Accessory Navicular Bone Arch Pain: Treatments That Work

Quick answer: Treatment for accessory navicular bone arch pain 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.

That painful, bony lump on the inner side of your foot — the one that rubs against every pair of shoes and aches after a full day on your feet — might not be a fracture, arthritis, or tendon tear. It might be a bone that was always there, one that most people never think about because it never causes problems. But when it does, it causes exactly the kind of persistent arch pain that sends people searching for answers.

” alt=”Accessory navicular bone arch pain treatment – Balance Foot & Ankle, Howell MI” width=”1200″ height=”630″ loading=”eager” fetchpriority=”high” decoding=”async” />

What Is the Accessory Navicular Bone?

The accessory navicular — also called the os tibiale externum — is an extra bone located on the medial (inner) side of the foot, just anterior to the ankle and posterior to the first metatarsal. It is present from birth, forming when a secondary ossification center in the navicular fails to fuse during skeletal development. It affects approximately 10–14% of the population, making it the most common accessory ossicle in the foot.

We classify the accessory navicular into three types. Type I is a small, free-floating ossicle within the posterior tibial tendon. Type II — the most symptomatic — is connected to the navicular by fibrocartilage (synchondrosis). Type III is a fully fused cornuate navicular that creates a prominent medial tuberosity. Types I and III rarely require surgery; Type II is where most of our treatment efforts focus.

The Arch Pain Connection: Why This Bone Causes So Much Trouble

The critical relationship is between the accessory navicular and the posterior tibial tendon — the primary tendon responsible for supporting your medial longitudinal arch. In a normal foot, the posterior tibial tendon inserts directly into the navicular. When an accessory navicular is present, that tendon either inserts into the extra bone itself or diverts its pull through the synchondrosis connecting the two bones.

The result: every step you take transfers force through that fibrocartilage junction. Over thousands of steps per day, that junction becomes inflamed, especially in flat-footed patients whose posterior tibial tendon is already under increased tension from overpronation. This is why custom orthotics — by controlling pronation — are so consistently effective. They address the root biomechanical driver, not just the symptom.

Recognizing Accessory Navicular Arch Pain

The hallmark symptom is specific, reproducible pain at the medial arch — you can usually point to it with one finger. It is accompanied by a visible or palpable bony prominence that is tender to direct pressure. This well-localized pattern distinguishes it from the more diffuse aching of plantar fasciitis or the posterior heel pain of Achilles tendinopathy.

• Medial arch or inner ankle bump — often visible as a prominence on the navicular side of the foot
• Pain after walking or standing for extended periods — typically worsening throughout the day and improving with rest
• Sharp pain with direct shoe pressure — the bump rubs against the shoe medial counter
• Arch fatigue and aching — the posterior tibial tendon working harder than normal
• Swelling over the medial midfoot — particularly after activity or a long day on your feet
• Onset or worsening after a sprain — ankle inversion injuries can disrupt the synchondrosis
• Flat-footed posture — most symptomatic accessory navicular patients have a low or collapsed medial arch

One pattern we see repeatedly: a woman in her 30s or 40s with a lifetime of flat feet starts a new job requiring extended time on hard floors. Within weeks the medial arch begins aching — and the culprit turns out to be a Type II accessory navicular that had been silent for decades.

Diagnosis at Our Clinic

Diagnosis combines clinical examination with imaging. On exam we identify the exact location of maximal tenderness, assess arch height with weight-bearing, check for posterior tibial tendon weakness (single-heel-rise test), and note any skin changes over the prominence. Weight-bearing X-rays confirm the accessory navicular and classify its type. When we need to assess the posterior tibial tendon’s integrity or check for synchondrosis injury, we order MRI — this is particularly important when surgery is being considered, because tendon condition significantly affects surgical planning.

Treatment: From Conservative to Surgical

Treatment follows a clear stepwise progression, starting with the most conservative and effective measures. Roughly 60–70% of patients achieve lasting relief without surgery.

Phase 1: Initial Conservative Management (Weeks 1–6)

• Activity modification — reduce or pause activities that provoke pain; avoid barefoot walking on hard surfaces
• Anti-inflammatory measures — NSAIDs, ice after activity, and in acute cases a corticosteroid injection near the synchondrosis
• Shoe adjustment — switch to shoes with a wide, soft toe box and medial arch support built-in; avoid rigid medial counters
• Immobilization — for acute synchondrosis injuries, a CAM walker boot for 4–6 weeks can allow significant inflammation to resolve

Phase 2: Orthotic and Rehabilitation Management (Weeks 6–16)

• Custom foot orthotics — the most reliably effective long-term intervention for accessory navicular arch pain
• Physical therapy — posterior tibial tendon strengthening, single-leg balance training, eccentric calf exercises, and gait retraining to reduce overpronation
• Taping techniques — low-Dye or arch taping provides immediate offloading of the navicular during transitional periods

Surgical Option: The Kidner Procedure

When 3–6 months of conservative management fails to provide meaningful relief, surgery is highly effective. The Kidner procedure involves removing the accessory navicular bone and reattaching or tightening the posterior tibial tendon to the native navicular. Outcomes data is excellent: published series report 85–95% patient satisfaction and return to full activity. The typical timeline is 6 weeks non-weight-bearing, 6 weeks in a progressive walking boot, then 6–8 weeks of physical therapy.

Why Custom Orthotics Work So Well for This Condition

Custom orthotics are the single most impactful conservative intervention for accessory navicular arch pain. A properly fabricated orthotic includes a deep heel cup to stabilize rearfoot mechanics, a medial longitudinal arch fill to support the collapsed midfoot, and a forefoot post to prevent the foot from rolling inward at terminal stance. Over-the-counter supports can provide temporary relief but rarely match the precision of a custom device for flat-footed patients with moderate to severe pronation.

In-Office Treatment at Balance Foot & Ankle

If home treatment isn’t providing relief for your flat feet and arch condition, our podiatry team at Balance Foot & Ankle can help with same-day evaluations and advanced in-office care.

Frequently Asked Questions

Are custom orthotics worth the cost for accessory navicular pain?

In most cases, yes — particularly for patients with significant flat feet. Custom orthotics address the underlying biomechanical driver of the pain rather than simply masking symptoms, and they can prevent progression to posterior tibial tendon dysfunction. Given that surgery costs significantly more and requires months of recovery, a well-made orthotic is almost always worth trying first. Many insurance plans cover custom orthotics with a podiatrist’s prescription.

Can I still run with an accessory navicular?

Many people run for years with an accessory navicular without any symptoms. If you are currently having pain, a temporary reduction in mileage combined with proper orthotics and supportive footwear will usually allow you to return to running within 6–8 weeks. If pain persists despite these measures, a short period of complete rest or immobilization may be necessary. We rarely recommend giving up running permanently — the goal is to optimize your biomechanics so the bone is no longer being stressed.

The Bottom Line

Accessory navicular arch pain is common, well-understood, and very treatable. The combination of custom orthotics, supportive footwear, and targeted physical therapy resolves symptoms in the majority of patients without surgery. For those who do need the Kidner procedure, outcomes are consistently excellent. The key is not ignoring the pain — the longer overpronation stress continues without correction, the greater the risk of developing posterior tibial tendon dysfunction. Call Balance Foot & Ankle at (810) 206-1402 — same-day appointments in Howell and Bloomfield Township, Michigan.

Sources

1. Sella EJ, Lawson JP, Ogden JA. “The accessory navicular synchondrosis.” Clinical Orthopaedics and Related Research. 1986.
2. Scott AT, et al. “Results of the Kidner procedure for symptomatic accessory navicular.” Journal of Foot & Ankle Surgery. 2007.
3. Micheli LJ, et al. “Symptomatic accessory navicular: management options.” Clinical Journal of Sport Medicine. 2019.
4. Johnson KA. “Tibialis posterior tendon dysfunction.” Clinical Orthopaedics. 2025.