IX. Cavitation Flashcards
Definition of cavitation
Formation of vapor and gas bubbles within fluid through the local reduction of pressure
What is the cracking sound?
Liquid is stretched, pressure inside the liquid drops below the vapor pressure. Bubble formation and subsequent collapse occur and a cracking sound is heard
True or false: Z joints with recorded cavitation showed greater gapping than those that did not have recorded cavitations
True
What causes the crack?
The collapse of the vapour bubble causes the crack, not its formation
What does cavitation do to a ship’s propellers?
Cavitation “… is responsible for the erosion of ship’s propellers and the blades of hydraulic turbines, and cavitation damage in many forms of hydraulic machinery and bearings.”
What happens when cavities or vapor-filled bubbles move into higher pressure areas?
Instant collapse with high energy release and extremely large stresses (think ship’s propellers)
Over 80% of cavitation of cavitation is
Carbon dioxide
Cavitation is _______ while _______ is the sound:
Bubbles; we don’t know!
Joint cracking is related to ____________ rather than bubble collapse
Cavity formation
What are 4 observable physical effects of cavitation?
Temporary transitory increase in passive ROM
Temporary increase in the joint space
“Refractory period” where no further cracking can be
Radiolucency with subsequent joint separation
What is the refractory period?
20-45 minutes
What is the capsular ligament “snap-back”
When the capsular ligament reaches its elastic limits and snaps away from the synovial fluid, producing cavitation at the capsular-synovial interface.
Can slow forces produce cavitation?
Yes: “slow forces also produce cavitations that are similar to those produced during HVLA”
More motion means
More cavitation
True or false: the cavitation sound did appear to be associated with the magnitude or rate of the applied P-to-A forces
FALSE: the cavitation sound did NOT appear to be associated…
What is the difference between joints that cavitate and joints that don’t cavitate?
Joints that cavitate already have a greater ROM than those that don’t cavitate
In cervical rotary adjustments, what side does the cavitation occur on?
The cavitation occurs on the side opposite the adjustive contact
Where do cavitation sounds come from?
“Sounds obtained are just as frequently produced by non targeted joints in the area”
Can practitioners accurately palpate where cavitation occurs?
No: “the practitioner cannot accurately palpate where the cavitation occurs”
How many cavitation(s) occur during a single manipulative procedure when a doc aims for one specific part?
“…more than one cavitation occurs during a single manipulative procedure, suggesting that lumbar spinal manipulation is not specific.”
Can knuckle cracking cause osteoarthritis?
No coorelation
Some joints are less likely to cavitate like:
SI joint
Some joint motions are more likely to cavitation like:
Supine thoracic resisted contacts and lumbar rotation
In lumbar rotation, where is greater gapping of the Z joints found?
More gapping on the up-side than Z joints on the down-side