(See also Overview of Foot and Ankle Disorders.)
The usual cause of hammer toe deformity is misalignment of the joint surfaces due to a genetic predisposition toward aberrant foot biomechanics and tendon contractures. Rheumatoid arthritis (RA) and neurologic disorders such as Charcot-Marie-Tooth disease (see Hereditary Neuropathies) are other causes. The 2nd toe is the most common digit to develop a hammer toe deformity (see figure Hammer toe). Second toe hammer toes commonly result from an elongated 2nd metatarsal and from pressure due to an excessively abducted great toe (hallux valgus deformity) causing a bunion. Unusually long toes often develop hammer toe deformities. Painful corns often develop in hammer toe deformity, particularly of the 5th toe. Reactive adventitial bursas often develop beneath corns, which may become inflamed.
Symptoms of hammer toe deformity include pain while wearing shoes, especially shoes with low and narrow toe boxes, and sometimes metatarsalgia.
Diagnosis of hammer toe deformity is clinical. Joints are examined for coexistent arthritis (eg, RA—see diagnosis of RA).
Shoes should have a wide toe box. Toe pads sold in pharmacies also help by shielding the affected toes from the overlying shoe. If conservative measures are ineffective, surgical correction of the deformity often relieves symptoms. If there is accompanying metatarsalgia, over-the-counter or prescription orthotic devices with metatarsal pads and cushioning may help alleviate the pain.