Flexor Hallucis Longus Tendinopathy: Posterior Ankle Pain in Dancers and Runners

Flexor hallucis longus (FHL) tendinopathy — stenosing tenosynovitis or tendinosis of the FHL as it passes through the fibro-osseous tunnel posterior to the medial malleolus between the medial and lateral posterior talar processes — is one of the most common overuse injuries in ballet dancers and a recognized cause of posterior ankle pain in running athletes. The FHL is the most powerfully loaded intrinsic muscle of the foot during the push-off phase of gait and during pointework in ballet, making it uniquely vulnerable to overuse injury in high-demand activities requiring repetitive plantarflexion.

Anatomy and Clinical Presentation

FHL anatomy: originates from the posterior fibula and interosseous membrane; courses medially posterior to the ankle in the FHL tunnel between the medial and lateral posterior talar processes (the os trigonum sits in this groove); passes beneath the sustentaculum tali and into the plantar foot where it inserts on the distal phalanx of the hallux. The ‘knot of Henry’: the FHL and FDL tendons cross beneath the navicular — triggering or locking at this level (distinct from the posteromedial ankle stenosis). Stenosing FHL tenosynovitis (‘dancer’s tendinopathy’): repetitive FHL loading produces synovial thickening and fibrous constriction within the posterior ankle tunnel — the thickened tendon and sheath cannot slide freely; triggers (locking of hallux flexion, usually between 10–30° of hallux plantarflexion) or snapping at the posterior ankle. Clinical findings: posteromedial ankle tenderness in the FHL groove; reproduction of pain and triggering with passive great toe dorsiflexion while the ankle is maximally plantarflexed; hallux triggering (inability to actively extend the hallux when locked in the bent position). Association with os trigonum: FHL tendinopathy and os trigonum syndrome coexist in 50–60% of dancers with posterior ankle pain.

Treatment

Conservative: activity modification — reduce or eliminate ballet or running; physical therapy for FHL eccentric strengthening and calf flexibility; ultrasound-guided corticosteroid injection into the FHL tendon sheath (not the tendon itself) — 70% short-term improvement; prolonged period (3–6 months) of conservative care appropriate before surgical consideration. Surgical release: endoscopic FHL tenolysis — posterior two-portal approach; excision of stenotic sheath and any fibrous adhesions; concurrent os trigonum excision if present; return to dance typically 3–4 months. Open approach: for severe stenosis with tendon damage requiring debridement or partial FHL repair; longer recovery (4–6 months). Dr. Biernacki at Balance Foot & Ankle diagnoses and treats FHL tendinopathy with ultrasound-guided injection and endoscopic surgical release at our Bloomfield Hills and Howell offices. Call (810) 206-1402.

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Frequently Asked Questions

How do I know if I sprained or broke my ankle?

Both cause pain, swelling, and difficulty walking. Key differences: fractures often cause more immediate severe pain, tenderness directly over bone (not just ligament), and inability to bear any weight. X-rays and the Ottawa Ankle Rules help determine if imaging is needed.

How long does an ankle sprain take to heal?

Grade I (mild): 1–2 weeks. Grade II (moderate): 3–6 weeks. Grade III (complete tear): 2–3 months. Chronic instability from improperly treated sprains can persist and may require surgery.

What is the best treatment for a sprained ankle?

RICE protocol (Rest, Ice, Compression, Elevation) for the first 48–72 hours, followed by protected weight-bearing as tolerated. Physical therapy rehabilitation is critical for high-grade sprains to restore strength and proprioception and prevent chronic instability.

Need Treatment at Balance Foot & Ankle?

Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin see patients at our Howell and Bloomfield Hills offices.

Book Online or call (810) 206-1402

Most Common Mistake We See

The most common mistake we see is: Waiting too long before seeking care. Fix: any foot pain lasting more than 4 weeks, or any sudden severe symptom, deserves a professional evaluation rather than more rest.

Warning Signs That Need Same-Day Care

Frequently Asked Questions

When should I see a doctor?

See a podiatrist if pain persists past 2 weeks, prevents normal activity, or is accompanied by red-flag symptoms (warmth, swelling, numbness, inability to bear weight).

Can I treat this at home?

Mild cases respond to RICE protocol (rest, ice, compression, elevation), supportive shoes, and OTC anti-inflammatories. Persistent symptoms need professional evaluation.

How long does it take to heal?

Most soft tissue injuries resolve in 2-6 weeks with appropriate care. Bone injuries take 6-12 weeks. Chronic conditions need longer-term management.

What is Foot pain?

Foot pain is a common foot/ankle condition that affects mobility and quality of life. Understanding the underlying cause is the first step in successful treatment. Our podiatrists at Balance Foot & Ankle perform a hands-on biomechanical exam, review your activity history, and use diagnostic imaging when appropriate to identify the root cause—not just treat the symptom. Many patients have been told to “rest and ice” without a deeper diagnostic workup; our approach is different.

Symptoms and warning signs

Common signs of foot pain include pain that worsens with activity, morning stiffness, swelling, tenderness when palpated, and difficulty bearing weight. If you experience sudden severe pain, inability to walk, visible deformity, numbness or color change, contact our office the same day or visit urgent care—these can signal a more serious injury such as a fracture, tendon rupture, or vascular compromise. Diabetics with any foot wound should seek same-day care.

Conservative treatment options

Most cases of foot pain respond to non-surgical care: structured rest, supportive footwear changes, custom orthotics, targeted stretching and strengthening protocols, anti-inflammatory medications when medically appropriate, and in-office procedures such as ultrasound-guided injections. We also offer advanced therapies including MLS laser therapy, EPAT/shockwave, regenerative injections, and image-guided procedures. Treatment is sequenced from least invasive to most invasive, and we explain the rationale at every step.

When is surgery considered?

Surgery is reserved for cases that fail 3-6 months of well-structured conservative care, when there is structural pathology (severe deformity, complete tear, advanced arthritis), or when imaging shows damage that will not heal without intervention. Our surgeons have performed 3,000+ foot and ankle procedures and prioritize minimally-invasive techniques whenever appropriate. We discuss recovery timelines, return-to-activity milestones, and realistic outcome expectations before any procedure is scheduled.

Recovery timeline and prevention

Recovery from foot pain varies based on severity and chosen treatment path. Conservative cases often improve within 4-8 weeks with consistent adherence to the protocol. Post-procedural recovery may range from a few days (in-office procedures) to several months (reconstructive surgery). Long-term prevention involves footwear assessment, activity modification, structured strengthening, and regular check-ins with your podiatrist if you have a history of recurrence. We provide written home-exercise plans and digital follow-up support.

In-Office Treatment at Balance Foot & Ankle

If home treatment isn’t providing relief for your foot and ankle conditions, our podiatry team at Balance Foot & Ankle can help with same-day evaluations and advanced in-office care.