Acute plastic deformation of the ulna in a skeletally mature individual.

Acute plastic deformation of a bone refers to traumatic bending or bowing without a detectable cortical defect. We present a case that is unusual in that bowing of the ulna occurred in a skeletally mature individual and was associated with injury to the distal radioulnar joint. In this patient, the symptoms were severe enough to warrant an ulnar osteotomy. The patient regained satisfactory function. Acute plastic deformity should be suspected whenever abnormal curvature of a long bone is noted, even in adults. If the distal radioulnar joint is dislocated, the deformation should be corrected as soon as possible to avoid permanent loss of forearm rotation.