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MSK PT > Biomechanics, Mvmts, Diagnostic Imaging of Lumbar Spine > Flashcards

Biomechanics, Mvmts, Diagnostic Imaging of Lumbar Spine Flashcards

1
Q

what motion occurs when every point on the bone moves in the same direction

A

translation

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2
Q

translation is caused by what force?

A

shear

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3
Q

what is the difference b/w stress and strain

A

stress = the applied or elongated force
strain = the extent to which the CNT is elongated

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4
Q

when do micro tears occur in collagen?

A

after > 4% of elongation

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5
Q

what is the resistance to deformation and the slope of the stress-strain curve

A

stiffness

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6
Q

if a constant force is applied to a collagenous structure for a more prolonged period, further mvmt is detectable

A

creep

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7
Q

why does creep occur

A

due to a gradual realignment of collagen fibers and proteoglycans

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8
Q

how do we apply the creep phenomenon

A

stretch

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9
Q

restoration of initial length of CNT occurs at a less rate and to a lesser extent than the deformation

A

hysteresis

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10
Q

what does hysteresis indicate?

A

that energy was lost during deformation

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11
Q

after several frequent repetitions of a stress, the structure becomes weaker

A

fatigue failure

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12
Q

in fatigue failure, material may fail under ______

A

normal stress

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13
Q

when is fatigue failure seen most often

A

overuse syndrome

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14
Q

during slow loading of the axial spine with compression, what happens to the:
- VB
- NP
- AF
- end plate

A

VB - approximates
NP - increase in pressure
AF - bulges radially
end plate - bows towards vertebrae

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15
Q

during slow axial compression of L spine, where is there a greater amt of bulging?

A

greater anteriorly vs posterolaterally

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16
Q

describe the creep phenomenon in relation to slow axial compression of the L spine

A

rapid creep of 1.5 mm in the first 2-10 min
then slower rate 1mm/hr - plateau is at 90 min

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17
Q

what is the weakest component of the disc

A

end plate

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18
Q

what is the intradiscal pressure of the lumbar spine in standing

A

100%

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19
Q

when do you have the least amt of intradiscal pressure

A

supine with knees up posture

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20
Q

what is the intradiscal pressure of the lumbar spine in sidelying

A

75% of standing (or decreases by 25% from standing)

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21
Q

what is the intradiscal pressure of the lumbar spine in supine

A

25 % of what standing pressure is

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22
Q

what is the intradiscal pressure of the lumbar spine in slight lean forward

A

increases by 50-100% (150% -200% of what it is in standing)

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23
Q

what is the intradiscal pressure of the lumbar spine in sitting

A

increases by 50%

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24
Q

what positions aggravate the disc or increase the intradiscal pressure?
what factors relieve it?

A

aggravating - sitting, leaning forward, lifting objects, jumping, twisting
relieving - SL, supine, supine with knees up

25
Q

with a normal disc, the facets take how much pressure?

A

abt 8%

26
Q

with a diseased disc, how much load does the facet take?

A

40-70%

27
Q

during axial distraction, what happens to the:
- disc
- capsules of facets

A

disc = less stiff
capsule = strong when subject to traction

28
Q

____ % of lengthening of the L spine during traction occurs due to ______ of lumbar Lordosis.
the remaining ______ % occur due to _____ of the VB

A

40% - flattening
60% - separating

29
Q

how much creep occurs immediately during axial distraction of L spine

A

1-2mm

30
Q

how does traction affect young vs old

A

lengthening is greater in young than old

31
Q

describe what is happening to the curve of the lumbar spine during flexion

A

straightening in the upper L spine
- does not occur at L5-S1

32
Q

describe the kinematics of flexion if the L spine

A

anterior sagittal rotation (rocking forward of VB) and anterior sagittal translation

33
Q

what happens to the facets in flexion

A

slide superior and anterior

34
Q

describe the pressure on the facets, anterior and posterior disc during flexion

A

facet and post disc = decrease in compression
anterior disc = compression increase

35
Q

what structure resists sagittal rotation (rocking of VB) in flexion

A

tension of capsule

36
Q

what structures resist segmental flexion (4, list in order of greatest to least)

A
  1. joint capsule (39%
  2. IV disc (29%)
  3. supraspinous lig and interspin lig
  4. lig flavum
37
Q

what are the top 2 structures that resist segmental flexion

A
  1. joint capsule
  2. IV disc
38
Q

what 4 things resist anterior sagittal translation of top VB on bottom VB during flexion at end range

A
  • direct impact on facet joint (C and J curves)
  • superior/anterior orientation of lateral fibers of annulus
  • iliolumbar and supraspinous lig
  • MF and ES
39
Q

about how much segmental flexion occurs at each segment?
L1-2
L2-3
L3-4
L4-5
L5-S1

A

L1-2 = 8 deg
L2-3 = 10
L3-4 = 12
L4-5 = 13
L5-S1 = 9

40
Q

what effect does bending alone have on the disc?
what about when you have bending + compression

A

alone = little effect
+ compression = causes failure in disc or pars interarticularis

41
Q

describe the kinematics of extension of VB in L spine

A

posterior sagittal rotation (rock backward) + posterior sagittal translation

42
Q

what happens to the facets during extension

A

approximation of inferior facet on superior facet
- slide inferior and posterior

43
Q

what happens to the WB status of the facet during extension

A

it becomes WB, whole IV joint becomes compressed

44
Q

what end feel should you feel with extension

A

bony from SP on SP

45
Q

what happens to the interspinous ligament during extension

A

buckles

46
Q

what 4 things restrict segmental extension of L spine

A
  • SP on SP
  • inferior articular process on the laminae below
  • ability of disc to allow compression
  • ability of ant structures to allow elongation
47
Q

about how much segmental extension occurs at each segment?
L1-2
L2-3
L3-4
L4-5
L5-S1

A

L1-2 = 5
L2-3 = 3
L3-4 = 1
L4-5 = 2
L5-S1 = 5

48
Q

most of the segmental extension occurs at what segments?

A

L1-2 and L5-S1

49
Q

describe what happens to the disc, I/L and C/L facets during axial rotation

A

disc = torsion
I/L facet = gapping
C/L = compression/approximation

50
Q

maximal segmental rotation is limited to ______ because collagen can only be elongated to ______

A

3 degrees
4%

51
Q

how much rotation does it take to increase tension in interspinous and supraspinous ligaments

A

< 1 degree

52
Q

what has the greatest resistance to rotation

A

65% - facet joint, ligaments, capsule
35% - from disc

53
Q

rotation + flexion increases the chances of injury to what structure?
Why?

A

annulus fibrosus b/c minimal contact of facet joints

54
Q

describe what happens to the facets during lateral flexion/side bending

A

I/L glides inferior
C/L glides superiorly

55
Q

if the segments in the thoracic or lumbar spine are in neutral, ROTATION is in the _____ direction of SIDE BENDING

which law is this?

A

Law 1 - rotation and SB in OPPOSITE directions

56
Q

if segments in the cervical, thoracic or lumbar spine are in full flexion or extension with the z-joints engaged (locked), ROTATION and SB occur _______

what law is this

A

Law 2 - occur to the same side

57
Q

if motion is introduced into a segment in any plane _______

what law is this?

A

motion in the other is reduced

law 3

58
Q

what is the standard view for radiographic views of the L spine

A

AP view

59
Q

what are the 4 basic projections of the L spine for radiograph

A

AP
lateral
R and L oblique
Lateral L5-S1

MSK PT (7 decks)

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