What it is

It is a painful condition caused by an extra bone or cartilage located on the inner side of the foot, next to the navicular bone, where the posterior tibial tendon attaches. Many people have one and never know, as it is present from birth. Accessory navicular syndrome refers to pain, redness, swelling and tenderness in this area. Symptoms often appear during adolescence, particularly with increased pressure from sports or footwear.

The condition is often triggered by trauma, high-impact activities, or poorly fitting shoes, and it is frequently associated with flat feet. Treatment options range from conservative measures like rest, ice, activity modification, and orthotics to surgical removal of the accessory bone if symptoms persist.

What happens when it occurs

Tendon traction and shoe pressure irritate the accessory bone and the tendon attachment. Reducing pressure and improving tendon capacity settles symptoms.

Common causes and risk factors

  • Foot shape with a prominent inner midfoot
  • Flat foot mechanics and reduced posterior tibial strength
  • Tight laces or stiff medial shoe counters
  • Training spikes in running or court sports

Who is most affected

Adolescents in running and court sports. Girls present more often than boys.

Typical symptoms

  • Tender bump on the inner midfoot
  • Pain with tight shoes, long walks, or running
  • Soreness with resisted foot inversion

When to seek care

If pain persists beyond two weeks, limits running, or if a bony lump becomes very tender and red.

How we diagnose

Clinical examination with palpation and strength tests. X‑ray confirms the accessory bone when needed. Ultrasound assesses the tendon attachment.

Management

  • Pain management and NSAIDs
  • Physiotherapy manual therapy
  • Footwear changes to reduce pressure over the bump
  • Posterior tibial and calf strengthening with foot intrinsic work
  • Temporary padding or orthoses to offload the area
  • Surgical excision and tendon reattachment for persistent cases. If conservative treatments fail, surgical removal of the accessory bone and repair of the posterior tibial tendon may be necessary.

Rehabilitation milestones

Phase 1 weeks 0 to 2: reduce pressure, isometrics, and gentle foot exercises.

Phase 2 weeks 2 to 6: heavy, slow tendon loading, balance, walking plan.

Phase 3 weeks 6 to 12: graded running, change of direction drills.

Phase 4 weeks 12 to 16: full sport integration.

Readiness to progress

  • Pain under the shoe upper resolved
  • Posterior tibial strength within 90 per cent
  • Run session completed without next-day soreness

Prevention

  • Choose shoes with softer medial uppers and adequate cushioning
  • Maintain posterior tibial and calf strength
  • Progress distance and change of direction drills gradually

Australia snapshot

  • Accessory naviculars are present in many Australians, although only a small share become painful.
  • Girls are present more often than boys in sports clinics
  • School and club seasons see most cases

Latest insights

Reduce shoe pressure and build tendon capacity. Most cases settle without surgery.

Keep a strength habit even when symptoms resolve.

Frequently Asked Questions

No. Many people have one and never feel it. Only a minority become painful.

Often not. Padding or simple orthoses, combined with the right shoe choice, can effectively reduce pressure.

Yes, with adjusted minutes and softer uppers as strength improves.

After a whole rehabilitation block, when pain persists and function is limited.

The bone remains, but pain resolves when pressure and tendon load are managed.

Comfortable fit with a softer inner upper and a stable midsole.

X‑ray confirms the bone when needed. Ultrasound helps with tendon assessment.