M1-2 Class Notes 3 Flashcards
What are the laws of spinal motion?
Fryette’s laws
Fryette’s laws of spinal motion: Law 1
Side bend to the right is accompanied by rotation to the left
Fryette’s laws of spinal motion: Law 1 applies to this type of motion in this part of the spine
- normal, neutral motion
- mostly lumbar spine
Fryette’s laws of spinal motion: Law 1 does not apply to:
C-spine
Fryette’s laws of spinal motion: Law 2
If facets are locked in full ext or flexion, R lateral flexion is accompanied by R rotation
Fryette’s laws of spinal motion: Law 2
How is it different between lumbar and cervical?
R lateral flexion accompanied by R rotation
Normal for cervical spine in neutral
Fryette’s laws of spinal motion: Law 3
The more motion you have in any one plane, the less you’ll have in any other plane
Fryette’s laws of spinal motion: Law 1 is useful to know for these techniques
Manual
Fryette’s laws of spinal motion: magnitude of secondary motion
SMALL
Mechanisms of rotation: Initial rotation occurs about this axis
Central/posterior axis in vertebral body
What structure interferes with rotation?
Facet joints
What happens when you rotate to the left with respect to axis of rotation and overall motion between vertebrae?
- Only go a few degrees until R facets approximate
- On impact, motion stops and R facets become a “hinge”
- L facets open up like a door to allow more rotation
R facets are the new axis of rotation
When facets open up like a hinge and axis of rotation changes, what other motions happen between the adjacent vertebrae?
Becomes gapped and distracted posteriorly
Once the facets open up like a door on one side with rotation, what happens to other vertebrae?
- levels below rotate in a cascade
- rotation works its way down the vertebral column
- almost simultaneous
What is a major component that limits rotational movement?
Synovial capsule on “door” side prevents over-rotation or excessive facet opening
How much rotation do we have at each segment before the motion stops?
About 3˚
What allows us to rotate more than just a few degrees?
Combined motion at multiple joints
If a pt has OA on the R facet joint, they would likely be most painful with (R/L) rotation.
L
Not absolute, but helpful in thinking about mechanics
According to Fryette’s law, L rotation would be accompanied by what movement?
R lateral flexion
Minimal, but it still happens
Because lateral flexion occurs with rotation, what forces are exacerbated?
Forces on the R facet joint
With sufficient loading, you can get this (with respect to facets)
- bony impaction between edges of facets on top and bottom segments
- can be a source of pain
Anterior translation of the vertebra during flexion is limited by what structure(s)?
- facet joints
- ALL
Facet activity with anterior translation
- loaded during flexion
- slide upward a bit
IVF volume and flexion
Increases
Facets stop excessive anterior translation during flexion to protect this
Central canal
When the L-spine is flexed, body weight exerts these forces on the IV joints
- compressive
- shear
Magnitude of forces on the IV joints is proportional to this
Angle of inclination of the interbody joint
Dogs: this is normal
Scotty dog
Dogs: Scotty dog with a collar
- Spondylolysis
- could be a stress fx or true fx
Dogs: Decapitated Scotty dog
- Spondylolisthesis
- head moves away from the body
This view of radiograph is used to asses effect of Scotty dog
Lateral
