Spine Biomechanics and Lumbar Pathology

Question 1

load distribution

Answer 1

80% load through vertebrae and interbody joint

20% through posterior elements

Question 2

Annulus fibrosis

Answer 2

concentric rings to contain the nucleus pulposus

Opposite directed collagen, fibers, 65° from vertical

Peripheral strength, flexibility protection from distraction, shear, torsion

Question 3

nucleus pulposus

Answer 3

70 to 90% water in younger individuals

shock absorber

Dehydrated discs can increase load to facet joints

Question 4

diurnal variation

Answer 4

Lose about 25% of fluid in disc during the day then you rehydrate it at night

Question 5

Zygapophyseal joint

Answer 5

Facet joint
synovial plane joint

Allows flexion, but also a restraint to excessive flexion to protect the IVD

Question 6

Zygapophyseal joint blocks excessive

Answer 6

anterior translation

Protects spinal cord
Contains fat plugs - may be a source of symptoms

Question 7

How do you name the movement?

Answer 7

superior vertebrae on the inferior vertebrae

Direction of anterior surface of the vertebral body

Question 8

OK- flexion and extension

Answer 8

Sagittal plane
Medial lateral axis
Forward and backward bending

Question 9

OK- lateral flexion to the right or left

Answer 9

Frontal plane
Anterior posterior axis
Side bending to the right or left

Question 10

OK- axial rotation to the right or left

Answer 10

Horizontal plane
Vertical axis
Rotation or torsion

Question 11

Fryettes laws

Answer 11

Coupled motions

Question 12

Type one mechanics

Answer 12

neutral

Coupled motions in opposite directions

lateral flexion to one side is accompanied by rotation to the opposite side

(left lateral flexion and right rotation)

Question 13

type 2 mechanics

Answer 13

non-neutral

Coupled motion in the same direction

Lateral flexion to one side is accompanied by rotation to the same side

(left lateral flexion and left rotation)

Question 14

type three mechanics

Answer 14

Motion in one plane reduces availability of motion in all remaining planes

Most relevant to lumbar mechanics

Question 15

lumbar flexion

Answer 15

Anterior rotation, transverse axis
Translate anteriorly, Sagittal axis

45-55 degrees of lumbar flexion

Question 16

lumbar flexion; anteriorly

Answer 16

compresses anterior disc
anterior longitudinal ligament laxity

Question 17

lumbar flexion… facet joint and spinous processes do what

Answer 17

Inferior articular process of superior vertebra moves superiorly on superior articular process of the inferior vertebra

Opening of facet joints

Separation of a spinous processes
Posterior ligaments, facet capsule tightens

increases the diameter of NF, spinal canal

Question 18

lumbar extension

Answer 18

Superior vertebra-
Rotates posteriorly , transverse axis
Translate posteriorly , sagittal axis

15 to 25° of lumbar extension

Question 19

Lumbar extension puts tension on…

Answer 19

Tension in the anterior disc, the ALL, and anterior musculature

Question 20

lumbar extension causes the facets to… and where is the laxity

Answer 20

Closing of facets. narrowing NF
Posterior ligaments and facet capsule lax

Inferior articular process of superior vertebra moves inferior on the superior process of the inferior vertebra

Question 21

Lumbo pelvic rhythm

Answer 21

coordinated movements between the lumbar spine and pelvis, during flexion extension

flexion - lumbar flexion, followed by anterior pelvic tilt
Extension - posterior pelvic tilt, followed by lumbar extension

Question 22

Clinical implications of Lumbopelvic rhythm

Answer 22

tight hamstrings
Weak hip extensors
Predisposing, anterior or posterior pelvic tilt
Limited hip or lumbar range of motion

Question 23

lumbar axial rotation

Answer 23

rotates around vertical axis
Translation dependent on level of involved segment

range of motion
5 to 7°
Limited by sagittal plane alignment, facet joints, facet separation

Anulus tension

Question 24

lumbar lateral flexion

Answer 24

rotates around anterior posterior axis
Translate laterally along horizontal axis

Side of convexity contralateral
Side of concavity ipsilateral

ROM is about 20° lumbar

Question 25

intrinsic muscles stabilizers

Answer 25

deep short, muscles, precision control
high degree of muscle spindles

Semispinalis
Multifidis
rotatores
interspinalis
intertransversarius muscles

Question 26

extrinsic muscles stabilizers

Answer 26

More superficial
Spans multiple segments
Important for course control of stabilization
Important role in torque production

Abdominals
Erector spinae
Quadratus lumborum
Psoas major
Hip muscles

Question 27

what has an important role to maintain intra-abdominal pressure for stability?

Answer 27

Diaphragm and pelvic floor muscles

Question 28

neural control system

Answer 28

Receive input from passive and active subsystems to determine requirement for maintaining stability

Effectiveness may be impaired with injury

Question 29

retraining system in order

Answer 29

Localized stabilization
General stabilization
Functional stabilization

At each level, you need to demonstrate mobility sufficient for movement
Stability. Balance, and proprioception.