Xray Rounds: Carpal Instabilities Heather Patterson PGY 2 September 7, 2006

Objectives Anatomy Exam Mayfield Classification of Carpal Injuries Bones Ligaments Exam Mayfield Classification of Carpal Injuries Cases

Anatomy: Bones PA: 3 smooth arcs Proximal and distal surfaces of the scapoid, lunate, triquetrum Proximal articular surface of the capitate and hamate NOTE: improper positioning can cause overlap patterns

Anatomy: Bones Lateral: 4 C’s Axis of the radius, lunate and capitate is collinear Proper position for laterall – radius and ulan should completely overlap one another and radial styloid should be centered over the distal radial articular surface

Anatomy: Liagments Extrinsic: Space of Poirer: Volar: Dorsal: 2 arcades V shaped Proximal & distal Space of Poirier Dorsal: Less strong than volar groups Space of Poirer: Between radiocapitate and radiotriquetral ligaments

Anatomy: Liagments Intrinsic: Attach carpals 2 key ligaments: Scapholunate Lunotriquetral

Anatomy: Bones Lateral: Scapholunate angle 30-60 degrees If <30 indicates lunotriquetral ligamentous injury >60 indicates scapholunate ligamentous injury Lines: axis of radius plus centre of lunate concavity AND long axis of scaphoid Proper position for laterall – radius and ulan should completely overlap one another and radial styloid should be centered over the distal radial articular surface

Anatomy: Bones Lateral: Capitolunate angle 10-20 degrees Requires a true lateral to be acurate ↑ angle Consider carpal ligamentous injury

Clinical Scaphoid Lister’s Tubercle Scapholunate joint Lunate and capitate Triquetrum and TFCC Scaphotrapezium joint Pisiform Hook of Hamate

Clinical Scaphoid Lister’s Tubercle Scapholunate joint snuffbox Lister’s Tubercle Prominence on radius, EPL wraps around this Scapholunate joint Immediately distal to Lister’s tubercle Lunate and capitate Immediately ulnar to scapholunate joint Triquetrum and TFCC Immediately distal to ulnar styloid Scaphotrapezium joint Base of thenar eminence Pisiform Base of hypothenar eminence Hook of Hamate Soft tissue distal and radial to pisiform

Clinical: Watson Shift Test Place thumb on volar aspect of scaphoid tuberosity and apply pressure while bringing wrist from ulnar to radial deviation Sensitivity: ~60-67%’ Specificity: poor Wolfe et al (1997) demontrated a 36% false positive rate with 25 healthy volunteers The scaphoid normally flexes as brought from ulnar to radial deviation.

Clinical: Lunotriquetral instability Kleinman shear test Reagan shuck test Linscheid compression test Kleinman _ pressure of dorsal lunate and other thumb over pisotriquetral joint with dorsally directed force reagan _ same but grasp entire pisotriquetral joint linsheid _ apply force in radial direction on the ulnar border of triquetrum

Mayfield Classification Mayfield classification based on extent of ligamentous injury

Stage I: Scapholunate Dissociation Disruption of scapholunate ligament Isolated scaphoid subluxation +/- rotation Xray: >3mm space between scaphoid and lunate “Terry Thomas” sign +/- signet ring sign Scapholunate angle >60 degrees 3 stages: dynamic instability with no radiographic evidence (clinical dx), rotary subluxation, scapholunate dissociation

Stage II: Capitate Dislocation Disruption of radiocapitate ligament and opening of Space of Poirier May be associated with scaphoid fracture Xray: PA: overlap of carpal rows Lateral: volar tilt of lunate but maintains articulation with radius dorsal dislocation of capitate Mayfield classification based on extent of ligamentous injury

Stage III: Lunotriquetral Dissociation Failure of radiotriquetral ligament Perilunate dislocation with triquetral dislocation May be associated with volar triquetral fracture Xray: Perilunate dislocation PA – overlap of triquetrum on lunate or hamate Mayfield classification based on extent of ligamentous injury

Stage IV: Lunate Dislocation Disruption of dorsal radiocarpal ligament Disruption of all intercarpal joints and most major carpal ligaments Associated #: Xray: PA: Lunate appears triangular, “piece of pie” Lateral: “Spilled teacup” sign Capitate and all carpals lie posterior to lunate on lateral Volar dislocation and forward rotation of lunate Capitate drops into lunate space Associated with scaphoid #

Cases Mayfield classification based on extent of ligamentous injury

Cases Mayfield classification based on extent of ligamentous injury

Cases Mayfield classification based on extent of ligamentous injury

Cases Mayfield classification based on extent of ligamentous injury

Cases Mayfield classification based on extent of ligamentous injury

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