Medically Reviewed by Dr. Jeffery Agnoli, DPM — Board-Certified Podiatrist, Balance Foot & Ankle Specialists, Michigan. Last updated April 2026.
Tarsal coalition — an abnormal bony, cartilaginous, or fibrous bridge between two tarsal bones — is the most common structural cause of rigid, painful flatfoot in adolescents, typically becoming symptomatic between ages 8–16 when ossification of the coalition bridge increases rigidity. The two most common coalition types are calcaneonavicular (CN) coalition (comprising 53% of cases) and middle facet talocalcaneal (TC) coalition (37% of cases) — each with distinct radiographic characteristics, clinical presentations, and surgical approaches.
Clinical Presentation and Diagnosis
Characteristic presentation: adolescent with painful flatfoot, stiff hindfoot that does not correct on single-leg heel rise (rigid valgus heel), peroneal muscle spasm (“peroneal spastic flatfoot” — the peroneal muscles contract to stabilize the coalited subtalar joint), and pain with walking on uneven terrain. CN coalition is best visualized on the oblique plain X-ray view — the “anteater sign” (elongated anterior calcaneal process extending toward the navicular). TC coalition (middle facet) requires CT imaging for definitive diagnosis — the standard X-ray may show the “C sign” (continuous C-shaped bone outline at the talar sustentaculum and posterior talus) but CT provides precise visualization of the coalition size and joint involvement critical for surgical planning.
Conservative and Surgical Management
Conservative management: immobilization in a short-leg cast or CAM boot for 4–6 weeks to reduce inflammation and pain, followed by custom orthotics providing hindfoot support and accommodating the limited subtalar motion. Surgical management: coalition resection — the bridge is excised and the space is interposed with fat graft (CN coalition) or extensor digitorum brevis muscle (CN coalition) to prevent re-ossification. Resection produces excellent outcomes when the coalition involves less than 50% of the posterior subtalar facet (TC coalition) — larger coalitions with secondary subtalar arthritis are treated with subtalar arthrodesis. Concurrent calcaneal osteotomy for hindfoot valgus correction improves outcomes for complex cases. Dr. Biernacki at Balance Foot & Ankle evaluates adolescent and adult rigid flatfoot with standing X-rays and CT when coalition is suspected. Call (810) 206-1402 at our Bloomfield Hills or Howell office.
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Frequently Asked Questions
When should I see a podiatrist?
See a podiatrist for any foot or ankle pain that persists more than 2 weeks, doesn’t improve with rest, limits your daily activities, or is accompanied by swelling, numbness, or skin changes. People with diabetes or circulation problems should see a podiatrist regularly even without symptoms.
What does a podiatrist treat?
Podiatrists diagnose and treat all conditions of the foot, ankle, and lower leg including plantar fasciitis, bunions, hammertoes, toenail problems, heel pain, nerve pain, diabetic foot care, sports injuries, fractures, and foot deformities — both surgically and non-surgically.
What can I expect at my first podiatry visit?
Your first visit includes a full medical history, physical examination of your feet and gait, and in-office diagnostic imaging if needed (X-rays, ultrasound). We’ll discuss your diagnosis and create a personalized treatment plan. Most visits take 30–45 minutes.
Need Treatment at Balance Foot & Ankle?
Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin see patients at our Howell and Bloomfield Township offices.
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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.