Extra Bone In Foot Accessory Navicular

Overview
An accessory navicular bone is an accessory bone of the foot that occasionally develops abnormally causing a plantar medial enlargement of the navicular. The accssory navicular bone presents as a sesamoid in the posterior tibial tendon, in articulation with the navicular or as an enlargment of the navicular. Navicular (boat shaped) is an intermediate tarsal bone on the medial side of the foot. It is located on the medial side of the foot, and articulates proximally with the talus. Distally it articulates with the three cuneiform bones. In some cases it articulates laterally with the cuboid. The tibialis posterior inserts to the os naviculare. The tibialis posterior muscle also contracts to produce inversion of the foot and assists in the plantar flexion of the foot at the ankle. Tibialis posterior also has a major role in supporting the medial arch of the foot. This supports is compromised by abnormal insertion of the tendon into the accessory navicular bone when present. This lead to loss of suspension of tibialis posterior tendon and may cause peroneal spastic pes planus or simple pes planus. But, yet a cause and effect relationship between the accessory navicular and pes planus is doubtful and is yet unproved clearly.



Causes
It is commonly believed that the posterior tibial tendon loses its vector of pull to heighten the arch. As the posterior muscle contracts, the tendon is no longer pulling straight up on the navicular but must course around the prominence of bone and first pull medially before pulling upward. In addition, the enlarged bones may irritate and damage the insertional area of the posterior tibial tendon, making it less functional. Therefore, the presence of the accessory navicular bone does contribute to posterior tibial dysfunction.

Symptoms
Symptoms of accessory navicular include. Bone lump on the inside of the foot. Redness and swelling. Pain.

Diagnosis
To diagnose accessory navicular syndrome, medical staff ask about the patient?s activities and symptoms. They will examine the foot for irritation or swelling. Medical staff evaluate the bone structure, muscle, joint motion, and the patient?s gait. X-rays can usually confirm the diagnosis. MRI or other imaging tests may be used to determine any irritation or damage to soft-tissue structures such as tendons or ligaments. Because navicular accessory bone irritation can lead to bunions, heel spurs and plantar fasciitis, it?s important to seek treatment.

Non Surgical Treatment
Although operative treatment, and removal of the accessory navicular is possible, this is not usually indicated at first. Conservative nonoperative treatment is best, the course depending on the severity of the symptoms. When the pain is very severe, which could indicate a fracture, a period of immobilization might be required. This is done by waring a fracture boot, or a cast, which can help the ossicle stay stable, aiding in healing. Immobilization usually lasts between 4 to 6 weeks. Afterwards, physical therapy exercise, or any appropriate home course, should be used to help strengthen the ankle and return the ankle and foot to full range of motion, and have no pain on movement. Sometimes crutches are used when weight bearing is too painful, but it is best to try to bear weight when possible.



Surgical Treatment
After the anesthesia is administered you will be heavily sedated and placed on your stomach. Surgeons will place a tourniquet around your thigh and an incision will be made on the inside of the foot. The posterior tibial tendon will be moved as necessary and the accessory navicular will be removed. Surgeons will repair the posterior tibial tendon with sutures or suture anchors, and the wound will be closed. A splint will be placed on the foot for stabilization and immobilization. You will be permitted to leave the surgical center once you have been cleared by the anesthesiologist. Plan ahead to have a friend or family member take your prescription to a pharmacy to pick up your post-op medication. Use narcotic pain medications before bed or if numbness in your foot begins to dull. Schedule a post-op visit for 4 weeks after the procedure.