Accessory Navicular Syndrome: Types, Clinical Presentation, and Surgical Treatment

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

The accessory navicular — an accessory ossicle present in 4–14% of the population on the medial aspect of the navicular bone — is a common incidental finding on foot X-rays that becomes symptomatic in a subset of patients, producing medial midfoot pain that is particularly common in adolescents and young adults with flatfoot deformity. Accessory navicular syndrome requires distinction from other medial midfoot pain conditions including posterior tibial tendon dysfunction, spring ligament injury, and navicular stress fracture.

Types and Pathomechanics

Type I (os tibiale externum): a small, oval-shaped sesamoid ossicle within the posterior tibial tendon substance adjacent to the navicular — not connected to the navicular; asymptomatic; incidental finding. Type II: a larger triangular ossicle connected to the navicular by a synchondrosis (fibrocartilaginous bridge) — the tibialis posterior tendon inserts partially onto this accessory ossicle rather than the navicular tuberosity; the most clinically significant type — stress and shear at the synchondrosis produces pain; associated with flatfoot deformity (the accessory ossicle displaces the tibialis posterior insertion inferiorly and reduces its arch-supporting mechanical advantage). Type III (cornuate navicular): complete fusion of the accessory ossicle to the navicular — typically asymptomatic. Symptoms: medial midfoot pain at the navicular prominence, worsened by athletic activity, tight shoe wear, and ankle dorsiflexion; the bony prominence makes shoe fitting difficult; tenderness directly over the accessory navicular. Imaging: weight-bearing AP foot X-ray identifies the accessory ossicle; MRI shows synchondrosis edema in acute symptomatic Type II.

Treatment

Conservative management: custom orthotics with medial arch support to reduce tibialis posterior loading; padding of the bony prominence; activity modification; immobilization in a boot for acute flares. Surgical treatment: Kidner procedure — excision of the accessory navicular and advancement of the tibialis posterior tendon insertion to the medial navicular — the standard procedure; post-operative non-weight-bearing for 4–6 weeks; return to activity at 3 months. Outcomes: 85–90% patient satisfaction with Kidner procedure. Dr. Biernacki at Balance Foot & Ankle evaluates medial foot pain with weight-bearing X-ray and MRI when accessory navicular syndrome is suspected. Call (810) 206-1402 at our Bloomfield Hills or Howell office.

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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.

Red Flags — When to See a Podiatrist Now

In Our Clinic: What We See

In-Office Treatment at Balance Foot & Ankle

If home care isn’t resolving your your foot or ankle concern, a visit with a board-certified podiatrist is the fastest path to accurate diagnosis and a personalized plan. At Balance Foot & Ankle Specialists, Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin offer same-day and next-day appointments at both our Howell and Bloomfield Hills offices. We perform on-site diagnostic ultrasound, digital X-ray, conservative care, advanced regenerative treatments, and minimally invasive surgery when indicated.

Call (810) 206-1402 or request an appointment online. Most insurance plans accepted, including Medicare, Blue Cross Blue Shield, Aetna, Cigna, and United Healthcare.

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 plan tailored to your foot type. 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 Hills offices.

Book Online or call (810) 206-1402

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