Update On Extracorporeal Shockwave Therapy
Extracorporeal shockwave therapy is now common in most clinics today.
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When extracorporeal shockwave therapy appeared on the equine scene in 1998, it was found only in specialty clinics. Today, the device's use has become more widespread, and funding has been poured into studies proving ESWT has merit. But in 1998 practitioners had none of this knowledge and results were largely anecdotal.
"As with most things new, ESWT originally claimed to fix everything from the hoof to the head," said Dr. Scott McClure, assistant professor of surgery at Iowa State University.
"Of course, this isn't true. However, we know now that there are a number of things that it truly works for."
On the other side of the coin, many practitioners and owners were suspicious of the product's efficacy.
"A number of people thought it didn't stimulate any healing, rather it just numbed the pain, McClure said. "This isn't so. There are a few days of analgesia, but studies are showing true positive effects on healing."
McClure started using the device in 1998 on a recommendation by David McCarroll, DVM, of Interstate Equine Services in Oklahoma, one of the first veterinarians to take the device from humans to horses.
Dr. McCarroll suggested that McClure work with the entrepreneurs who were looking to prove that the device could work in equine orthopedics.
"The original application was for navicular syndrome and hocks predominantly, which were the areas where we couldn't help with surgery," McClure said.
Shockwave treatment was also touted for tendon and ligament injuries and less frequently for stress fractures.
The machines themselves have changed greatly since 1998. The first generation ESWT units introduced to the veterinary field were expensive, bulky and difficult to transport.
"The current generation of ESWT units are small, portable and affordable to the point that the average equine and small animal practice can purchase and utilize these units, while providing high quality medicine and generating desirable profits," said Gerhard Kinas from Focus It, LLC, in Roswell, Ga.
Uses: Fact and Fiction
Manfred Menzi of Healthtronics in Marrieta, Ga., said focused-shockwave units that allow the practitioner to focus energy up to four inches inside the animal are now used more frequently on sore backs.
Although McClure said he doesn't often see patients with back pain, he has used ESWT for this purpose in several cases.
"I've used ESWT on cervical arthritis situations and I really thought those horses responded pretty nicely. Dr. Kent Allen does a lot of backs for the hunter/jumper and dressage world and he's seen some positive results."
The mobile machines also gave rise to a little creative usage among practitioners who used the device on other areas of the body.
"It's certainly been tried on everything, from ringbone to emotional disorders," said Charles Vail, DVM, from Littleton Large Animal Clinic Equine Hospital in Littleton, Colo.
Networking with colleagues along with presentations at AEEP led Dr. Vail to consider ESWT a valid therapeutic modality.
ESWT vs. RPWT
Originally there was confusion between extracorporeal shock wave therapy and radial pressure wave therapy, and many people assumed that the two are the same.
Initially there was no differentiation between radial pressure wave devices (DolorClast from EMS and Masterpulse MP100 from Storz Medical) versus more expensive and much higher energy, focused shockwave devices (VersaTron Shockwave System from HMT and PiezzoVet 100 from Wolf [note: Wolf no longer distributes in the U.S.])," Menzi said. "Today it is obvious that the two kinds of devices used are completely different.
Scott McClure, DVM, Ph.D., Dipl. ACVS, professor of surgery at Iowa State University, said ESWT is a focused shock wave.
The wave meets the physical definition of a shock wave. The maximum energy is deposited at the focal point, at whatever depth is chosen. It has a lot of valid research behind it and a number of studies going on in veterinary medicine to support or refute claims.
Manfred Menzi, of High Medical Technologies in Marietta, Ga., adds that the protocol commonly used for ESWT is two to three treatments on soft tissue and bony structures, three weeks apart, one treatment on backs and navicular.
RPWT is a radial pressure wave therapy, which is a more appropriate name than its common name of radial shock wave therapy.
The maximum energy is deposited on the surface and the energy dissipates from there," Dr. McClure said. "The wave is a pressure wave, not a shock wave. There isn't much research in veterinary medicine with RPWT other than some analgesic information.
Menzi said the protocol for using RPWT is often limited to trigger-point application and for therapy of sub-surface structure, five to six treatments one week apart.
Vail and his colleagues use ESWT with success for ringbone, painful splints, periostial events and lumbar back pain.
"My perception is that the extracorporeal shock wave therapy has better applications in the non-articular areas of lameness and pain, for example, ringbone. This may not be the universal perception, but I think when you have intra-articular situation, shock wave would not be your first consideration for therapy, and it would probably be one of the last resorts."
And although anecdotal evidence may get more and more practitioners reaching for the device, research is backing up these claims.
"Now we finally have all the controlled studies on focused shock waves coming out to prove its effectiveness for specific indications, namely tendons, navicular and osteoarthritis," Menzi said.
The studies Menzi refers to will be presented at the annual American Assn. of Equine Practitioners Dec. 4 and 5 by David Frisbie DVM, Ph.D., and Scott McClure, DVM, Ph.D., Dipl. ACVS.
The studies reportedly show that the device can improve tendon healing, lessen the symptoms of navicular syndrome and also have positive effects on osteoarthritis.
Part of the study on osteoarthritis was presented by Wayne Mcllwraith, BVSc, DVM, Ph.D., FRCVS, DSc, Dipl. ACVS, at the 2004 European College of Veterinary Surgeons Congress in Prague, The Czech Republic.
Dr. Mcllwraith reported that there was a "clear demonstration of reduction of synovitis and capsulitis that precedes the development of osteoarthritic change. Parameters reflective of inflammation were reduced with shockwave therapy."
Early studies in shockwave therapy reported that microfractures in rodents were common after use. However, McClure's study presented at the 2003 AAEP convention showed that with equines no tissue changes occurred from using either ESWT or radial pressure wave therapy.
It was also speculated that the analgesic effect from the use of ESWT or RPWT was actually the destruction of nerve receptors, but. McClure's study also refuted this observation.
McClure's research in 2003 also proved that this analgetic effect is short term – up to 4 days after treatment, and is transient.
"However, racing regulators still feel strongly that ESWT is a blocking mechanism and may, in fact, allow a horse to perform when he shouldn't," Vail said.
"There is no question that there is a period of analgesia after therapy.
"However, it's not like a block; the pain receptors have simply been dulled a little bit. But racing regulatory doesn't know or understand the difference. I think in an effort to be prudent they are saying for now, let's give it a few days."
"In the U.S., each state's racing commission makes its own decision with regulations that differ from 14 days prior to competition to banning shockwave devices used at race tracks and training facilities," Kinas said. "Ideally, all practitioners that utilize shockwave therapy or plan to utilize it should negotiate with the racing commission as a standard rule."
The Federation Equestre Internationale now requests that treatment be held five to 10 days before a race or competition.
"Sedation used for treatment will make horses test positive anyway," McClure said.
Abuses with ESWT have been reported in the United States.
"There have been reports of race horses being shocked prior to a race so that they would run better," said Kinas. "Ironically, while this is an abuse and is not the purpose of ESWT, it offers further anecdotal evidence of shockwave therapy's efficacy."
"Racing commisions as well as FDA restrict use of devices to licensed veterinarians only," Menzi adds. "Trainers and horse owners must not use these devices."
Prices, Then And Now
The first generation of nonmobile extracorporeal shock wave therapy equipment in 1998 had a price tag of $450,000.
As veterinarians were getting over the sticker shock, prices began dropping, and focused shockwave devices are now available for around $40,000 and radial pressure wave devices for around $20,000.
Although this may still seem quite a lot for smaller practices, lease options are available.
Focus It LLC, for instance, offers start-up financing for shockwave equipment, which allows the practice to pay $100 to $250 per month (depending on the device) for the first year while establishing their shockwave clientele.
"I'm wildly optimistic in the proper indications. We just don't know what all the indications are," Vail said. "What is ESWT good for and what is it not good for? I am, however, quite certain that in the future, in terms of lameness and soundness, horses' working lives will be extended with devices such as these."
"The use of shockwave in the management of degenerative joint disease is a major breakthrough," Menzi said.
"This is not a state-of-the-art indication for shock wave yet. However, experienced shockwave users are already utilizing the device on osteoarthitic joints [new evidence is to be presented at the AAEP convention in Denver].
"In the days to come shock wave will be used much more frequently on osteoarthritis in combination with or instead of other therapy forms."
"ESWT really does stimulate healing, and studies have come out recently in rats and dogs that show neovascularization, and we've seen something very similar in our horse studies," McClure said.
"In human medicine, ESWT has established its place as an alternative with successful results to enhance patients' lives," said Kinas. "ESWT is used as a non-invasive alternative if conventional therapies have failed and/or surgery has poor results.
"We predict likewise will be happening in the veterinary field. A veterinary shockwave organization, similar to the human shockwave organization, would be helpful to lead the way and help to adapt the latest and future shockwave application, such as using shockwaves to release trigger points and non-invasive acupressure therapy."
Sharon Biggs is a frequent contributor to Veterinary Practice News.
This article first appeared in the October 2004 issue of Veterinary Practice News.
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