Lumbar Spine

Question 1

osteology/structure of lumbar spine take home messages

Answer 1

66% lordosis L4-S1 (radiographic - 47-64 degrees)
facets are 90 degrees from transverse, 45 degrees from frontal (superior facet faces posteromedial)
Functional segmental unit
-2 vertebrae and IVD
-anterior portion: bodies, discs, ALL (compression)
-posterior - SP, TP, facets, LF, PLL (guide motion)

Question 2

osteokinematics of lumbar spine take home messages

Answer 2

flex/ext
-12-2- per segment
rotation
-2 per segment (L5S1 has 6)
lat flex
-6 per segment

Question 3

compare/contrast with other regions take home messages

Answer 3

C1C2 - lots of rotation (20 from transverse)
-limited LF
C3-C7
-45 from frontal/transverse
-F/E, LF
T1-T12
-60 from transverse, 20 from frontal 
-limited F/E, LF, some rotation

Question 4

risk factors for injury

Answer 4

compression and shear exposure
-repetitive lifting
prolonged sitting, standing
-psychosocial factors
posture (reduced lordosis = bad)

Question 5

OHSA max limits for

• compression
• shear

Answer 5

compression
-10,000 Newtons
shear
-3,000 Newtons

Question 6

single cycle overload

• what is tested
• what is the test’s purpose
• what were the findings

Answer 6

in vitro test of porcine functional spinal unit
C3C4 level
single test to failure in pure compression
findings
-primarily endplate fractures
-no IVD injuries

Question 7

cumulative exposures

Answer 7

more indicative of a back injury
the area under the curve
-time from box pickup to placement

Question 8

combined cyclic loading

Answer 8

torsion increases the rate at which herniation occurs

Question 9

IVD herniation

-what does it look like?

Answer 9

not like a jelly donut
track initiation
-pulposus begins to make its way through weak layers of annulus until it goes all the way through
a bulging disc can lead to local inflammation
-can cause the pain

Question 10

multifactorial problem of LBP

• how many patients have an identifiable structural defect
• what are other areas that may contribute to the problem

Answer 10

15%
other factors
-control of whole body movement
-muscle activation patterns
-current research investigating motor control, loading and injury

Question 11

firefighter study - early findings

Answer 11

low back loads are high in firefighting activities
loading patterns highly sensitive to personal movement strategies
-suggests we should do personalized intervention and training
personal factors (gender, fitness, movement competency) can influence movement behavior and injury potential

Question 12

static standing posture

• primary loads are…
• constant flexion moment
• -creates…
• resisted by…

Answer 12

primary loads
-body weight
-muscle activity
-pre-stress from ligaments
-external loads
constant flexion moment
-anterior shear
-must be resisted by extensor muscles

Question 13

posture influences joint loading and the specific tissues that are stresses
-how

Answer 13

moment arms
ligamentous constraints
bony restraints
active restraints
more on this later

Question 14

erector spinae buttress anterior shear

Answer 14

actions of erector spinae to combat constant flexion moment

• acts in opposite direction of shear
• acts in same direction of compression

Question 15

compression estimation

• underestimate loading if…
• excessive muscle contraction/loading may have detrimental effects through _____

Answer 15

underestimate loading if we don’t include muscle activity

excessive muscle contraction/loading may have detrimental effects through increased compression

Question 16

why is lifting with a flexed back bad?

Answer 16

increased demand on extensor muscles
_____
_____