Fixed Lunate Flexion Deformity in Distal Radius Fractures.

Carpal malalignments in malunion of distal radius fracture are considered as an adaptive response of the carpus to loss of normal architecture of the distal radius. This condition leads to mechanical overload, ligament attenuation and progressive dynamic instability around the wrist joint. Radial corrective osteotomy is suggested as a treatment option of carpal malalignment after distal radius malunion. In radiocarpal malalignment, the lunate is usually observed in flexion in contrast to its extension posture in the more common midcarpal malalignment. We report two cases of fixed lunate flexion deformity after a distal radius fracture, in which reduction and fixation of fresh fracture or corrective osteotomy of malunion were not successful. Arthritic changes were observed in the radiolunate joint on arthroscopy. Thus, fixed flexion deformity of the lunate might be associated with posttraumatic arthritic change in the radiolunate joint.