How is an accessory navicular treated? – World Pakistan

The accessory navicular, also known as os naviculare accessorium or os tibiale externum, is an additional bone or cartilage located on the inner side of the foot, near the navicular bone and tendon of the posterior tibial muscle. While this extra bone is present in about 10-12% of the population, it often remains asymptomatic. However, for some individuals, the accessory navicular can become problematic, leading to a range of issues that can affect mobility, comfort, and quality of life. One of the most common problems associated with an accessory navicular is pain, typically referred to as “Accessory Navicular Syndrome.” Pain occurs due to irritation or inflammation of the accessory bone and surrounding tissues. Factors that can exacerbate this pain include activities involving repetitive stress on the foot, such as running or dancing, can lead to inflammation in the area. Shoes that are too tight or rub against the prominence of the accessory navicular can cause discomfort. The posterior tibial tendon, which plays a crucial role in arch support, may experience increased strain if the accessory navicular disrupts its function. This pain can significantly limit daily activities and athletic performance, particularly in individuals who rely heavily on their feet for work or sports.

The presence of an accessory navicular can disrupt the natural biomechanics of the foot. The posterior tibial tendon may have difficulty maintaining proper arch support due to its attachment to the accessory bone rather than the navicular. This can lead to a flatfoot deformity. The weakened support may cause the arch to collapse, resulting in flatfoot, which further exacerbates pain and dysfunction. Compensation for pain or instability in the foot may result in an uneven gait, potentially causing secondary issues in the knees, hips, or lower back. Strain on the posterior tibial tendon may lead to tendonitis, further compromising the structural integrity of the foot. These biomechanical complications underscore the accessory navicular’s potential to affect more than just localized foot function.

Diagnosing issues related to the accessory navicular can be challenging for several reasons due to the varied symptoms. The symptoms of accessory navicular syndrome overlap with other foot conditions, such as plantar fasciitis or posterior tibial tendon dysfunction. While X-rays or MRI scans can confirm the presence of an accessory navicular, interpreting whether it is the primary cause of the symptoms requires clinical expertise. Many individuals are unaware they have an accessory navicular until symptoms develop, often after an injury or prolonged discomfort. An accurate diagnosis is crucial to differentiate between asymptomatic and symptomatic cases and to guide effective treatment plans. The classification of an accessory navicular is typically based on its size, shape, and attachment to the navicular bone. These classifications help in understanding the potential clinical implications and guiding treatment.

The accessory navicular is generally categorized into three types: Type I: Sesamoid. This is a small, round or oval bone embedded within the posterior tibial tendon. It is located proximal to the navicular bone. This type is considered a sesamoid bone rather than being directly connected to the navicular. Clinically, this is usually asymptomatic and discovered incidentally on imaging. It rarely causes issues since it does not interfere significantly with foot mechanics. Type II: Synchondrosis. This is a larger, triangular or heart-shaped bone that is connected to the navicular by a cartilage or fibrocartilaginous bridge. This type is the most common and clinically significant type. It is most commonly associated with pain and dysfunction (Accessory Navicular Syndrome). The cartilaginous connection can become inflamed or irritated due to stress, trauma, or overuse. It may contribute to biomechanical issues like flatfoot deformity. Type III: Fused. This is a larger bone that has fused with the navicular, forming a single, enlarged navicular bone. This fusion results in a prominent bony structure on the medial aspect of the foot. This type is less likely to cause symptoms compared to Type II. The prominence can create irritation or discomfort due to pressure from footwear.

Treatment options for problems caused by an accessory navicular range from conservative to surgical, each with its challenges. Conservative approaches often focus on reducing pain and inflammation, stabilizing the foot, and improving functionality. Custom arch supports can help redistribute pressure and reduce strain on the posterior tibial tendon. Exercises to strengthen the foot and ankle muscles may improve stability and alleviate pain. Using a walking boot or cast can reduce stress on the affected area, but prolonged immobilization may lead to muscle weakening. However, these measures often provide temporary relief and may not address the underlying biomechanical issues. Surgery is considered for persistent cases that do not respond to conservative treatment. Common surgical procedures include an excision of the accessory navicular: Removing the accessory bone to eliminate the source of irritation. If the posterior tibial tendon is involved, it may need to be reattached to the navicular bone for better function. While surgery has a high success rate in resolving symptoms, it comes with risks such as infection, prolonged recovery, or incomplete resolution of pain.

Although often asymptomatic, an accessory navicular can become a source of significant pain and dysfunction for some individuals. Problems associated with this condition range from localized discomfort to systemic biomechanical issues that impact overall mobility. The challenges in diagnosing and treating accessory navicular-related problems further complicate the management of this condition. A combination of careful diagnosis, tailored conservative treatment, and, when necessary, surgical intervention can help mitigate its effects. Increased awareness and understanding of the accessory navicular are essential for both patients and healthcare providers to ensure effective management and improved outcomes.