musculoskeletal and connective tissue disorders
Hammer Toe Deformity
Introduction
Hammer toe deformities result from an imbalance of the digital extensor and flexor tendons that typically causes a contracture at the proximal interphalangeal joint. This progresses to a rigid Z-shaped deformity that can lead to dorsal subluxation and eventual dislocation at the metatarsophalangeal joint. Diagnosis is clinical. Weight-bearing radiographs are helpful to determine severity. Treatment is modification of footwear, taping/splinting, and/or orthotics. (See also Overview of Foot and Ankle Disorders .) 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 (RA) and neurologic disorders such as Charcot-Marie-Tooth disease (see Painful Calluses and Corns 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 . Diagnosis of hammer toe deformity is clinical. Joints are examined for coexistent arthritis (eg, rheumatoid arthritis—see Diagnosis ). In hammer toe, usually the second toe, or sometimes another lesser toe, develops a fixed Z-shaped deformity. 