Hammer Toe Deformity

(See also Overview of Foot and Ankle Disorders Overview of Foot and Ankle Disorders Most foot problems result from anatomic disorders or abnormal function of articular or extra-articular structures (see figure ). Less commonly, foot problems reflect a systemic disorder (see... read more .)

The usual cause of hammer toe deformity is a tendon imbalance that leads to a misalignment of the joint surfaces. This imbalance may originate as an injury or is due to a genetic predisposition toward aberrant foot biomechanics and tendon contractures. Rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is a chronic systemic autoimmune disease that primarily involves the joints. Rheumatoid arthritis causes damage mediated by cytokines, chemokines, and metalloproteases.... read more and neurologic disorders such as Charcot-Marie-Tooth disease (see Hereditary Neuropathies Hereditary Neuropathies Hereditary neuropathies include a variety of congenital degenerative peripheral neuropathies (eg, Charcot-Marie-Tooth disease). (See also Overview of Peripheral Nervous System Disorders.) Hereditary... read more ) are other causes. The second toe is the most common digit to develop a hammer toe deformity (see figure ). Second digit hammer toes commonly result from an elongated second metatarsal and from pressure due to an excessively abducted great toe (hallux valgus deformity or bunion Bunion Bunion is a prominence of the medial portion of the head of the first metatarsal bone. The cause is often variations in position of the first metatarsal bone or great toe, such as lateral angulation... read more ). Unusually long toes often develop hammer toe deformities.

Painful corns Calluses and Corns Calluses and corns are circumscribed areas of hyperkeratosis at a site of intermittent pressure or friction. Calluses are more superficial, cover broader areas of skin, and are usually asymptomatic... read more often develop in hammer toe deformity, particularly at the dorsal aspect of the proximal interphalangeal joint or the dorsal lateral aspect of the fifth toe. Reactive adventitial bursas often develop beneath corns, which may become inflamed. Calluses may develop on the plantar aspect adjacent to the metatarsal head. As the deformity becomes more rigid, the altered function of the toe creates a retrograde buckle force at the metatarsal head causing excessive plantar pressure during ambulation. This leads to both sagittal and transverse plane deformity of the toe at the metatarsophalangeal joint.

Symptoms of hammer toe deformity include pain while wearing shoes, especially shoes with low and narrow toe boxes, and sometimes metatarsalgia Metatarsalgia Metatarsalgia is a general term for pain in the area of the metatarsophalangeal joints. (See also Overview of Foot and Ankle Disorders.) Most common causes include Freiberg disease Metatarsal... read more .

Diagnosis of hammer toe deformity is clinical. Joints are examined for coexistent arthritis (eg, rheumatoid arthritis—see diagnosis of rheumatoid arthritis Diagnosis Rheumatoid arthritis is a chronic systemic autoimmune disease that primarily involves the joints. Rheumatoid arthritis causes damage mediated by cytokines, chemokines, and metalloproteases.... read more ).