As a complication of Smiths fracture, traumatic entrapment and closed rupture of the extensor pollicis longus tendon may occur rarely at the fracture site and cause loss of thumb extenion. Traumatic entrapment of the extensor pollicis longus tendon in Smiths fracture which was anatomic barrier of successful closed reduction was first described by Hunt in 1969. Since then, several authors reported another few cases.

The mechanism of tendon rupture in Smiths fracture is thought that the sharp dorsal edge of the proximal fragment may tear the stretched muscular tendon unit during extreme wrist flexion.

We experienced a case of traumatic rupture of the extensor pollicis longus tendon associated with a closed Smiths fracture and report this case with our treatment method.