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Carpal Instability: an overview. Abdelsalam Eid Assistant Professor of Orthopaedic Surgery. Zagazig University. Wrist Stabilizers. Complex interlocking shapes Intrinsic and extrinsic ligaments Extrinsic ligaments Volar stronger than dorsal Intrinsic ligaments
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Carpal Instability: an overview AbdelsalamEidAssistant Professor of Orthopaedic Surgery. Zagazig University Abdelsalam Eid, Zagazig University
Wrist Stabilizers • Complex interlocking shapes • Intrinsic and extrinsic ligaments • Extrinsic ligaments • Volar stronger than dorsal • Intrinsic ligaments • Important interosseous ligaments are SLIL and LTIL Abdelsalam Eid, Zagazig University
Axes of Motion Abdelsalam Eid, Zagazig University
Kinematics • Rows • Proximal and Distal with scaphoid as a bridge • Motion within and between rows • Columns • Central(flex/ext) lunate,capitate,hamate • Lateral (longitudinal stability) scaphoid,trapezoid,trapezium • Medial (rotation) triquetrum Abdelsalam Eid, Zagazig University
Kinematics • Center of rotation : head of capitate Abdelsalam Eid, Zagazig University
Force Transmission • Principal force transmission is through capitate lunate and proximal pole of scaphoid • 75% radius 25% ulna Abdelsalam Eid, Zagazig University
KinematicsWhat happens when the wrist moves • Radial deviation : scaphoid flexes “pulling” lunate into palmar flexion • Ulnar deviation : scaphoid extends pulling lunate into dorsiflexion • Triquetrohamate helicoid joint • Ulnar deviation : hamate rotates into “low” position distal causing the triquetrum to dorsiflex pulling lunate into dorsiflexion • Radial deviation : : hamate rotates into “high”position proximal causing the triquetrum to palmar flex pulling lunate into palmar flexion • So in conclusion, in radial deviation the proximal row flexes and in ulnar deviation it extends Abdelsalam Eid, Zagazig University
Pathomechanics Carpal Instability intercalated segment lunate is in state of dynamic balance scaphoid induced to flexunder compressive load and induces flexion force on lunate triquetral inherently prefers to extend and induces extension force on lunate dynamic balance interrupted, lunate follows unbalanced force Abdelsalam Eid, Zagazig University
L T S Abdelsalam Eid, Zagazig University
Definition~ Carpal Instability • Carpal malalignment caused by injury or disease Abdelsalam Eid, Zagazig University
Classification of Carpal Instability • CID (dissociative) • DISI • VISI • CIND (non-dissociative) • Radiocarpal,Midcarpal,Ulnar translocation • CIC (complex) • Perilunate Dislocation • CIA (adaptive) • instability not in carpus • malunited wrist fr. Abdelsalam Eid, Zagazig University
Carpal instability terminology • dynamic • Neg Xray;+ve stress testing e.g.Watson:+ve cineradiography • static • +ve plain films • Degenerative • Secondary • Kienbock’s ; SNAC MUN ORTHOPEDICS
Normal wrist Abdelsalam Eid, Zagazig University
Groups ...CID carpal instability dissociative Instability due to loss of linkage between individual carpal bones bones of same row short ligaments Proximal Dissociative Carpal Instability (DISI and VISI) unstable scaphoid non-union scapholunate dissociation lunotriquetral dissociation Distal Dissociative Carpal Instability CID very rare rupture of ligaments of distal row Acute -> repair/ Chronic ->fuse Abdelsalam Eid, Zagazig University
Dorsal Intercalated SegmentInstability Abdelsalam Eid, Zagazig University
Volar Intercalated SegmentInstability Abdelsalam Eid, Zagazig University
Scaphoid Nonunion proximal scaphoid pole follows unconstrained lunate and triquetrum and rotates into extension ( hump back deformity) DISI treat the scaphoid N U Most common Abdelsalam Eid, Zagazig University
Scapholunate Instability • complete disruption of SL ligament • scaphoid flexes • lunate and triquetrum rotate into extension • DISI • Recent -> Open and repair dorsal portion of SL interosseous lig. • stabilise with K wires two months Abdelsalam Eid, Zagazig University
Scapholunate Instability MUN ORTHOPEDICS
Chronic SL instability • degenerative changes • SLAC • 4 corner fusion with resection of scaphoid • PRC Abdelsalam Eid, Zagazig University
Lunotriquetral dissociation • dissociative VISI • Lunate loses support from triquetrum • palmar flexion of lunate with the scaphoid • less common • acute -> repair • late -> lunotriquetral arthrodesis Abdelsalam Eid, Zagazig University
Groups ...CIND nondissociative carpal instability dysfunction between rows instability at radiocarpal or midcarpal joints Abdelsalam Eid, Zagazig University
Non-dissociative radiocarpal instability • dorsal malunion of distal radius • not a true carpal instability • adaptive • corrective osteotomy Abdelsalam Eid, Zagazig University
Groups CIC carpal instability complex CID & CIND perilunate dislocation instabilities not otherwise classifiable Abdelsalam Eid, Zagazig University
Perilunate Dislocation • Still missed in ER • Ttt of choice : open reduction & repair of ligaments/bones • Dorsal and volar approach • Late: fusion or PRC Abdelsalam Eid, Zagazig University
Thank you. Abdelsalam Eid, Zagazig University