[Distal Radius Intra-Articular Malunion Corrected with Arthroscopy Assisted Open Osteotomy: a Case Report].

Distal radius malunions, particularly those involving both intra-articular and extra-articular components, present significant surgical challenges. While extra-articular osteotomies are well-established, intra-articular corrections - especially at the sigmoid notch - are rarely described and difficult to execute. This case report introduces a novel technique combining arthroscopic and open approaches for the correction of a complex distal radius malunion. A patient with persistent pain and functional impairment following conservative treatment of a distal radius fracture was diagnosed with a complex malunion, featuring dorsal angulation, an intra-articular die-punch fragment, and distal radioulnar joint (DRUJ) incongruity with a 2 mm articular step-off at the sigmoid notch. A combined extra- and intra-articular osteotomy was performed under arthroscopic guidance using a dry technique via posterior DRUJ portals. The intra-articular fragment was mobilized and repositioned under arthroscopic and fluoroscopic visualization, followed by osteosynthesis with a dorsal plate. Postoperative imaging confirmed alignment correction. At 12 months, the patient reported full, painless prono-supination, near-complete wrist range of motion, and satisfaction with the outcome. The technique allowed for precise osteotomy execution despite challenges including limited DRUJ visualization. This is the first documented case of a sigmoid notch osteotomy guided by dry arthroscopy through DRUJ portals. The approach demonstrates the feasibility of combining arthroscopic visualization with traditional osteotomy techniques to address complex distal radius malunions. Despite technical limitations, this method offers a promising avenue for precise intra-articular correction and joint preservation in select patients.