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Carpal Instability: Anatomy, Kinematics, Imaging, and Classification

2021; Radiological Society of North America; Volume: 41; Issue: 5 Linguagem: Inglês

10.1148/rg.2021210044

1527-1323

Dyan V. Flores, Darwin Fernández Umpire, Catalina Mejía Gómez, Thales Aguiar Saad, Luís Cerezal, Mini N. Pathria,

Elbow and Forearm Trauma Treatment

HomeRadioGraphicsVol. 41, No. 5 PreviousNext Musculoskeletal ImagingFree AccessRadiographics FundamentalsCarpal Instability: Anatomy, Kinematics, Imaging, and ClassificationDyan V. Flores , Darwin Fernández Umpire, Catalina Mejía Gómez, Thales Saad, Luis Cerezal, Mini N. PathriaDyan V. Flores , Darwin Fernández Umpire, Catalina Mejía Gómez, Thales Saad, Luis Cerezal, Mini N. PathriaAuthor AffiliationsFrom the Department of Radiology at St Paul's Hospital, University of British Columbia, 1081 Burrard St, Vancouver, BC, Canada V5Z 1M9 (D.V.F.); Medico Radiólogo en Clínica Internacional, Lima, Peru (D.F.U.); Ayudas Diagnósticas Sura, Medellín, Colombia (C.M.G.); Centro da Imagem Diagnósticos, Cabo Frio, Brazil (T.S.); Diagnóstico Médico Cantabria DMC, Santander, Spain (L.C.); and UCSD Medical Center, San Diego, Calif (M.N.P.).Address correspondence to D.V.F. (e-mail: [email protected]).Dyan V. Flores Darwin Fernández UmpireCatalina Mejía GómezThales SaadLuis CerezalMini N. PathriaPublished Online:Sep 1 2021https://doi.org/10.1148/rg.2021210044MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In AbstractThe full digital presentation is available online.This online presentation provides an overview of the pertinent anatomy, biomechanics, classification, and imaging features of carpal instability.The wrist comprises 20 articulations binding 15 bones: the radius and ulna, eight carpal bones, and five metacarpal bases. The distal carpal row (trapezium, trapezoid, capitate, and hamate) is less mobile than the proximal carpal row (scaphoid, lunate, triquetrum, and pisiform). Varying biomechanical theories describe motion between the bone in terms of columns, links, or rows. The wrist is stabilized by two groups of ligaments: (a) intrinsic ligaments, which connect carpal bone to carpal bone; and (b) extrinsic ligaments, which connect carpal bone to the radius, ulna, or metacarpal. The importance of the scapholunate and lunotriquetral interosseous ligaments is well recognized. The dorsal scapholunate and volar lunotriquetral ligaments are the most functionally important. The dorsal intercarpal, dorsal radiolunotriquetral, and volar scaphotrapeziotrapezoid ligaments are critical secondary stabilizers of the scapholunate joint. The radioscaphoid, radioscaphocapitate, and long radiolunate ligaments at the volar wrist play important roles in both scapholunate and midcarpal joint stability.Radiography is the first line of imaging in assessment of carpal instability, allowing measurement of the scapholunate interval and the scapholunate and radiolunate angles. Stress and dynamic views allow evaluation of relationships between bones during movement. Arthrography with videofluoroscopy enables kinematic assessment but is limited by poor soft-tissue contrast and spatial and temporal resolution. US is useful in dynamic evaluation of scapholunate instability, but its role in evaluation of other forms of instability is limited. CT arthrography and MRI are the modalities of choice in assessment of the bones and ligaments.The Mayo classification subdivides carpal instability into four types. Carpal instability dissociative (CID) refers to intracarpal instability within either the proximal or distal carpal rows. Scapholunate instability is the most common type of dissociative wrist instability. It is a spectrum of injury that includes scapholunate dissociation, dorsal intercalated segmental instability, and scapholunate advanced collapse (Fig 1). Lunotriquetral instability is less common than scapholunate instability and manifests with volar intercalated segmental instability. Axial carpal dislocation or distal CID is characterized by splitting of the wrist into columns and is far less common compared with proximal CID. Carpal instability nondissociative (CIND) refers to instability between carpal rows and is characterized clinically by clicking or snapping because of disturbed midcarpal joint kinematics. Midcarpal joint movement is analogous to the motion of dart throwing. With radial deviation, the proximal carpal row moves en masse to the ulna, while the distal row translocates toward the radius, the scaphoid flexes, and the lunocapitate joint extends. The reverse pattern occurs with ulnar deviation or on release of the dart. Carpal instability combined exhibits features of both CID and CIND. It is subclassified on the basis of the structures involved into purely ligamentous injury (lesser arc) or ligamentous injury with fractures (greater arc). Carpal instability adaptive is carpal malalignment in response to an extrinsic noncarpal deformity such as fracture and malunion of the radius and can mimic features of midcarpal CIND (Fig 2).Figure 1. Illustration demonstrates the biomechanics of scapholunate dissociation. With failure of the scapholunate interosseous ligament or partial tear of the dorsal intercarpal ligament, dorsal radiocarpal ligament, or a critical volar ligament such as the scaphotrapeziotrapezoid ligament or the long radiolunate ligament, there is loss of the normal alignment and consequent movement between the scaphoid and lunate. With axial load, the scaphoid preferentially flexes volarly, while the lunate, being pulled by the triquetrum with an intact lunotriquetral ligament, dorsiflexes (arrows).Figure 1.Download as PowerPointOpen in Image Viewer Figure 2. Carpal instability adaptive. Sagittal T1-weighted MR image demonstrates a malunited fracture with posttraumatic deformity of the distal radius (arrows), dorsal inclination of the articular surface (arrowhead), and dorsal tilting of the lunate (*). Carpal malalignment can occur in response to an extrinsic noncarpal deformity such as fracture and malunion of the radius and can mimic features of midcarpal CIND.Figure 2.Download as PowerPointOpen in Image Viewer Get the Flash Player to see this video.Movie 1: Carpal Instability: Anatomy, Kinematics, Imaging, and ClassificationDownload Original Video (321.6 MB)Recipient of a Magna Cum Laude award for an education exhibit at the 2020 RSNA Annual Meeting.References1. Berger RA. The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg Am 1996;21(2):170–178. Crossref, Medline, Google Scholar2. Berger RA, Imeada T, Berglund L, An KN. Constraint and material properties of the subregions of the scapholunate interosseous ligament. J Hand Surg Am 1999;24(5):953–962. Crossref, Medline, Google Scholar3. Craigen MA, Stanley JK. Wrist kinematics: row, column or both?. J Hand Surg [Br] 1995;20(2):165–170. Crossref, Medline, Google Scholar4. Ghatan AC, Hanel DP. 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Crossref, Medline, Google ScholarArticle HistoryReceived: Feb 27 2021Revision requested: Apr 19 2021May 17 2021Accepted: May 27 2021Published online: Sept 01 2021Published in print: Sept 2021 FiguresReferencesRelatedDetailsAccompanying This ArticleCarpal Instability: Anatomy, Kinematics, Imaging, and ClassificationSep 1 2021Default Digital Object SeriesRecommended Articles Imaging of Sports-related Hand and Wrist Injuries: Sports Imaging SeriesRadiology2016Volume: 279Issue: 3pp. 674-692Preoperative and Postoperative Imaging of Scapholunate Ligament Primary Repair and Modified Brunelli ReconstructionRadioGraphics2021Volume: 42Issue: 1pp. 195-211Avulsion Injuries of the Hand and WristRadioGraphics2020Volume: 40Issue: 1pp. 163-180Distal Radioulnar Joint: Normal Anatomy, Imaging of Common Disorders, and Injury ClassificationRadioGraphics2022Volume: 43Issue: 1Four-dimensional CT Analysis of Wrist Kinematics during Radioulnar DeviationRadiology2018Volume: 289Issue: 3pp. 750-758See More RSNA Education Exhibits Alingment is Everything: The Kinematics, Imaging Findings and Management of Carpal InstabilityDigital Posters2020Way to Approach Wrist Instability: Tips for Radiology ResidentsDigital Posters2019It's All in the Wrist: The Classification, Repair, and Postoperative Appearance of Intrinsic Wrist Ligament TearsDigital Posters2019 RSNA Case Collection Trans-scaphoid Perilunate DislocationRSNA Case Collection2020Lunate DislocationRSNA Case Collection2020Kienbock's DiseaseRSNA Case Collection2021 Vol. 41, No. 5 Slide PresentationAbbreviations Abbreviations: CID carpal instability dissociative CIND carpal instability nondissociative Metrics Altmetric Score PDF download