The Clinical
E~~icacy
o~
Ultrasound
An Honors Thesis
by
Susan Renae Naab
for
-
Dr. James E. Griffin
Thesis Director
Ball State University
Muncie, Indiana
May 1986
Expected Date of Graduation:
--
Spring, 1986
SpC:>:1
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-
~
<::_ ..... 15
LD
dAr:'
, 2..4The Clinical Efficacy of Ultrasound
Abstract
The
primary
to further
objective of this particular thesis project is
examine
the clinical
investigation of clinical
first
examining
ultrasonic energy.
the
efficacy
ultrasound would
inherent
properties
l
coupling agents
l
of
without
acoustic
l
and
including the suggested
and treatment techniques.
neglected topic of ultrasonic
-
be complete
No
Consideration is given to the various aspects
of therapeutic application of ultrasound
dosages
of ultrasound.
The
induced physiological effects
their implications is expounded upon.
often
and
Select clinical conditions
with which ultrasound is a viable treatment choice are enumerated
and their ramifications discussed.
and
situations
which
Numerous clinical
indicate/contraindicate
ultrasound as a treatment modality
the
are listed at the
conditions
use
of
conclusion
of the project as a brief and useful reference for the clinician.
ii -
The Clinical
E~~icacy
o~
Ultrasound
Table of Contents
Abstract
ii
Properties of Acoustic Energy
1
Characteristics of Ultrasonic Energy
1
Thermal Effects of Ultrasonic Energy
3
Non-Thermal Effects of Ultrasonic Energy
4
Ultrasound versus Conventional Thermotherapy
7
Clinical Ultrasonic Frequencies
10
Continuous versus Pulsed Ultrasound
11
Suggested Ultrasound Intensity and Dosage Levels
12
Importance of Calibration of Ultrasonic Generators
14
Coupling Agents and their Significance .
15
Phonophoresis and its Indications
17
General Physiological Effects of Ultrasound
18
Effects of Ultrasound on Muscle Blood Flow .
19
Direct effects of Ultrasound on Muscle Torque
20
Tissue Repair via Ultrasound
20
Tissue Damage via Ultrasound
21
Clinical Conditions in which Ultrasound is Used
22
Indications and Contraindications for Ultrasonic Therapy
28
Bibliography
29
- iii -
-
The Clinical Efficacy of Ultrasound
PROPERTIES OF ACOUSTIC ENERGY
Since ultrasound is recogni2ed as a form of acoustic energy,
a review of the inherent
properties of acoustic energy will
in ensuring a more thorough understanding of the
of ultrasound.
Acoustic energy
vacuum; therefore, molecules
is incapable
aid
characteristics
of penetrating
or larger units
of matter must
a
be
used as a vehicle for the acoustic energy-s conduction.
Inefficient
gas or mixture of
,-
acoustic
gases.
energy travel is obtained through any
Degassed liquids,
gas-free, provide a medium through
transmitted well.
obtained through
density.
or those which
which the acoustic energy
are
is
Optimum transmission of acoustic energy can be
solids
SUbstances
These properties
also
which
hold true
possess
for the
a
energy
high
of
ultrasound.
CHARACTERISTICS OF ULTRASONIC ENERGY
In
the
strictest
sense,
ultrasound
is
having a frequency greater than 20,OnO Hert2
defined as sound
a frequency which
is too high for stimulation of the sensory receptors of the human
ear.15
Ultrasound therapy involves the conversion of
energy into
ultrasonic
rarefraction
this high
waves
are
whose
frequency, which
is,
frequency
transverse
beam
in
is
acoustic energy.
waves
inversely
turn, inversely
- 1 -
of
electrical
Generally,
condensation
proportional
proportional
to
to
and
the
the
penetration. s
In other words, as the frequency of ultrasound
is
increased, the energy-s depth of penetration is decreased.
For
ultrasound to be effective, its energy must be absorbed.
In the atmosphere, ultrasonic energy is almost entirely
by the nitrogen, oxygen, and carbon
the human body, protein bearing
The
absorbed
dioxide in its midst.15
tissues are the major
of ultrasonic
energy.
tissue
percentage of
protein is
bone, 15-20%;
and nerve, 10-15%.s
muscle at
which
25%;
bears
absorbers
the
the amino-acid
highest
followed closely
by
The fatty tissue is quite low
in protein, considering that only the surrounding loose
tissue contains
In
polymers which
collagen
are inherent
to
proteins.
Since human
soft tissue
consists
of 70-90%
water,
addition to proteins and other solids, the velocity of sound
in
and
ultrasound in soft tissue is standardly considered to be 1500 mls
-- the same as that for
water.15
The velocity of ultrasound
in
cortical bone, the most dense solid in the body, is considered to
be 3500
The
m/s.15
velocity values
energy is
is
dramatic
difference
understandable,
transmitted
most
between
remembering
efficiently
these
that
through
two
acoustic
high
density
solids such as cortical bone.
At tissue interfaces, the absorption of ultrasonic energy is
accompanied by a considerable amount of reflection and refraction
phenomena
occurs when
-
which account for
the acoustic
selective heating.
impedance
differ, whereas refraction involves
between two
2 -
tissue
the actual bending of
waves as they travel from one medium to the next. s
-
Reflection
layers
sound
Pathological
and
sharply
within the periosteum and at
result
from
periosteum
this
and
localized temperature increases,
or near bone-tendon junctions,
reflection
tendons
are
of
ultrasonic
especially
can
energy.15
to
these
pathological temperature increases secondary to their poor
blood
supply and relatively low water content.
dissemination of the reflected
susceptible
The
These properties
energy rather difficult.
make
Nature
has made a provision for this problem by supplying the periosteum
with
an
abundance
receptors, which
of
sensory
enable
the
noxious stimulus and move
receptors,
patient to
away from the
including
become
thermal
aware
the patient possesses an intact sensory system.
of a
deep, dull ache
(periosteal overheating), which
of the ultasonic
energy~s
the
energy source prior
pathological changes taking place within the tissues
relate a feeling
of
of a
to
providing
The patient
very sudden
necessitates a rapid
may
onset
diminution
intensity.15
THERMAL EFFECTS OF ULTRASONIC ENERGY
For an effect
of ultrasonic energy to be purely thermal
in
origin, it must be such that it is capable of being achieved by a
technique that
is
of
mechanical vibratory
thermal energy.
a
non-acoustic
energy
An increase
of
nature.
ultrasound
is
in the temperature
Much
of
the
converted
of the
into
target
tissue results when energy is absorbed from the ultrasonic
beam.
If the local
45 D C,
tissue temperature
hyperemia (an increased
reaches between
amount of
blood in
40° and
the area)
results,
assisting in the resolution of chronic inflammatory processes
the area. 11
The combined
effect of tissue temperature rise
- 3 -
in
and
-
which
are
responsible
spasmolysis. 3
of histamine-like
the release
nicromassage result in
for
capillary
this
compounds
hyperemia
and
Tissue temperatures above 45°C are damaging to the
area tissues, yet can be
prevented by utilizing either a
moving
applicator technique or a low average intensity during ultrasound
application.
A
coefficient
which a
has
tissue will
been
absorb
devised which tells the extent to
energy from
intensity absorption coefficient.
bone is capable of
and
muscle
2.5
ultrasonic frequency of
comparatively low
should allow the
allows a subsequent
the
energy
than
muscle,
fat
at
In ideal circumstances,
1.0 MHz.5
the absorption
weakened and
Muscle-s
more energy than
more
ultrasonic beam
being considerably
region.
times
value of
sound beam
According to this coefficient,
absorbing 10 times
absorbs
a
the fat
without overheating
intermediate
absorption
enhanced generation
the
coefficient for
to penetrate
an
fat
without
the
fatty
coefficient
value
of heat
in the
itself and leaves a reduced intensity ultrasonic beam with
muscle
which
to reach the highly absorbing bone.
NON-THERMAL EFFECTS OF ULTRASONIC ENERGY
One
non-thermal
effect
which
ultrasound is that of acoustic
has
streaming.
been
attributed
When tissue is
sonated, the vibration of the transducer generates an
field in
cyclically
-
which
unidirectional
repeated
components. 1 1
movement
oscillatory
Acoustic streaming
is
is this
of
being
ultrasonic
superimposed
movements
to
the
unidirectional
upon
tissue
flow
which is particularly prevalent at boundaries such as the surface
-
4 --
of bubbles, membranes of cells,
this acoustic
streaming are
and organelles.
such
The effects
of
responses
are
that cellular
produced which may aid in stimulating tissue repair. 10
Acoustic
streaming is also known to induce changes in diffusion rates
membrane permeability,
synthesis and
possibly altering
tissue
millisecond range
repair in
pulses
ultrasonic machines
of
process. 10 . 11
the
which are
are long
the rates
delivered
enough
by
to produce
and
protein
Since
the
conventional
this
acoustic
streaming, reduction of the potentially dangerous thermal effects
at the
upper intensity
energy flow
while
ranges can
still
be achieved
retaining the
by pulsing
beneficial
the
effects
of
acoustic streaming.11
A
second
Bicroaassage.
effect of
non-thermal
The effect of
the ultrasound
tissue which
actual
therapeutic
result.
compressions
effect
that
micromassage is caused by the
and the
mechanical reactions
These reactions
and
is
expansions
are
of
the
of
wave
of
the
pressure
changes,
tissue
itself,
resulting in a micromassaging effect on the absorbing tissue. 3
•
15
When the micromassage is combined with a tissue temperature rise,
compounds
are
released
which
subsequently
result
in
local
hyperemia and spasmolysis. 3
Perhaps
the
most
widely
studied
ultrasound is that of cavitation.
process of generation of
by the motions. 5
effect
Cavitation is defined as
bubbles by a
motions of such bubbles, and
non-thermal
sound field, the
the physical effects brought
of
the
various
about
Cavitation is classified as two separate types:
stable and transient.
In stable cavitation, the voids or bubbles
- 5 -
remain intact
while oscillating
streaming occurring
for many
cycles with
them. s ,1o.11
around
Transient
acoustic
cavitation
occurs when the voids or bubbles grow suddenly and then
under the changing pressure of
process taking
less than
the ultrasonic field, the
period. 10 ,11
the wave
phase in transient cavitation is
temperature rises approaching
at
rather
collapse
I04°K within the
local
bubble and
Although cavitation
than
MHz
occurs
is
evidence that cavitation could be produced by exposure levels
at
of clinical ultrasound
frequencies,
with
there
the upper end
kHz
The
entire
associated with huge but
gross damage to cells and tissues. 11
more readily
collapse
apparatuses and
therefore
its effects must be considered. 11
Standing
wave
radiation
pressure forces have been another
type of non-thermal effect observed
Blood flow inhibition
been exposed to
frequency of 3
has occurred in
low intensities
MHz.5
with the use of
Blood
ultrasound.
chick embryos which
of continuous
cells have been
have
ultrasound at
observed to
into preferred positions in the sound field, separate
a
enter
themselves
by half a wavelength, and then remain in stationary bonds.
Dyson
et al. (1971) observed that if this effect took place in arteries
and arterioles
would be exposed
in humans
treated with
to conditions of
ultrasound, the
reduced oxygen
tissues
availability.
This effect can be minimized by moving the sound head in a manner
such that the direction of the vessels relative to the
direction
of the propagation of the ultrasound is varied continuously.s,10
Relaxation
of
polypeptide
non-thermal mechanism by
bonds
has
which ultrasonic
- 6 -
been suggested as a
energy relieves
pain
.-
caused by
excess proliferation
ultrasound becomes
an effective
motion where limitation
scar
tissue
of connective
means
is secondary
formation.
The
of increasing
to extensive
hypertrophic
exclusively from the epidermal margin.
tendon extensibility
and
relaxation
tissue. 1 5
scar
Thus,
range
of
hypertrophic
which
comes
Significant increases
of
skeletal
muscle
in
upon
absorption of ultrasound may also be attributed to the relaxation
of polypeptide bonds within the tissues.
ULTRASOUND VERSUS CONVENTIONAL THERMOTHERAPY
There
are
ultrasonic
a
considerable
therapy
possesses
number
over
of
the
advantages
various
that
forms
conventional thermotherapy, the electromagnetic energies.
-
advantages often provide
rationale necessary to
the clinician with
decide upon the
of
These
the confidence
most efficient
and
modality
for patient care.
Perhaps
the
property inherent to ultrasonic energy that is
.ost often considered
other forms of
depth of
when choosing to
electromagnetic energy
penetration.
approximately 50t of
With an
is ultrasound-s
the ultrasonic energy
penetration is desired,
the clinician
frequency
when
12
•
over
superior
ultrasonic frequency
depth of 5 cm within the soft tissues.
lower ultrasonic
utilize ultrasound
of 1
will penetrate to
When an even
15
may decide
50t
a
deeper
upon using
considering that
Mc,
of
a
the
energy of 90 kc ultrasound will, within the soft tissues, reach a
-
depth of 10 cm. 1 5
These energy penetration values become
significant
one
when
electromagnetic energy
recalls
only
that
the
penetrate to
- 7 -
various
a
depth of
rather
forms
of
1-2
cm,
-.
causing a
more
superficial
tissue
achieved with ultrasound. 15
the deeper lying
temperature
rise
than
is
When the clinician desires to affect
tissues of the
body, ultrasound often
becomes
the physical agent of choice.
Another characteristic inherent to ultrasonic energy is that
the least
amount
tissues which
of
are
ultrasonic energy
the
most
is
absorbed
homogenous. 15
The
in
those
most
nearly
homogenous tissue in the human body is subcutaneous fat; thus, an
insignificant amount
tissue.
of ultrasonic
This property
transmitted through the
the underlying
target
energy is
of ultrasound
allows the
subcutaneous fat
tissues.
absorbed by
When
this
energy to
and efficiently
the
various
reach
forms
electromagnetic energy are utilized, a significant amount of
-
be
of
the
energy is absorbed by the sUbcutaneous fat, causing excessive fat
temperature rise
transmitted to
and preventing
the
the
energy to
underlying tissues.
be
efficiently
Thus, when
a
deeper
tissue temperature rise is achieved by electromagnetic energy, it
is primarily caused
by the reaction
of cutaneous nerves
secondary conduction, making the heating of deeper lying
and/or
tissues
fairly inefficient with electromagnetic energy.
An often cited disadvantage of electromagnetic energy in the
form of
short wave
or microwave
energy is
that of
"hot-spot"
formation and SUbsequent risk of tissue damage to adjacent tissue
in the presence of
metal implants.15
Since metal implants
more homogenous than the surrounding tissues, the metal
reflects
the
ultrasonic
energy
.-
-
8 --
instead
of
are
actually
absorbing
or
concentrating the
energy.17
In
this
manner,
abnormal
heat
buildup is avoided with the use of ultrasonic energy.
Another significant advantage of ultrasound over the various
forms of electromagnetic energy is that of providing pain
via mechanisms other
relief
than through a
tissue temperature rise
or
thermal effect of ultrasonic energy.
The non-thermal effects
of
ultrasound provide the clinician with a tool to combat a
of pathologies
not
significantly affected
forms of electromagnetic
In
the
by
the
variety
traditional
energy.3.1a.21.22.2~
past, a variety of means have been employed to heat
localized tissue volumes
treatment of
to uniform levels
radio-frequency
inductive heating.
With these forms of heating,
inhomogeneities
(fat distribution,
bone,
the
nonuniform
electrical
heat
Alternatively,
heating.
usually,
or
acoustic
and
types
which
substantially
compromised
energy
Ultrasonic energy
foci has enabled the
tissue
field
patterns
microwave
hyperthermic
or
disrupt
cancer
in the
provides
differ)
with
subsequent
clinical
efficacy.
reasonably
focusing into
spot or
production of highly homogenous,
thermal patterns in regularly shaped tumors.
uniform
distributed
non-toxic
Since overall tumor
response {size reduction, growth delay> has been found to
on
thermal
homogeneity,
simple, inexpensive
shaped
means
of
focus
can
ultrasound
configuring a
thermal
depend
provides
a
field
to
distribute heat optimally.16
A
study
has
ultrasonic energy
been
conducted
versus
various
subsequently establish
the most
to
types
evaluate
of
effective and
- 9 -
the effects of
thermotherapy
the least
and
time-
consu.ing mode
of treatment
for
recent soft
tissue
injuries.
This study revealed therapeutic superiority of ultrasound on soft
tissue injuries
over
the conventional
forms
of
thermotherapy
including short-wave diathermy,
infrared, and paraffin
Ultrasound also
added advantage
tolerated by
which
156
possesses
a majority
individual
the
of patients.
ultrasonic
In
of
baths. 19
being
well
an investigation
treatment
sessions
performed, there were no cutaneous burns, reports of
in
were
substantial
discomfort, or indications of systemic symptoms. 2D
CLINICAL ULTRASONIC FREQUENCIES
When
considering
the
significance
of
the
variety
of
ultrasonic frequencies, it is imperative that one is aware of the
inverse frequency-energy
penetration ratio
which
predominates.
The governing of this ratio is such that the lower the ultrasonic
frequency, the less energy that is absorbed per volume of tissue;
thus, the depth of penetration is greater. 2D
As the
clinician-s
objective becomes that of directly affecting those tissues
which
lie progressively deeper to the superficial layer of tissues, the
lower the frequency of ultrasound is chosen.
In an investigation involving 107 patients with the clinical
diagnosis of
osteoarthritis
vertebrae treated
significantly
of
with either
greater
number
the
knee,
89
kc or
of
patients
1
hip,
shoulder,
"c ultrasound;
receiving
the
or
a
low
frequency had longer-lasting relief from pain than those patients
receiving the
-
1 Mc
ultrasound
result has been attributed
treatments.1~
This
significant
to the aforementioned superior
- 10 -
depth
of
penetration
of
ultrasonic
energy
inherent
to
the
lower
frequency ultrasound, making the absorption of ultrasonic energy
by
sensory
Of
and
all
motor
the
ultrasonic
approximately 90t
are 1
reason for the great
possessing
this
nerves
in
greater
generators
Me in
in
frequency.
quantities
clinical
Theoretically,
majority of clinical ultrasonic
frequency
is
compromise between those which
that
a
use,
1
Mc
the
generators
generator
produce thermal effects
is
a
(thought
to be generators that are 2 Mc and higher in frequency> and those
which produce non-thermal effects (thought to be generators
are 500 ke or lower
,-
must not only
in frequency>.15
take into
The clinician,
consideration the depth
that
therefore,
of the
target
tissue, but also whether predominately the thermal or non-thermal
properties will significantly affect the pathology
b~ing
treated.
CONTINUOUS VERSUS PULSED ULTRASOUND
Ultrasonic
generators
are
continuous or pulsed form of
form of ultrasound
penetration
and
effects. 1 ,12
of delivering either a
ultrasonic energy.
is capable
is
capable
utilized
of achieving a
more
for
its
The
continuous
greater depth
heating/thermal
Conversely, the pulsed form of ultrasound is
beneficial for
producing the
those achieved
by
physiological effects
heating the
target
of
often
other
than
the
added
tissues with
ability of using higher peak intensities with less risk of tissue
damage, especially between the periosteum/bone
-
The
pulsed
adhesions,
variety
increasing
of
ultrasound
the
healing
- 11 -
is
rate
interface. 1 ,12,17
effective
in
in
tissue
reducing
which
is
positioned directly
over
superficial
especially specific, small treatment
bones,
and
in
areas, or those
treating
conditions
in which pathologically overheating the target tissues may become
a reality.17
SUGGESTED ULTRASOUND INTENSITY AND DOSAGE LEVELS
When
selecting
clinician must
ultrasound dosage and intensity levels, the
physiologic
and
therapeutic responses rather than merely arbitrarily setting
the
generator-s
contemplate
intensity
the
desired
According
dial.
principle. a subthreshold
-
both
quantity of
to
the
Arnt-Schultz
energy will
not cause
demonstrable physiological change;
application of threshold
above energy
absorbing
will
stimulate
the
tissue
to
a
and
normal
function; and finally, the application of a supramaximal quantity
of energy will destroy
the absorbing tissue
functioning normally.B
Although
or prevent it
this principle is quite
there is presently disagreement as to the level of
from
valid,
subthreshold,
threshold, and supramaximal quantities of energy for anyone cell
or tissue; yet careless treatment into the supramaximal range can
obviously be dangerous.
In
1982,
recom.ended the
the
Burdick
following
Corporation
guide for
of
Milton,
selecting
Wisconsin
intensities
of
ultrasound: 0.5-1.0 w/cm2 for direct application of ultrasound to
an acute injury
near the skin-s
surface and add
0.5 w/cm2
,----'-----
e~~~<!~ti~~ ___~ rom th~~ __metho~ an~/or __ i'0 ury. !-~pe,
that
-
whatever
method
is
ultimately determines the
Burdick Corporation
used
the
patient-s
ultrasound-s intensity
attempted to
- 12 -
clarify their
for
----
reali zing
comfort
level. 17
level
The
recommendations
with these treatment examples: 1.0-1.5 w/cm 2 would be required to
treat an acute injury
near the skin-s
application technique
and 2.0-2.5
treat a chronic injury deep
application technique.
placed upon
of the
actually reaching the patient and
dosage
levels
-
sound head-s
energy
be
output
the amount of energy which
agent -- values
of
ultrasonic
is
which
however,
may
have
healing, nerve conduction, and
cell
permeability even within the
When
to
indirect
Investigations have shown,
different effects on tissue
0.2-3.0 w/cm 2 . B
be necessary
vital importance has to
across the coupling
are not widely agreed upon.
that different
indirect
within the tissue using an
the proportion
lost in transmission
w/cm2 would
Obviously,
17
surface with an
energy
narrow clinical intensity range
determining the most effective
ultrasound
treatment, the clinician should consider the following: depth
target tissue, type of tissue
interposed between the sound
and target tissue, frequency of
non-thermal
sensation. B
energy, type
effects
of
desired,
Instead of
,15,17
intensity for any given
coupling agent,
and
most
applying
thermal
gentle
sensation
of
ultrasound at
treatment, regardless of
intensity scale. s
the reading on
,15
- 13 -
with
each
type
patient
a
patient and/or pathology, the
warmth/tingling
of
and/or
importantly,
fixed
clinician
should select an intensity of ultrasound which gives the
a
of
head
the apparatus, brand and age
apparatus, size of treatment area, continuous versus pulsed
of ultrasonic
of
patient
ultrasound
the apparatus-s
output
IMPORTANCE OF CALIBRATION OF ULTRASONIC GENERATORS
There has been found to be wide disparity of actual acoustic
output among
to
the
length of time since the apparatus-s most recent calibration
and
the amount
clinical ultrasound
of
use/abuse
apparatuses secondary
the apparatus
has
undergone.
This
information becomes rather significant when considering that some
clinicians may
guage
a
patient-s treatment
intensity output scale instead
intensity
of using the patient-s
by
the
sensation
as a guide when treating a patient with diminished sensory input.
Generally.
the
intensity
output
indicated
on
an
ultrasound
apparatus is considered to be unreliable when it has failed to be
calibrated within the last
there
is
standardized
electric> power output
six
enforced
and
Until such time
months.~5
measurement of
acoustic
that
(rather
than
ultrasound generators,
gentle sensation of warmth is perhaps the clinician-s best
of intensity.
This procedure, of course, brings up the
concerning the
patient with
system and/or an
a deficit
in the
emotional disturbance.
a
gUide
question
sensory
nervous
Significant damage
unlikely to occur if the intensity used on the trunk or
is
proximal
extremity does not exceed 1.5 w/cm2 and distal extremity does not
exceed 0.5 w/cm2, assuming
for a period of 5 minutes
an area of 150
cm2 is being
treated
with a steadily moving sound head
and
the apparatus has been calibrated within the last six months.15
An
investigation
surveying
the
use
and
performance
of
ultrasonic therapy equipment in Pinellas County, Florida revealed
that, in general, the ultrasonic therapy units in use were out of
calibration, with
a
majority
of
- 14 -
the
units
appearing
to
be
incapable of delivering a prescribed amount of ultrasonic
to the patient. 2 3
The
lack of calibration of equipment
energy
capable
of measuring acoustic output was listed as one of twenty-four
of
the more significant medical equipment problems in the "Study
of
the Dimensions and Problems Associated with Equipment Malfunction
and Accidents in Hospitals" conducted for the California Hospital
Association -- a complaint which was also the most com.on
by the
users of
illustrate the
the
apparatus. 2 3
necessity for
accurate means with which to
These findings
both frequent
voiced
once
again
calibration and
an
measure the acoustic output of
the
ultrasound apparatus.
COUPLING AGENTS AND THEIR SIGNIFICANCE
When
ultrasound
coupling medium in
ointment,
or
overlying
the
cream
is
given
the form
must
designated
to
a
patient,
of a liquid
be
applied
treatment
some
type
or semi-solid
to
the
area.
lotion,
patient-s
This
of
skin
procedure
minimizes the amount of air trapped in the pores of the skin when
the sound head
is applied,
allowing for a
transmission of the ultrasonic
of using a coupling
energy.15
agent is the
much more
efficient
An additional
benefit
reduction of friction
between
the surface of the sound head and the patient-s skin.
There
is disparity as to which ultrasound coupling agent is
the most efficient in transmitting energy from the transducer
the patient.
In an investigation conducted by Reid and
dealing with
the transmissivity
measured
near
by
field
of various
measurement
(commercial thixotropic agent),
transmitting a
- 15 -
Cummings
coupling agents
technics,
aquasonic
mean of
to
as
gel
72.60\,
was discovered to be the most efficient energy transmitting agent
when using an 870 kc/s ultrasound generator with continuous
transmission. 7 . s
Glycerol
substitute for the
aquasonic gel; whereas
was
found
to
be
an
wave
acceptable
water, ECG
couplant,
and liquid paraffin were next in order of decreasing transmission
efficiency.7.s
Interestingly
enough, the
liquid
paraffin,
a
commonly used coupling medium, transmitted as little as 19.06% of
the ultrasonic energy.s
Therefore, this investigation
revealed
that the choice of coupling agent may significantly influence the
effective therapeutic dosage
of ultrasonic
energy available
to
the patient.
Transmissivity
through various coupling agents was measured
in an investigation designed by
Warren and his colleagues
far field measurement techniques through a thin film of
and then a large volume of degassed water.
be 75-100% as efficient
was as
Thus,
efficient as,
Warren-s
as the degassed
or
more so,
investigation
couplant
Glycerol was found to
water, and mineral
than the
leads
using
the
degassed
clinician
oil
water.15
to
the
reasonable conclusion that when choosing a coupling agent for use
with the direct contact technique,
the minor differences in
the
coupling agents- transmissivity is not a major concern.
When using the direct contact technique, and especially when
using the stationary technique, the clinician should keep in mind
that the ultrasound transducer becomes warm, liquifying
gels and emulsions in the
of body segments which are
process.
Also, the skin
located more proximal are
coupling
temperatures
relatively
high in comparison to distal segments; and liquification of
- 16 -
gels
and emulsions is more probable.
it may drain off the
When a coupling agent liquifies,
treatment area, providing for a
non-uniform transmission of
ultrasonic energy.15
relatively
Therefore,
a
more viscous coupling medium must be used in those instances when
liquification may adversely affect
the uniformity of
ultrasound
transmission.
The
most
effective
technique seems to
capable
of
couplant
be ordinary
transmitting
for
use
with the immersion
tap water, a
ultrasound
presence of massive bubble formation.
couplant which
efficiently
~ater~s
even
is
in
the
acoustic impedance
is fairly close to that of the soft tissue in the body, and
when
preheated can aid the clinician in achieving both maximal thermal
and non-thermal effects with the ultrasonic energy.15
PHONOPHORESIS AND ITS INDICATIONS
Phonophoresis
medication
patient~s
are
is
driven
a
process by which whole molecules of
away
from
skin, and into the
of exposure to
the
This
to radiation pressure
transmission of high frequency
containing a specific
through
target tissue structures by
ultrasonic energy.12
force is secondary
transducer,
movement or
medication and into
Phonophoresis is capable of driving
the target
driving
ultrasonic
frequencies).
tissue. 15
medications to the depth
A
five
minute
the
couplant
ultrasonic energy penetration (up to 5 cm for 1 Mc and 10 cm
90 kc
a
virtue
changes caused by
sound waves through the
a
of
for
phonophoretic
treatment appears adequate to drive enough medication to
provide
substantial pain relief if the treatment area is not greater than
150 cm 2
•
15
- 17 -
hydrocortisone
medication
used
inflammatory
in
treatment
phonophoretic
15
effects.12.
Other
for
the
is
cream
anti~
its
medications
with
used
phonophoresis include: 10% hydrocortisone with xylocaine ointment
{for anesthetic}, Myoflex
dexamethosone
and
lidocaine
2%
ultrasonic energy to
Cream (aspirin), or
gel. 12 . 15
a combination
of
The
of
ability
transiently increase membrane
may be the reason for the
pain relief exhibited by the
anti~inflallmatory,
since diffusion of an
permeability
patient,
analgesic, or anesthetic
agent is enhanced by the external application of ultrasound. 15
SOlie
indications
treatment include the
for
the
application
following: postacute
of
phonophoretic
soft tissue
trauma,
tendonitis, muscle strains, contusions, and as an alternative
injective therapy.12
The
clinician
contraindications to the medications
should also
consider
used for the
to
any
phonophoresis
and to ultrasound itself prior to applying the treatment.
GENERAL PHYSIOLOGICAL EFFECTS OF ULTRASOUND
When
exposing
an
osteoarthritic
lesion to clinical ultrasonic
may act to
joint or a periarticular
energy, the physiological
block pain transmission
by vibration or
tissue temperature or by a combination of the twO.
the physiological
effects observed
when
14
tissue is
effects
by rise
in
Generally,
exposed
to
therapeutic levels of ultrasonic energy are considered to include
the following: increased blood
enhanced
-
tissue
and lymph flow rates,
metabolism,
greater
connective
extensibility, relaxation of skeletal muscle, elevated
activity,
increased
cellular
~
transmembrane
18
~
hyperemia,
tissue
enzYllatic
permeability,
•
and
diminution
of
peripheral
nerve
conduction
velocity
(with
ultrasound intensity between 0.5-1.5 w/cm2) which may produce
effect.5.13.15.17.26
~nalgesic
stimulate inhibition of
of
adhesions
hemato.as. 17
and
with
ultrasound
nonbacterial inflammation,
calcific
deposits,
and
may
reabsorption
breaking
up
of
Ultrasound is also the logical modality choice when
the clinician desires
bursa,
Additionally,
an
the
to increase
mechanical
the perfusion
action
of
the
of a
calcific
ultrasonic
waves
affecting the bursal sac. 13
EFFECTS OF ULTRASOUND ON MUSCLE BLOOD FLOW
Most
of
the
measurements
to
determine
the
ultrasound on muscle blood flow have be done via
techniques.
This technique gives
effects
of
plethysmography
rise to two major errors:
(1)
plethysmography fails to differentiate between the blood flow
in
the various tissue compartments of skin, adipose tissue,
muscle,
and bone;
over
and (2)
large volume
plethysmography measures
instead of
the well
ultrasound is applied
of change in total
blood flow
defined region
to which
a
the
in the process allowing the small degree
limb blood flow to
mask the large change
in
the small volume of tissue which is actually being sonated. 26
In
an
investigation conducted by Wyper and his colleagues,
the technique of xenon-133 washout was used to measure the
blood flow in the vastus
between
the
ages
of
lateralis muscle of 7 adult
21
therapeutic ultrasound. 26
and
45
during
the
local
volunteers
application
of
The implication of their investigation
was that most of the ultrasonic energy had been dissipated in the
tissue other than muscle,
perhaps at the muscle-bone
- 19 -
interface.
Thus,
the
investigators
determined
inefficient means of enhancing
ultrasound
as
a
muscle blood flow, with
rather
exercise
and microwave energy being more efficient alternatives. 2 6
DIRECT EFFECTS OF ULTRASOUND ON "USCLE TORQUE
Although
there
have been numerous investigations conducted
illuminating the physiological
effects of
ultrasound, few
focused on the direct
effects on the muscle
colleagues
research
performed
to
itself.
determine
the
have
Black
and
effect
of
continuous ultrasound to the anterior tibialis muscle compartment
on ankle dorsiflexion
torque assessed
and 60 minutes after treatment.
that
,-
despite
the
known
immediately, 30
minutes,
The conclusion of this study was
physiologic
effects
of
clinical
ultrasound, merely one treatment of ultrasound, when used
exercise, does
not
alter
torque during a volitional
peak maximal
activity.
1
isometric
or
before
isotonic
Further investigation
is
essential in this particular area to determine whether or not the
peak isotonic or isometric torques are affected significantly
a series of therapeutic ultrasound treatments rather than
by
merely
one.
TISSUE REPAIR VIA ULTRASOUND
In
the
continuing attempt to discover which aspects of the
tissue repair process are
affected by ultrasound,
have been
cells
examining
the
which
are
investigators
essential
for
the
production of healthy granulation/scar tissue -- the fibroblasts.
-
The following changes occuring
have
been
observed:
(I)
during the tissue repair
stimulation
- 20 -
of
protein
process
synthesis;
(2)
ultrastructural
changes
including
plasma
alteration, vacuolation, and dilation of the granular endoplasmic
reticulum;
{4}
(3)
decrease
modification
of
in
loco.otor
electrophoretic
behavior;
and
mobility;
(5)
temporary
elevation of intracellular calcium ion concentration. 10
Evidence
illustrates that the stimulation of protein synthesis induced
ultrasound
is
associated
permeability.11
The
with
an
significance of
lysosomes contain hydrolytic enzymes
secondary to
the
increase
increased
in
this finding
lysosomal
is that
whose activity is
permeability
of
their
the
enhanced
membranes.
This, in turn, may stimulate protein synthesis, an integral
of the tissue repair process,
by
by increasing the availability
part
of
precursor substances within the cells. 1 o , 1 1
TISSUE DAMAGE VIA ULTRASOUND
Pain
has
been
individual makes
described
to a
as the total set of responses an
stimulus
cause, tissue damage. 1 4
by that noxious stimUlus.
Tissue
which causes,
or is
about
damage is the response
to
prompted
When pieces of skin which were exposed
to ultrasound for a total time duration of 14 hours over a period
of 7.5 months were exa.ined, the investigators found that excised
skin samples
exhibited a
minor chronic-infla.matory
irritation
which included: increased keratosis, augmented pigmentation,
minor loosening
tissue. 2 5
of
the cutaneous
Twenty-five
exceeded all
years
therapeutic and
completed,
a
follow-up
enough, no
significant
and
after
subcutaneous
this
study
was
performed.
histological traits
- 21 -
connective
investigation
diagnostic ultrasound
or
and
limits
that
was
Interestingly
anomalies
were
discovered.
Therefore,
residual
effects
of
conscientiously
applied ultrasound treatments are most likely to be negligible.
CLINICAL CONDITIONS IN WHICH ULTRASOUND IS USED
Periarticular Pathologies:
Clinical
of
ultrasonic
periarticular
pathologies
arthritis, sprains,
Clinicians base
skeletal
and
the
increased
on
various
•
13
the promotion
30
years.
these
musculo-
physiological
effects
and
of
tissue
tissue extensibility,
relaxation. 9
bursitis,
approximately
energy: augmentation
threshold, and the alteration
effects may be
tendonitis,
modality for
permeability
enhancement of fibrous
to muscle
as
for
this
the
ultrasonic
capillary
such
strains
use of
pathologies
attributed to
energy has been used for the treatment
blood
metabolism,
elevation of
of neuromuscular activity
The results
of these
of healing,
flow,
pain
leading
physiological
diminution of
muscle
spasm and pain, and range of motion facilitation.9
In a
contolled,
Downing and
randomized double-blind trial performed by
Weinstein,
tendonitis, subacromial
patients
suffering
bursitis,
from
or adhesive
supraspinatus
capsulitis
were
studied to determine whether or not the application of ultrasound
diminishes pain and
increases range of
motion further than
usual program of range of motion exercises or the combination
range of
motion
exercises and
drugs. 9
This pilot
non-steroidal
study determined
significant further benefit over
-
exercises
or
the
treatment
anti-inflammatory drugs
adds
treatment with range of
and range
- 22 -
of
of
anti-inflam.atory
that ultrasound
combination
the
of
no
motion
non-steroidal
motion exercises. 9
The
-
clinician should be
aware that
this investigation
was a
pilot
study and additional clinical trials to determine the efficacy of
ultrasound is
warranted
prior
to
disposing
ultrasound
as
a
treatment modality with these pathologies.
There
continues
to
be
suffering from some form of
apparent calcium
tissue.
small
percentage
of
upon or
been found to be
patient-s pain,
yet the
within the
the
periarticular
relaxation of the
-
pathologies
exact mechanism
area skeletal muscle
could
be
of
through
Pain
relief
secondary
to
and/or the apparent
net
result of resorption of the abnormal calcium deposition
affected tissue.
an
irritated
an effective means
which the pain is relieved has not been determined.
from
patients
periarticular pathology who have
salt deposition
Ultrasound has
relieving the
a
from the
15
Burns:
The
formation of scar contractures in extensive, deep burns
is unavoidable, so
much so
that the
transplanted tissue
scars and contracts from 30-40% in dimension. 21
applied to
connective
number of new
tissue,
cellular forms and
Ultrasound, when
stimulating
effect:
the
nuclei increases, the
fibrous
structures change morphologically with a predominance of
elastic
fibers,
traumatized
placement of the newly
of the
coarse
scar)
nerve
is
reinnervated,
and
is
facilitated. 2 1
Tissue
proper
the
formed collagenous fibers (the
therefore, become elastic and
-
has a
forms
precursor
transplants,
mobile by ultrasound-s ability
to
improve nutrition, increase metabolism, accelerate reinnervation,
and
strengthen
the
regenerative
- 23 -
processes
in
general.
In
addition to the aforementioned effects on the tissue
transplant,
the use of ultrasonic energy in the treatment of burns may result
in:
(I)
loosening
{2} stimulating
supple scar,
exercise. 3
and
removing
growth of
and {3}
the
necrotic
granulation
permitting the
These effects allow the
tissue
tissue and
early use
crust,
obtaining
of
a
therapeutic
burn patient to return to
a
more normal lifestyle as early as possible.
When
choosing an agent with which to treat burn wounds, the
clinician must strive
safe debridement of
proliferation,
staining the
toward a relatively
eschar without
altering
the
tissue. 2 2
modality to use.
The
painless, rapid,
interfering with
patient-s
body
Ultrasound just
apparent cleaning
epithelial
metabolism,
may be
and
the
effects of
or
treatment
ultrasound
result from the cavitation phenomena at the interface between the
liquid coupling
agent
and
the
tissue
to
be
cleaned.
The
cavitation action actually draws particles of contamination
from the relatively stiff tissue surface. 2 2
acts to
debride
the
burn
wound,
microorganisms from the wound area
away
Thus, the ultrasound
removing
sepsis-
in the process.
causing
Addition
of
electrolyte or a chemical agent in the liquid coupling medium may
further enhance the effect of the ultrasonic action. 2 2
Dermis Disorders:
Psoriasis,
a benign
hyperproliferative
effectively regressed by ultrasonic
42-4SDC range. 2 0
An
investigation
colleagues, while illustrating
regressed via ultrasound, failed
disease,
induced hyperthermia in
performed by
that the
Orenberg
psoriatic lesions
to make a definitive
- 24 -
has been
the
and
were
statement
about the length
of remission
induced. 2 0
The
response of
the
psoriatic lesions seems to be temporary, with the clearing of the
lesion being limited to the
that the earliest
field of treatment.
and most consistent
Orenberg
noted
change histologically
the psoriatic lesions was one of tissue repair, the
in
reappearance
or enhancement of the granular layer. 2D
Ultrasound
of
has also been successfully used in the treatment
characterized by
single
lesions,
or
occurring
board-like,
in
the
legs
painful,
tender,
sharply
bordered
indurated,
of
patients
with
HS is often either undiagnosed, or
insufficiency.~
cellulitis, or
other clinical
entities,
stasis dermatitis.
HS responds
disease
skin
a
well-circumscribed, chronic,
multiple,
as phlebitis,
(HS),
sclerodermiformis
hypodermitis
venous
misdiagnosed
Unlike
favorably
to
these
ultrasound
treatments.
DupuJ[tren-s Contracture:
Dupuytren-s
contracture is characterized by the dimpling of
skin on the medial border of
the
underlying
circulation with
skin.1B
An
the hand as it becomes adherent
fascia,
causing
alteration
atrophy
and cicatrization
investigation performed by
that the appearance
and dimples tended
improvement in
of the contractured
to become
circulation
of
natural color distribution in the
hand
the
the
local
underlying
Markham and Wood
hand improved,
less noticeable,
of the
in
to
and the
brought about
skin of the palm.1B
showed
nodules
general
a
more
Clinical
ultrasound acts to soften the skin overlying the contracted bands
of
fascia
and
subsequently
diminishes
- 25 -
the
severity
of
the
deformity -- thus, the surgery
following becomes easier and
the
improvement in local circulation leads to enhanced wound healing.
After
the
clinical
surgical
wounds
ultrasound
have
reduces
healed,
the
hypertrophic
application
scarring
and,
of
when
combined with gentle active and passive movement, accelerates the
post-surgical recovery.
Plantar Warts:
The
plantar
wart,
verruca
characterized by a thickening of
epithelium
with
a
probable
research determined
the
plantaris,
is a dermal lesion
the outer cornifying layers
viral
etiology.15.24
direct method
to
,-
plantar warts
were destroyed
25 of
in
Vaughn-s
be superior
underwater method in the treatment of plantar warts.
the 30
to
the
All of
the
patients
treated by the direct method, whereas only 21 of the 41
(SIt)
treated
by
the
underwater
lesion. 24
resolution of the dermal
either form remains
tendernes~i
method
of the affected area
(83t)
patients
experienced
total
Nevertheless, ultrasound
a viable treatment
of
modality, with pain
in
and
being diminished in addition
to
the lesion being abolished in a majority of the cases.
Fracture Healing:
Fibular fracture repair has been shown to be accelerated and
modified through the treatment of ultrasound.
Brookes and
Dyson
found ultrasound treatment to be most effective when given during
the first
-
two
weeks
inflammatory and early
the
fracture
sites
after
injury.
During
proliferative phases
are
being
-
26 .-
cleared
this
occur.
of
debris,
time,
the
Therefore,
factors
stimulating repair
are being
released, and
cell migration
division are most active, leading to the formation of a
and soft callus which unite the bone fragaents. 2
stimulated by the ultrasound
tends to be
and
blastema
The bone repair
of the juvenile
type,
involving direct ossification with little production of cartilage
when the ultrasound treatment is confined to the first two
after injury.
When the
ultrasound treatment is confined to
the
growth may be accelerated
and
third and fourth weeks, cartilage
bony
union
weeks
delayed. 2
and
Brookes
Dyson
also
determined
ultrasound treatment at 1.5 MHz to be more effective than at
3.0
"Hz, postulating that since thermal effects tend to be greater at
higher frequencies and all other
.-
decrease
in
effectiveness
at
factors are kept constant,
higher
frequencies
the
suggests
non-thermal involvement in the stimulation of fracture repair. 2
-
27 -
a
INDICATIONS AND CONTRAINDICATIONS FOR ULTRASONIC THERAPY
Indications for the Clinical Use of Ultrasound:
o Strained and Torn Liga.ents
o Inflamed Tendons and Tendon Sheaths
o Lacerations and Other Soft Tissue Damage
o Hypertrophic Scar Tissue Sensitivity and Tension
o Varicose Ulcers
o Amputation Neuromata
o Strained and Torn "uscles
o Inflamed and Damaged Joint Capsules
o Fasciitis
o Treatment
Soreness
(Applicable
after
Mobilization
Techniques)
o Chronic Arthritis
o Plantar Warts
o Pressure Sores
o Chronic Systemic Peripheral Arterial Diseases
o Organized Hematoma
o Fracture Healing (within the first two weeks after injury)
o Dermis Disorders
Contraindications for the Clinical Use of Ultrasound:
o Whenever Tissue Temperature Rise Hinders Normal Function
o Thoracic Area of Pacemaker Patient
o Area of Malignancy
o Area Overlying Epiphyseal Centers
o Healing Fractures (after the first two weeks after injury)
o Local Sonation Over Thrombophlebitis or Plebothro.bosis
- 28 -
-
The Clinical
E~~icacy
of Ultrasound
Bibliography
.-
-
1.
Black, K. D. et al.: Alterations in Ankle Dorsiflexion
Torque as a Result of Continuous Ultrasound to the
Anterior Tibial Compartment.
Physical Therapy, 64:
910-913, 1984.
2.
Brookes, M. and Dyson, M.:
Stimulation of Bone Repair by
Ultrasound.
Ultrasound, 61-66, 1982.
3.
Bulcke, L. and Faure, J.: Ultrasonic Treatment of Burns.
J. BeIge de Rhuematologie et de Medicine Physique, 20:
239--248, 1965.
4.
Cantwell and Rowe: Hypodermitis Sclerodermiformis:
Successful Treatment with Ultrasound. Arch. Dermatol.,
118: 312-314, 1982.
------
5.
Coakley, W. T.:
Biophysical Effects of Ultrasound at
Therapeutic Intensities.
Physiotherapy, 64:
166, 1978.
6.
Cosentino, A. B. et al.:
Ultrasound Effects on
Electroneuromyo- graphic Measures in Sensory Fibers of
the Median Nerve.
Physical Therapy, 63:
1788-1792,
1983.--
7.
Cummings, G. E. and Reid, D. C.:
Efficiency of Ultrasound
Coupling Agents.
Physiotherapy, 63:
255-257, 1977.
8.
Cummings, G. E. and Reid, D. C.:
Factors in Selecting the
Dosage of Ultrasound: With Particular Reference to the
Use of Various Coupling Agents.
Physiotherapy Canada,
1973.
9.
Downing, D. S. and Weinstein, A.:
Ultrasound Therapy of
Subacromial Bursitis: A Double Blind Trial.
Physical
Therapy, 66: 194-199, 1986.
10.
Dyson, M.:
Non-Thermal Cellular Effects of Ultrasound.
British Journal of Cancer, 45: 165-171, 1982.
11.
Dyson, M. and Suckling, J.:
Stimulation of Tissue Repair by
Ultrasound:
A Survey of Mechanisms Involved.
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