Summary Distal radius malunion is the most common complication of distal radius fractures Diagnosis is made with orthogonal radiographs of the wrist demonstrating decreased radial inclination, increased dorsal tilt, excessive volar tilt, loss of radial height, or increased ulnar variance Treatment can be nonoperative or operative depending on the severity of the deformity, level of functional impairment, and risk of progression Epidemiology Incidence occurs in approximately 17% of all distal radius fractures occurs in 11% of distal radius fractures treated operatively occurs in 24% of distal radius fractures treated definitively with cast immobilization Location intra-articular or extra-articular Risk factors post-reduction malalignment osteoporosis Etiology Pathophysiology mechanism of malunion basic login to view 3 more bullets advanced login to view 10 more bullets Associated conditions incongruity of the (DRUJ) loss of forearm rotation hand weakness carpal instability triangular fibrocartilage (TFCC) tears ulnocarpal joint degenerative change Anatomy Distal radius Osteology responsible for 80% axial load of the wrist login to view 13 more bullets Arthrology articulates with scaphoid login to view 1 more bullet lunate login to view 1 more bullet distal ulna login to view 1 more bullet Biomechanics basic changes to the volar tilt can cause incongruity of the DRUJ which leads to tightening of the interosseous membrane (IOM), loss of forearm rotation, and loss of flexion and extension arc of motion login to view 4 more bullets decreased radial inclination can decrease the mechanical advantage of the flexor tendons leading to hand weakness radial shortening can lead to increased ulnar positive variance and is associated with a shift of force transfer from the radiocarpal to the ulnocarpal joint advanced dorsally angulated malunion can yield 2 types of carpal instability login to view 2 more bullets dorsally angulated can lead to carpal malalignment Presentation History usually prior fall onto outstretched hand can result in the setting of either previous operative or non-operative management Symptoms common symptoms Pain login to view 7 more bullets weakness of grip reduced range of motion of the wrist login to view 1 more bullet Physical exam inspection deformity indicative of volar or dorsal malunion can be apparent palpation delineate areas of pain range of motion decreased wrist flexion decreased wrist extension decreased wrist radial/ulnar deviation decreased forearm pronation/supination strength record bilateral grip strength with a dynamometer instability DRUJ login to view 2 more bullets vascular Allen test neuro evaluate for coinciding carpal tunnel syndrome and complex regional pain syndrome Imaging Radiographs recommended views bilateral wrist series login to view 3 more bullets optional views anatomic, or tilted, lateral view for better visualization of the articular surface and lunate facet findings Radiographic criteria Measurement Normal Radial height (PA) 8-14mm Radial inclination (PA) 21°-25° Articular stepoff (PA) Congruous Volar tilt (Lateral) 7°-15° Ulnar variance < 1mm change (neutral) CT indications intra-articular malunions rotational deformities in axial plane DRUJ instability login to view 2 more bullets MRI indications evaluate for concomitant soft tissue injuries login to view 1 more bullet Treatment Nonoperative NSAIDs, physical therapy, adaptive splinting indications login to view 3 more bullets modalities login to view 2 more bullets outcomes login to view 1 more bullet Operative Osteotomy, ORIF, +/- bone grafting indications login to view 8 more bullets bone grafting login to view 2 more bullets outcomes login to view 2 more bullets Denervation procedure posterior interosseous nerve (PIN) and/or anterior interosseous nerve neurectomy login to view 5 more bullets Ulnar-sided procedures indications login to view 4 more bullets techniques login to view 6 more bullets Techniques Osteotomy with ORIF technique dorsally angulated login to view 7 more bullets volarly angulated MDRF login to view 6 more bullets intra-articular login to view 12 more bullets pros/cons dorsal approach login to view 3 more bullets volar approach login to view 3 more bullets opening-wedge osteotomy login to view 1 more bullet closing-wedge osteotomy login to view 2 more bullets Bone grafting indications significant void created with opening-wedge osteotomies graft options autograft (structural or nonstructural) login to view 7 more bullets allograft login to view 5 more bullets technique can be placed with either volar or dorsal approach Denervation procedure posterior interosseous nerve (PIN) and/or anterior interosseous nerve neurectomy approach login to view 1 more bullet technique login to view 4 more bullets Ulnar-sided procedures indications ulnar abutment syndrome login to view 2 more bullets DRUJ instability TFCC tears symptomatic ulnar styloid nonunion approach USO login to view 1 more bullet distal ulna procedures (i.e distal ulna resection, "wafer" resection, hemiresection-interposition, DRUJ fusion, DRUJ arthroplasty login to view 1 more bullet technique ulnar abutment syndrome login to view 10 more bullets DRUJ instability or arthrosis login to view 11 more bullets TFCC tears login to view 6 more bullets symptomatic ulnar styloid nonunion login to view 7 more bullets Complications Flexor or extensor tendon irritation or rupture incidence 20% of the overall complication incidence rate are tendon related login to view 3 more bullets risk factors higher rate in patients who had a distraction-type osteotomy significant dorsal callus formation volar plate fixation dorsal osteophyte hardware prominence nerve injury complex regional pain syndrome nonunion infection posttraumatic arthrosis