Extensor indicis proprius syndrome: A case report

Abstract

A 24-year-old right-handed carpenter complained of a 4-month history of pain on the dorsum of his right distal forearm. The pain was mild at rest and severe upon performing heavy work. On physical examination, he was found to have minimal swelling on the dorsum of the distal third of the forearm. The swelling became more prominent when he made a fist. It was moderately tender to palpation. He had no pain when he made a tight fist with the wrist in neut r a l or when he flexed the wrist with fingers extended. When he was asked to flex the wrist actively or passively and flex the metacarpophalangeal joints, he developed severe pain localized to the dorsum of the forearm. MRI of the forearm showed hypertrophy of the EIP muscle (Fig. 1). At surgery, a thickened fourth extensor compartment was released and was noted to be 3 cm long. With the wrist and fingers in neutral position, 0.5 cm of EIP muscle extended into the fourth extensor compartment (Fig. 2A). When the wrist was flexed 60 ~ 1 cm of the muscle extended into the compartment (Fig. 2B). When the wrist and index finger were fully flexed, 2 cm of the muscle extended into the compar tment (Fig. 2C). The muscle belly of the EIP appeared hypertrophied but was of normal color and consistency. No significant tenosynovitis of EIP or extensor digitorum communis tendons was found. The wound was closed without closing the extensor retinaculum, and the wrist was splinted for 1 week. Active finger exercises were encouraged within pain tolerance the day after surgery. The patient was painfree and had full range of motion of the wrist at the 1 year follow-up examination. He had no subluxation of the extensor tendons on wrist extension. The grip strength was strong and equal on both sides.