What You Should Know About Shockwave Therapy

Author(s): 
By Lowell Scott Weil, Jr., DPM, MBA

   Last year, I wrote “Extracorporeal shockwave therapy (ESWT) has a long way to go to prove it has overwhelming medical benefits that are claimed by the manufacturers, but it is still in the early stages of its evolution. With time, it will be necessary to prove these claims through prospective studies.” (See “Extracorporeal Shockwave Therapy: Hope Or Hype?,” page 46, November 2003 issue.)    While this article is not intended to prove beyond a statistical doubt that ESWT works, emerging research via prospective placebo-controlled, double-blind studies shows that ESWT is effective and should be considered a proven technology.    Employing ESWT for the treatment of musculoskeletal (MSK) disorders evolved in Europe in the early 1990s. ESWT is a derivative of lithotripsy, the mechanical breaking up of renal stones with sound waves. ESWT has been considered valuable in treating many different MSK disorders including plantar fasciitis, epicondylitis, tendinitis and non-unions of bone. In all situations, it is considered the non-invasive alternative to surgery.    Clinicians should only consider ESWT for treating a pathology after more common, accepted and proven non-invasive treatments have failed.    In the United States, ESWT received its first FDA-approved indication for the treatment of plantar fasciitis. Up to 15 percent of podiatric visits result from painful plantar fasciitis. Given the prevalence of plantar fasciitis in the U.S., with over 1 million people suffering from it annually, it has become the epicenter of debate about ESWT.    Numerous studies have proven that 80 to 90 percent of people suffering with plantar fasciitis will be treated successfully with conservative treatment over a six-month period of time. There is little debate over the most effective conservative management options for plantar fasciitis although the only randomized, proven method is the use of night splints in the chronic cases.    However, continued controversy abounds regarding the proper method of treating the 10 to 20 percent of plantar fasciitis sufferers who do not respond to conservative care in a timely fashion.    Over the years, many different procedures have been described for treating chronic heel pain. These procedures include: large incisional sectioning of the plantar fascia with removal of bone spur; only sectioning the plantar fascia; decompressing a branch of the lateral calcaneal nerve with partial sectioning of the plantar fascia; minimally invasive techniques with or without an endoscope; in-step fasciotomies; and more recently, injections of different chemical agents, either Botox or alcohol. For the past four years, ESWT has been on the list of available treatments in the U.S.

Understanding The Different Shockwave Technolologies

   Electrohydraulic, electromagnetic, piezoelectric and radial are four different technologies that are currently utilized to create medical shockwave.    The electrohydraulic system is also known as spark gap technology and was employed with the first generation of shockwave machines. A spark plug is used to generate heat and a sonic pulse, resulting in cavitation. Eisenmenger first described the electromagnetic principle in 1962. This 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.    The piezoelectric principle employs a high voltage current, which is applied to a substantial number of piezo crystals mounted on the inside of a sphere. The piezoelectric effect causes deformation of the crystals, inducing a shockwave. The focal point or area of maximal therapeutics is at some fixed distance away from the shock wave generator in the electrohydraulic, electromagnetic and piezoelectric machines.    The radial principle has a focal point that differs from the other three technologies. The focal point of the radial principle is directly at the device-skin interface and is dispersed in a megaphone fashion from the head of the radial device.    There have been several proposed theories when it comes to the mechanism of action of shockwave. Research by Wang described the mechanism of MSK-ESWT as multiple microtraumas that promote neovascularization to the tissue that one is treating. Others have compared the process to that of tenderizing meat whereby repeated pounding on the meat will break up the interstitial fascia or scar tissue, and make the meat more pliable.    In a study of the Achilles tendons of mongrel dogs versus a placebo, Wang showed that shockwave not only promotes neovascularizaton but also facilitates the release of growth factors PCNA, VEGF and eNOS. Shockwave treatments have been employed for several different MSK applications including the treatment of tendonitis, calcifying tendonitis, periarticular shoulder calcification, plantar fasciitis, medial and lateral epicondylitis, osseous non-unions and avascular necrosis.    Currently, there is no consensus on the use of low-energy shockwaves, which do not require local anesthesia, and high-energy shockwaves, which require local or regional anesthesia for the treatment of chronic plantar fasciitis. There is no consensus for differentiating between low-energy and high-energy shockwaves as multiple physical parameters are involved.    While the clinical effect of both protocols appears to be comparable, there is clear evidence of increasing side effects as the energy level increases. Although these side effects do not appear to be significant from a macroscopic view, local tissue and nerve tissue may be affected. No local anesthesia is required for low-energy shockwaves so related side effects are lacking.    The only “disadvantage” of low-energy shockwaves is that one has to provide a repeat application. A comparison of the effectiveness of low-energy and high-energy shockwaves has not been studied.

Shockwave Therapy Or Surgery For Chronic Plantar Fasciitis?

   Why have surgeons continued to change their procedure of choice over the years despite citing literature with good to excellent early results? It is probably the same reason why there are over 100 bunion operations. They are searching for the procedure that is predictable over the long term with the least amount of complications and disability for the patient.    We have certainly heard surgeons proclaim minimally invasive surgery as being 95 percent successful with immediate weightbearing and no complications. Certainly, those statistics are far from reality. Whenever one performs invasive surgery, there are risks. It is not uncommon to hear of the patient who underwent an endoscopic plantar fasciotomy (EPF) and wound up having severe nerve injury to branches of the plantar nerve.    We have also encountered the patient who had open sectioning of the plantar fascia and removal of the bone spur only to wind up in severe pain for months, unable to work or pursue normal activities over that time frame. While these scenarios may be unusual, they are certainly more common than we would like.    ESWT has emerged as a noninvasive, minimal risk procedure for chronic conditions such as plantar fasciitis. ESWT allows patients to return to activities of daily life within one or two days with immediate return to most jobs and normal daily shoegear. Complications of ESWT for plantar fasciitis have been virtually non-existent.    In 2002, we published a paper in JFAS showing 82 percent success with ESWT. This success rate was comparable to our success rate with the minimally invasive plantar fasciotomy (83 percent), which we published in JFAS in 1994. This pilot study was a retrospective study and we are certainly aware that only a randomized, prospective, placebo-controlled study can provide evidenced based medicine.    However, this is true of all the studies on surgical outcomes for plantar fasciitis as these studies are similarly designed as retrospective without the control of a placebo group. Therefore, our study shows that outcomes with ESWT are comparable to surgical outcomes without the risks, complications and disability inherent to surgery.    Without a doubt, the literature is controversial when it comes to the relative benefit of ESWT. Opponents of ESWT point to literature that shows its ineffectiveness when it is compared to placebo. One can selectively quote literature to support a stance on ESWT either way.    However, some of the oft-discussed papers against ESWT have been scientifically flawed. The paper most often cited by the opponents of ESWT is by Buchbinder out of Australia. This study included patients who had heel pain for as little as six weeks and ESWT energy levels were given to each patient’s tolerance rather than having a uniform standard application throughout the study. Furthermore, the energy levels used were far less than those recommended in the U.S.    Additionally, the placebo group was administered a small dose of ESWT that could have theoretically been therapeutic. Lastly, the study was performed by a non-clinician who worked for the government of a national health care system. The motives of the study were skewed from the beginning.    Critics will also point out that ESWT is extremely expensive. However, the cost of new technologies is often high as it is with new pharmaceuticals. The benefits of ESWT in terms of social costs are immeasurable. Patients are able to return to activities of daily life and work immediately. There are no costs of lost work to either the patient or employer. There are virtually no risks or complications with ESWT whereas postoperative nerve injuries and infections can require intense medical care that can run into tens of thousands of dollars. These are just some of the examples of the overall cost benefit of ESWT over surgical options.

What Studies Say About Electrohydraulic, Piezoelectric And Radial Devices

   Over the past two years, the Weil Foot and Ankle Institute has been fortunate to be involved with five different randomized, double-blind, placebo-controlled studies on the effectiveness of shockwave. Three of the studies were multicenter, pivotal studies for the purpose of securing a PMA from the FDA. The other two were single site studies.    Two of the multicenter FDA studies utilized sedation. One study involved the electrohydraulic device whereas the other study involved the piezoelectric device. Both studies had a rigorous exclusion criteria with qualified patients having pain for greater than six months and medical treatment for at least four months that included at least four of the following: arch support (custom or OTC), antiinflammatory medication for at least four weeks, cortisone injection, physical therapy, night splints, stretching exercises and/or shoe modifications.    Patients were given sedation and the appropriate heel was anesthetized with 6 to 10 cc of 0.5% Marcaine plain. Computer randomization then determined whether the patient would receive active treatment or a sham treatment (no treatment). These patients were then followed for three months by a podiatric physician, who was not aware of the treatment that was provided to these patients.    The electrohydraulic device showed that 60 percent of the active group improved by more than 50 percent while only 38 percent of the sham group improved by more than 50 percent. This compares favorably to the Ossatron FDA study results.    The piezoelectric study showed that 48 percent of the active group had an improvement of greater than 50 percent while 50 percent of the sham group had more than 50 percent improvement.    However, there was a greater improvement in the Roles and Maudsley criteria for the active treatment group than the sham treatment group, and the active failures had more improvement than the sham failures. Composite scores from all sites are still undergoing statistical analysis.    A third randomized, double-blind, placebo-controlled multicenter study used radial shockwave therapy. Although local anesthetic was available for patients who had severe pain during treatment, no one required the injections.    The study had a rigorous inclusion criteria similar to the aforementioned studies. Computer randomization determined whether patients were treated with an active handpiece or a sham handpiece every two weeks for three treatments. A blinded physician then followed these patients for three months.    For this study of 242 randomized patients, 125 received active treatment while 118 received the sham treatment. The active group improved their visual analog scale (VAS) of pain from a baseline of 7.1 to 3.6 three months after the treatment. The sham group improved from 6.7 to 5.9 at three months.    The active group significantly outperformed the sham group using the Roles and Maudsley criteria. Fifty-seven percent of the active group achieved successful alleviation of their morning pain while only 40 percent of the sham treatment group had this success. Fifty percent of the active group had success treating their activity pain while only 33 percent of the sham group succeeded with treatment of their activity pain.

Using ESWT To Treat Bilateral Heel Pain And Painful Morton’s Neuroma

   A single center study focused on the use of ESWT for treating bilateral heel pain. Patients were only eligible for the study if they had been unsuccessfully treated for bilateral heel pain for greater than six months, they had a visual analog pain scale > 6, and systemic causes of the heel pain had been ruled out. Researchers sedated the patients and both heels received 6 to 10 cc of 0.5% Marcaine plain. Computer randomization determined which foot was to be treated.    Researchers used an electrohydraulic ESWT device at a level of 19 Kv and applied 2,000 pulses on the treated foot. The sham foot received no treatment. The patients then followed up with a blinded physician for three months.    This study showed that 70 percent of the active treatment group improved and 52 percent of the sham treatment group improved. Sixty-five percent of the active group improved by more than 50 percent while only 47 percent of the sham treatment group improved by more than 50 percent. Sixty-five percent of the active treatment group achieved a VAS of less than 3 while only 39 percent of the sham treatment group had a VAS less than 3.    According to the study, 4 percent of participants had no improvement in either foot while 39 percent of the participants had improvement in both feet.    A single center study focused on the use of ESWT for treating painful Morton’s neuroma. Patients were only included in the study if they had been unsuccessfully treated for Morton’s neuroma pain for greater than six months, they had a visual analog pain scale > 6, and they had been offered surgical treatment as an option to EWST.    Researchers sedated the patients and injected the third interspace with 3 to 5 cc of 0.5% Marcaine plain. Computer randomization determined whether the patients received active treatment or sham treatment.    Researchers utilized an electrohydraulic ESWT device at a level of 21 Kv and applied 2,000 pulses to the treated foot. The sham foot received no treatment. The patients then followed up with a blinded physician for three months.    The study revealed that 83 percent of the active treatment group improved by more than 50 percent while only 25 percent of the sham treatment group improved by 50 percent. Seventy-five percent of the active treatment group had a VAS of less than 3 three months following the procedure while only 25 percent of the sham treatment group had the same findings. Eight percent of the active treatment group had no improvement while 50 percent of the sham treatment group had no improvement three months following the procedure.    No surgical procedure for heel pain, epicondylitis, calcific shoulder tendinitis, Achilles pathology or Morton’s neuroma has ever been subject to the rigors of a prospective, placebo-controlled, double-blind study the way ESWT has.

Final Notes

   At the Weil Foot and Ankle Institute, we treat plantar fasciitis for at least four months with a strict conservative protocol that has been detailed in multiple publications. A vast majority of patients will respond to that conservative approach in that time frame.    After thoroughly ruling out other etiologies, we present patients with the option of ESWT or surgery to relieve their chronic heel pain.    Financial concern is the only issue that keeps patients from choosing the surgery option. In some cases, we provide the treatment pro bono to those who would be best served but just cannot afford the treatment.    At this time, one should consider ESWT a proven treatment for plantar fasciitis and part of any care pathway for physicians who treat the foot. In the future, research may reveal it appropriate to move to ESWT earlier in the treatment pathway if certain diagnostic criteria are met and show that ESWT is more likely to help than other conservative options.    Additionally, it is possible that ESWT will actually reduce overall costs if less money is spent on non-productive conservative care and physician visits, and if there is less chance of lost productivity and days off work from pain, physician visits and surgical recovery. Employers and patients alike may be crying out for ESWT to be utilized and the health insurance companies will have to listen. Dr. Weil is the Fellowship Director of the Weil Foot and Ankle Institute in Des Plaines, Ill. He is a Fellow of the American College of Foot and Ankle Surgeons. CE Exam 125 Choose the single best response to each question listed below. 1. Numerous studies have proven that between ___ to ____ percent of people with plantar fasciitis will be treated successfully with conservative treatment over a six-month period of time. a) 50 to 60 b) 90 to 100 c) 80 to 90 d) 60 to 70 e) 70 to 80 2. Which of the following musculoskeletal disorders has extracorporeal shockwave therapy (ESWT) been considered valuable in treatment? a) epicondylitis b) plantar fasciitis c) osseous non-unions d) tendonitis e) all of the above 3. The electromagnetic principle of shockwave therapy … a) is also known as spark gap technology. b) was employed with the first generation of shockwave machines. c) involves the passing of an electrical current through a coil, which produces a strong magnetic field. d) employs a high voltage current which is applied to a substantial number of piezo crystals mounted on the inside of a sphere. e) a and b 4. The piezoelectric principle of shockwave therapy … a) is also known as spark gap technology. b) was employed with the first generation of shockwave machines. c) involves the passing of an electrical current through a coil, which produces a strong magnetic field. d) employs a high voltage current which is applied to a substantial number of piezo crystals mounted on the inside of a sphere. e) a and b 5. The focal point or area of maximum therapeutics is at some fixed distance away from the shock generator in all currently available shockwave devices except those with _______ technology. a) radial b) electrohydraulic c) piezoelectric d) electromagnetic e) a and b 6. One multicenter FDA study that involved using an electrohydraulic shockwave device to treat chronic plantar fasciitis found that _____ percent of the active treatment group improved by more than 50 percent. a) 50 b) 60 c) 70 d) 80 e) 90 7. Another multicenter FDA study that involved using a piezoelectric shockwave device to treat chronic plantar fasciitis found that _____ percent of the active treatment group improved by more than 50 percent. a) 38 b) 58 c) 78 d) 28 e) 48 8. A randomized, double-blind, placebo-controlled multicenter study of radial shockwave therapy for chronic plantar fasciitis found that _____ percent of the active treatment group had successful alleviation of their morning pain three months after treatment. a) 57 b) 47 c) 67 d) 87 e) 77 9. Three months after treatment, a single center study of ESWT for bilateral heel pain revealed … a) 70 percent improvement for the active treatment group. b) 50 percent improvement for the active treatment group. c) 40 percent improvement for the active treatment group. d) 60 percent improvement for the active treatment group. e) 80 percent improvement for the active treatment group. Instructions for Submitting Exams Fill out the enclosed card that appears on the following page or fax the form to the NACCME at (610) 560-0502. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam. Responses will be accepted up to 12 months from the publication date.
 

 

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