Medically reviewed by Dr. Tom Biernacki, DPM
Board-certified podiatric surgeon | Balance Foot & Ankle, Howell & Bloomfield Hills, MI
Last reviewed: May 2026
| Feature | Calcaneonavicular Coalition | Talocalcaneal Coalition |
|---|---|---|
| Frequency | ~45% of tarsal coalitions | ~50% of tarsal coalitions |
| Location | Anterior calcaneus → navicular | Middle subtalar facet (sustentaculum) |
| Classic X-ray sign | Anteater sign (oblique view) | C-sign, talar beaking (lateral view) |
| Best plain film view | Oblique foot view | Harris axial (heel) view |
| Pain location | Lateral foot / sinus tarsi | Medial hindfoot / sustentaculum |
| Surgical success rate | 80–90% with resection | 70–80% with resection (if <50% facet) |
| Interposition material | Extensor digitorum brevis (EDB) | Fat graft or FHL tendon |
| Recovery Phase | Timeline | Activity Level |
|---|---|---|
| Post-op immobilization | 0–3 weeks | NWB cast; foot elevated |
| Protected weight-bearing | 3–6 weeks | Walking boot; partial WB |
| PT / mobilization | 6–12 weeks | Subtalar ROM; peroneal strengthening |
| Return to sport (low impact) | 3–4 months | Cycling, swimming, walking |
| Return to sport (full) | 4–5 months | Running, cutting sports; with custom orthotics |
Quick answer: A calcaneonavicular coalition is an abnormal bridge of bone or cartilage connecting the heel bone (calcaneus) to the navicular. It is present from childhood, usually becomes painful in adolescence, and limits hindfoot motion — the classic cause of a rigid, painful flatfoot. Many cases settle with immobilization and orthotics; persistent ones respond well to surgical resection. We treat this regularly at our Howell and Bloomfield Hills practices. Call (810) 206-1402.
The most important clinical decision with Calcaneonavicular Coalition isn’t which treatment to start with — it’s identifying the correct subtype. That changes everything. Call (810) 206-1402.
What Is Tarsal Coalition?
Tarsal coalition is a congenital abnormal union between two or more tarsal bones. The two most common types are calcaneonavicular coalition (CN coalition, accounting for ~53% of cases) and talocalcaneal coalition (~37%). The bridge can be bony (synostosis), cartilaginous (synchondrosis), or fibrous (syndesmosis).
Symptoms of Calcaneonavicular Coalition
Symptoms typically appear in adolescence (ages 8–12 for CN coalition) when the coalition ossifies and limits motion. Classic presentation: painful rigid flatfoot, peroneal muscle spasm (peroneal spastic flatfoot), limited subtalar motion, and pain with prolonged walking or sports. Ankles sprain frequently due to limited hindfoot motion. Some coalitions are asymptomatic and found incidentally.
Diagnosis
Lateral X-ray shows the “anteater sign” — elongation of the anterior calcaneal process bridging toward the navicular. Oblique foot X-ray best visualizes the coalition. CT scan is definitive for bony coalitions. MRI evaluates cartilaginous and fibrous coalitions and secondary cartilage damage.
Conservative Treatment
Activity modification, custom orthotics with arch support, short-leg cast or boot for 4–6 weeks for acute pain episodes, and physical therapy. Conservative care works best for fibrous or cartilaginous coalitions without degenerative changes.
Surgical Treatment: Resection
Surgical resection (removal of the coalition bar with fat graft or extensor digitorum brevis muscle interposition) is the first-line surgery for symptomatic patients who fail conservative care. Results are excellent with pain relief and improved subtalar motion in 80–85% of appropriately selected patients. Resection is not indicated if significant subtalar arthritis is present — fusion becomes the appropriate option in that scenario.
FAQs
Is calcaneonavicular coalition hereditary? Yes — it is an autosomal dominant condition. Other family members may have the same condition, often asymptomatically.
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- Mosca VS. “Subtalar coalition in children.” Foot Ankle Clin. 2015;20(2):265-281.
- American Academy of Orthopaedic Surgeons (AAOS), OrthoInfo. “Tarsal Coalition.”
- Lemley F, et al. “Current concepts review: Tarsal coalition.” Foot Ankle Int. 2006;27(12):1163-1169.
In-Office Treatment at Balance Foot & Ankle
If home treatment isn’t providing relief for your flat feet, our podiatry team at Balance Foot & Ankle can help with same-day evaluations and advanced in-office care.
Same-day appointments available. (810) 206-1402
AAOS OrthoInfo: Calcaneonavicular Coalition
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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.