Summary Carpal instability nondissociative (CIND) is defined as instability between carpal rows (either radiocarpal or midcarpal) radiocarpal instability (between radius and proximal row) midcarpal instability (between proximal and distal row) Epidemiology incidence rare < 1 per 100,000 annually Etiology Pathophysiology radiocarpal instability ("inferior arc injury") high-energy injury ulnar translation signifies global rupture of extrinsic ligaments distal radius malunion is the most common cause may be purely ligamentous or have associated ulnar and radial styloid fractures Associated conditions intracarpal injury (scapholunate or lunotriquetral ligament) acute carpal tunnel syndrome compartment syndrome Anatomy Volar extrinsic ligaments radioscaphocapitate (RSC) long radiolunate short radiolunate radioscapholunate Classification Overview table of wrist instability Presentation History usually no history of trauma (midcarpal) high energy trauma (radiocarpal) Symptoms subluxation that may or may not be painful complain of wrist giving way irritating clunking sign "clunk" when wrist is moved ulnarly from flexion to extension with an axial load Physical exam generalized ligamentous laxity Imaging Radiographs recommended views required AP and lateral of the wrist optional cineradiographs findings sudden subluxation of proximal carpal row with active radial or ulnar deviation on cineradiograph ulnar translation diagnosis made when >50% of lunate width is ulnarly translated off the lunate fossa of the radius Treatment Nonoperative immobilization +/- splinting indications first line of treatment midcarpal instability is most amenable to splinting Operative immediate open repair, reduction, and pinning indications ulnar translation associated with styloid fractures outcomes poor results with late repair ligament reconstruction has poor long term results midcarpal joint fusion indications midcarpal instability (preferred over ligamentous reconstruction) late diagnosis that failed nonoperative management outcomes will lead to 20-35% loss of motion osteotomy with malunion correction indications distal radius malunion wrist arthrodesis indications failure of above treatments outcomes fusion of radiocarpal joint leads to a 55-60% loss of motion distal pole of the scaphoid excision can improve postoperative range of motion with radioscapholunate fusion Prognosis volar dislocation is more severe than dorsal