Wrist Planes of Motion Joints involved radiocarpal intercarpal Three axes of motion flexion-extension radial-ulnar deviation prono-supination Normal and function motion flexion (65 normal, 10 functional) login to view 1 more bullet extension (55 normal, 35 functional) login to view 1 more bullet radial deviation (15 normal, 10 functional) login to view 1 more bullet ulnar deviation (35 normal, 15 functional) login to view 1 more bullet Wrist Biomechanics Three biomechanic concepts have been proposed: Link concept three links in a chain composed of radius, lunate and capitate login to view 3 more bullets advantage login to view 2 more bullets disadvantage login to view 4 more bullets Column concept lateral (mobile) column login to view 2 more bullets central (flexion-extension) column login to view 3 more bullets medial (rotation) column login to view 2 more bullets Rows concept comprises proximal and distal rows login to view 1 more bullet motion occurs within and between rows Carpal Relationships Carpal collapse normal ratio of carpal height to 3rd metacarpal height is 0.54 Ulnar translation normal ratio of ulna-to-capitate length to 3rd metacarpal height is 0.30 Load transfer distal radius bears 80% of load distal ulna bears 20% of load login to view 2 more bullets Wrist Ligaments The ligaments of the wrist include extrinsic ligaments login to view 2 more bullets intrinsic ligaments login to view 2 more bullets Characteristics volar ligaments are secondary stabilizers of the scaphoid volar ligaments are stronger than dorsal ligaments dorsal ligaments converge on the triquetrum Space of Poirier center of a double "V" shape convergence of ligaments central weak area of the wrist in the floor of the carpal tunnel at the level of the proximal capitate between the volar radioscaphocapitate ligament and volar long radiolunate ligament (radiolunotriquetral ligament) login to view 4 more bullets in perilunate dislocations, this space allows the distal carpal row to separate from the lunate in lunate dislocations, the lunate escapes into this space Extrinsic Ligaments Volar radiocarpal ligaments radial collateral radioscaphocapitate login to view 4 more bullets long radiolunate login to view 4 more bullets radioscapholunate login to view 4 more bullets short radiolunate login to view 1 more bullet Volar ulnocarpal ligaments ulnotriquetral ulnolunate ulnocapitate Dorsal ligaments radiotriquetral login to view 2 more bullets dorsal intercarpal (DIC) radiolunate radioscaphoid Intrinsic (Interosseous) ligaments Proximal row scapholunate ligament login to view 11 more bullets lunotriquetral ligament login to view 7 more bullets Distal row trapeziotrapezoid ligament trapeziocapitate ligament capitohamate ligament Palmar midcarpal scaphotrapeziotrapezoid scaphocapitate triquetralcapitate triquetralhamate