(See also Overview of Foot and Ankle Disorders.)
Sesamoiditis is a common cause of metatarsalgia. The 2 semilunar-shaped sesamoid bones aid the foot in locomotion. The medial bone is the tibial sesamoid, and the lateral bone is the fibular sesamoid. Direct trauma or positional change of the sesamoids due to alterations in foot structure (eg, lateral displacement of a sesamoid due to lateral deviation of the great toe) can make the sesamoids painful. Sesamoiditis is particularly common among dancers, joggers, and people who have high-arched feet or wear high heels. Many people with bunions have tibial sesamoiditis.
The pain of sesamoiditis is beneath the head of the 1st metatarsal; the pain is usually made worse by ambulation and may be worse when wearing flexible thin-soled or high-heeled shoes. Occasionally, inflammation occurs, causing mild warmth and swelling or occasionally redness that may extend medially and appear to involve the 1st metatarsophalangeal joint. Sesamoid fracture can also cause pain, moderate swelling, and possibly inflammation.
With the foot and 1st (big) toe dorsiflexed, the examiner inspects the metatarsal head and palpates each sesamoid. Tenderness is localized to a sesamoid, usually the tibial sesamoid. Hyperkeratotic tissue may indicate that a wart or discrete callus is causing pain.
If inflammation causes circumferential swelling around the 1st metatarsophalangeal joint, arthrocentesis is usually indicated to exclude gout and infectious arthritis.
If fracture, osteoarthritis, or displacement is suspected, x-rays are taken. Sesamoids separated by cartilage or fibrous tissue (bipartite sesamoids) may appear fractured on x-rays. If plain x-rays are equivocal, MRI may be done.
Simply not wearing the shoes that cause pain may be sufficient. If symptoms of sesamoiditis persist, shoes with a thick sole and orthotics are prescribed and help by reducing sesamoid pressure. If fracture without displacement is present, conservative therapy may be sufficient and may also involve immobilization of the joint with the use of a flat, rigid, surgical shoe.
Nonsteroidal anti-inflammatory drugs (NSAIDs) and injections of a corticosteroid/local anesthetic solution can be helpful. Although surgical removal of the sesamoid may help in recalcitrant cases, it is controversial because of the potential for disturbing biomechanics and mobility of the foot. If inflammation is present, treatment includes conservative measures plus local infiltration of a corticosteroid/anesthetic solution to help reduce symptoms.
Dancers, joggers, and people who have high-arched feet, wear high heels, or have bunions can develop pain at the sesamoids beneath the head of the 1st metatarsal.
Pain is worse when weight-bearing, particularly when wearing certain shoes.
Diagnose based on clinical findings; exclude infection with synovial fluid analysis when swelling is present and exclude suspected fracture with x-rays.
Prescribe new, thick-soled shoes, orthotics that decrease pressure on the sesamoids, or both.