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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
What are the arthrokinematics of thumb CMC abduction?
- rolls palmar - slides dorsal
26
What are the arthrokinematics of thumb CMC adduction?
- rolls dorsal - slides palmar
27
What are the arthrokinematics of finger MCP & IP flexion?
- roll and slide palmar
28
What are the arthrokinematics of finger MCP & IP extension?
- roll and slide dorsal
29
What are the arthrokinematics of finger MCP abduction?
- rolls and slides away from middle digit
30
What are the arthrokinematics of finger MCP adduction?
- rolls and slides toward middle digit
31
What are the arches of the hand?
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
Why cant you abduct your MCP joints very well when they are flexed?
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
What is skiers thumb?
- ulnar collateral ligament damage - thumb pulled into abduction toward proximal wrist
34
What is the functional position of the hand?
- wrist extension: 20-30 w/ slight ulnar deviation - MCP flexed: 35-45 - IP flexed: 15-30 - thumb CMC abduction: 35-45
35
Why are orthoses created to maintain the functional position of the hand?
- necessary to preserve functional potential - prevents adaptive shortening of tendons and ligaments
36
What is trigger finger?
- nodule forming usually in first finger tendon - nodule is forced through digital sheath creating an audible snap
37
Why are flexor pulleys important for the fingers?
- important for holding tendons against the bones and joints - without then the tendons would bowstring away from the bones/joints
38
What is tenodesis and how can we use it as therapists functionally?
- stretching of a polyarticular muscle across 1 joint which generates a passive movement at other joints - useful with paralyzed finger flexors (C6)
39
What is the difference between intrinsic plus position and the extrinsic plus position?
Intrinsic +: MCP flexion & IP extension Extrinsic +: MCP hyperextension & IP flexion
40
Which muscles produce each position of intrinsic plus and extrinsic plus?
Intrinsic +: lumbricals & interossei Extrinsic +: FDS, FDP, ED
41
How does the extensor mechanism work?
- 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
Walk through the process of opening the fingers
- 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
What is Dupuytren's Contracture?
- progressive shortening/thickening of palmar fascia of the hand - flexed posture of fingers - oblique retinacular ligaments tighten leading to flexed PIP & extended DIP
44
Explain thumb zigzag deformity from RA
- 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
Explain palmar dislocation of MCP joints from RA
- rupture of collateral ligaments allows proximal phalanx to dislocate in palmar direction
46
Explain ulnar drift from RA
- 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
Explain swan neck deformity from RA
- PIP hyperextension - DIP flexion - palmar plate ruptures allowing interinics to pull PIP into hyper extension - DIP flexes due to passive tension in FDP
48
Explain boutonniere deformity from RA
- PIP flexion (lateral band slips palmar) - DIP hyperextension (stretched lateral band) - rupture of central band & triangular ligament
49
What nerve is damaged, where is it damaged, and what muscles are involved with claw hand?
- ulnar nerve lesion - intrinsics paralyzed of digits 4&5
50
What nerve is damaged, where is it damaged, and what muscles are involved with Ape hand?
- median nerve just proximal to the wrist - intrinsics paralyzed - MCP doesn't flex well - thumb doesn't oppose
51
What nerve is damaged, where is it damaged, and what muscles are involved with the hand of benediction?
- median nerve at elbow or forearm - thenar muscles - FDP & FDS 2nd & 3rd digits can't flex
52
Explain carpal tunnel and its functional consequences
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
What is prehension?
- the ability of fingers/thumb to grasp or seize objects
54
What are the AAOS norms for finger MCP flexion/extension?
Flexion: - 90 Extension: - 45
55
What are the AAOS norms for finger PIP flexion and extension?
Flexion: - 100 Extension: - 0
56
What are the AAOS norms for finger DIP flexion/extension?
Flexion: - 90 Extension: - 0
57
What are the AAOS norms for thumb CMC abd/flexion/extension?
ABD: - 70 Flexion: - 15 Extension: - 20
58
What are the AAOS norms for thumb MCP flexion/extension?
Flexion: - 50 Extension: - 0
59
What are the AAOS norms for thumb IP flexion/extension?
Flexion: - 80 Extension: - 20

Biomechanics Winter 2024 (6 decks)

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