Accessory Navicular Syndrome – When an Extra Bone Causes Pain

Accessory Navicular Syndrome – When an Extra Bone Causes Pain Do you have a small bump on the inside of your foot that's become increasingly painful? You might have an accessory navicular bone—an extra bone that some people are born with. When this bone causes pain and inflammation, it's called accessory navicular syndrome. At Central Florida Foot & Ankle Institute, we help patients with this condition find relief and return to their normal activities. Let's explore what you need to know about this common anatomical variation. Understanding the Accessory Navicular The accessory navicular is a small extra bone located on the inner side of the midfoot, near the main navicular bone. Approximately 10 14% of the population has this anatomical variation, but most people never experience symptoms. When the accessory navicular does cause pain—typically from inflammation or irritation—it's diagnosed as accessory navicular syndrome. The condition becomes symptomatic when repetitive stress or trauma irritates the bone and the surrounding soft tissues, particularly where the posterior tibialis tendon attaches to it. Who Develops Accessory Navicular Syndrome? Anatomical Predisposition Having an accessory navicular bone is a hereditary trait, meaning it often runs in families. If your parents have an accessory navicular, you're more likely to have one as well. However, having the bone doesn't guarantee you'll develop symptoms. Age and Activity Level Accessory navicular syndrome most commonly appears in adolescents and young adults, typically between ages 10 30. It often emerges during growth spurts when bones and tendons are changing rapidly. Athletes and very active individuals are at higher risk because increased foot stress can irritate the bone and tendon. Biomechanical Risk Factors Certain foot types and movement patterns increase symptom risk: Flat feet or overpronation – places excessive stress on the posterior tibialis tendon High arched feet – can put pressure on the accessory navicular Tight Achilles tendon – increases stress throughout the foot Ankle instability – causes compensatory stress patterns Poor foot mechanics – such as intoeing or outtoeing Recognizing the Symptoms The Classic Presentation Patients typically report a painful bump on the inner side of the foot, just below the ankle. This bump is the accessory navicular bone, which becomes tender and inflamed when irritated. Pain Patterns You might experience: Pain that's worse with activity and improves with rest Swelling and redness over the bump Pain when wearing certain shoes, especially tight or supportive ones Difficulty with activities that involve pushing off the inner foot Tenderness to direct pressure on the bump Pain that worsens with prolonged walking or running Impact on Daily Life As the condition progresses, the pain can affect your ability to: Participate in sports and exercise Wear favorite shoes comfortably Walk for extended periods Stand for long periods at work Perform activities that require lateral movements How We Diagnose Accessory Navicular Syndrome Clinical Assessment When you visit Central Florida Foot & Ankle Institute, our podiatrists will examine the inside of your foot, looking for the characteristic bump. We'll ask about when the pain started, which activities make it worse, and whether you've had any injuries. We'll also assess your foot structure, arch shape, and walking pattern to identify biomechanical factors contributing to your symptoms. Imaging Studies X rays clearly show the accessory navicular bone and help us confirm the diagnosis. X rays also reveal any arthritis or bone changes that might be developing. Ultrasound allows us to visualize the posterior tibialis tendon and assess inflammation around the bone, helping us understand the degree of soft tissue involvement. MRI may be recommended if we need detailed images of the tendons and soft tissues or if we're considering surgical intervention. Treatment Options for Pain Relief Conservative Care Works for Most Patients Approximately 90% of people with accessory navicular syndrome improve with conservative treatment. Our goal is to reduce inflammation and stress on the bone and tendon. Rest and Activity Modification Temporarily reducing high impact activities gives the irritated tissues time to heal: Switch from high impact to low impact exercise (running to swimming or cycling) Take frequent rest breaks during activity Avoid activities that directly stress the accessory navicular Use ice after activities to reduce inflammation Custom Orthotics Custom shoe inserts are often the most effective conservative treatment. We design orthotics that: Support your arch and reduce overpronation Offload stress from the accessory navicular Improve overall foot mechanics Reduce stress on the posterior tibialis tendon Provide cushioning and protection Many patients experience immediate pain relief with proper orthotics and can return to full activity within weeks. Footwear Mo