Niko -> RE: ultrasound (September 2, 2012 10:02:42 PM)
Any conclusion drawn on the effectiveness of ultrasound that is black or white based on current evidence and scientific principles is not mature enough in my opinion. There is a lot of gray area and most researchers are honest enough to admit that. I know that the black or white is very appealing and that we do not like or tolerate ambiguity in clinical practice, but we shouldn't be disappointed with the gray. I think that most of us are not comfortable with the gray and therefore stop using modalities like utlrasound or specific forms of manual therapy etc. More data is needed to help us make appropriate choices. So considering the studies that Proud provided I agree with Harper (and I think Sebastian agreed as well), any study looking for something specific there is a good dose of confirmation bias.
Having said that, Proud, reading the articles that you provided I could not find strong evidence-based conclusions from studies done in vivo suggesting that we should not use the ultrasound to accelerate tissue healing (and again I'm not talking about pain output in the brain). Moreover, I could not find any strong evidence suggesting that cavitation does not occur in live tissue during the timeframe of tissue healing at the specific location of trauma. I think this statement is relevant: "The absence of proof is not the proof of absence". Even if cavitation happens only in cell cultures and not live tissue, cavitation may not be the complete answer to the bioeffects of US ( I have found a relevant article below).
Going back to the researchers' bias, the review study that you provided in the other thread has a purpose (http://ptjournal.apta.org/content/81/7/1351.full):
"The purpose of this review is to examine the literature regarding the biophysical effects of therapeutic ultrasound to determine whether these effects may be considered sufficient to provide a reason (biological rationale) for the use of insonation for the treatment of people with pain and soft tissue injury"
First of all, the word pain is thrown in there as a reason to use US, again, US has nothing to do with pain output in the brain. Then it is clear that the authors are looking for a yes US or no US answer there. The study would have been more appealing to me if the purpose was finding what conditions/parameters may be more beneficial than others: frequency, timeframe, dosage, pt population etc. If the conclusion was that there is no difference in relevant outcomes based on different conditions/parameters, then I 'll take that and move on.
The second review study that you provided : http://ptjournalonline.org/content/81/7/1339.full also focuses on pain as an outcome /reason for US use, and also points out that the parameters of each of the studies were highly variable. The great variability of the individual studies makes the meta analysis study less valuable. (Again I agree with Harper)
Now to talk specifics: the non thermal effects of US may not be limited to cavitation and microstreaming as this article suggests:
It discusses "The concept of the absorption of ultrasonic energy by enzymatic proteins leading to changes in the enzymes' activity"
The following discussion regarding the frequency resonance hypothesis is relevant:
"The frequency resonance hypothesis differs from acoustic streaming and cavitation at the basic levels. First, acoustic streaming relates to the movement of objects from one place to another as a function of the force of the wave. In terms of ultrasound therapy, phonophoresis is commonly used to move medication transdermally. Second, cavitation relates to the oscillation of microscopic gas bubbles that may, in turn, affect the cell or cellular process. However, the frequency resonance hypothesis relates to the absorption of ultrasound by proteins and protein complexes that may directly result in alterations to signaling mechanisms within the cell, either by inducing a conformational shift or by disrupting a multimolecular complex.
In any case, the mechanical effects of ultrasound may result in either the activation or inactivation of an enzymatic protein or a dissociation of a protein complex, leading to alterations in signal transduction. The frequency resonance hypothesis may describe the molecular mechanism or mechanisms responsible for alterations in cellular membrane properties,34,39,41,46,49 increases in protein production,* and modulation of enzyme activity.7–16,54–56
Frequency resonance and shearing forces on multimolecular complexes may combine to produce the nonthermal effects of therapeutic ultrasound. Collectively, the experiments reviewed here support the frequency resonance hypothesis and demonstrate that therapeutic ultrasound may modulate signal-transduction pathways and gene products associated with the inflammatory response and cells directly involved in the healing response (see Table).
The logical argument is that in vitro effects cannot be directly applied to clinical treatment protocols. However, from a cellular biology point of view, a strong argument can be made that if a stimulus reaches a critical threshold (eg, consider depolarization thresholds) the cell will respond, regardless of whether the cell is in vitro or in vivo (eg, insulin, histamine, aspirin, or any of the proteins listed in the Table). "
These are some older post op tendon healing studies in vivo not focusing on pain as an outcome:
This is a 2012 study in vivo for nerve injuries
other than that,
"anything to do with the nucleus pulposus is a moot point with US since you cant not get the sound waves at physical therapy levels to the disc anyway
ovpt, my argument at that point was that tissue is tissue so it doesn;t matter if it is a rat or a human. It is not about treating the nucleus pulposus specifically.
Another thing to consider in regards to increasing cellular activity in a nucleus pulposus (in vitro) is how do we reliably know that a specific NP is the reason for pain, needs more cell proliferation...but not too much, and once this perfect amount of proliferation occurs will the pain be gone.
Until we have reliable data showing there is consistent pain producing threshhold for decreased PG levels in a disc and that once this level has been restored pain is abolished, and PG level consistently can be restored by US on live people, I won't be sounding patients with LBP.
Honker, again it is not about sounding patients discs, is about human or other animal cells responding the same. I think it is not recommended to sound the low back or anywhere close to air filled cavities (intenstines, lungs etc). Also, US effects have no direct effect on pain in the brain. I care if the tissue healing process can be accelerated so I can tell the patient that the tissue is now healed, lets move on to help dessensitizatize the nervous system. If that happens, then I want to know under which excact conditions /parameters (timeframe, dosage, pt population, location of injury etc)
I think you may be underestimating the power of the image of the therapist using a fancy machine for the healing of the tissues. It is not so much the fact that they should feel anything, it is the fact that YOU, a very nice and professional person pays close attention to them, and even does the US himself to help their healing! You must admit that this is as much a potential placebo-elicitor as buzz of IFC.
How can I underestimate this? I was arguing in favor of this with you last month, remember? therapeutic equipment vs therapeutic hands. I totally understand the placebo is part of it, I said one can argue is less powerfull because you don't feel much with US. Since we can't quantify placebo I think this won't lead us anywhere.
First of all, how do you know there is even tissue damage? Are you not mainly treating a chronic pain population? Isn't tissue damage a non-issue in that population and thus US rather useless?
How do I know tissue damage? local tissue signs (morphology, color, temp etc), timeframe of injury, mechanism of injury so on(not pain sensitivity btw as that can be misleading). I do not treat only chronic pain population. I work with a multidisciplinary team not chronic pain clinic. I often see same day traumatic injuries. Regardless, Im interested in many areas of PT including pediatrics, stroke and spinal cord injury rehab and many more, outpatient ortho is just where I focus on today.