Carpal Instability: an overview Abdelsalam Eid Assistant Professor of Orthopaedic Surgery. Zagazig University Abdelsalam Eid, 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

Abdelsalam Eid, Zagazig University Axes of Motion Abdelsalam Eid, Zagazig University

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

Abdelsalam Eid, Zagazig University Kinematics Center of rotation : head of capitate Abdelsalam Eid, Zagazig University

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

Kinematics What 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 flex under 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

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

Abdelsalam Eid, Zagazig University Normal wrist Abdelsalam Eid, Zagazig University

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 Segment Instability Abdelsalam Eid, Zagazig University

Volar Intercalated Segment Instability Abdelsalam Eid, Zagazig University

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

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

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

Abdelsalam Eid, Zagazig University Thank you. Abdelsalam Eid, Zagazig University