To investigate the effect on distal radioulnar joint (DRUJ) stability of ulnar shortening osteotomy for treatment of distal radius fracture malunion.

The model of distal radius fracture(AO type 23C1.2) malunion with radial shortening was created on 10 fresh adult upper limb cadaver specimens. The distal radius fracture was fixed with volar locking plate, and the oblique step ulnar shortening osteotomy was made. The changes of maximum pronation and supination torques from no internal fixation, Kirschner wires fixation and locking plate fixation for ulnar shorting osteotomy were compared.

The maximum pronation and supination torques were (1.59±1.03) N•m and (1.85±1.21) N•m in the control model, (1.44±0.93) N•m and (1.63±1.18) N•m in the distal radius fracture model, (1.22±0.83) N•m and (1.20±0.83) N•m in the only ulnar shortening osteotomy model, (1.24± 0.78) N•m and (1.30±0.87) N•m in Kirschner wires fixation model, (1.37±0.85) N•m and (1.71±1.44) N•m in locking plate fixation model. Compared with the only ulnar shortening osteotomy model, there were no differences in the maximum pronation and supination torques of the Kirschner wires fixation model, while there were significant differences in that of the locking plate model fixation. There were significant differences in the maximum pronation torque and no differences in the maximum supination torque between the Kirschner wires and the locking plate fixation models.

The oblique step ulnar shortening osteotomy, similar to tenon-mortise structure, with no internal fixation or just percutaneous Kirschner wires fixation combined with external immobilization to control wrist rotation, is an effective method for treatment of ulnar-sided wrist pain caused by malunited distal radial fractures.

Radius fractures; Biomechanics; Ulnar shortening osteotomy; Distal radioulnar joint