Could Extracorporeal Pulse Activated Therapy (EPAT) Have An Impact For Forefoot Pathology?

In a recent lecture at the American Association for Women Podiatrists’ Scientific Conference, Stephen Kominsky, DPM reviewed the relevant anatomy and biomechanics involved with treating predislocation syndrome and overlapping second toe, and emphasized surgical approaches. Although I did learn techniques that may influence my surgical choices, this is a condition for which I continuously seek better treatments.

With plantar plate pathology, I long thought there was a clear line (based on the degree of deformity and symptoms) delineating when conservative management may succeed and when surgery is the right choice. However, over the past year, my use of extracorporeal pulse activated therapy (EPAT) and amniotic stem cell allograft for this forefoot pathology has blurred those lines a bit. 

The plantar plate of the second MPJ is a complex, thick structure of type 1 collagen, starting plantar distally from the metatarsal and inserting onto the plantar aspect of the proximal phalanx. It provides attachments for the deep transverse metatarsal ligament, interosseous ligaments, collateral ligaments and fibers of the plantar aponeurosis. The plantar plate functions to stabilize the MPJ and prevent hyperextension. Injury is most commonly caused by repeated overload and overuse, which is triggered, in turn, by multiple biomechanical factors.¹

For this blog, the focus is on EPAT. High-energy extracorporeal shock wave therapy (ESWT) is painful, expensive, and often performed in a surgical setting. Low-energy EPAT can be performed in an outpatient setting, where it is tolerated well. One can perform high-energy ESWT in one 20-minute treatment with the patient under regional anesthesia whereas low-energy ESWT does not require any anesthesia but needs three or four applications. 

The ideal method for applying shockwave therapy is not clear. Trials in the literature vary in regard to intensity and frequency of the sound waves, the duration of treatment, and the number and timing of treatments. This makes it difficult to compare studies and data. However, without question, I have found that EPAT is more accessible and we can use this modality more easily in our offices. 

With EPAT, the amount of energy and the frequency of application influences the biological effect on the target tissue. The administration of sound waves creates vibration, which is transmitted through the tissue. This causes local injury to the tissue with a subsequent increase of blood flow and migration of growth factors to the area of treatment. The exact mechanism of action is unknown but there are several theories on what is happening during extracorporeal shock wave therapy. These theories include fragmentation with increased pressure in areas of calcium deposition, induction of an inflammatory response leading to an inflammatory mediated healing process and neovascularization with increased blood flow to the treated site. There is also the belief that the hyperstimulation may be inhibiting pain perception.^2-4

A literature search was void of any studies looking at the use of EPAT for forefoot pathology. Much of the findings with the use of shockwave therapy for Achilles tendinopathy have been contradictory. One randomized trial showed ESWT to be superior to no treatment and comparable to eccentric training.³ Another randomized double-blind trial showed no difference between patients treated with ESWT and those treated with a placebo or sham shockwave therapy.⁵

Multiple studies have reported improvement at eight and 12 weeks after ESWT with the best results at 12 weeks after use. A more recent 2017 study published in the Journal of Foot and Ankle Surgery showed clinically relevant and statistically significant efficacy of ESWT for chronic plantar fasciitis with a 63 percent and 79 percent reduction in pain in active and non-active duty military populations respectively.⁶

Though the literature is not rich with evidence and statistically significant results, EPAT has found its way into many podiatry offices. In my office, it has become a star. The positive results in the more typical areas of the plantar fascia, Achilles and posterior tibialis tendons has led me to branch into using this modality in the forefoot region. While I have found best results at eight to 12 weeks after the third EPAT treatment in the more typical aforementioned areas of use for this modality, I have seen earlier results for chronic injury of the plantar plate of the second metatarsophalangeal joint.

Of course, clinicians still need to address the biomechanical issues of these patients with appropriate orthotics or shoes. However, for me, EPAT is now playing a role when taping and immobilization is more on the conservative side, and surgical intervention in moderate presentations is not the most ideal approach.

Dr. Schwartz is the Scientific Conference Chair and a Past President of the American Association for Women Podiatrists. She is board-certified in foot surgery by the American Board of Foot and Ankle Surgery and is in private practice with Foot and Ankle Specialists of the Mid-Atlantic in Washington, DC and Chevy Chase, MD. 

References

1. Banks A, Downey M, Martin D, Miller S. McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery. 3^rd ed. Philadelphia: Lippincott, Williams & Wilkins; 2001:253-269.
2. Carulli C, Tonelli F, Innocenti M, Gambardells B, Muncibi F. Effectiveness of extracorporeal shockwave therapy in three major tendon diseases. J Orthopaed Traumatol. 2016;17(1):15-20.
3. Wilson M, Stacy J. Shock wave therapy for Achilles tendinopathy. Curr Rev Musculoskelet Med. 2011;4(1):6-10.
4. Andres BM and Murrell GAC. Treatment of tendinopathy: what works, what does not, and what is on the horizon. Clin Orthop Relat Res. 2008;466(7):1539-1554.
5. Rasmussen S, Christensen M, Mathiesen I, Simonson O. Shockwave therapy for chronic Achilles tendinopathy: a double-blind, randomized clinical trial of efficacy. Acta Orthop. 2008;79(2):249-256.
6. Purcell RL, Schroeder IG, Keeling LE, Formby PM, Eckel TT, Shawen SB. Clinical outcomes after extracorporeal shock wave therapy for chronic plantar fasciitis in a predominantly active duty population. J Foot Ankle Surg. 2018;57(4):654-657.