This page covers the clinical evaluation, evidence-based treatment options, and recovery timeline for flexor hallucis longus tendinopathy at Balance Foot & Ankle in Michigan. For same-week appointments at our Howell or Bloomfield Hills offices, call (810) 206-1402.
| Condition | Location | Key Symptom | Provocative Test | Imaging | Distinguishing Feature |
|---|---|---|---|---|---|
| FHL Tendinopathy / Tenosynovitis | Posterior ankle / FHL tunnel / knot of Henry | Posteromedial ankle pain; worse push-off and ballet demi-pointe | FHL stretch test (passive big toe dorsiflexion); resisted plantarflexion of hallux | MRI: fluid in FHL sheath; tendon thickening | Hallux triggering (trigger toe) — snapping / locking in demi-pointe |
| Posterior Tibial Tendon Dysfunction (PTTD) | Posterior medial malleolus → navicular insertion | Medial ankle pain; progressive flatfoot | Single-leg heel raise weakness / pain | MRI: PTT tears; spring ligament pathology | Progressive arch collapse; inability to complete single-leg heel raise |
| Tarsal Tunnel Syndrome | Medial ankle — posterior tibial nerve | Burning / tingling into plantar foot and toes | Tinel’s sign over tarsal tunnel | MRI / ultrasound: space-occupying lesion; EMG/NCS confirms | Neurologic symptoms (burning, numbness) vs pure tendon pain |
| Os Trigonum Syndrome | Posterior talus — os trigonum impingement | Posterior ankle pain in plantarflexion (not dorsiflexion) | Forced plantarflexion compression test | X-ray lateral: os trigonum; MRI: bone edema at posterior process | Pain maximal in forced plantarflexion, not toe dorsiflexion |
| FHL Partial / Complete Tear | FHL tunnel retromalleolar or knot of Henry | Acute pop + weakness of hallux plantarflexion | Resisted hallux plantarflexion weakness | MRI: partial / complete FHL tear | Acute mechanical event; hallux plantarflexion strength deficit |
| Treatment | Indication | Protocol | Success Rate | Return to Activity |
|---|---|---|---|---|
| Activity Modification + Boot | Acute FHL tenosynovitis; all patients — first-line | Limit push-off; CAM boot 4–6 weeks; avoid ballet/dance positions that load FHL | 60–70% resolution with structured rest | 6–10 weeks |
| Physical Therapy — Eccentric Loading | Chronic FHL tendinopathy; after acute phase | Eccentric toe plantarflexion program; calf flexibility; intrinsic foot strengthening | 65–75% improvement at 12 weeks | 3–4 months |
| Ultrasound-Guided Corticosteroid Injection | Persistent tenosynovitis; no tear on MRI; failed conservative care | Inject FHL sheath under ultrasound guidance; combined with structured PT | 50–65% at 3 months; avoid intratendinous injection | 4–6 weeks post-injection before loading |
| FHL Tenoscopy (Endoscopic Release) | Stenosing tenosynovitis; trigger toe; failed 3–6 months conservative care | Endoscopic decompression of FHL fibro-osseous tunnel; release of constricting fibrous bands | 85–90% resolution of triggering and pain | 4–6 weeks; return to dance 3–4 months |
| Open Tenosynovectomy + Repair | Partial or complete FHL tear; failed endoscopic treatment; large FHL nodule | Open excision of degenerated tissue; primary tendon repair or FDL transfer for complete rupture | 80–90% functional improvement | 3–5 months depending on repair complexity |
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Medically Reviewed | Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle, Michigan
Quick Answer:
Quick Answer: Flexor hallucis longus (FHL) tendinopathy causes pain behind the medial ankle or under the big toe joint during push-off and toe flexion activities. It is common in dancers, runners, and athletes. Dr. Biernacki at Balance Foot & Ankle evaluates and treats FHL tendon problems in Michigan with conservative management and surgical release when needed.
The flexor hallucis longus (FHL) is the powerful muscle-tendon unit that flexes (plantar flexes) the big toe. Its tendon runs behind the medial ankle, through a fibro-osseous tunnel in the subtalar region, beneath the sustentaculum tali, and into the plantar surface of the hallux. FHL tendinopathy is one of the most important and underappreciated causes of posterior medial ankle pain and big toe plantar pain—particularly in dancers, runners, and pushing-off athletes. Balance Foot & Ankle’s Dr. Tom Biernacki provides expert evaluation and treatment for FHL problems in Michigan.
Why FHL Matters: The Dancer’s Tendon
FHL tendinopathy is often called the “dancer’s tendon” injury because ballet dancers—who work extensively in plantar flexion and relevé (on the tips of the toes)—develop FHL pathology at high rates. However, this injury is not exclusive to dancers. Runners pushing off repetitively, gymnasts, climbers, and any athlete requiring forceful big toe flexion can develop FHL tendinopathy. The tendon’s course through the fibro-osseous tunnel posterior to the medial malleolus creates a compression zone where friction and stenosis develop.
Two Presentations of FHL Pathology
FHL tendinitis/tendinosis (posterior medial ankle): Pain behind the medial ankle, worsened by push-off, plantar flexion, and resisted big toe flexion. Swelling and tenderness are palpable posterior to the medial malleolus in the FHL tunnel. Triggering/stenosing tenosynovitis (plantar big toe): The tendon becomes thickened and catches in its plantar tunnel at the first MTP joint—causing a painful “trigger” or “clicking” sensation when flexing the big toe. This presentation mimics trigger finger and is treated similarly. Both patterns can occur simultaneously.
Diagnosis
Clinical examination reveals tenderness posterior to the medial malleolus, pain with resisted FHL testing (having the patient plantarflex the big toe against resistance), and in some cases an audible or palpable tendon catching. MRI is the gold standard for visualizing tendon thickening, intratendinous signal change, tenosynovial fluid, and any associated accessory ossicle at the posterior talus (os trigonum) that may contribute to posterior impingement and FHL compression. Ultrasound provides dynamic real-time tendon visualization—excellent for identifying triggering and guiding therapeutic injection.
Treatment
Conservative treatment includes rest from aggravating activities, NSAIDs, physical therapy (eccentric strengthening, flexibility, gait retraining), and orthotics with appropriate first ray accommodation. Corticosteroid injection into the FHL tendon sheath must be approached with caution—tendon injection carries rupture risk and is generally not recommended; peritenonous injection (peritendinous rather than intratendinous) is preferred. When conservative management fails—particularly stenosing tenosynovitis with triggering—surgical FHL tendon sheath release (similar to trigger finger release) provides reliable relief. Associated os trigonum causing posterior impingement may require concurrent excision.
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✅ Pros / Benefits
- Early diagnosis prevents progression from mild tendinopathy to stenosing tenosynovitis requiring surgical release
- Dynamic ultrasound examination provides real-time visualization of tendon triggering unavailable with static MRI
- Surgical FHL sheath release has excellent outcomes for stenosing tenosynovitis with rapid functional recovery
❌ Cons / Risks
- FHL tendinopathy is often missed because it requires specific examination testing (resisted toe flexion, medial ankle palpation)
- Conservative care requires significant activity modification—challenging for dancers and competitive athletes mid-season
- Corticosteroid injection into the FHL tendon carries rupture risk and should be used judiciously
Dr. Tom Biernacki’s Recommendation
FHL tendinopathy is one of those diagnoses that should be on every podiatrist’s radar when evaluating posterior medial ankle pain or big toe plantar pain in athletes. The classic presentation in a dancer with posterior ankle pain worsened by relevé is textbook—but I also see it in runners who do a lot of hill repeats and pushes. The key physical exam move is resisted big toe plantarflexion while palpating the posterior medial ankle: reproduction of their pain confirms the FHL. Once you know it’s FHL, treatment is logical and usually successful.
— Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle
Frequently Asked Questions
What is the difference between FHL tendinopathy and Achilles tendinopathy?
Both involve posterior ankle pain but at different anatomic locations. Achilles tendinopathy is pain at or above the heel insertion of the Achilles tendon—the large tendon directly behind the ankle. FHL tendinopathy is pain behind the medial (inner) ankle in the groove posterior to the medial malleolus, and/or pain under the plantar big toe joint. Physical examination distinguishes these easily: Achilles tenderness is midline, FHL tenderness is medial and reproduced by resisted toe flexion.
Can FHL tendinopathy cause big toe clicking?
Yes. Stenosing FHL tenosynovitis (triggering) causes a painful catching or clicking sensation when flexing the big toe—similar to trigger finger in the hand. The thickened tendon catches in its plantar fibro-osseous tunnel. Some patients can reproduce the click on command. This presentation typically requires surgical release of the tendon sheath for definitive resolution.
Is FHL tendinopathy serious?
FHL tendinopathy is not immediately dangerous but significantly impacts athletic performance and quality of life. Untreated, progressive inflammation can lead to tendon thickening, stenosing tenosynovitis, and occasionally partial tearing. Early intervention with activity modification, physical therapy, and appropriate footwear changes resolves most cases before surgical intervention is necessary.
How long does FHL tendinopathy recovery take?
Mild acute FHL tendinopathy may resolve in 4–8 weeks with appropriate activity modification and physical therapy. Chronic tendinosis with significant tendon changes requires 3–6 months of consistent conservative management. Stenosing tenosynovitis with triggering may require surgical release after conservative measures fail, with return to activity typically at 6–12 weeks post-procedure.
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When should I see a podiatrist?
If symptoms persist past 2 weeks, affect your normal activity, or are accompanied by red-flag symptoms (warmth, redness, swelling, inability to bear weight).
What does treatment cost?
Most diagnostic visits and conservative treatments are covered by Medicare and major insurers. Out-of-pocket costs vary by your specific plan.
How quickly can I get an appointment?
Most non-urgent cases see us within 5 business days. Urgent cases (sudden pain, possible fracture) typically same or next business day.
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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.
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