Wrist and Hand. Wrist Radiocarpal Mid-carpal (intercarpal) zmaintain length- tension relationship...
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Transcript of Wrist and Hand. Wrist Radiocarpal Mid-carpal (intercarpal) zmaintain length- tension relationship...
Radiocarpal
Radius and Radioulnar disk (concave)
Scaphoid (navicular), lunate, and triquetrum (proximal wrist bones)
Ligaments
Ulnocarpal complex meniscus homologue -
radiotriquetral ligament
triangular fibrocartilage - articular disk
Kinematics
Extension
distal carpals on fixed proximal carpals
neutral (scaphoid-capitate close-packed)
Kinematics
Extension scaphoid travels w/ distal
carpals 450 ext.
scaphoid & lunate close-packed scaphoid travels w/ proximal carpals
Hand
Flexor Tendons surrounded by synovial sheaths reinforced by pulleys (5/3) minimize force/pressure prevent bowstringing
Tendon Excursion and Pulleys
Sliding of flexor/extensor tendons proximal jts. > distal joints FS > FP Flexors > extensors Extrinsics > intrinsics
Balance of Power
Extrinsic vs. IntrinsicsIntrinsic - clawing counteract extrinsics stabilize proximal phalanx tendons volar to AOR lumbricales critical for timing
Hand/Wrist Injuries
Etiology of CTS forceful exertions repetitive*/prolonged activities awkward postures localized contact stresses vibration cold temp.
Carpal Fractures
80:20% load distribution between radius:ulna
scaphoid (60-70%) hyperextension beyond 950
lunate
Finger Injuries
Boutonniere (Button-Hole) Deformity dorsal synovitis /capsular distension
thinning & lengthening of central
tendon
Finger InjuriesBoutonniere (Button-Hole) Deformity dorsal subluxation of proximal phalanx (PIP) palmar displacement (dislocation) of lateral
bands of long extensors MCP / PIP DIP /
Finger Injuries
Swan-Neck DeformityFlexor synovitis flexor forces on MCPstretching of collateral ligaments and
palmar plate at PIP
Finger Injuries
Swan-Neck Deformitydorsal displacement of lateral bands
of extensors intrinsic tightening with MCP flexion
position of lateral bands pull of
extensor tendon reciprocal DIP flexion
Thumb Injuries
Gamekeeper’s/skier’s thumb
MCP ulnar collateral ligament
20 to tensile loading (chronic or acute)
excessive abduction/hyperextension