FOCUSED
EXTRACORPOREAL SHOCKWAVE THERAPY
( ESWT )
QUESTIONS AND
ANSWERS
What
is ESWT?
ESWT, a new, non-invasive technology, has become a popular treatment agent/tool for equine musculoskeletal problems. Results include accelerated healing, improved healing, and lessening of pain. A shock wave is a high pressure ( acoustic ) wave with very high amplitude, rapid rise time, and short pulse duration. These waves are generated outside the body ( extracorporeal ) and can be focused at a specific site within the body.
What
is the origin of ESWT?
Veterinarians have taken existing science in human beings and applied it to horses and dogs. This type of therapy was originally used to treat human beings with kidney stones, by breaking up the stones without the need for invasive surgery. This technique has been around for years now, and in the process of treating patients this way, it was discovered that many of them had other unrelated aches and pains disappear.
What
type of shock waves exist and how are they generated?
Currently,
there exists three different variations of shockwave therapy technology based on
the manner in which the machine generates the therapeutic shockwaves.
-
Piezoelectric:
an electric pulse causes
expansion of piezoelectric crystals
-
Electrohydraulic:
vaporization of fluid across a spark gap
-
Electromagnetic:
pushing a membrane with opposite electric current
(Radial
shockwave therapy, sometimes included, differs from the above listed forms
in that it delivers the shock wave directly to the injured tissue.
Because of this, the energy wave produced is different.
The wave diminishes as it travels to the affected tissue and affects
all nearby and uninjured tissues; therefore, RSWT is usually not classified
as extracorporeal shockwave therapy.)
Why
choose the focused electrohydraulic form of shock wave therapy?
The
electrohydraulic system described in 1962 was employed with the first generation
of shockwave machines. This principle involves the passing of an electrical
current through a coil, which produces a strong magnetic field. The subsequent
compression of the fluid creates a shockwave.
Why
is it important that shock waves are “focused”?
The
tighter the focus area, the more precisely the shock waves can be delivered to
specific tissues. This means a
greater concentration of therapeutic energy on the specific injured tissue as
well as less trauma to the surrounding tissues.
How
does ESWT work?
When the
shock waves meet tissues of different densities, the energy contained in the
shock waves is released and interacts with the tissue.
-
the shock wave exerts mechanical
pressure and tension force on the afflicted tissue.
As a result, both localized circulation and metabolism are increased in
the treated tissue which promotes healing.
-
secondary waves are created which
break down pathological deposits of calcification in the soft tissues.
-
the shock wave appears to
stimulate osteoblast cells which are responsible for bone healing and new bone
production.
-
shock waves cause a decrease in
pain perception
However,
the exact mechanisms of action of shock waves on bone or soft tissues are not
known and the effects are influenced by the pressure, energy flow, and pulse
frequency.
What
conditions benefit from shock wave therapy?
The
single largest cause of decreased performance in show and pleasure horses is
lameness originating from the musculoskeletal system. The most widespread use of
ESWT has been for proximal suspensory desmitis (PSD). Currently, the use of ESWT
is used primarily on horses that have not responded to other therapies or have
injuries that typically heal slow or inconsistently.
-
suspensory ligament injury (PSD)
-
tissue calcification
-
back/neck pain
-
navicular disease
-
fractures or joint ankyloses
-
fatigue injury to bone
-
bucked shins
-
bone spavin
Before
shock wave therapy can be used, a patient needs a thorough examination to
determine the specific affected area. Examination
usually includes a general physical examination, a lameness (orthopedic)
examination, and radiography. It may
also be necessary to perform an ultrasound examination or to perform nerve
blocks. Shock wave therapy appears to be an exciting and extremely advantageous
tool in the arsenal of lameness treatment methods.
What
is the treatment protocol?
The area
to be treated is clipped and thoroughly cleaned, and a gel is applied to ensure
good transmission of the energy waves. The
treatment requires sedation and during treatment
a local analgesic effect may be induced. As
a result, horses usually tolerate the procedure well.
The exact treatment protocol is customized to each horse and specific
diagnosis. Some problems need only a
single treatment, while others may require 3 to 5 treatment sessions at
intervals ranging from
What
are the advantages of using ESWT as a therapeutic modality?
-
non-invasive and surrounding
tissues are unaffected by the shock waves
-
accelerated healing
-
improved healing
-
positive results in previously
non-responsive conditions, injuries that usually are slow to heal, and injuries
that heal
inconsistently
-
attenuation of pain
-
minimal aftercare, discomfort, and
recovery time
-
no drug residues
What
are the disadvantages of using ESWT as a therapeutic modality?
-
horses may be slightly sore after
treatment
-
analgesic (decreased pain) period
following treatment so horses should not be subjected to strenuous activities
for at least 4 days after ESWT where local analgesia might pre-dispose the horse
to injury
Because
of this multiple racing jurisdictions have instituted or are
considering regulations concerning when a horse can compete after being
-
initial treatment cost
Dr.
Lyda W. Denney 12-‘07
Dr.
Lyda W. Denney
12-‘07