Update on shockwave therapy for plantar fasciitis. (Technology & Treatment).

Two years ago, the FDA approved the first device that uses extracorporeal shock wave therapy (ESWT) to treat chronic plantar fasciitis (see The Clinic). The device, known as an orthopedic lithotriptor, is used for cases that have failed after six months of conventional therapy. As the approval process for additional devices begins, it's worth examining the benefit of the treatment and the options available.

Orthopedic lithotriptors are adaptations of machines used to pulverize kidney stones. They create high-energy shock waves that are focused from outside the body to the area of interest. At present, the Healthtronics Ossatron and the Dornier Epos Ultra are the only orthopedic lithotriptors that are FDA-approved for the treatment of chronic plantar fasciitis. The electrohydraulic Ossatron has a larger focal zone (the area where the pressure is the greatest). It is egg-shaped and relies on physician skill to target the desired area. The electromagnetic Dornier has a focal zone more like a pencil. Devices using other technologies are currently being studied and may be approved in the future.

One study reported improvement with the Ossatron device based on patients' perception of pain and investigator assessment using a calibrated pressure gauge. The results of 119 patients in the treatment group showed a 62.2% successful outcome based on assessment at 12 weeks after treatment, versus 44% in a placebo group comprised of 116 patients. The self-assessment success outcomes were 60% and 48%, respectively. Based on the probability value and other factors, however, the conclusion that the treatment was successful was not statistically significant.

A more recent study at the American College of Foot and Ankle Surgeons reported an 82% satisfaction rate after a mean treatment time of 8.4 months with another electrohydraulic device and steroid injection given at the shockwave session, This preliminary study was based on 40 treated feet. Currently, these researchers are exploring the effectiveness of the electrohydraulic Ithotriptor against two newer technologies, piezoelectric and radial. The initial results for these ESWT machines have been promising, Lowell Weil, Jr., DPM, FACFAS and director of the Foot and Ankle Fellowship at the American College of Foot and Ankle Surgeons, states that, anecdotally, patients that have had the steroid injections after the procedure seem to improve more quickly. And in a clinical study by Dornier, 61.6% of the patients showed good to excellent results after three months.

The widely reported JAMA study from last October has some constraints. First, half of the patients had plantar fasciitis for less than six months. This is a problem because 85 to 90% of patients with plantar fasciitis respond to conservative therapy. As a result, many patients in the study would be expected to get better without an ESWT treatment. Second, patients were given several low energy treatments as opposed to one high energy treatment. The FDA has only approved high energy treatments. This raises questions as to whether the study's conclusions were a result of the failure to use enough energy for a therapeutic dose. Third, all patients were allowed to continue with conservative therapy. This confounds the results since it is not possible to distinguish between the effects of orthotics alone and of orthotics and ESWT treatment. By contrast, in the FDA studies, all patients were required to stop all conservative therapy during the course of the study.

Based on my own experience and conversations with other doctors, it appears that patients who have plantar fasciitis without other accompanying problems like neuritis inflammation of the nerves) seem more likely to respond to ESWT. Keep in mind that sedation under the care of an anesthesiologist s often necessary to tolerate the higher energy treatments. Patients who have had the problem for several years seem less likely to respond, perhaps because they may be more likely to have other complicating factors in addition to plantar fasciitis. Yet the technology also may benefit runners with insertional Achilles tendinitis. A multi-center study in Italy found that 80 patients had 78% improvement after 30 days using electrohydraulic devices. And it is important to remember that ESWT must be combined with other treatments such as stretching and orthotics, otherwise the benefits may be short lived.

Dr. Pearl is a consultant at the National Institutes of Health and has a private practice in Arlington, VA. Special thanks to Anthony Lavigna, PhD, for help editing studies.

(Clin. Orthop., 2001, Vol. 387, No. 6, pp. 47-59; Journ. Foot & Ankle Surgery, 2002, Vol. 45, No. 3; JAMA, 2002, Vol. 288, No. 11, pp. 1364-1372; 3rd Congress of Int'l Soc. Musculoskeletal Shockwave Therapy, Naples, 2000; personal corresp. Lowell Weil, Jr., DPM, FACFAS, Director, Foot & Ankle Fellowship, Am. Coll. Foot & Ankle Surgeons)