Foot pain isn't resolving?
Same-week appointments at Howell & Bloomfield Hills
Medically Reviewed | Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle, Michigan
Quick Answer:
Quick Answer: An accessory navicular is an extra bone or cartilage on the inner side of the foot near the navicular bone — present in about 10–14% of the population. It often causes pain and swelling over the inner arch and ankle. Dr. Biernacki evaluates the three subtypes (Type I ossicle, Type II synchondrosis, Type III cornuate) with weight-bearing X-rays and MRI. Type II is the most painful variant due to the fibrocartilaginous junction becoming inflamed. Conservative treatment — custom orthotics, physical therapy, cast immobilization — resolves symptoms in 70–80% of patients within 3–6 months. The Kidner procedure (surgical excision with posterior tibial tendon advancement) is reserved for refractory cases and yields excellent long-term outcomes.
An accessory navicular — also called os tibiale externum — is a congenital extra bone or large cartilage mass on the inner side of the foot, adjacent to the navicular. Approximately 10–14% of the population has one; most never cause symptoms. However, when the accessory navicular becomes symptomatic, it produces aching pain and a visible bony prominence on the inner midfoot that worsens with activity, shoe pressure, and prolonged standing.
Three Subtypes — Why It Matters
Radiographic classification directly guides treatment. Type I (25–30%): a small sesamoid-like ossicle within the posterior tibial tendon — rarely symptomatic. Type II (50–60%): a larger ossicle connected to the navicular by a fibrocartilaginous synchondrosis — the most painful variant; stress across this junction triggers periostitis and tendinopathy. Type III (10–20%): fully fused with the navicular, forming a cornuate (horn-shaped) navicular — moderately symptomatic, often causing a prominent bump. Weight-bearing X-rays and MRI (to assess posterior tibial tendon integrity and bone marrow edema) are standard at Balance Foot & Ankle.
Conservative Treatment: 70–80% Success Rate
Initial management is non-surgical and succeeds in the majority of patients. Custom foot orthotics are the cornerstone — a medial arch support offloads the navicular and reduces tension on the posterior tibial tendon. UCBL-style orthotics providing deep heel cup control are particularly effective in patients with concomitant flatfoot. Activity modification and shoe changes eliminate direct pressure over the prominence. Short-leg casting or boot immobilization for 6–8 weeks reduces inflammation and allows the fibrocartilaginous junction to stabilize. Physical therapy targeting posterior tibial tendon strengthening, calf stretching, and proprioception training is added once acute pain resolves. Corticosteroid injection into the synchondrosis provides pain relief in refractory cases, though repeated injections risk weakening the posterior tibial tendon.
Kidner Procedure: When Surgery Is Necessary
For patients who fail 4–6 months of conservative care, the Kidner procedure is the standard surgical option. Dr. Biernacki excises the accessory ossicle through a medial incision, releases any adhesions, and re-advances the posterior tibial tendon into a more plantar position on the navicular — theoretically improving the tendon’s mechanical advantage. Post-operative casting for 4–6 weeks is followed by progressive physical therapy. Published outcomes report 85–90% patient satisfaction at 2-year follow-up. In patients with associated flatfoot deformity, a concurrent flatfoot reconstruction (medializing calcaneal osteotomy or subtalar arthroereisis) may be recommended to address the underlying structural problem.
Pediatric and Adolescent Considerations
Accessory navicular syndrome is particularly common in adolescents during growth spurts, when rapid bone growth increases tension on the posterior tibial tendon. Girls are affected more than boys. In skeletally immature patients, the synchondrosis often matures and fuses naturally, so conservative treatment is strongly preferred and extended before any surgical decision. Low-impact activities such as swimming and cycling can help maintain fitness during recovery. Dr. Biernacki counsels families on realistic timelines and return-to-sport expectations for student athletes.
Dr. Tom's Product Recommendations
PowerStep Pinnacle Maxx Full Length Arch Support
⭐ Highly Rated | Foundation Wellness Partner | 30% Commission
High-arch orthotic with dual-layer EVA cushioning and firm arch support. Ideal for accessory navicular pain — reduces navicular stress and posterior tibial tendon tension with every step.
Dr. Tom says: “”After 6 months of inner ankle pain, PowerStep orthotics in my shoes gave me the relief I needed to keep hiking.””
Active adults with accessory navicular pain and mild flatfoot
Severe flatfoot requiring custom UCBL device
Disclosure: We earn a commission at no extra cost to you.
PowerStep Pinnacle BLUE Premium Insoles
⭐ Highly Rated | Foundation Wellness Partner | 30% Commission
Medium-profile OTC orthotic with biomechanical stabilization shell. Reduces navicular load and is compatible with most athletic and casual shoes.
Dr. Tom says: “”PowerStep Pinnacle got me through volleyball season after my doctor said I had an extra bone causing my ankle pain.””
Adolescent athletes with accessory navicular during sports season
Patients needing custom offloading of a large prominent mass
Disclosure: We earn a commission at no extra cost to you.
✅ Pros / Benefits
- Conservative care resolves symptoms in 70–80% without surgery
- Custom orthotics provide long-term biomechanical support and prevent recurrence
- Kidner procedure has 85–90% patient satisfaction with excellent long-term outcomes
❌ Cons / Risks
- Type II synchondrosis often requires 4–6 months of conservative treatment before improvement
- Surgical recovery involves 4–6 weeks non-weight-bearing followed by PT
- Associated flatfoot deformity may require concurrent reconstruction for durable results
Dr. Tom Biernacki’s Recommendation
In my Michigan practice, accessory navicular is one of the most common causes of inner ankle and arch pain I see in adolescent athletes and active adults. The key is correctly identifying the subtype — Type II synchondrosis cases are the ones that truly hurt, and custom orthotics with medial arch support are almost always my first move. Most patients never need surgery if we catch it early and get them in proper footwear. For the rare patient who needs the Kidner procedure, outcomes are very rewarding — they typically get back to full activity within 3–4 months post-op.
— Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle
Frequently Asked Questions
What does accessory navicular pain feel like?
You’ll typically feel a dull, aching pain on the inner side of your foot just above the arch, near the ankle. There’s often a visible bump that is tender to touch. Pain worsens with prolonged standing, walking, or direct shoe pressure on the prominence.
Will my accessory navicular ever go away on its own?
In children and adolescents, the fibrocartilaginous junction sometimes fuses naturally as they mature, reducing pain. In adults, the bone itself won’t disappear without surgery, but many people achieve full symptom relief with orthotics and activity modifications without ever needing the bone removed.
Can I still play sports with an accessory navicular?
Many athletes manage the condition successfully with custom orthotics and modified footwear during activity. During acute flares, reduced impact training (swimming, cycling) maintains fitness while allowing healing. Return to full sport typically requires resolving inflammation and strengthening the posterior tibial tendon.
Is the Kidner procedure a major surgery?
It is outpatient surgery performed under regional anesthesia. The incision is typically 3–5 cm on the inner ankle, and recovery involves a few weeks of non-weight-bearing, then gradual return to activity over 3–4 months. Most patients report high satisfaction with pain relief.
Michigan Foot Pain? See Dr. Biernacki In Person
4.9★ rated | 1,123 Reviews | 3,000+ Surgeries
Same-week appointments · Howell & Bloomfield Hills
Frequently Asked Questions
What causes this condition?
Causes include mechanical stress, biomechanical imbalance, age-related changes, and sometimes systemic disease. Our clinical exam plus imaging identifies the specific driver.
Can it go away on its own?
Mild cases sometimes resolve with rest and supportive footwear. Persistent symptoms past 4-6 weeks rarely resolve without active treatment.
Is surgery required?
Most patients resolve with non-surgical care. Surgery is reserved for refractory cases or structural deformity.
Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon 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 reached over one million views.
- Plantar Fasciitis: Diagnosis and Conservative Management (PubMed)
- Plantar Fasciitis (APMA)
- Diagnosis and Treatment of Plantar Fasciitis (PubMed / AAFP)
- Heel Pain (APMA)