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Biomechanics Winter 2024 > Wrist-hand > Flashcards

Wrist-hand Flashcards

1
Q

What is the sequence of concave-convex on the wrist and hand?

A

Radioulnar -> concave
Proximal row -> convex
Proximal row -> concave
Distal row -> convex

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2
Q

Why is the scaphoid susceptible to avascular necrosis?

A
  • not great blood supply
  • BV’s enter either distally or at waist of the scaphoid
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3
Q

What happens neurologically if the ligaments of the wrist are damaged?

A
  • mechanoreceptors can’t communicate with the CNS in order to initiate a protective mechanism to reflexively contract a muscle
  • loss of proprioception
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4
Q

Which ligaments play a role in scapholunate stability at the wrist?

A
  • scapholunate ligament
  • scaphocapitate ligament
  • dorsal radiocarpal ligament
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5
Q

What are the osteokinematics of the wrist?

A

2 degrees of freedom
- flexion/EXT
- radial/ ulnar deviation

AoR = capitate

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6
Q

What are the functional ROM’s for the wrist for ADL?

A

Flex: 40
Ext: 40
RD: 10
UD: 30

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7
Q

What are the consequences at the wrist and hand of a radial nerve lesion?

A
  • no wrist/hand extension
  • loss of sensation of dorsal lateral half of hand/fingers
  • “wrist drop”
  • grip strength lost
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8
Q

What is the dart throwers motion?

A
  • as wrist extends, it tends to radially deviate
  • as wrist flexes, it ulnarly deviates
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9
Q

What is the roll of the TFCC?

A
  • it is a disc and ligaments
  • holds distal ends of radius/ulna/carpals together during pronation and supination
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10
Q

Which row of carpals is most susceptible for zigzag collapse?

A
  • proximal row
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11
Q

What are the arthrokinematics of wrist flexion of the radiocarpal and midcarpal joints?

A

RCJ:
- roll anterior
- slide posterior

MCJ:
- roll anterior
- slide posterior

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12
Q

What are the arthrokinematics of wrist extension of the radiocarpal and midcarpal joints?

A

RCJ & MCJ:
- roll posterior
- slide anterior

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13
Q

What are the arthrokinematics of wrist radial deviation of the radiocarpal and midcarpal joints?

A

RCJ & MCJ:
- roll radially
- slide ulnarly

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14
Q

What are the arthrokinematics of wrist ulnar deviation of the radiocarpal and midcarpal joints?

A

RCJ & MCJ:
- roll ulnarly
- slide radially

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15
Q

What is the difference between DISI and VISI?

A

Dorsal Intercalated Segment Instability:
- distal lunate faces dorsally

Volar ISI:
- distal lunate faces volarly

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16
Q

What is DeQuervain’s tenosynovitis?

A
  • inflammation of first compartment in extensor retinaculum & tendons through it (APL & EPB)
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17
Q

What is Kienbock’s Disease?

A
  • lunate avascular necrosis
  • “lunatomalacia” -> softening of lunate
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18
Q

What is positive ulnar variance?

A
  • distance the ulnar head extends distal to reference line
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19
Q

What is negative ulnar variance?

A
  • distance ulnar head extends proximal to reference line
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20
Q

What is ulnar impaction syndrome?

A
  • encroachment of distal ulna on proximal TFC, triquetrum, or lunate
  • associtaed with excessive ulnar variance
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21
Q

What is ulnar variance mostly due to?

A
  • radial displacement
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22
Q

What are some consequences of a distal radius fracture?

A
  • disrupt the ulnar (25 degrees) & palmar (10 degrees) tilts of the radius
  • alters arthrokinematics
  • shortened radius
  • positive ulnar variance
  • alters the length-tension relationship of muscles
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23
Q

What are the arthrokinematics of thumb CMC & MCP flexion?

A
  • roll and slides ulnarly
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24
Q

What are the arthrokinematics of thumb CMC & MCP extension?

A
  • rolls and slides radially
25
Q

What are the arthrokinematics of thumb CMC abduction?

A
  • rolls palmar
  • slides dorsal
26
Q

What are the arthrokinematics of thumb CMC adduction?

A
  • rolls dorsal
  • slides palmar
27
Q

What are the arthrokinematics of finger MCP & IP flexion?

A
  • roll and slide palmar
28
Q

What are the arthrokinematics of finger MCP & IP extension?

A
  • roll and slide dorsal
29
Q

What are the arthrokinematics of finger MCP abduction?

A
  • rolls and slides away from middle digit
30
Q

What are the arthrokinematics of finger MCP adduction?

A
  • rolls and slides toward middle digit
31
Q

What are the arches of the hand?

A

Proximal transverse:
- distal row of carpals (keystone is capitate)

Distal transverse:
- through MCP joints (keystone is 2nd & 3rd MCP)

Longitudinal:
- follows 2nd and 3rd “rays” (keystone is 2nd and 3rd MCP)

32
Q

Why cant you abduct your MCP joints very well when they are flexed?

A

1) cord parts of collateral ligaments are taut in flexion
- this increases compressive forces b/w joint surfaces

2) at 70 degrees flexion, proximal surface of phalanx contacts flat part of metacarpal heads
- this blocks abduction

33
Q

What is skiers thumb?

A
  • ulnar collateral ligament damage
  • thumb pulled into abduction toward proximal wrist
34
Q

What is the functional position of the hand?

A
  • wrist extension: 20-30 w/ slight ulnar deviation
  • MCP flexed: 35-45
  • IP flexed: 15-30
  • thumb CMC abduction: 35-45
35
Q

Why are orthoses created to maintain the functional position of the hand?

A
  • necessary to preserve functional potential
  • prevents adaptive shortening of tendons and ligaments
36
Q

What is trigger finger?

A
  • nodule forming usually in first finger tendon
  • nodule is forced through digital sheath creating an audible snap
37
Q

Why are flexor pulleys important for the fingers?

A
  • important for holding tendons against the bones and joints
  • without then the tendons would bowstring away from the bones/joints
38
Q

What is tenodesis and how can we use it as therapists functionally?

A
  • stretching of a polyarticular muscle across 1 joint which generates a passive movement at other joints
  • useful with paralyzed finger flexors (C6)
39
Q

What is the difference between intrinsic plus position and the extrinsic plus position?

A

Intrinsic +: MCP flexion & IP extension

Extrinsic +: MCP hyperextension & IP flexion

40
Q

Which muscles produce each position of intrinsic plus and extrinsic plus?

A

Intrinsic +: lumbricals & interossei

Extrinsic +: FDS, FDP, ED

41
Q

How does the extensor mechanism work?

A
  • uses a combination of bands (central: from ED; lateral: from central band) that attaches to distal/middle phalanx to help the extrinsic/intrinsic muscles act on the phalanges
  • also called the dorsal hood
  • interossei and lumbricals attach here
42
Q

Walk through the process of opening the fingers

A
  • passive resistance from finger flexors
  • ED pulls MCP toward extension
  • ED, lumbricals, and interossei pull on extensor mechanism
  • intrinsics prevent ED from hyperextending MCPs
  • wrist flexors offset ED pull
43
Q

What is Dupuytren’s Contracture?

A
  • progressive shortening/thickening of palmar fascia of the hand
  • flexed posture of fingers
  • oblique retinacular ligaments tighten leading to flexed PIP & extended DIP
44
Q

Explain thumb zigzag deformity from RA

A
  • chronic synovitis = weakened connective tissue = joint instability
  • CMC flexion due to rupture of anterior oblique and RCL
  • CMC dislocated
  • thumb adductors & flexors shortened
  • MCP hyperextension
  • EPL & EPB bowstring
  • IP flexion
45
Q

Explain palmar dislocation of MCP joints from RA

A
  • rupture of collateral ligaments allows proximal phalanx to dislocate in palmar direction
46
Q

Explain ulnar drift from RA

A
  • ED is allowed to slip to ulnar side of the AoR due to a rupture of expansion hood
  • ED could slip palmar creating a flexion force
  • creates ulnar translation @ wrist
47
Q

Explain swan neck deformity from RA

A
  • PIP hyperextension
  • DIP flexion
  • palmar plate ruptures allowing interinics to pull PIP into hyper extension
  • DIP flexes due to passive tension in FDP
48
Q

Explain boutonniere deformity from RA

A
  • PIP flexion (lateral band slips palmar)
  • DIP hyperextension (stretched lateral band)
  • rupture of central band & triangular ligament
49
Q

What nerve is damaged, where is it damaged, and what muscles are involved with claw hand?

A
  • ulnar nerve lesion
  • intrinsics paralyzed of digits 4&5
50
Q

What nerve is damaged, where is it damaged, and what muscles are involved with Ape hand?

A
  • median nerve just proximal to the wrist
  • intrinsics paralyzed
  • MCP doesn’t flex well
  • thumb doesn’t oppose
51
Q

What nerve is damaged, where is it damaged, and what muscles are involved with the hand of benediction?

A
  • median nerve at elbow or forearm
  • thenar muscles
  • FDP & FDS 2nd & 3rd digits can’t flex
52
Q

Explain carpal tunnel and its functional consequences

A

3 potential mechanisms
1) overcrowding due to a small tunnel, water retention, or inflammation/swelling
2) mechanical stress related to occupation or chronic repetitive stress
3) fibrotic changes

  • functional consequences could be loss of opposition, thenar atrophy, poor grip/manipulation, and potential adduction contracture
53
Q

What is prehension?

A
  • the ability of fingers/thumb to grasp or seize objects
54
Q

What are the AAOS norms for finger MCP flexion/extension?

A

Flexion:
- 90

Extension:
- 45

55
Q

What are the AAOS norms for finger PIP flexion and extension?

A

Flexion:
- 100

Extension:
- 0

56
Q

What are the AAOS norms for finger DIP flexion/extension?

A

Flexion:
- 90

Extension:
- 0

57
Q

What are the AAOS norms for thumb CMC abd/flexion/extension?

A

ABD:
- 70

Flexion:
- 15

Extension:
- 20

58
Q

What are the AAOS norms for thumb MCP flexion/extension?

A

Flexion:
- 50

Extension:
- 0

59
Q

What are the AAOS norms for thumb IP flexion/extension?

A

Flexion:
- 80

Extension:
- 20

Biomechanics Winter 2024 (6 decks)

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