As many as 14% of people have an ?accessory? or extra bone or piece of cartilage on the inner side of the foot. An accessory navicular is an inborn condition that affects only a minority of the population. It is not part of normal bone structure and therefore is not present in most people. It may be found when the foot is x-rayed for other reasons, or when irritation develops. Patients may not be aware of it until a change in their activity, growth spurt or new footwear creates friction. Most cases of accessory navicular syndrome are treated conservatively.
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 of accessory navicular include. Bone lump on the inside of the foot. Redness and swelling. Pain.
An initial assessment is an orthopaedic office begins with a thorough history and complete physical exam, including an assessment of the posterior tibial tendon and areas of tenderness. Associated misalignments of the ankle and foot should be noted. Finally, weight-bearing x-rays of the foot will help in making the diagnosis. Sometimes, an MRI may be needed to see if the posterior tibial tendon is involved with the symptoms or getting more clarity on the anatomy of the accessory navicular.
Non Surgical Treatment
Patients with a painful accessory navicular may benefit with four to six physical therapy treatments. Your therapist may design a series of stretching exercises to try and ease tension on the posterior tibial tendon. A shoe insert, or orthotic, may be used to support the arch and protect the sore area. This approach may allow you to resume normal walking immediately, but you should probably cut back on more vigorous activities for several weeks to allow the inflammation and pain to subside. Treatments directed to the painful area help control pain and swelling. Examples include ultrasound, moist heat, and soft-tissue massage. Therapy sessions sometimes include iontophoresis, which uses a mild electrical current to push anti-inflammatory medicine to the sore area.
Once the navicular inflammation has lessened it is not necessary to perform surgery unless the foot becomes progressively flatter or continues to be painful. For these children, surgery can completely correct the problem by removing the accessory navicular bone and tightening up the posterior tibial tendon that attaches to the navicular bone. The strength of this tendon is integral to the success of this surgery as well as the arch of the foot. Following surgery the child is able to begin walking on the foot (in a cast) at approximately two weeks. The cast is worn for an additional four weeks. A small soft ankle support brace is then put into the shoe and worn with activities and exercise for a further two months.