release of the constricting sheath without the extensive open exposure of prior techniques. Recovery is significantly faster than with open procedures: weight-bearing resumes within days, and dancers can typically return to full pointe work within 8–12 weeks of endoscopic release.

Foot or Ankle Pain? We Can Help.

Balance Foot & Ankle — Howell & Bloomfield Township, MI

📅 Book Online
📞 (810) 206-1402

Your Board-Certified Podiatrists

Dr. Tom Biernacki, DPM

Board-Certified · FACFAS

Dr. Carl Jay, DPM

Board-Certified Podiatrist

Dr. Daria Gutkin, DPM

Podiatrist

Dr. Tom Biernacki, DPM

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.