Recovery From Accessory Navicular Bone Removal

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
An accessory navicular develops as a result of a congenital anomaly and is found more often in women. If the bone is large, it may rub against a shoe, causing pain. Because of its location, the posterior tibial tendon may pull on the bone during walking or running, causing the fibrous tissue that connects the accessory navicular to the navicular to tear and become inflamed.

Symptoms
Adolescence is a common time for the symptoms to first appear. This is a time when bones are maturing and cartilage is developing into bone. Sometimes, however, the symptoms do not occur until adulthood. The signs and symptoms of accessory navicular syndrome include A visible bony prominence on the midfoot (the inner side of the foot, just above the arch) Redness and swelling of the bony prominence. Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity.

Diagnosis
Upon examining a foot with a symptomatic accessory navicular, there will often be a bony prominence on the inside of the foot, just below and in front of the inside ankle bone (medial malleolus). The size of this prominence will vary from small to quite large. Pressing over this area will often cause discomfort. There may be an associated flat foot deformity as this can occur in patients with an accessory navicular. Stressing the posterior tibial tendon by raising the heel up and down on one foot, or by forcing the foot to the inside against resistance, may aggravate the symptoms as these maneuvers stress the posterior tibial tendon which is attached on the inside of the accessory navicular bone. Patients may walk with a slight limp due to the pain.

Non Surgical Treatment
Most children?s symptoms are improved or resolved by taking a break from activities that irritate their feet. shoe fit inserts that pad the accessory navicular area are also helpful. If your child?s symptoms do not improve, your physician may recommend a below-the-knee cast or walking boot. Surgery is rarely needed.



Surgical Treatment
If non-surgical treatment fails to relieve the symptoms of accessory navicular syndrome, surgery may be appropriate. Surgery may involve removing the accessory bone, reshaping the area, and repairing the posterior tibial tendon to improve its function. This extra bone is not needed for normal foot function.