Quick answer: Posterior Ankle Impingement Os Trigonum Syndrome 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.
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What Is Posterior Ankle Impingement?
Posterior ankle impingement syndrome is a condition in which soft tissue or bony structures at the back of the ankle become compressed (impinged) during extreme plantarflexion—the downward-pointing motion of the foot. It is particularly common in ballet dancers who perform en pointe, soccer players who kick with a plantarflexed foot, gymnasts, and other athletes whose sports require extreme ankle plantarflexion. The result is deep posterior ankle pain that is reproduced by passively forcing the ankle into maximum plantarflexion—a finding called the “nutcracker” test.
Os Trigonum: The Most Common Cause
The os trigonum is an accessory (extra) bone found behind the ankle in approximately 7–14% of the population. It forms from a secondary ossification center at the posterior process of the talus that fails to fuse to the main talar body during adolescent development—a process that normally occurs between ages 8 and 13. When present, the os trigonum can be pinched between the posterior tibia and the calcaneus during plantarflexion, producing synovitis, edema, and pain in the posterior ankle. Even without a discrete os trigonum, a prominent Stieda’s process (elongated posterior talar process) can produce identical impingement symptoms.
Symptoms and Clinical Diagnosis
Posterior ankle impingement presents as deep posterolateral ankle pain that worsens with plantarflexion activities such as going up on tiptoe, pushing off in running, or pointing the foot. Athletes often note increased pain during plantarflexion-heavy drills and relief when activity is stopped. The posterior ankle is tender to deep palpation between the lateral malleolus and the Achilles tendon. The passive plantarflexion test (forced plantarflexion by the examiner) reproduces symptoms and confirms the diagnosis clinically.
Imaging begins with lateral ankle X-ray to identify the os trigonum or Stieda’s process. MRI is essential for assessing soft tissue involvement—including FHL tendon tenosynovitis (inflammation of the flexor hallucis longus tendon, which passes through the posterior ankle groove), posterior joint synovitis, and bone marrow edema in the os trigonum—and rules out other pathology.
Conservative Treatment
Initial management involves rest from provocative plantarflexion activities, NSAIDs, and ice. Corticosteroid injection into the posterior ankle recess under ultrasound guidance provides diagnostic confirmation and therapeutic benefit, often offering weeks to months of symptom relief. Physical therapy focuses on posterior ankle stretching, FHL strengthening, and proprioception. Conservative care resolves symptoms in many recreational athletes but often provides only temporary relief in high-level dancers and athletes who must continue provocative activities.
Surgical Treatment: Os Trigonum Excision
When conservative treatment fails—or when the athlete cannot tolerate activity modification required for non-surgical management—surgical excision of the os trigonum or Stieda’s process is highly effective. The procedure can be performed through an open posteromedial or posterolateral incision or, increasingly, through a two-portal posterior ankle arthroscopy approach. Arthroscopic excision offers advantages of smaller incisions, direct visualization of associated FHL tenosynovitis (which is addressed simultaneously), and faster rehabilitation compared to open surgery.
Recovery after arthroscopic os trigonum excision involves 2–4 weeks in a boot with limited weight-bearing, followed by progressive physical therapy. Dancers typically return to full pointe work at 8–12 weeks; other athletes return to sport at 6–10 weeks. Patient satisfaction rates following surgical excision exceed 90% in appropriately selected patients.
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Dr. Tom on posterior ankle impingement — os trigonum, dancer’s ankle, ballet/soccer presentation, plantarflexion pain, FHL tenosynovitis overlap, arthroscopic excision, recovery.
Posterior Impingement Kit
Conservative + post-scope stack. Dr. Tom’s kit:
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Plantarflexion limit.
Hindfoot alignment.
Post-scope inflammation.
Topical posterior ankle relief.
Related: Posterior Scope · Impingement Overview · Book Posterior Ankle Eval
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If foot or ankle pain has been bothering you for more than a few weeks, home care alone may not be enough. Balance Foot & Ankle offers same-week appointments at our Howell and Bloomfield Hills clinics — no referral needed in most cases. Bring your current shoes and a short list of symptoms and we’ll build you a treatment plan in one visit.
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Dr. Tom Biernacki, DPM is a board-certified foot & ankle surgeon (ABFAS & ABPM) 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 made him one of the most-followed foot & ankle educators on YouTube.