Extracorporeal Shockwave Therapy (ESWT) for Running Injuries

Soft tissue injuries are common to runners and athletes who depend on their legs to get them where they need to go. About 65% of regular runners get hurt each year. It’s estimated that the average runner will sustain one injury for every 100 hours he or she runs.¹ When an injury occurs, athletes and weekend warriors are usually looking for solutions to get them back on the road as soon as possible. This blog article reviews how shockwave therapy works and can be used to treat running injuries.

Terminology

Names that refer to therapeutic shockwave are varied. This can create confusion when trying to investigate this technology. Common names include but are not limited to:

• ESWT: Extracorporeal Shockwave Therapy
• FSW: Focused Shockwave
• EPAT: Extracorporeal Pulsed Activation Therapy
• RSW: Radial Shockwave
• AWT: Acoustic Wave Therapy

What is Shockwave Therapy?

Shockwave therapy transmits harmless acoustic pressure waves into tissue to influence biological activity, resulting in an analgesic effect and expediting the healing process. There are two types of shockwave, Focused Shockwave and Radial Shockwave. These should not be confused with High Energy devices used in Lithotripsy (breaking down kidney stones).

Shockwave therapy can treat:

• Plantar Fasciitis and Non Specific Heel Pain ^2,3
• Lower Limb Tendinopathies ²
• Hip and Groin Tendinopathies ²
• Myofascial Trigger Points ²
• Reduce Muscle Pain and Aches ²

The list of indications continues to grow as the literature base expands.

Research has shown that Shockwave therapy can provide up to 89% positive outcomes after 3 one weekly sessions versus placebo or alternative treatment modalities when treating different types of tendinopathies.⁴

How does shockwave help tissue?

Low to medium energy waves, that can be created via different mechanisms, create a phenomenon referred to as mechanotransduction. In simple terms, it is the process of imparting brief, physical deformation to cells that lead to biochemical changes. These changes have the potential to positively impact pain and tissue repair.⁵

“Mechanotransduction” is a biological pathway to which many cell types (including Stem Cells) sense and process the mechanical information from the extracellular environment. These biomechanical forces are converted in biochemical responses, thus influencing some fundamental cell functions such as migration,
proliferation, differentiation, and apoptosis.⁶

Are all soundwaves the same?

Some clinicians falsely assume that shockwave equipment is similar to therapeutic ultrasound (US) since they both utilize soundwaves. It should be noted that therapeutic ultrasound uses a lower intensity sound wave (20 to 1000 mW/cm²) that is delivered at a higher frequency (0.7 to 3.3 MHz.).⁸ Therapeutic US waves look like this:

_{Image obtained from reference 7}

Continuous US creates thermal effects in tissue by alternating compression and rarefaction of sound waves within tissue. Maximum energy absorption in soft tissue occurs from 2 to 5 cm and intensity decreases as the waves penetrate deeper.⁸

FSW vs RSW

 

Clearly the most notable difference is the impulse they create. FSW devices create a ‘true’ shockwave. RSW create what has been termed as a Radial Pressure Wave (RPW). Hence why you will see this term used for RSW along with others including Extracorporeal Activation Therapy (EPAT). At the time of
its conception in 1998, RSW was marketed as Radial Shockwave and it is still marketed this way today.

Comparative research studies between the FSW and RSW for lower limb tendinopathies on the whole shows no significant difference in outcomes. This is with the exception of insertional tendinopathies, where FSW has been shown to be more effective. So apart from this, why choose FSW, as it is more expensive? For therapists the additional cost is warranted if they are seeing bone pathologies, calcific deposits, deep structures or treating men’s health issues.

There are three ways to generate a focused shockwave. The two most widely used in clinics are electromagnetic and Piezoelectric. Both transmit the shockwave energy over a large area of the skin and the energy is then cumulated to a focal point within the tissue. This means that the energy
transmission is acceptable to most patients. With electromagnetic generation the focal point is around 6cm deep with a therapeutic effect down to 12cm. To treat more superficial tissue than this the focal point is raised by stand offs that are fitted to the handpiece. The energy of focused shockwaves is measured in mJ/mm2 and is referred to as the Energy Flux Density (EFD).

For Radial shockwave devices there are two types of generation, air compressor or electromagnetic.
The latter being quite new to the market and currently not supported by any robust or reliable research evidence. The energy from these devices are transmitted through transmitters. The shape, design and material of these transmitters determines the amount of energy being produced. Inevitably there is a huge variation in type and quality between different manufacturers. Only a few manufacturers publish the EFD value of their transmitters. Most simply quote bar pressure. This is the pressure created within the barrel of the handpiece. However, two different manufacturer’s devices, at the same bar pressure, can produce different EFD vales from their respective transmitters. For runners who may have tried shockwave treatments unsuccessfully you may well find success with a different radial shockwave device

Hopefully this review will provide some clarity for readers that are looking to better understand how ESWT can help various conditions.

Patient compliance, the role of modalities

Exercise is often uncomfortable but needed for patients suffering from Achilles and Patella tendinopathies and plantar fasciitis.⁹ Adding modalities such as shockwave and laser therapy can help manage pain in the clinic which can open doors to more advanced loading exercises. Keeping pain in check can help promote steady progress over the 3-4 week course of treatment commonly needed to restore higher levels of function when adding ESWT to a plan of care (POC).

Quick review how to use shockwave for runners:

• ESWT is a trusted treatment option for clinicians treating pain associated with a variety of tendinopathies, with unique advantages relative to other interventional treatments.
• RSW technology is the most commonly used ESWT device globally. This is partially due
  to the lower costs associated with these devices which makes them an attractive entry
  point into shockwave technology. While cost is one factor, RSW popularity is primarily
  due to its effectiveness in helping to treat tendon disorders. A 2015 systematic review
  showed that RSW treatments were 88.5% effective when compared to other treatments
  for common musculoskeletal pathologies. FSW was found to be 81.5% effective in the
  same study.⁴ While the physical properties of the RSW differ from the FSW, RSW
  has been repeatedly shown to be as effective in treating soft tissue pathologies in the
  extremities as FSW where tendons are relatively superficial.⁴
• FSW can provide higher energy treatments at depths of up to 12.5 cm. While potent, FSW
  has the ability to be more precise with the energy it delivers and at specified depths. This
  is ideal for clinicians that utilize diagnostic ultrasound to identify the depth and degree of
  soft tissue lesions they are treating. FSW is very simple to use as it allows clinicians to
  apply specific energy levels (mJ/mm2) at precise depths by dialing in the desired energy
  flux density (EFD) on the screen and then setting the treatment depth of the focal area by
  choosing the correct stand-off that fits on the handpiece.

Interested in furthering your understanding of using Shockwave and Laser Therapy for treating patients with lower leg injuries? Download our Treatment guide HERE.

References

1. Running Injuries. Yale Medicine. https://www.yalemedicine.org/conditions/running-injury#:~:text=About%2065%20percent%20of%20regular%20runners%20get%20hurt
2. RPW User Manual. https://enovis-medtech.eu/media/storage.djoglobal.eu/en_US/Documents/Support_documents/IFU_13-28670_US_Rev_A_Intelect_RPW_2_DIGITAL_Final.pdf
3. Focus Shock Wave User Manual. https://www.djoglobal.eu/media/storage.djoglobal.eu/en_US/Documents/Documents_2023/13-00061-US_RevE_USA_IFU,_FOCUS_SHOCKWAVE-EN.pdf
4. Schmitz C, Császár NB, Milz S, et al. Efficacy and safety of extracorporeal shock wave therapy for orthopedic conditions: a systematic review on studies listed in the PEDro database. Br Med Bull. 2015;116(1):115-138.
5. d’Agostino MC, Craig K, Tibalt E, Respizzi S. Shock wave as biological therapeutic tool: From mechanical stimulation to recovery and healing, through mechanotransduction. Int J Surg. 2015;24(Pt B):147-153.
6. Romeo P, Lavanga V, Pagani D, Sansone V. Extracorporeal shock wave therapy in musculoskeletal disorders: a review. Med Princ Pract. 2014;23(1):7-13.
7. What are shock waves? Physics and Technology. STORZ MEDICAL - The Shock Wave Company. Accessed January 9, 2024. https://www.storzmedical.com/us/physics-and-technology
8. Uddin SMZ, Komatsu DE, Motyka T, Petterson S. Low-Intensity Continuous Ultrasound Therapies—A Systematic Review of Current State-of-the-Art and Future Perspectives. J Clin Med. 2021;10(12):2698. Published 2021 Jun 18.
9. Silbernagel KG, Hanlon S, Sprague A. Current Clinical Concepts: Conservative Management of Achilles Tendinopathy. J Athl Train. 2020;55(5):438-447.