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 initial fracture displacement secondary displacement after loss of reduction with cast immobilization failure of internal fixation advanced dorsally angulated most common apex volar deformity dorsal tilting can produce carpal collapse similar to that seen in dorsal intercalated segment instability (DISI) volarly angulated apex dorsal deformity radial shortening associated with the largest change in distal radial ulnar joint (DRUJ) kinematics intra-articular associated with initial intra-articular displacement of >2mm 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 comprised of 3 columns radial column includes the radial styloid and scaphoid fossa functions serves as buttress to resist radiocarpal translation load-bearing platform with the wrist in ulnar deviation serves as an anchor for the radioscaphocapitate ligament to prevent ulnar translation of the carpus intermediate column includes the lunate fossa functions to transmit load from the carpus to the forearm ulnar column includes the TFCC and distal ulna functions to aid in the stability of the DRUJ Arthrology articulates with scaphoid via scaphoid fossa lunate via lunate fossa distal ulna via ulnar/sigmoid notch 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 decreased volar tilt limits flexion and supination increased volar tilt limits extension and pronation 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 adaptive midcarpal dorsal intercalated segment instability dorsal radial subluxation with maintenance of midcarpal alignment 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 localizing symptoms to the radial or the ulnar side impacts treatment approaches, particularly for the distal ulna location radiocarpal articulations (dorsal and volar) ulnocarpal articulations (ulnar dorsal and volar) midcarpal articulations (dorsal and volar) TFCC (ulnar sided) DRUJ (ulnar sided) weakness of grip reduced range of motion of the wrist pronation and supination affected to a greater extent 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 DRUJ shuck test pain with instability is indicative of positive test vascular Allen test neuro evaluate for coinciding carpal tunnel syndrome and complex regional pain syndrome Imaging Radiographs recommended views bilateral wrist series posteroanterior (PA) lateral oblique 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 subtle chronic instability can be evaluated on sequential CT scans, with the forearm held in a neutral position, full supination, and full pronation, and compared with the contralateral side >50% translation is abnormal MRI indications evaluate for concomitant soft tissue injuries TFCC Treatment Nonoperative NSAIDs, physical therapy, adaptive splinting indications very low physical demands complex regional pain syndrome unable to comply with the rehabilitation protocol modalities physical/occupational therapy maximize hand/wrist range of motion (ROM) and strengthening outcomes patients 18 to 65 years old are more likely to have adverse clinical outcomes Operative Osteotomy, ORIF, +/- bone grafting indications symptomatic malunion following failed closed reduction and casting with secondary displacement failed internal fixation loss of radial height, inclination, or volar tilt with associated mechanical symptoms decreased grip strength decreased ROM instability on stress testing bone grafting indications opening-wedge osteotomy outcomes extra-articular malunion correction is associated with a complication rate of 50% the complication rate is higher with distraction-type osteotomy Denervation procedure posterior interosseous nerve (PIN) and/or anterior interosseous nerve neurectomy indications debilitating pain in the setting of concurrent infection low demand activity level maintained hand and wrist function Ulnar-sided procedures indications maintained radial inclination and radial tilt with ulnar positive variance DRUJ instability TFCC tears ulnar styloid non-union techniques hemiresection-interposition ulnar diaphyseal shortening osteotomy ulnar dome "wafer" resection with ligament preservation DRUJ fusion with proximal pseudoarthrosis (Suave-Kapandji) complete distal ulna excision (Darrach) prosthetic replacement of ulnar head or entire DRUJ Techniques Osteotomy with ORIF technique dorsally angulated approach dorsal between 2nd and 4th extensor compartments volar extended FCR osteotomy opening or closing-wedge volarly angulated MDRF approach extended FCR osteotomy opening-wedge fixation options standard or locked volar plates intra-articular approach dorsal between 2nd and 4th extensor compartments with dorsal capsulotomy should be utilized when dorsal subluxation is present volar extended FCR or carpal tunnel approach should be utilized when volar subluxation is present osteotomy intra-articular or extra-articular comparable outcomes intra-articular osteotomies can be arthroscopy-aided can utilize the push-pull screw technique to restore radial height after osteotomy pros/cons dorsal approach technical ease of osteotomy mechanical advantage of fixation on the tension side of the MDRF potential extensor tendon irritation volar approach allows for visual approximation of the volar cortex, which increases stability if properly aligned could obviate the need for bone grafts with well-aligned volar cortex potential flexor tendon irritation opening-wedge osteotomy usually necessitates bone grafting closing-wedge osteotomy potential advantage of direct bone-bone contact and fixation with compression across the osteotomy site can increase positive ulnar variance and routinely requires an ulnar shortening osteotomy Bone grafting indications significant void created with opening-wedge osteotomies graft options autograft (structural or nonstructural) structural bicortical iliac crest bone graft (ICBG) has demonstrated union over 7 weeks with improved supination nonstructural cancellous ICBG cancellous distal radius comparable results to iliac crest structural autograft allograft cancellous chips demineralized bone matrix fresh frozen allograft carbonated hydroxyapatite calcium phosphate technique can be placed with either volar or dorsal approach Denervation procedure posterior interosseous nerve (PIN) and/or anterior interosseous nerve neurectomy approach neurectomy is performed through a dorsal longitudinal incision proximal to the distal radioulnar joint and extends proximally for 3–4 cm technique PIN The extensor tendons of the fourth extensor compartment are retracted ulnarly, exposing the floor of the fourth compartment. On the radial aspect of the fourth compartment, the PIN is identified, and a 1 cm portion is removed. AIN The interosseous membrane is divided, exposing the AIN as well as the anterior interosseous artery. The anterior interosseous nerve is isolated and a 1 cm portion is excised Ulnar-sided procedures indications ulnar abutment syndrome positive ulnar variance can occur with or without associated radial shortening DRUJ instability TFCC tears symptomatic ulnar styloid nonunion approach USO direct approach to the subcutaneous border of the ulna distal ulna procedures (i.e distal ulna resection, "wafer" resection, hemiresection-interposition, DRUJ fusion, DRUJ arthroplasty longitudinal incision over the distal ulna between the tendons of the extensor and flexor carpi ulnaris technique ulnar abutment syndrome positive ulnar variance Milch: ulnar diaphyseal shortening osteotomy contraindicated with DRUJ arthrosis ideal for isolated radial shortening Feldon: ulnar dome "wafer" resection with ligament preservation requires intact TFCC indicated in angular deformities Darrach: complete distal ulna resection salvage procedure avoid overaggressive excision DRUJ instability or arthrosis Bowers: hemiresection-interposition requires intact TFCC indicated in angular deformities Sauve-Kapandji: DRUJ fusion with proximal pseudoarthrosis younger patients with incongruity and degenerative change can restore free forearm rotation arthroplasty: prosthetic replacement of ulnar head or entire DRUJ salvage procedure creation of a one-bone forearm eliminates forearm rotation remains as the ultimate salvage operation for persistent pain TFCC tears symptoms generally resolve without intervention for central perforations long-standing distal radius malunions may preclude primary repair if symptomatic feasibility of repair should be confirmed with wrist arthroscopy if TFCC can not be primarily repaired and DRUJ remains unstable a ligamentous reconstruction can be performed Adams: ligament reconstruction with a palmaris tendon autograft brachioradialis wrap reconstruction symptomatic ulnar styloid nonunion small fragments with stable DRUJ excision large fragments with DRUJ instability direct repair headless compression screw tension band excision with repair of TFCC to fovea Complications Flexor or extensor tendon irritation or rupture incidence 20% of the overall complication incidence rate are tendon related most common tendon involved is the extensor pollicis longus average time to tendon rupture is 10 weeks postoperatively observed with dorsal (extensor tendon rupture) and volar plate (flexor tendon rupture) fixation 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