Xray Rounds: Carpal Instabilities Heather Patterson PGY 2 September 7, 2006
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Transcript of Xray Rounds: Carpal Instabilities Heather Patterson PGY 2 September 7, 2006
Xray Rounds:
Carpal Instabilities
Heather PattersonPGY 2
September 7, 2006
Objectives • Anatomy
– Bones– Ligaments
• Exam– Bones– Ligaments
• 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
• Extrinsic:– Volar:
• 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
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
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
– 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
• Kleinman shear test
• Reagan shuck test
Clinical: Lunotriquetral instability
Linscheid compression test
Mayfield Classification
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
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
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
• 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
Stage IV: Lunate Dislocation
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