What Studies Say About Shock Wave Therapy
By David Zuckerman, DPM
November Issue, 2002
article from Podiatry Today
As podiatric physicians and surgeons, we would like to treat chronic plantar fasciitis without the risks and complications that are inherent to common plantar fascia releases. We have studied lower extremity biomechanics and have been taught that with all surgical procedures, we must understand and respect the function of the human foot and how each surgical procedure changes its specific function and stability.
However, studies of extracorporeal shockwave therapy (ESWT) have proven that we can cure chronic, insertional plantar fasciitis without exposing patients to any of the known risks (ranging from infection and nerve entrapment to reflex sympathetic dystrophy (RSD) and calcaneal-cuboid syndrome) associated with any type of surgical plantar fascia release.
How Do Shockwaves Work?
So how does this noninvasive treatment work? Well, there is nothing mystical or cryptic about a shockwave. It is nothing more than a sonic boom. A shockwave is produced by electromagnets generating a signal through water. The signal is directed through a lens to direct all of the energy to a single focal point. Using an ESWT device enables you to place the patient’s foot on that focal point, where it receives all the directed energy to the damaged tissue.
A shockwave has certain physical characteristics. There is a high peak pressure (sometimes more than 100 Mpa), but the average pressure of shockwaves is approximately 50 Mpa with a short lifecycle of approximately 10 ns. In addition, there is, by definition, a fast initial rise in pressure of less than 10 ns and a broad frequency spectrum that is typically in the range of 16-20 Hz.
When a shockwave enters tissue, it may break up and reflect the absorption of kinetic energy by the precise body structures (bone, fat, tendon, ligaments), which are exposed to the shockwave.(1) All techniques of shockwave production (electrohydraulic, electromagnetic and piezoelectric) depend on the conversion of electrical energy to mechanical energy.(1)
When a sound wave is transmitted into tissue, there are two levels of transmission: low energy and high energy. Low energy has an analgesic effect by either disrupting the cell membranes partially or completely. When high energy (any energy greater then 0.28mJ/mm2) comes in contact with the damaged tissue, there is a direct biological interaction. The body will react by increasing blood flow to the area, initiating vascular neogenesis and a reparative cycle. When you apply high energy to the insertion of a damaged plantar fascia, the reparative healing begins. This process leads to fibroblastic production and new healthy tissue in the area that was once avascular tissue.
What The Early Studies Revealed
So what do the studies reveal about the effectiveness of this technology? Scientists began testing shockwaves on animals to determine the effects on wound healing. They were able to show that low energy shockwaves stimulated wound healing and high energy shockwaves prolonged wound healing.(2) Another study tested the effect of shockwaves on non-union fractures. The results showed that shockwaves stimulated osteoblastic activity in pseudarthrosis and could be used to heal fractured bones.(2)
Dahmen, et. al., first used shockwaves to treat soft tissue pain in proximity to bone. They administered a total of 4,892 shockwave sessions to 512 patients.2 More than 30 different syndromes were treated with 52 percent of the patients having good results, 28 percent improved and only 3 percent requiring surgery. Dahmen's work was the beginning for ESWT for tendopathies.
Ching-Jen Wang, et. al., investigated the effectiveness of shockwaves on painful heel spurs. The prospective clinical trial involved 66 patients, including 45 males and 21 female patients with an average age of 47.7 years.(3)
Each treatment with the OssaTron device (Healthtronics) consisted of 1,000 impulses of shockwaves with a 14 kv generator voltage. Twelve patients received a second treatment and two received three treatments each. All of the patients in this study had the standards for pre-ESWT applied: pain for at least six months, failure to improve with at least three conservative treatments (i.e. steroid injection, NSAIDs, orthosis and physical therapy). Exclusion criteria included patients with severe PVD, patients under the age of 18, those who had cardiac pacemakers, those with systemic/local infection and those who were pregnant.(3)
(Please note that when talking about treatments, in order to compare treatment protocols, you need to provide the energy applied in mJ/mm2 at the focal site of the specific ESWT device you use. The study by Ching-Jen Wang, et. al., used the OssaTron, but didn’t specify the amount of energy that was used. However, at this time, the study remains a very important study supporting ESWT effectiveness.)
The clinical results in this study were very encouraging. At the week 12 evaluations, 80.4 percent of the patients noted complete or nearly complete resolution of symptoms, and 17.1 percent noted partial improvement.(3)
In my opinion, this study reached two very important conclusions. The first conclusion is that shockwave treatment for a painful heel spur may improve from week six to week 12. This study showed additional shockwave sessions improved the patients’ heel spur symptoms when the first treatment failed to show improvement.
Getting A Handle On Studies That Offered Follow-Up Results
One of the first studies to offer one-year evaluations revealed very positive results in using high-energy shockwave treatments to treat painful calcaneal spurs.(4) If you include both "pain-free" and "improved" patients with this high-energy treatment, the study depicts 85 percent patient satisfaction one year out from treatment.
These researchers do not mention the type of ESWT equipment they used but their treatment protocol is very similar to the treatment protocol Dornier MedTech submitted to the FDA for its clinical trial.(4) This article notes the amount of shockwave pulses (3,000 impluses for 83 patients) and the high energy levels (.30 mJ/mm2.) This type of reporting makes it possible for any ESWT practitioner to compare any treatment protocol to that of his or her own.
A group led by Lowell Scott Weil Sr., DPM, and Lowell Scott Weil Jr., DPM, recently treated 40 feet with high energy ESWT.(5) The average kv used was 20.6 with an average of 2,506 pulses delivered to the foot. All patients treated were under IV sedation and received a post-EWST local steroid injection. The mean follow-up time was 8.4 months.
Results of the study showed that 82 percent of the patients were satisfied with treatment results. Researchers noted no long-term serious complications.(5)
Beginning in January 1999, I used the Orbasone Machine to treat 100 patients, using the standard treatment protocol as outlined by the manufacturer.(6, 7) This consisted of 16 kv (0.6mJ/mm2), applying 3,000 pulses to the insertional plantar fascia medial attachment. All patient treatments were either administered with local anesthesia or an administration of low energy to prepare for high-energy treatment.
A one-year follow up revealed that 83 percent of patients reported satisfaction with this treatment protocol. I concluded ESWT was very effective for treating chronic heel pain associated with proximal, insertional plantar fasciitis.(6)
What About The FDA Study On The Epos Ultra?
Earlier this year, Dornier MedTech garnered FDA approval for its Epos Ultra device, which has already been in use for many years in Europe and Canada. The FDA clinical trial was a multi-center, double-blind, randomized study consisting of 150 patients.(7) Seventy-five patients received treatment and 75 received a placebo treatment.
As far as the criteria for inclusion in the study went, each of the 150 patients must have had plantar fasciitis for two years. Three failed conservative treatments were the minimum. Also, it should be noted that patients who had autoimmune diseases, diabetes, peripheral vascular disease or had had previous heel spur surgery were excluded from the study.(7)
The treatment protocol consisted of 3,800 shocks of high energy, 0.36mJ/mm2, at 240 pulses per minute. In order to make sure the energy was directed at the insertion site, researchers used inline ultrasound guidance. They administered shockwaves under direct visualization at all times. They also used local anesthetic to ensure patients could tolerate the procedure, and at no time needed to employ general or IV sedation.(7)
Patients were examined at three days, six weeks, 12 weeks, six months and one year. The FDA reporting was up to 12 weeks, which is standard. However, a continuation of the study was followed up to one year by the treatment centers involved in the study. Researchers used visual analog scale (VAS) scores (0-10 with 10 being the highest degree of pain) and the Roles & Maudsley Pain Evaluation to determine the efficiency of ESWT at the different timeframes.(7)
An average pre-ESWT VAS was 7.7 for the baseline FDA study. Three to five days after treatment, the VAS score was 5. Week six showed average scoring of 4.6. Week 12 showed a 3.4 score and revealed that over 60 percent of the patients experienced a good to excellent result. In six months, VAS scores dropped to 2.2 and finally dropped to a low of 0.6 at the one-year mark. This was a 92 percent reduction in pain from the initial pre-ESWT score of 7.7.(7)
The Roles and Maudsley scoring was impressive. Ninety-four percent of the patients treated with the Epos Ultra scored either a 1 or a 2 out of four scoring grid. The following is the definition of each level for scoring recorded:
Excellent: no pain, no restriction for movement and activity
Good: occasional pain, no restriction for movement and activity
Fair: with pain during rest and exertion or loading
Poor: daily activities limited by pain
(It should be noted that at 12 weeks, 56 out of the 75 people who received a placebo treatment were offered the opportunity to to cross over into the study to receive the ESWT.)
In Conclusion
The FDA studies indicate, as do other studies and my own three-year involvement with ESWT, that shockwave therapy is very effective and safe for chronic, proximal, insertional plantar fasciitis with or without heel spurs.
The results are excellent with no long-term complications. ESWT has none of the problems or serious complications that result from any type of fascial release with or without heel spur resection. These patients don’t have to worry about the increased risks of infection, nerve entrapment, RSD, fracture and additional biomechanically induced pain due to the main support system of the human foot being cut.
As podiatric foot and ankle specialists, we are at the frontier of this amazing technology. We can now treat the over 250,000 cases of insertional plantar fasciitis that won’t respond to other treatments. I hope more podiatrists reach out and understand just how beneficial ESWT is to their patients and to their practice.
Many podiatrists won’t offer ESWT to their patients due to the economic cost of the procedure. However, I believe that as time passes, more and more insurance companies will take a look at this marvelous procedure. Don’t let non-insurance coverage stop you from providing a non-invasive procedure to your patients. Patients need to know about all of the treatment options, especially the non-invasive ones, before considering surgical therapy.
Dr. Zuckerman is the Podiatric Medical Director for Excellence Shockwave Therapy Group, a group of over 45 podiatric physicians and surgeons who provide ESWT in outpatient settings. A Fellow of the American College of Foot And Ankle Surgery, Dr. Zuckerman practices in Woodbury, NJ.
References
(1) Musculoskeletal Shockwave Therapy, Coombs, Schaden, Zhou, Greenwich Medical Media, Ltd. 2000.
(2) Use of Extracorporeal Shockwave in the Treatment of Pseudoarthrosis, Tendinopathy and Other Orthopedic Diseases, Gerald Haupt, Journal of Urology Vol 158, July 1997.
(3) Use of Extracorporeal Shockwave in the Treatment of Pseudoarthrosis, Tendinopathy and Other Orthopedic Diseases, Gerald Haupt, Chapter 12, Heel Spurs, author Ching-Jen Wang, Journal of Urology Vol 158, July 1997.
(4) Perlick L, Boxberg W, Giebel G. “Hochenergetische Stosswellenbehandlung des schmerzhaften Fersensporns,” Unfallchirurg 1998 Dec;101(12):914-8 22. (This article is written in German.)
(5) Weil, Jr., LS, Roukis, TS, Weil, Sr., LS, Borrelli, TS. “Extracorporeal Shockwave Therapy for the Treatment of Chronic Plantar Fasciitis: Indications, Protocol, Intermediate Results, and a Comparison of Results to Fasciotomy,” Journal Of Foot And Ankle
Surgery 41(3):166-172, 2002.
(6) Zuckerman, D. Personal surveys published on web site heelspurs.com.
(7) Dornier MedTech Physician Training Manual.1999 US Distributor. 1155 Roberts Blvd. Kennesaw, GA