Os Naviculare (Accessory Navicular)

Os Naviculare Overview

An Os Naviculare (or accessory navicular) is an extra bone or cartilage on the inside of the foot, just above the arch. While this is a normal anatomical variation found in around 10–15% of the population, it can sometimes become painful and symptomatic, especially in adolescence or after injury or overuse.

Os Naviculare Symptoms and Diagnosis

Symptoms typically include:

• Pain and swelling over the inner arch of the foot

• Tenderness when wearing tight shoes or boots

• Flattening of the arch or the appearance of flatfoot

• Pain that worsens with activity or walking

Diagnosis is usually made by clinical examination and confirmed with X-rays. In some cases, MRI or ultrasound may be used to assess soft tissue inflammation or posterior tibial tendon involvement.

Os Naviculare Causes

• Repetitive stress or overuse (e.g. running, ballet, sports)

• Direct trauma or sprain

• Tight or ill-fitting footwear

• Underlying foot shape or flatfoot

• Posterior tibial tendon dysfunction

Os Naviculare Treatment and Prevention

Most cases can be managed without surgery, using:

• Activity modification to reduce stress on the foot

• Supportive, cushioned footwear

• Custom orthotics to offload pressure from the bony area

• Ice and anti-inflammatory medications

• Physiotherapy to strengthen the surrounding muscles and improve foot mechanics

• Immobilisation in a boot or cast for 2–4 weeks in more severe cases

Injection Therapy

In persistent cases, Mr Hester may recommend a steroid injection to reduce inflammation and provide symptom relief.

Os Naviculare Surgery

Surgery is considered when conservative management fails. The most commonly performed procedure is a Kidner procedure, where the accessory navicular is removed and the posterior tibial tendon is reattached to the native navicular bone.

In many cases, a calcaneal osteotomy (heel shift) is also performed. This involves shifting the heel bone slightly inward to realign the foot shape, offload the medial arch, and improve overall foot function.

The procedure is typically performed as a day case under general anaesthetic.

Risks of surgery may include:

• Pain

• Bleeding

• Infection

• Scarring

• Damage to nearby nerves or blood vessels

• Deep vein thrombosis (DVT) or pulmonary embolism (PE)

• Failure to resolve symptoms

• Need for further surgery

Os Naviculare Surgery Recovery

Following surgery, you will be placed in a cast and remain non-weight-bearing for six weeks to allow for proper healing of the bone and tendon. You will be advised to keep the leg elevated and the cast clean and dry during this time.

At six weeks, the cast will be removed, and you will gradually transition into a walking boot with physiotherapy support.

Expected Recovery Timeline

0–6 weeks

Non-weight-bearing in cast. Foot elevated. Rest and healing.

6 weeks

Cast removed. Transition to boot. Begin weight-bearing and gentle movement.

6–12 weeks

Progressive physiotherapy. Walking improves. Swelling may persist.

12 weeks+

Return to full activity if pain-free. Ongoing strengthening and footwear support.