Tarsal Coalition: The Hidden Cause of Rigid Flatfoot &

Quick answer: Treatment for tarsal coalition rigid flatfoot subtalar stiffness treatment follows a stepwise approach: 1) conservative care first (rest, ice, supportive footwear, OTC anti-inflammatories), 2) physical therapy and targeted exercises, 3) in-office treatments (injections, custom orthotics) if conservative fails at 4-6 weeks, 4) surgery for refractory cases. Most patients resolve at step 1 or 2. Call (810) 206-1402.

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

Tarsal coalition is an abnormal bridge — bony, cartilaginous, or fibrous — connecting two or more of the tarsal (hindfoot and midfoot) bones that should remain separate. Present in approximately 1–2% of the population but frequently asymptomatic until adolescence or early adulthood, tarsal coalition is a common cause of rigid flatfoot, recurrent ankle sprains, and peroneal spastic flatfoot that is frequently initially attributed to simple muscle strain or ligament sprain.

Types of Tarsal Coalition

Calcaneonavicular (CN) Coalition

The most common type — a bridge between the calcaneus (heel bone) and navicular at the anterior margin of the subtalar region. CN coalitions are best visualized on the oblique foot X-ray (the “anteater nose” sign, where the calcaneus elongates anteriorly toward the navicular). CT or MRI confirms the diagnosis and characterizes whether the coalition is bony, cartilaginous, or fibrous.

Talocalcaneal (TC) Coalition

The second most common type — occurring at the middle facet of the subtalar joint. TC coalitions are more difficult to identify on plain X-rays (the “C-sign” and talar beaking are radiographic clues); CT is often required for definitive diagnosis and surgical planning. TC coalitions tend to be more painful and more likely to require surgical treatment than CN coalitions.

Why Tarsal Coalition Causes Symptoms

The subtalar joint complex normally provides hindfoot inversion-eversion for walking on uneven surfaces and absorbs rotational forces during gait. A coalition restricts this motion — creating rigid, fixed hindfoot malalignment (typically hindfoot valgus and flatfoot) and transmitting abnormal forces to the midfoot, ankle, and peroneal muscles.

The peroneal muscles reflexively contract to protect the restricted subtalar joint — producing the characteristic “peroneal spastic flatfoot” in which the peroneals are in constant protective spasm, making the foot appear everted and preventing passive inversion.

When Symptoms Develop

Many coalitions are asymptomatic through childhood. Symptoms typically emerge during adolescence (age 8–16) as the coalition ossifies and progressive restriction of subtalar motion creates increasing stress on adjacent structures. Presenting symptoms: progressive flatfoot that parents notice, recurrent ankle sprains from altered biomechanics, activity-related hindfoot or ankle pain, and inability to perform activities that require hindfoot flexibility.

Treatment

Conservative Management

Initial treatment for symptomatic coalition involves activity modification, a short-leg walking cast or boot for 4–6 weeks to allow acute inflammation to resolve, anti-inflammatory medication, custom orthotics with medial arch support, and physical therapy. Conservative management is appropriate as first-line treatment and provides durable relief in many patients with fibrous or cartilaginous coalitions and mild symptoms.

Surgical Resection

Surgical coalition resection — removing the abnormal bridge and placing a fat or muscle interposition graft to prevent recurrence — is indicated when conservative management fails and when imaging confirms the coalition is appropriate for resection (joint surface damage is not too severe, coalition size is manageable). CN coalition resection has excellent outcomes (>80% success) in adolescent patients. TC coalition resection success rates are lower (60–70%) and depend heavily on the percentage of the middle facet involved.

Flatfoot Reconstruction

When secondary deformity (flatfoot, hindfoot valgus) has become fixed and significant, coalition resection alone may be insufficient — reconstruction of the flatfoot deformity (calcaneal osteotomy, lateral column lengthening) is performed simultaneously.

Frequently Asked Questions

How long does treatment take to work?

Most patients see improvement in 4-8 weeks with consistent conservative care. Persistent symptoms after 8 weeks need imaging and escalation.

When is surgery needed?

Surgery is reserved for cases that fail 3-6 months of conservative care, structural deformities, or fractures requiring stabilization.

Is this covered by insurance?

Most diagnostic visits and conservative treatments are covered by Medicare and major insurers. Custom orthotics often require diabetic or post-surgical justification.

What is Foot pain?

Foot pain is a common foot/ankle condition that affects mobility and quality of life. Understanding the underlying cause is the first step in successful treatment. Our podiatrists at Balance Foot & Ankle perform a hands-on biomechanical exam, review your activity history, and use diagnostic imaging when appropriate to identify the root cause—not just treat the symptom. Many patients have been told to “rest and ice” without a deeper diagnostic workup; our approach is different.

Symptoms and warning signs

Common signs of foot pain include pain that worsens with activity, morning stiffness, swelling, tenderness when palpated, and difficulty bearing weight. If you experience sudden severe pain, inability to walk, visible deformity, numbness or color change, contact our office the same day or visit urgent care—these can signal a more serious injury such as a fracture, tendon rupture, or vascular compromise. Diabetics with any foot wound should seek same-day care.

Conservative treatment options

Most cases of foot pain respond to non-surgical care: structured rest, supportive footwear changes, custom orthotics, targeted stretching and strengthening protocols, anti-inflammatory medications when medically appropriate, and in-office procedures such as ultrasound-guided injections. We also offer advanced therapies including MLS laser therapy, EPAT/shockwave, regenerative injections, and image-guided procedures. Treatment is sequenced from least invasive to most invasive, and we explain the rationale at every step.

When is surgery considered?

Surgery is reserved for cases that fail 3-6 months of well-structured conservative care, when there is structural pathology (severe deformity, complete tear, advanced arthritis), or when imaging shows damage that will not heal without intervention. Our surgeons have performed 3,000+ foot and ankle procedures and prioritize minimally-invasive techniques whenever appropriate. We discuss recovery timelines, return-to-activity milestones, and realistic outcome expectations before any procedure is scheduled.

Recovery timeline and prevention

Recovery from foot pain varies based on severity and chosen treatment path. Conservative cases often improve within 4-8 weeks with consistent adherence to the protocol. Post-procedural recovery may range from a few days (in-office procedures) to several months (reconstructive surgery). Long-term prevention involves footwear assessment, activity modification, structured strengthening, and regular check-ins with your podiatrist if you have a history of recurrence. We provide written home-exercise plans and digital follow-up support.

Visit Balance Foot & Ankle — Same-Day Appointments Available

Our podiatry team serves patients throughout Michigan including Howell, Brighton, and Bloomfield Hills. If you’re dealing with heel pain, ingrown toenails, or a foot injury, we have same-day appointment availability.