What is an Accessory Navicular Syndrome?

The accessory navicular bone exists as an extra bone or piece of cartilage located on the inner side of the foot just above the arch. Some people with this bone develop a painful condition known as accessory navicular syndrome when an injury aggravates the bone and/or posterior tibial tendon.

People with an accessory navicular bone tend to only notice the condition if it causes problems. However, some patients develop a painful condition known as Accessory Navicular Syndrome when the bone or posterior tibial tendon are aggravated. This may result from:

  • Trauma, such as a foot or ankle sprain
  • Chronic irritation from poorly fitted shoes
  • Excessive activity or overuse of the foot

Many patients with accessory navicular syndrome will also present with flat feet. Fallen Arches put more strain on the posterior tibial tendon, which produces inflammation and irritation of the accessory navicular.

What Causes an Accessory Navicular Syndrome?

Genetic predisposition: ANS is often considered to be an inherited condition. Certain individuals may have a genetic predisposition that increases their likelihood of developing an accessory navicular bone.

Developmental abnormalities: During fetal development, the bones in the foot gradually form and fuse together. In some cases, the accessory navicular bone fails to fuse properly with the main navicular bone. This can lead to the presence of an extra bone in the foot, causing ANS.

Overuse or repetitive stress: Engaging in activities that place repetitive stress on the foot, such as running, jumping, or participating in sports, can potentially exacerbate the symptoms of ANS. Continuous strain on the foot may irritate the tendon or surrounding tissues, leading to pain and inflammation.

Trauma: Injury or trauma to the foot, such as a sprained ankle or a direct blow to the foot, can contribute to the development of ANS. The trauma may disrupt the normal alignment and functioning of the bones and soft tissues in the foot, including the accessory navicular.

Foot structure and biomechanics: Certain foot structures or biomechanical abnormalities can increase the likelihood of developing ANS. For example, having flat feet (pes planus) or a foot with excessive pronation (inward rolling of the foot) may place additional stress on the accessory navicular, leading to pain and inflammation.

Symptoms of Accessory Navicular Syndrome

Symptoms of Accessory Navicular Syndrome commonly appear during adolescence, the time when bones mature and cartilage develops into bone tissue. However, sometimes the symptoms do not appear until adulthood. The symptoms of accessory navicular syndrome include:

  • A bony bump on the midfoot (the inner side of the foot, just above the arch)
  • Swelling and redness of the bony prominence
  • Vague throbbing and pain in the arch of the midfoot, usually during or after periods of activity

Treatment for an Accessory Navicular Syndrome

Rest and activity modification: Avoiding activities that worsen the symptoms, such as running or jumping, can help reduce pain and allow the foot to heal. Resting the foot and modifying activities may be sufficient for mild cases.

Immobilization: Immobilizing the foot with a cast, walking boot, or orthotic device can provide support, protect the affected area, and promote healing. These devices may help relieve pain and reduce stress on the foot.

Pain management: Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, can help reduce pain and inflammation. However, it’s important to consult with a healthcare professional before taking any medication.

Physical therapy: A physical therapist can guide you through exercises and stretches to strengthen the foot muscles, improve flexibility, and correct any biomechanical issues. They may also use modalities like ultrasound or electrical stimulation to aid in pain relief and healing.

Orthotic devices: Custom-made shoe inserts or orthotic devices can help support the arch and correct foot alignment. These can help redistribute pressure and reduce strain on the accessory navicular bone.

Shoe modifications: Wearing proper footwear that provides good arch support and cushioning can help alleviate symptoms. Shoes with a wide toe box and low heel can also reduce pressure on the foot.

Corticosteroid injections: In some cases, corticosteroid injections may be used to reduce pain and inflammation. However, these injections are typically reserved for severe cases and are not a long-term solution.

Surgery: If conservative treatments do not provide relief or if the condition is severe, surgical intervention may be considered. Surgery typically involves removing the accessory navicular bone and repairing any associated soft tissue issues. Surgery may also be combined with procedures to correct foot alignment or address other related foot conditions.

The choice of treatment depends on factors such as the severity of symptoms, activity level, and individual preferences. It’s important to consult with a healthcare professional, such as an orthopedic specialist or a podiatrist, to determine the most appropriate treatment plan for your specific case of ANS.