Posterior Ankle Impingement and Os Trigonum Syndrome: Causes Diagnosis and Treatment

Quick answer: Posterior Ankle Impingement Os Trigonum Syndrome 2 is a clinical condition that responds to evidence-based treatment when caught early. Symptoms include pain, swelling, and altered function. Diagnosis requires clinical exam, often imaging. Treatment ladder: conservative care first (4-6 weeks), then targeted interventions if needed. Call (810) 206-1402.

Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Township, MI. Last updated April 2026.

What Is Posterior Ankle Impingement?

Posterior ankle impingement is pain at the back of the ankle caused by compression of soft tissue or bony structures between the posterior tibia and the calcaneus (heel bone) during plantarflexion — the motion of pointing the foot downward. The condition is also known as os trigonum syndrome when a small accessory bone called the os trigonum is the primary impinging structure.

At Balance Foot & Ankle, we diagnose and treat posterior ankle impingement in athletes, dancers, and active patients throughout Southeast Michigan.

The Os Trigonum and Why It Causes Pain

The os trigonum is an accessory ossicle — a small separate bone — located at the posterior aspect of the talus. Approximately 7 to 14 percent of people have an os trigonum, and most never experience symptoms. In some individuals, particularly those whose activities require repeated or extreme plantarflexion, the os trigonum becomes compressed between the posterior tibia and calcaneus, irritating the surrounding soft tissue and producing pain.

In patients without an os trigonum, a prominent posterior talar process (the Stieda process) can produce the same impingement syndrome. Soft tissue impingement from thickened joint capsule or scar tissue is another mechanism that does not involve bone.

Who Gets Posterior Ankle Impingement?

Ballet dancers are the classic population — the en pointe position places the ankle in extreme plantarflexion repeatedly. Soccer players and football kickers who plantarflex forcefully are also commonly affected. Gymnasts, swimmers with powerful flip turns, and downhill runners placing the ankle in repeated plantarflexion are other at-risk groups. The condition can affect anyone but is most prevalent in athletes whose sport demands repeated end-range plantarflexion.

Symptoms and Diagnosis

Posterior ankle pain that worsens with plantarflexion is the cardinal symptom. Patients often describe deep pain at the back of the ankle just above the heel during activities that point the foot. Pain at rest or with dorsiflexion is less characteristic and raises other diagnoses. Local tenderness directly behind the ankle between the Achilles tendon and the fibula is typical on examination. The plantarflexion impingement test — passive end-range plantarflexion that reproduces posterior pain — supports the diagnosis. Lateral X-ray confirms the presence of an os trigonum or prominent posterior talar process. MRI evaluates bone edema and adjacent soft tissue pathology and is particularly valuable in cases without clear bony findings.

Non-Surgical Treatment

Activity modification to reduce plantarflexion demands, anti-inflammatory medications, and physical therapy form the foundation of non-surgical management. A corticosteroid injection around the os trigonum, guided by ultrasound or fluoroscopy, is an effective diagnostic and therapeutic tool. Many patients with posterior ankle impingement achieve adequate pain relief with conservative management and return to sport without surgery.

Surgical Treatment: Os Trigonum Excision

When non-surgical treatment fails after 3 to 6 months, surgical removal of the os trigonum is highly effective. The procedure is performed arthroscopically through two small posterior portals, allowing visualization and excision with minimal disruption of surrounding structures. Recovery involves protected weight bearing for 2 to 4 weeks followed by progressive return to activity. Most athletes return to full sport participation within 6 to 12 weeks of surgery.

If you have posterior ankle pain with pointing your foot, contact Balance Foot & Ankle for evaluation. We provide expert foot and ankle care throughout Southeast Michigan.

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Posterior Ankle Impingement Treatment in Michigan

Posterior ankle impingement and os trigonum syndrome cause pain at the back of the ankle, particularly with plantarflexion. Dr. Tom Biernacki at Balance Foot & Ankle offers both conservative and surgical treatment including arthroscopic os trigonum excision at our Howell and Bloomfield Township offices.

Learn About Our Ankle Treatment Options | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Mouhsine E, et al. “Posterior ankle impingement syndrome: diagnosis and treatment.” Sports Medicine. 2002;32(7):419-432.
2. Ribbans WJ, et al. “Posterior ankle impingement: diagnosis and treatment.” Foot and Ankle Clinics. 2015;20(4):603-613.
3. Guo QW, et al. “Arthroscopic treatment for posterior ankle impingement syndrome: a systematic review.” Arthroscopy. 2016;32(6):1164-1170.

In-Office Treatment at Balance Foot & Ankle

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