[Carpal malalignment following distal radius fracture]

Adaptive carpal malalignment is the consequence of malunion of the distal radius. Since the radial metaphysis and capitate have to be aligned, any disorientation of the radial epiphysis will force the proximal carpal row to adapt, as it is the only mobile element. There are two types of adaptation depending where the compensative occurs: (1) midcarpal - leading to flexion between the lunate and capitate, with the lunate maintaining a normal relationship with the radial epiphysis axis; (2) radiocarpal - combining flexion and dorsal displacement of the lunate relative to the axis of the radial epiphysis, with the midcarpal joint remaining aligned. Clinically, adaptive carpal malalignment is not the first reason for consultation in cases of distal radius malunion. It occurs in cases of moderate deformity with preserved pronation-supination in a young patient who has good mobility. It generates dorsal pain that may be associated with a snapping sensation. The diagnosis requires strict lateral X-ray views. Over time, the wrist becomes stiff but analgesic and is often well tolerated functionally. This type of deformity has not been shown to lead to osteoarthritis. Osteotomy to correct the malunion is the only way to treat adaptive carpal malalignment in active young patients who have a mobile but painful wrist.