[Unilateral congenital aplasia of the scaphoid and dysplasia of the trapezium (a case report)].

Aplasia of the carpal scaphoid bone in association with dysplasia of the trapezium is a rare disorder. A right-handed, 66 years old male, suffering from a trapeziometacarpal arthritis on the right side is reported. X rays, MRI and CT-scan reveal an absence of scaphoid and a dysplasia of the trapezium. The lunate remains in place on the radius but is oriented in dorsi flexion. The capitate is dorsally and radially subluxated. Trapezium inclination of the joint at the base of the first metacarpal (trapezial tilt) is 32 degrees greater than on the opposite side which is normal (48 degrees). Radial styloid is hypoplasic. The scaphoid fossa is not covered with cartilage and subchondral sclerotic bone. The intercarpal joints show no trace of arthritis. There are no other deformation on the radial segment of the hand and the forearm. This congenital absence of scaphoid remains asymptomatic and well tolerated excepting the dysplasic trapeziometacarpal joint.