Accessory Bones of the Foot: Os Naviculare, Os Peroneum, Os Vesalianum, and Clinical Significance

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

Accessory ossicles of the foot — small supernumerary bones resulting from failure of secondary ossification centers to fuse during skeletal development — are incidental radiographic findings in approximately 20–30% of the population and are asymptomatic in the vast majority of cases. However, specific accessory bones become clinically significant when their synchondroses become painful from trauma, overuse, or when they interfere with adjacent tendon mechanics — and misidentifying them as fractures leads to inappropriate treatment. Each common accessory bone has a characteristic location, imaging appearance, and syndrome of symptoms when symptomatic.

Os Naviculare (Accessory Navicular)

Prevalence: 12–14% of the population; three subtypes: Type 1 (os tibiale externum — small sesamoid bone in the posterior tibial tendon, medial to the navicular tuberosity); Type 2 (the most clinically significant — a large accessory ossicle connected to the navicular by a synchondrosis, with the posterior tibial tendon inserting partially onto it); Type 3 (cornuate navicular — fully fused, prominent navicular tuberosity). Type 2 symptomatic os naviculare (Kidner’s syndrome): medial midfoot pain at the navicular tuberosity; direct shoe pressure pain; worsened by walking and athletic activity; the PTT’s insertion on the accessory ossicle rather than the navicular creates mechanical disadvantage and medial arch instability. Treatment: rest, NSAIDs, medial arch orthotics; corticosteroid injection at the synchondrosis; surgical excision of the os naviculare with PTT advancement to the navicular (Kidner procedure) for refractory cases.

Os Peroneum and Os Vesalianum

Os peroneum: small ossicle within the peroneus longus tendon as it courses around the cuboid in the peroneal groove — present in 20% of patients; becomes clinically significant when the synchondrosis fractures (from inversion ankle sprain or direct trauma) producing peroneus longus tendon dysfunction with lateral midfoot pain; X-ray shows os peroneum migration compared to prior imaging; MRI confirms PTL tear or synchondrosis disruption. Os vesalianum: accessory ossicle at the base of the 5th metatarsal — adjacent to the 5th metatarsal styloid; must be distinguished from avulsion fracture (avulsion fractures are perpendicular to the long axis; os vesalianum is a rounded, smooth ossicle with sclerotic borders). Os trigonum: previously discussed — posterior talus accessory ossicle; symptomatic with forced plantarflexion. Os calcaneus secundarius: at the anterosuperior calcaneus; can cause anterior ankle sinus tarsi pain. Dr. Biernacki at Balance Foot & Ankle diagnoses accessory bone syndromes and manages both conservative and surgical treatment. 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 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

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 treatment isn’t providing relief for your foot and ankle conditions, our podiatry team at Balance Foot & Ankle can help with same-day evaluations and advanced in-office care.

Frequently Asked Questions

When should I see a podiatrist?

If symptoms persist past 2 weeks, affect your normal activity, or are accompanied by red-flag symptoms (warmth, redness, swelling, inability to bear weight).

What does treatment cost?

Most diagnostic visits and conservative treatments are covered by Medicare and major insurers. Out-of-pocket costs vary by your specific plan.

How quickly can I get an appointment?

Most non-urgent cases see us within 5 business days. Urgent cases (sudden pain, possible fracture) typically same or next business day.