What is Extracorporeal Shockwave Therapy?

Extracorporeal Shockwave Therapy (ESWT) is a treatment modality that has been making waves over the past several years in the sports and orthopedic injury world. Maybe you've heard of a friend or teammate having this treatment, or perhaps you're wondering if it is something that will help your injury. If you've been wondering what shockwave is, how it works, the pros and cons, and if it may be right for you, this blog will answer your questions.

History of Shockwave

Although ESWT has gained popularity in the past several years, the technology is not new. The technology was first used in 1982 to treat kidney stones. The shockwaves were used to break up the stones so that they could be passed more easily. Further research in the 1980s showed that ESWT could help improve fracture healing. The use of shockwave for plantar fasciitis was first researched in 1996, and subsequent studies examined its use for various upper and lower limb tendinopathies.

How Does it Work?

ESWT units produce non-linear waves with high peak pressure and low tensile amplitude. The waves have two phases: First, the positive phase produces mechanical force from the wave. Then, there is a negative phase in which the waves produce cavitation and gas bubbles, which implode at high speeds creating a second wave of shockwave.

There are three forms of shockwave:

• Focused: This type of shockwave produces higher energy and a maximal force at deeper levels, and therefore can affect deeper tissues. This is produced by hydraulic, electromagnetic, and piezoelectric devices.

• Radial: Pneumatic or ballistic devices produce lower energy waves, which have the greatest pressure at the skin surface, and decreased pressure as depth increases.

• Combined: These shockwave units can produce both radial and focused shockwaves for a multimodal effect.

The exact mechanism by which shockwave works is still unknown. However, there are many proposed theories of how shockwave can promote healing. Shockwave is thought to:

• Increase neovascularization (new blood vessels) at the tendon bone junction

• Increase the proliferation of tenocytes

• Increase osteoprogenitor differentiation

• Increase leukocyte infiltration

• Increase growth factor and protein synthesis, leading to collagen (the building blocks of tendons, ligaments, and cartilage and framework for bone) synthesis and tissue remodeling

• Reduce calcification in the soft tissue

• Decrease inflammation

• Hyperstimulate nociceptors which alters pain receptor transmission and increases local pain inhibiting substance

• Stimulate nociceptive G-fibers which is both analgesic and my increase tendon remodeling via neuropeptide release, fibroblast stimulatoin and vasodilation

In less "science-y" terms, this means that shockwave helps to promote healing by stimulating new cell generation, influx of cells that promote healing, and increase blood flow to bring nutrients to the damaged area. Another effect is immediate reduction in pain. This is due to changes at the level of the pain receptors, not due to immediate healing.

What Can be Treated with Shockwave?

Shockwave has been studied for the treatment of tendons, bones, joints, and spasticity. Shockwave seems to be especially effective in the treatment of chronic tendinopathies and plantar fasciitis. For boney injuries, it has demonstrated benefit for treating delayed healing bone stress injuries and non-union fractures, as well as osteonecrosis and avascular necrosis of the femoral head. It has also been shown to help decrease spasticity and pain in people with cerebral palsy or who have had a stroke.

What does treatment look like?

As with all PT related questions, it depends (if you know, you know). Every person's treatment varies based on the type of injury, how long it has been going on, as well as individual factors. But there are some generalizations among treatment.

First, the head of the shockwave unit remains in contact with the skin. Shockwave is administered to the areas of greatest pain, and has been shown to be most effective when secondary pain generators are also treated. An example of this would be if someone had posterior tibialis tendinopathy, the shockwave would be used directly on the tendon at the area of pain, and may also be used to address the posterior tibialis muscle, as well as the gastrocnemius and soleus (calf muscles), depending on clinical exam findings. The actual treatment of shockwave is painful, but afterwards usually leads to decreased pain after treatment.

Treatment usually requires around 3-5 sessions completed 1 x/ week. There also is benefit to coupling ESWT with physical therapy and guided return to activity to progressively load the tissue, safely.

Contraindications and Side Effects

ESWT is a relatively safe intervention, and can be used widely. There are however, a few contraindications for its use, and if a patient has one of these conditions, they would not be eligible to receive shockwave. Some contraindications are relative, and only apply in certain cases such as with a certain dosage of shockwave. Other conditions need to be considered before a patient receives shockwave. Similarly, there are some side effects, which patients must be aware of before consenting to this treatment.

Hard Contraindications (Do Not Pass Go):

• Active infection at the site

• Malignant tumor at the site of shockwave (okay if patient has cancer diagnosis but not near shockwave site)

• Pregnancy

Contraindications for Hi-Energy Treatments (Relative Contraindications):

Energy of >2.9-.60 mJ/mm2 (usually used for treatment of bone or calcfici tendinopathy) should not be used if any of the following are true:

• brain or nerve, lung or pleura in treatment focus

• significant coagulopathy (clotting disorders)

• epiphyseal plate (growth plate) in treatment focus

The following are not contraindications, but require clinician consideration or risk vs benefit, and potential increased monitoring if ESWT is elected: Cardiac pacemakers or other implants, the use of NSAIDs or anticoagulants currently, and recent corticosteroid injection.

Side Effects:

• Pain at site of application

• Skin Redness

• Skin Bruising

• Hematoma (a more severe type of bruise under the skin)

• Nerve Irritation (may cause numbness or tingling)

• Superficial Swelling

• Headache

• Migraine

• *2 cases reported of achilles tendon rupture within 2 weeks of shockwave treatment in females over the age of 60

Many of these side effects can be reduced with proper clinical decision making regarding the intensity of shockwave used, and post ESWT interventions. Topical analgesics and acetaminophin can be used to help manage local pain and swelling. In the case of a partial tear in a person with concern for tendon health, a period of decreased activity may be recommended to reduce the already very low risk of tendon rupture.

As with all interventions, the decision to incorporate ESWT into a treatment plan is made as a joint decision between the provider and patient after considering benefits, risks, and patient goals. ESWT may be a beneficial adjunct treatment in addition to physical therapy to help runners overcome tendinopathies, which are some of the most common running related injuries. Precision Performance and Physical Therapy is excited to be adding Shockwave Treatment to our Atlanta Runners' Clinic location! If you are interested in scheduling an appointment to see if ESWT is right for you, call 404.343.3314 or email admin@precisionpt.org.

Thanks for reading!

Dr. Elizabeth Karr PT, DPT, OCS

References:

Tenforde AS, Borgstrom HE, DeLuca S, et al. Best practices for extracorporeal shockwave therapy in musculoskeletal medicine: Clinical application and training consideration. PM&R. 2022;14(5): 611-619. doi:10.1002/pmrj.12790

Reilly JM, Bluman E, Tenforde AS. Effect of Shockwave Treatment for Management of Upper and Lower Extremity Musculoskeletal Conditions: A Narrative Review. PM R. 2018 Dec;10(12):1385-1403. doi: 10.1016/j.pmrj.2018.05.007. Epub 2018 Jun 1. PMID: 29775801.