Wrist Biomechanics and Carpal Instability - PowerPoint PPT Presentation

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Title:

Wrist Biomechanics and Carpal Instability

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Double V shape with weak area ; space of Poirier. Important interosseous ligaments are SLIL and LTIL ... ve ballottement test. Beware ulnar impaction syndrome ... – PowerPoint PPT presentation

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Title: Wrist Biomechanics and Carpal Instability


1
Wrist Biomechanics and Carpal Instability
2
Wrist Biomechanics
  • Anatomy
  • Kinematics
  • Force transmission

3
Anatomy
  • 8 bones
  • Complex interlocking shapes
  • Intrinsic and extrinsic ligaments

4
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5
Wrist ligaments
6
Wrist ligaments
  • Volar stronger than dorsal
  • Double V shape with weak area space of Poirier
  • Important interosseous ligaments are SLIL and
    LTIL
  • Dorsal ligaments tend to converge on triquetrum

7
Kinematics
  • Three axes of motion
  • FEM 90 70 degrees
  • Flex/ext split between radiocarpal midcarpal
  • RUD 20 50 degrees
  • PSM 90 90 degrees

8
Axes of Motion
9
Kinematics
  • Rows
  • Columns (Navarro)
  • Oval ring
  • Longitudinal columns (Weber)
  • Link Joint

10
Link Joint
11
Kinematics
  • Rows
  • Proximal and Distal with scaphoid as a bridge
  • Motion within and between rows
  • Columns
  • Central(flex/ext) lunate,capitate,hamate
  • Lateral (mobile) scaphoid,trapezoid,trapezium
  • Medial (rotation) triquetrum

12
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13
Kinematics
  • Center of rotation head of capitate

14
Kinematics
  • Radial deviation scaphoid flexes proximal pole
    goes dorsal pulling lunate into palmar flexion
  • Ulnar deviation scaphoid extends proximal pole
    goes volar pulling lunate into dorsiflexion

15
Kinematics
  • Triquetrohamate helicoid joint
  • Ulnar deviation low position distal and
    dorsiflexed pulling lunate into dorsiflexion
  • Radial deviation highposition proximal and
    palmar flexed pulling lunate into palmar flexion

16
Force Transmission
  • Principal force transmission is through capitate
    lunate and proximal pole of scaphoid
  • 75 radius 25 ulna

17
Classification of Carpal Instability
  • CID (dissociative)
  • DISI
  • VISI
  • CIND (non-dissociative)
  • Radiocarpal,Midcarpal,Ulnar translocn
  • CIC (complex)
  • Perilunate Dislocation

18
Progressive periLunate Instability
  • Stage I scapholunate instability
  • Stage II capitate dislocation
  • Stage III triquetral dislocation
  • Stage IV lunate dislocation
  • Spectrum of injury

19
PLI
20
Mechanism of injury
  • Impact on thenar side of wrist causes
    hyperextension , ulnar deviation and intercarpal
    supination
  • Progressive damage around lunate
  • Bony or ligamentous

21
Normal wrist
22
Volar Intercalated Segment Instability
23
Dorsal Intercalated Segment Instability
24
Gilula lines
25
Carpal Angles
26
Carpal Height
  • L2/L1 0.54
  • New ratio L2/capitate 1.57

27
Scapholunate Instability
  • Most common form
  • Rarely diagnosed acutely
  • Local tenderness
  • Scaphoid shift(Watson)
  • Associated with other injuries eg distal radius

28
Scapholunate Instability Classification
  • Type 1 dynamic
  • Neg Xrayve Watsonve cine
  • Type 2 static
  • ve plain films
  • Type 3 degenerative
  • Type 4 secondary
  • Kienbocks SNAC

29
Scapholunate Instability Radiographs
  • Scapholunate gap gt2mm
  • Foreshortened scaphoid
  • Cortical ring sign
  • Taliesnik,s V sign
  • Lack of parallelism?

30
Scapholunate Instability
31
DISI
32
Scapholunate Instability
33
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34
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35
Scapholunate Instability Treatment
  • Acute (0-3 wks) open repair vs
    arthroscopically-assisted PCP x 8wks
  • Chronic (gt4 wks) repair reconstruction
  • STT
  • Blatt
  • SLC

36
Scapholunate instability
37
Acute repair SLIL
38
Blatt Capsulodesis
39
STT Fusion
40
STT Arthrodesis
41
Scapholunate Instability Arthrosis
  • SLAC
  • PRC
  • Arthrodesis
  • RSL

42
Triquetrolunate instabliity
  • Limited understanding of ulnar side
  • TL or TH ??
  • Ulnar pain post injury
  • Click
  • ve ballottement test
  • Beware ulnar impaction syndrome
  • Conservative Rx rarely need limited fusion

43
VISI
44
Perilunate Dislocation
  • Perilunate Lunate are same basic injury
  • Still missed in ER
  • Rx of choice open reduction repair of
    ligaments/bones
  • Dorsal and volar approach
  • Late fusion or PRC

45
Lesser and Greater arcs
46
Perilunate Dislocation
47
Perilunate repair
48
Ulnar Translocation
  • Rare
  • Difficult to treat
  • Non-traumatic causes RA,Madelungs

49
Ulnar Translocation
50
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51
Carpal Instability Unresolved Issues
  • Role of arthroscopy
  • Method of reconstruction SLIL eg bone-tendon-bone
  • Ulnar side pathomechanics
  • Role of MRI

52
Grade III
53
Grade IV
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