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

2. 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

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

4. 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

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

6. 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

7. 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

8. 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

9. Abdelsalam Eid, Zagazig University

10. Definition~ Carpal Instability
Carpal malalignment caused by injury or disease
Abdelsalam Eid, Zagazig University

11. 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

12. 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

13. Abdelsalam Eid, Zagazig University
Normal wrist
Abdelsalam Eid, Zagazig University

14. 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

15. Dorsal Intercalated Segment Instability
Abdelsalam Eid, Zagazig University

16. Volar Intercalated Segment Instability
Abdelsalam Eid, Zagazig University

17. 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

18. 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

19. Scapholunate Instability
MUN ORTHOPEDICS

20. Chronic SL instability
degenerative changes
SLAC
4 corner fusion with resection of scaphoid
PRC
Abdelsalam Eid, Zagazig University

21. 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

22. Abdelsalam Eid, Zagazig University
Groups ...CIND
nondissociative carpal instability
dysfunction between rows
instability at radiocarpal or midcarpal joints
Abdelsalam Eid, Zagazig University

23. Non-dissociative radiocarpal instability
dorsal malunion of distal radius
not a true carpal instability
adaptive
corrective osteotomy
Abdelsalam Eid, Zagazig University

24. Abdelsalam Eid, Zagazig University
Groups CIC
carpal instability complex
CID & CIND
perilunate dislocation
instabilities not otherwise classifiable
Abdelsalam Eid, Zagazig University

25. 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

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