An accessory navicular is an extra bone beside the inner arch of the foot. Many people have one without pain and do not need treatment. When the area becomes symptomatic, a clinician needs to assess the bone, its connection to the main navicular and the nearby posterior tibial tendon. The finding is not an automatic reason for PRP, an operation or a course of injections.
Why can an extra bone hurt?
The accessory bone sits near the navicular, close to the tendon that helps support the arch. Symptoms can follow pressure from footwear, repeated loading or a foot or ankle injury. Some people notice a tender prominence, swelling or pain along the inside of the arch. The same symptoms can also have other causes.
Accessory navicular syndrome means that the extra bone and associated tissues are contributing to symptoms. A scan that identifies an accessory bone is not enough to make that conclusion on its own. The examination should show whether the location and loading pattern fit, and whether another problem needs attention.
Is it a problem only in teenagers?
Symptoms often arise during adolescence, but adults can have them too. An accessory navicular is a developmental variation rather than a new growth that appears because of exercise. Its shape, the surrounding structures and the stresses placed on the foot can influence whether it becomes painful.
If a child or teenager has persistent foot pain, arrange an appropriate clinical assessment rather than using an adult injection pathway as the default. Age, growth and the differential diagnosis affect management. Adults should also avoid assuming that an old scan finding explains a new injury without being examined.
Ask about a diagnosis-led assessment
What should a foot assessment cover?
A clinician looks at the precise pain location, the prominence, arch shape, walking and tendon function. They ask about previous injuries, footwear, work, sport and the activities you can no longer do comfortably. Changes in strength, swelling or the ability to bear weight can alter the next step.
An X-ray can help identify the accessory bone and its relationship to the navicular. Further imaging may be considered if a tendon injury, stress injury or another cause remains uncertain. The aim is to connect the clinical findings to a useful decision, not to collect scans without a question.
What are the usual first treatment options?
If the bone is not causing symptoms, treatment is generally unnecessary. When it is painful, conservative care often starts with reducing provoking activity, reviewing footwear and considering support or an insert. Some people need a walking boot or other temporary protection, selected by the clinician.
Rehabilitation and advice about loading can help return the foot to the demands of daily life or sport. Pain medicines or anti-inflammatory treatment may be considered where appropriate to the person's medical history. These are options to discuss, not instructions to self-treat an undiagnosed painful foot.
How do you know whether the plan is working?
Useful measures include walking tolerance, comfort in normal shoes, swelling and ability to progress agreed activities. A pain diary can help if it records what you did and how symptoms behaved afterwards. It is less useful if it encourages repeated testing of the most painful movement every day.
Ask when to review progress and what would prompt further investigation. If a support or boot is recommended, clarify how long to use it and how to return to activity. A clear progression is more helpful than either pushing through persistent pain or resting indefinitely without a reassessment point.
Discuss an assessment route with our team
When might surgery be discussed?
A foot and ankle specialist may consider surgery for persistent symptoms that have not improved with appropriate conservative treatment. The decision takes account of the accessory bone, tendon, foot structure and function. The operation is individual, and may involve more than simply removing a visible bump.
Discuss the expected rehabilitation, risks and time away from work or sport. Surgical studies do not provide a guaranteed result for every person. It is reasonable to ask why the clinician thinks the accessory navicular is the main pain source and which alternatives have been considered before a procedure is planned.
Where does PRP fit?
The clinical sources used here describe conservative care and selected surgery. They do not establish PRP as a routine treatment for accessory navicular syndrome. PRP cannot remove the extra bone or change its shape, and evidence from unrelated tendon conditions cannot be treated as proof for this problem.
A separate posterior tibial tendon disorder may need its own investigation and discussion. That does not turn every accessory navicular into an injection indication. Before any proposed injection, ask what structure is being treated, what condition-specific evidence supports it and what outcome would justify continuing the plan.
When should foot pain be assessed urgently?
Seek prompt care after an injury if you cannot bear weight, have severe swelling or a visible deformity. A red, hot foot with fever, a wound that looks infected or a sudden major change in function needs urgent advice. New numbness, a cold foot or colour change should not wait for a routine consultation.
If pain is gradual but persistent, arrange a review before it steadily restricts walking or sport. Do not assume that an inner-foot bump is harmless when the symptoms have changed, and do not assume that it is dangerous simply because an X-ray names an extra bone. The clinical context determines the next step.
Start with the diagnosis and your goals
The London PRP Clinic can discuss the appropriate assessment route for foot and tendon pain. Bring previous images, footwear information and a short account of the activities that matter to you. A useful plan may involve support, rehabilitation, imaging or a specialist opinion, with injection suitability considered only where the diagnosis and evidence support it.
Contact The London PRP Clinic about your symptoms
Evidence and further reading
Cleveland Clinic: accessory navicular bone, reviewed 2026
Information reviewed 4 November 2026. This article is general information, not a diagnosis or personal treatment advice. Seek urgent care for severe or rapidly worsening symptoms. Assessment and treatment depend on your individual circumstances.