Navicular accessory bone, also known as os naviculare or accessory navicular, is a common anatomical variant in the foot that can sometimes cause discomfort or pain, particularly in athletes or individuals who place high stress on their feet. While many people with this accessory bone remain asymptomatic, others may experience chronic pain, inflammation, or difficulty with footwear, necessitating medical intervention. Navicular accessory bone surgery is a specialized orthopedic procedure designed to alleviate pain, restore function, and improve overall foot mechanics, particularly when conservative treatments such as orthotics, physical therapy, and anti-inflammatory medications fail.
Understanding the Navicular Accessory Bone
The navicular bone is a critical component of the midfoot, providing support to the arch and facilitating proper gait mechanics. The accessory navicular is an extra bone or piece of cartilage located on the medial side of the foot, adjacent to the navicular bone. This anatomical variation is present in approximately 4-21% of the population and can be categorized into three types based on its morphology
- Type I Small sesamoid bone within the posterior tibial tendon, usually asymptomatic.
- Type II Larger, triangular or oval-shaped bone connected to the navicular bone by a synchondrosis, often associated with pain and tendon dysfunction.
- Type III Enlarged navicular bone, also called cornuate navicular, which may create prominence and discomfort in shoes.
Type II accessory bones are most commonly implicated in symptomatic cases, where mechanical irritation or tension on the posterior tibial tendon leads to pain and inflammation. This is often exacerbated by physical activity, tight footwear, or biomechanical abnormalities such as flatfoot deformity.
Indications for Surgery
While many cases of accessory navicular remain asymptomatic, surgical intervention may be considered when conservative management fails. Key indications for navicular accessory bone surgery include
- Persistent medial foot pain unresponsive to rest, orthotics, or anti-inflammatory medications.
- Posterior tibial tendon dysfunction or irritation caused by the accessory bone.
- Difficulty fitting shoes due to bony prominence.
- Functional limitations during sports or daily activities.
- Recurrent inflammation or bursitis around the navicular bone.
Before surgery is considered, patients typically undergo diagnostic imaging such as X-rays, MRI, or CT scans to assess the size, type, and exact location of the accessory bone, as well as to evaluate the condition of surrounding tendons and soft tissues.
Preoperative Considerations
Successful navicular accessory bone surgery requires careful preoperative planning. Factors considered by orthopedic surgeons include
- Patient age, activity level, and overall foot biomechanics.
- Extent of posterior tibial tendon involvement or degeneration.
- Presence of coexisting foot deformities, such as flatfoot or forefoot abduction.
- Medical history, including conditions affecting bone healing, such as diabetes or smoking.
Preoperative discussions also cover expected outcomes, recovery timelines, and potential risks, such as nerve injury, infection, or incomplete pain relief. Patients are often advised to discontinue certain medications, arrange for post-surgical support, and follow preoperative protocols to optimize recovery.
Surgical Techniques
Navicular accessory bone surgery can be performed using different approaches depending on the size of the bone, tendon involvement, and patient-specific anatomy. Common techniques include
Excision of Accessory Bone
This procedure involves the surgical removal of the accessory navicular while preserving the posterior tibial tendon. A small incision is made over the medial aspect of the foot, the accessory bone is carefully excised, and any associated inflamed soft tissue or bursa is removed. This technique is often preferred for patients with minimal tendon involvement and localized pain.
Kidner Procedure
The Kidner procedure is a more comprehensive approach that addresses both the accessory bone and posterior tibial tendon dysfunction. The procedure involves excision of the accessory bone and advancement or reattachment of the posterior tibial tendon to the navicular bone to restore tendon tension and foot stability. This technique is particularly beneficial in patients with flatfoot deformity or significant tendon irritation.
Minimally Invasive Approaches
Recent advancements in surgical technology have introduced minimally invasive techniques for accessory navicular removal. These approaches use smaller incisions, specialized instruments, and sometimes endoscopic assistance to reduce tissue trauma, minimize scarring, and expedite recovery while achieving effective hemostasis and pain relief.
Postoperative Care and Rehabilitation
Recovery following navicular accessory bone surgery is a gradual process that requires adherence to postoperative protocols. Key components include
- Immobilization A cast, walking boot, or splint is typically applied for several weeks to protect the surgical site and allow initial healing.
- Weight-bearing restrictions Partial or non-weight-bearing is often recommended initially, progressing to full weight-bearing as tolerated.
- Pain management Analgesics and anti-inflammatory medications are used to control postoperative pain and swelling.
- Physical therapy Rehabilitation exercises focus on restoring range of motion, strengthening the posterior tibial tendon, and improving foot biomechanics.
- Gradual return to activities Patients are guided in progressively resuming daily activities and sports to avoid overloading the healing structures.
Recovery timelines vary depending on surgical technique, bone size, and patient factors, but most patients can expect significant improvement in pain and function within three to six months.
Potential Complications
As with any surgical procedure, navicular accessory bone surgery carries potential risks. Common complications include
- Infection at the surgical site.
- Nerve irritation or numbness around the incision.
- Incomplete pain relief if tendon dysfunction persists.
- Delayed bone or tendon healing, particularly in patients with comorbidities.
- Recurrence of bony prominence if resection is incomplete.
Close follow-up with the orthopedic surgeon and adherence to rehabilitation protocols are essential to minimize complications and achieve optimal outcomes.
Outcomes and Prognosis
When performed appropriately, navicular accessory bone surgery offers excellent outcomes. Studies report high rates of pain relief, improved foot function, and patient satisfaction. Patients often experience reduced footwear discomfort, enhanced mobility, and the ability to return to sports or physical activities without limitations. Long-term prognosis is favorable, especially when combined with correction of any underlying biomechanical abnormalities and structured rehabilitation.
Navicular accessory bone surgery is an effective intervention for patients experiencing persistent pain, tendon dysfunction, or functional limitations due to an accessory navicular. Through precise surgical techniques, careful preoperative planning, and structured postoperative rehabilitation, orthopedic surgeons can alleviate symptoms, restore proper foot mechanics, and improve quality of life. As knowledge of foot anatomy and biomechanics continues to advance, surgical approaches for accessory navicular management will continue to evolve, offering patients reliable solutions for this common anatomical variation.