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

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

4. 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

5. 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

6. 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

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

8. 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

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

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

11. 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

12. 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.

13. 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

14. Mayfield Classification
Mayfield classification based on extent of ligamentous injury

15. 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

16. 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

17. 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

18. 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 #

19. Cases
Mayfield classification based on extent of ligamentous injury

20. Cases
Mayfield classification based on extent of ligamentous injury

21. Cases
Mayfield classification based on extent of ligamentous injury

22. Cases
Mayfield classification based on extent of ligamentous injury

23. Cases
Mayfield classification based on extent of ligamentous injury

24. Cases

25. Cases

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28. Cases

29. Cases