Medically Reviewed | Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle, Michigan
Quick Answer:
Quick Answer: Posterior ankle impingement syndrome occurs when soft tissue or bony structures become compressed between the posterior tibia and calcaneus during extreme plantarflexion—most commonly in dancers (particularly ballet) and soccer players. The os trigonum, an accessory ossicle present in approximately 7–14% of the population posterior to the talus, is the most common bony cause. Other contributors include a prominent posterior talar process (Stieda’s process), FHL tendon sheath inflammation, and posterior capsular/synovial impingement. Symptoms include deep posterior ankle pain with plantarflexion (pointe position in ballet), tenderness behind the Achilles and peroneal tendons, and pain with passive plantarflexion (positive nutcracker test). MRI and CT demonstrate ossicle size, bone marrow edema, and FHL involvement. Conservative treatment includes activity modification, corticosteroid injection, and physical therapy. Arthroscopic or open os trigonum excision and posterior ankle debridement resolves symptoms in 85–90% of appropriate surgical candidates.
Treatment at Balance Foot & Ankle: EPAT Shockwave for Heel Pain →
Posterior ankle impingement is a condition where structures at the back of the ankle get pinched during activities that require extreme downward foot flexion—like pointing the foot in ballet, pushing off in soccer, or going down stairs. The pain is deep, behind the ankle, and reproducible with that specific motion. Dr. Tom Biernacki at Balance Foot & Ankle specializes in this often-delayed diagnosis in dancers and athletes, and provides both conservative and surgical management.
The Os Trigonum — The Most Common Cause
The os trigonum is an accessory bone located at the posterior talus—the result of a secondary ossification center that failed to fuse with the main talar body. Present in approximately 7–14% of the population, it is usually asymptomatic. However, in activities requiring repetitive extreme plantarflexion (ballet pointe, soccer ball striking, gymnastics), the os trigonum can become pinched between the posterior tibia and calcaneus—causing acute pain from a fracture through its cartilaginous junction with the talus, or chronic impingement syndrome from repetitive microtrauma and surrounding inflammation. Distinguishing an os trigonum from a posterior talar fracture requires careful clinical and imaging evaluation.
Other Causes of Posterior Impingement
Not all posterior ankle impingement involves an os trigonum. A prominent posterior talar process (Stieda’s process)—an elongated native portion of the talus—produces the same mechanical impingement. FHL (flexor hallucis longus) tendon sheath tenosynovitis from the tendon’s course through a fibroosseous tunnel at the posterior ankle contributes to impingement symptoms, particularly in ballet dancers who note triggering or catching of the great toe with plantarflexion. Posterior synovitis and capsular scarring from prior ankle sprains can produce soft tissue impingement independently.
Diagnosis
The hallmark clinical test is the nutcracker test (passive plantarflexion compression test)—forceful passive plantarflexion reproduces the deep posterior ankle pain. Tenderness is localized to the posterolateral ankle between the Achilles and peroneal tendons. X-ray (lateral and lateral plantarflexed views) visualizes the os trigonum and Stieda’s process. MRI demonstrates bone marrow edema in the os trigonum (confirming active impingement vs. incidental finding), FHL tenosynovitis, and posterior synovitis. CT provides superior bony detail for surgical planning.
Conservative Treatment
Activity modification (cessation of the provocative activity—often ballet or soccer) combined with a short period of boot immobilization reduces acute inflammation. Corticosteroid injection into the posterior ankle recess provides significant temporary relief and is both diagnostic (complete relief supports surgical candidacy) and therapeutic. Ultrasound-guided injection ensures precise delivery to the posterior impingement space. Physical therapy focuses on FHL flexibility, intrinsic foot strengthening, and posterior chain stretching. Most acute cases in athletes who can modify activity resolve with conservative care; chronic cases in professional dancers who cannot stop their sport often require surgery.
Surgical Treatment
Arthroscopic posterior ankle debridement with os trigonum excision is the definitive treatment for refractory posterior impingement. Two posterior portals allow visualization and removal of the os trigonum, debridement of the FHL sheath, resection of Stieda’s process if present, and synovectomy of the posterior recess. Success rates of 85–90% are reported. Return to dance or sport typically occurs at 3–4 months post-operatively. Dr. Biernacki evaluates all surgical candidates thoroughly, including pre-operative diagnostic injection confirmation, before committing to operative treatment.
Dr. Tom's Product Recommendations
Bloch Dancewear Pointe Shoe Pad — FHL Protection
⭐ Highly Rated | Foundation Wellness Partner | 30% Commission
Gel toe pads and pointe shoe cushions for ballet dancers reduce forefoot pressure during pointe work—allowing partial activity modification during posterior impingement conservative treatment. While impingement involves the back of the ankle, total load reduction through proper forefoot cushioning can reduce overall plantarflexion demand.
Dr. Tom says: “During my os trigonum conservative treatment, Dr. B recommended I keep extra cushioning in my pointe shoes and reduce time en pointe. These pads helped me maintain some training during the healing phase.”
Best for: Ballet dancers with posterior ankle impingement during conservative activity modification phase
Not ideal for: Non-dancers; patients requiring complete cessation of dance activity for healing
Disclosure: We earn a commission at no extra cost to you.
Hyperice Venom 2 — Heat & Vibration Posterior Ankle Therapy
⭐ Highly Rated | Foundation Wellness Partner | 30% Commission
Wearable heat and vibration therapy wrap for posterior ankle impingement symptom management. Heat improves tissue extensibility for pre-activity FHL stretching; vibration reduces perceived pain through gate-control mechanisms. Useful for athletes managing posterior impingement conservatively during restricted training.
Dr. Tom says: “I’m a soccer player with an os trigonum and this wrap has become part of my pre-training warm-up. It loosens up my posterior ankle so I can train at reduced intensity while healing.”
Best for: Athletes with posterior impingement managing conservatively; pre-activity warm-up to reduce FHL stiffness
Not ideal for: Acute inflammation requiring ice rather than heat; post-surgical period without physician clearance
Disclosure: We earn a commission at no extra cost to you.
✅ Pros / Benefits
- Diagnostic posterior ankle injection confirms impingement and predicts surgical success before committing to operation
- Arthroscopic os trigonum excision achieves 85–90% good-to-excellent outcomes with 3–4 month return to sport
- FHL tenosynovitis component identified and treated simultaneously during surgical debridement
❌ Cons / Risks
- Professional dancers who cannot stop training during conservative management often require surgery sooner
- Posterior arthroscopic portals are technically demanding—experience with posterior ankle arthroscopy is required
- Return to full pointe work after surgery takes 3–4 months of graduated rehabilitation
Dr. Tom Biernacki’s Recommendation
Posterior ankle impingement in dancers is one of my favorite surgical cases—when a ballet dancer has been unable to go en pointe for a year because of an os trigonum, and we remove it arthroscopically and she’s back dancing at four months, that’s incredibly rewarding. But we always try conservative treatment first. A diagnostic injection that gives complete relief for three weeks tells us surgery will work. Then we plan it properly.
— Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle
Frequently Asked Questions
How do I know if I have an os trigonum?
Posterior ankle pain that worsens specifically with pointing your foot downward (plantarflexion), tenderness behind and below the outside ankle bone, and reproduction of your pain with the passive plantarflexion compression test are the hallmarks. X-ray from the side with the foot pointed reveals the os trigonum—a round or oval bony fragment posterior to the talus. MRI confirms active impingement vs. incidental finding with bone marrow edema.
Can an os trigonum heal without surgery?
An acute fracture through a pre-existing os trigonum can heal with adequate immobilization (boot or cast for 6–8 weeks), especially in patients who can stop the provocative activity. Chronic posterior impingement syndrome in patients who continue dance or sports training rarely resolves completely without surgery—the impingement mechanism recurs with every extreme plantarflexion. Surgical excision is definitive and highly effective.
Is posterior ankle arthroscopy safe?
Posterior ankle arthroscopy carries a small risk of injury to the sural nerve (sensory nerve running near the lateral portal) and the Achilles tendon. In experienced hands, complication rates are low (3–5%). The arthroscopic approach avoids the larger incisions of open surgery, reducing recovery time, infection risk, and postoperative stiffness. Dr. Biernacki selects surgical approach based on lesion complexity and patient anatomy.
How long is recovery from os trigonum surgery?
Patients typically begin partial weight-bearing 1–2 weeks post-operatively and transition to full weight-bearing in a regular shoe at 4–6 weeks. Dancers begin structured return-to-dance programming at 6–8 weeks, with full return to pointe work at 3–4 months post-op. Soccer players return to full training at a similar timeline. A supervised physical therapy program is essential during recovery.
Michigan Foot Pain? See Dr. Biernacki In Person
4.9★ rated | 1,123 Reviews | 3,000+ Surgeries
Same-week appointments · Howell & Bloomfield Hills
📞 (810) 206-1402 Book Online →
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.
- Diagnosis and Treatment of Plantar Fasciitis (PubMed / AAFP)
- Heel Pain (APMA)
- Hallux Valgus (Bunions): Evaluation and Management (PubMed)
- Bunions (Mayo Clinic)
Related Treatments at Balance Foot & Ankle
Our board-certified podiatrists offer advanced treatments at our Bloomfield Hills and Howell locations.
Recommended Products from Dr. Tom