Accessory Navicular Syndrome

Accessory navicular syndrome can be frustrating because the problem may look like a simple bump on the inside of the foot, yet it can become painful enough to interfere with walking, exercise, or wearing regular shoes. The accessory navicular itself is not necessarily a problem; many people have one without symptoms. The issue develops when the area becomes irritated, particularly when the accessory bone is stressed or the posterior tibial tendon is involved. The severity of symptoms, foot structure, activity level, and response to nonsurgical care all help determine the appropriate treatment. 

Anatomy

The navicular is a bone on the inner side of the midfoot that plays an important role in maintaining the arch. The posterior tibial tendon attaches near the navicular and helps support the arch and control the foot during walking.

An accessory navicular is an additional piece of bone or cartilage located along the inner side of the foot near the navicular. It is a congenital anatomical variation rather than something that develops simply because of poor footwear or activity. The accessory bone may remain completely painless throughout life. Symptoms can develop when repetitive stress, pressure from footwear, trauma, or increased activity irritates the area and the posterior tibial tendon.

Accessory navicular bones are relatively common and can occur in either foot. They are seen more frequently in females, adolescents, and people with flat feet. Symptoms often become noticeable during adolescence, when activity levels increase and the bones and soft tissues of the foot continue to mature.

Symptoms

The most common complaint is pain along the inner side of the foot, usually directly over the bony prominence. Patients may describe aching, tenderness, or irritation around the arch. Symptoms can become more noticeable after sports, prolonged standing, walking, or other repetitive activity.

A prominent bump may rub against shoes and become swollen or red. Tight or rigid footwear can make symptoms worse because it places direct pressure on the accessory navicular.

Flat feet can also increase stress in this area. When the arch collapses or the foot rolls inward, the posterior tibial tendon has to work harder to support the foot. This can increase tension around its attachment and contribute to persistent symptoms.

Diagnosis

The diagnosis begins with a physical examination. We look at the alignment of the foot, the shape of the arch, the location of tenderness, and the relationship between the accessory navicular and the posterior tibial tendon. Direct pressure over the prominence commonly reproduces the patient’s pain.

Weight-bearing X-rays are generally the most useful initial imaging study because they show the accessory navicular and the overall alignment of the foot. They can also help determine the size and relationship of the accessory bone to the navicular.

Accessory navicular bones are commonly divided into three types:

·   Type I: A small, separate bone within the posterior tibial tendon. These are usually not symptomatic.

·   Type II: Connected to the navicular by a fibrocartilaginous connection. This type is more commonly associated with symptoms because the connection can become irritated.

·   Type III: The accessory navicular is fused to the navicular and creates a larger prominence along the inner side of the foot.

MRI is not required in every case but may be useful when we need to evaluate the posterior tibial tendon, surrounding inflammation, or another source of pain.

Conditions That Look Similar

Pain in the inner side of the foot does not always come from an accessory navicular. Posterior tibial tendinopathy, navicular stress injury, fractures, and other inflammatory or structural conditions can produce similar symptoms.

The location of tenderness, foot alignment, activity history, physical examination, and imaging help distinguish these problems. This is particularly important when the amount of pain does not match the appearance of the accessory navicular on an X-ray.

Nonsurgical Treatment

Most symptomatic accessory navicular cases can initially be treated without surgery. The goal is to reduce irritation, support the arch, and allow the tissues around the accessory bone and posterior tibial tendon to settle.

Treatment may include activity modification, supportive footwear, ice, and anti-inflammatory medication when appropriate. Wider shoes with adequate cushioning can reduce direct pressure over the prominence.

Custom orthotics can be particularly helpful when flatfoot or abnormal foot mechanics are contributing to symptoms. By supporting the arch and improving the way the foot loads during walking, orthotics can reduce stress around the posterior tibial tendon and accessory navicular.

Physical therapy may also be used to improve strength, flexibility, and foot mechanics. When symptoms are more significant, temporary immobilization in a walking boot or cast can allow the irritated area to rest.

The specific combination of treatments depends on the severity and duration of symptoms, the patient’s activity level, and the underlying foot mechanics. 

When Surgery Becomes Appropriate

Surgery is considered when pain remains significant despite an appropriate course of nonsurgical treatment and continues to interfere with normal activities or desired physical activity.

The most common surgical approach is removal of the symptomatic accessory navicular. When the posterior tibial tendon is involved, the tendon may also need to be repaired, advanced, or repositioned as part of the procedure.

The Kidner procedure is a commonly used approach in which the accessory navicular is removed and the posterior tibial tendon is addressed to restore its appropriate function and reduce irritation along the inner side of the foot. The exact procedure depends on the patient’s anatomy, tendon function, foot alignment, and the relationship between the accessory bone and the navicular.

Surgery is not simply based on the presence of a type of accessory navicular. The clinical examination and persistence of symptoms despite appropriate conservative care are important in determining whether an operation is warranted.

Recovery

Recovery requires a period of protection and gradual progression. Depending on the procedure and the surgeon’s protocol, patients may initially use a cast or walking boot and may have restrictions on weight bearing.

As healing progresses, physical therapy can help restore range of motion, strength, balance, and normal walking mechanics. Swelling and sensitivity around the surgical site can persist after the initial healing period, particularly because the surgery is performed over an area that is exposed to shoe pressure.

Return to higher-impact activity should be gradual. Full recovery commonly takes several months, and the timeline varies depending on the procedure, the patient’s activity level, and whether additional foot reconstruction is necessary.

Potential Complications

As with any surgical procedure, complications can occur. These may include infection, wound-healing problems, persistent pain, numbness or irritation around the incision, nerve injury, and continued symptoms related to abnormal foot mechanics.

Persistent pain does not always mean that the accessory navicular has returned. Ongoing symptoms may instead be related to posterior tibial tendon dysfunction, flatfoot, inadequate rehabilitation, or another source of pain. Careful evaluation is important when symptoms continue after treatment.

Long-Term Outlook

The presence of an accessory navicular does not necessarily mean that a person will develop problems. Many people never require treatment. When symptoms occur, most cases can be managed with appropriate nonsurgical care.

For patients who continue to have significant symptoms despite conservative treatment, surgical removal of the accessory navicular with appropriate management of the posterior tibial tendon can provide meaningful improvement in pain and function. A 2025 study evaluating modified Kidner procedures found significant improvements in pain and foot function among athletes and nonathletes, supporting the procedure as an effective option for appropriately selected patients who have failed nonsurgical treatment.

The goal of treatment is not simply to remove a bone seen on an X-ray. The goal is to relieve pain, protect the posterior tibial tendon, improve foot mechanics when necessary, and allow the patient to return to normal activities.

When to See a Doctor

Persistent pain, swelling, or tenderness over the inner side of the foot should be evaluated when it interferes with walking, exercise, footwear, or daily activities. Earlier evaluation can also help determine whether the accessory navicular is actually responsible for the symptoms or whether another condition is causing the pain.

After surgery, increasing pain, significant swelling, drainage, fever, new numbness, or difficulty moving the foot should prompt timely contact with the surgical team. Severe or rapidly worsening symptoms may require urgent evaluation.

Non surgical options

Supportive footwear and appropriate activity modification can reduce unnecessary stress on the inner side of the foot. Maintaining strength and flexibility around the foot and ankle can also support healthy mechanics.

Adequate nutrition, including sufficient protein, calcium, and vitamin D, supports bone and tissue health during recovery. After surgery, activity should progress according to the healing stage rather than returning immediately to high-impact exercise.

Accessory navicular syndrome is best approached as a combination of an anatomical variation and the symptoms it creates. Not every accessory navicular needs treatment, and surgery is generally reserved for persistent symptoms that do not improve with appropriate nonsurgical care. A careful examination, appropriate imaging, and attention to the mechanics of the entire foot help guide treatment and improve the likelihood of returning to comfortable daily activity.