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

Accessory Navicular Syndrome: What It Is & How to Treat It

Many people are surprised to learn they have an “extra bone” in their foot — but accessory navicular is present in about 10–14% of the population. Most people never know it exists. For some, however, this anatomical variant becomes a significant source of arch pain. Here’s what Michigan podiatrists want you to know.

What Is an Accessory Navicular?

The navicular bone sits on the inner (medial) aspect of the midfoot. An accessory navicular is an extra piece of bone or cartilage adjacent to the navicular — specifically on its medial side, near the arch. It forms during childhood development and is considered a normal anatomical variant, not a pathological finding on its own.

There are three types (Geist classification):

• Type I (os tibiale externum): A small sesamoid bone within the posterior tibial tendon — usually incidental
• Type II: A large ossicle connected to the navicular by fibrocartilage — most commonly symptomatic
• Type III (cornuate navicular): Fused to the navicular — an enlarged navicular prominence

Why Does It Cause Pain?

The posterior tibial tendon — the main tendon supporting the arch — inserts at the navicular bone. When an accessory navicular is present (especially Type II), the tendon’s force is partially transferred to the accessory bone rather than the navicular. This creates a fibrocartilaginous synchondrosis (the junction between the two bones) that can become irritated and painful, especially with activity.

Contributing factors include flat feet, repetitive stress, foot trauma, and ill-fitting footwear that presses on the prominence.

Symptoms of Accessory Navicular Syndrome

• Pain, redness, and swelling over the arch, specifically at the navicular prominence
• Pain worsens with activity and improves with rest
• A visible and palpable bony bump on the inner arch
• Symptoms often onset or worsen in adolescence (growth spurts) or following foot trauma
• Shoe irritation over the prominence

Diagnosis

• Weight-bearing X-rays: Identify the accessory navicular and assess foot alignment (flat foot degree)
• MRI: Evaluates the synchondrosis for edema/disruption; assesses posterior tibial tendon integrity
• Bone scan: Shows increased uptake at the synchondrosis in active cases

Treatment Options

Conservative Treatment (Highly Effective for Most)

• Custom orthotics: The cornerstone of treatment — arch support reduces stress on the posterior tibial tendon insertion and the synchondrosis. Often dramatic improvement.
• Activity modification: Reducing high-impact activities during acute flares
• Immobilization: A walking boot for 4–6 weeks during acute exacerbations allows the synchondrosis to settle
• Footwear modification: Extra-depth shoes or shoes with soft uppers avoid pressure on the prominence
• Physical therapy: Posterior tibial tendon strengthening, calf stretching
• Ice and NSAIDs: Reduce acute inflammation

Corticosteroid Injection

A carefully placed injection at the synchondrosis can reduce pain and swelling, particularly in acute flares. This is not a permanent solution but buys time for activity modification and orthotics to take effect.

Surgical Treatment (Kidner Procedure)

Surgery is reserved for cases that fail 6+ months of conservative care. The Kidner procedure involves:

1. Removing the accessory navicular
2. Reattaching the posterior tibial tendon firmly to the navicular
3. Optionally, flatfoot correction if significant pes planus is present

Recovery is 6–8 weeks in a cast, then gradual return to activity. Success rates exceed 80% for pain relief.

Accessory Navicular vs. Plantar Fasciitis

Both cause arch pain, but the location differs — plantar fasciitis is worst at the heel, while accessory navicular pain is at the inner midfoot. X-rays can confirm the diagnosis. Both may require custom orthotics as a component of treatment.

Ready to Get Relief? We’re Here to Help.

Board-certified podiatrists Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin see patients daily at our Howell and Bloomfield Township, MI offices.

📅 Book Online
📞 (810) 206-1402

Related Conditions

• Flat Feet Treatment
• Custom Orthotics
• Plantar Fasciitis

Relief for Accessory Navicular Pain

An extra bone on the inner arch can cause chronic pain and difficulty with footwear. Our podiatrists offer both conservative management and surgical solutions.

View Our Treatment Options | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Choi YS, et al. Accessory navicular syndrome: etiology, pathogenesis, and treatment. Foot Ankle Int. 2014;35(6):626-633.
2. Kiter E, et al. Management of symptomatic accessory navicular. Foot Ankle Clin. 2019;24(4):657-671.
3. Leonard ZC, et al. The accessory navicular. Foot Ankle Spec. 2010;3(6):324-328.

Most Common Mistake We See

The most common mistake we see is: Waiting too long before seeking care. Fix: any foot pain lasting more than 4 weeks, or any sudden severe symptom, deserves a professional evaluation rather than more rest.

Warning Signs That Need Same-Day Care

Differential Diagnosis: What Else Could It Be?

Not every case of accessory navicular syndrome is straightforward. In our clinic we routinely rule out three look-alike conditions before confirming the diagnosis. If your symptoms don’t match the classic presentation, one of these may explain the pain — which is why physical exam matters more than self-diagnosis.

Condition	How It Differs
Posterior tibial tendon dysfunction	Pain along the tendon course with progressive flatfoot; may coexist.
Medial midfoot sprain	Ligamentous tenderness without a prominent bony bump.
Navicular stress fracture	Dorsal midfoot pain with impact; confirmed on MRI, not an accessory bone.

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