Wrist and Hand. Wrist Radiocarpal Mid-carpal (intercarpal) zmaintain length- tension relationship...

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Wrist and Hand

Transcript of Wrist and Hand. Wrist Radiocarpal Mid-carpal (intercarpal) zmaintain length- tension relationship...

Wrist and Hand

Wrist

RadiocarpalMid-carpal

(intercarpal)

maintain length-tension relationship for hand musculature

Distal Radius

FacetsLateral (46%) scaphoidMedial (43%) lunateInferior disk (11%) triquetrum

Radiocarpal

Radius and Radioulnar disk (concave)

Scaphoid (navicular), lunate, and triquetrum (proximal wrist bones)

Ligaments

volar - thick, strong dorsal - thinner,

fewer unique function extrinsic intrinsic

Ligaments

Radiocarpal superficial

deep

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

Kinematics

Flexion opposite extension

Hand

Flexor Tendons surrounded by synovial sheaths reinforced by pulleys (5/3) minimize force/pressure prevent bowstringing

Flexor Tendons

60 900 of PIP flexion

40% in tension in restraining pulley

Tendon Excursion and Pulleys

Tendon Excursion and Pulleys

Tendon Excursion and Pulleys

Sliding of flexor/extensor tendons proximal jts. > distal joints FS > FP Flexors > extensors Extrinsics > intrinsics

Pulley Disruption

Bowstringing excursion at a joint weakness at

other joints

Pulley Disruption

Pulley Disruption

Balance of Power

Extrinsic vs. IntrinsicsIntrinsic - clawing counteract extrinsics stabilize proximal phalanx tendons volar to AOR lumbricales critical for timing

Hand/Wrist Injuries

CTD/RSI

CTS inflammation in CT compressive neuropathy

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

Mallet Finger distal terminal tendon/slip rupture

flexion of DIP

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

Finger Injuries

Swan-Neck DeformityMCP PIP / DIP

Thumb Injuries

Gamekeeper’s/skier’s thumb

MCP ulnar collateral ligament

20 to tensile loading (chronic or acute)

excessive abduction/hyperextension

Thumb Injuries

Bennett’s Fx fx subluxation of

trapeziometacarpal joint

intraarticular fx of 1st MET

axial compression