Accessory Navicular Syndrome
An accessory navicular is an extra bone or piece of cartilage on the inner side of the foot. Most people never notice it, but in some it becomes painful — that is accessory navicular syndrome.
What it is
The navicular is a bone on the inner side of the midfoot. A minority of people are born with an extra ossicle — the accessory navicular — next to it, where the posterior tibial tendon attaches. Having one is common and usually causes no trouble; the "syndrome" is when it becomes irritated and painful.
Symptoms
- A visible bony bump on the inner arch, below and in front of the ankle
- Aching or throbbing in the midfoot, especially after activity
- Redness and tenderness over the bump where shoes rub
- Sometimes a flatter arch on that side
Why it becomes painful
Pain often starts after an ankle sprain or injury, from repetitive irritation in sport, or from shoes rubbing the prominence. Because the posterior tibial tendon attaches nearby, an irritated accessory navicular and posterior tibial tendon problems can occur together and both affect the arch.
Treatment
Most cases settle with conservative care: rest from aggravating activity, ice, a short spell in a walking boot or cast for a bad flare, supportive shoes, and orthotics with arch support to offload the area. Physiotherapy helps restore strength. If pain keeps returning despite these measures, surgery to remove the extra bone and reattach the tendon may be discussed.
When to see a professional
See a podiatrist or orthopaedic specialist for a persistent painful bump on the inner arch, particularly after a sprain or if the arch is flattening. Imaging confirms the accessory bone and rules out a fracture.
Frequently asked questions
- Is an accessory navicular dangerous?
- No. It is a common, harmless anatomical variation. It only matters if it becomes painful, which is then called accessory navicular syndrome.
- Do I need surgery for accessory navicular syndrome?
- Usually not. Most people improve with rest, supportive footwear and orthotics. Surgery is reserved for pain that keeps returning despite good conservative care.
- Can it cause flat feet?
- It can be associated with a flatter arch because the nearby posterior tibial tendon helps support the arch. Treating both together gives the best result.
Sources & further reading
- Accessory navicular syndrome, www.foothealthfacts.org
- Midfoot pain, www.mayoclinic.org
- Inner foot pain, www.apma.org