Shockwave Therapy: Benefits, Risks, and Applications

Shockwave therapy is a non-invasive treatment modality utilizing high-energy sound waves to address various medical conditions, particularly those affecting the musculoskeletal system. These sound waves travel through the skin, penetrating underlying tissues to stimulate healing and reduce pain. While generally considered safe, understanding both the benefits and potential risks is crucial before considering this treatment option.

What is Shockwave Therapy?

The clinical term for shockwave therapy, particularly when used for erectile dysfunction, is low-intensity shockwave therapy (LiSWT). During the treatment, a small wand-like device uses targeted sound waves to stimulate tissue and encourage blood flow, which can also speed up the healing process. The pulses are delivered through skin contact. The waves are generated by a small machine, travel through a cable and an applicator wand and into your injured tissues. Shockwave therapy does not require any incisions.

It's important to distinguish shockwave therapy from radial wave therapy, which is commonly advertised as a noninvasive treatment for erectile dysfunction available at both medical and non-medical facilities.

How Does Extracorporeal Shockwave Therapy (ESWT) Work?

Extracorporeal shockwave therapy (ESWT) uses a device to produce shock waves and transmit them to a certain area of the body. During an ESWT session, a handheld device sends acoustic pulses through the skin to targeted areas of damaged tissue. These pulses create what's known as "microtrauma." This controlled microtrauma helps stimulate your body's natural healing processes. Increased blood flow to the area improves circulation and metabolism, prompting the production of new cells. These pressure waves result in a biological effect within the body, promoting certain processes and helping to reduce pain. When these pressure waves pass through the body’s tissues, they cause a biological response that promotes healing, repair, and pain relief. However, researchers do not yet fully understand exactly how these therapeutic effects occur.

ESWT takes time to work and tends to involve multiple sessions over time. A single session can involve hundreds or thousands of shock waves. ESWT treatment requires multiple doses and sessions.

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Inside the machine is a projectile contained in a tube. The machine uses compressed air to accelerate the projectile up to 62 mph within the tube. When the projectile strikes the head of the applicator, it creates energy that is converted into acoustic pressure waves. Depending on which head we use on the handheld applicator, the pressure waves can penetrate tissue up to 6 cm, reaching deeper than massage or at-home percussive therapy devices.

Types of Shockwaves: Focused vs. Radial

Multiple devices can administer shock waves. Some produce focal shock waves, while others produce radial waves.

Focal Shock Waves (FSWT): FSWT features the generation of a pressure field that converges in the adjustable focus at determined depths in specific tissues where maximal pressure is achieved. Focal shock waves have a higher intensity that can reach areas deep within the tissue. A special generator produces them, and a lens focuses and sends them into the body. Focused shockwaves can be generated via three methods: electrohydraulic (EH), electromagnetic (EM) and piezoelectric (PE). Due to the fact that the acoustic impedance of water and biologic tissue is comparable, focused shockwaves are generated in water. Therefore, reflection is limited and propagation of waves into the body is facilitated. The similarity between EH, EM and PE is that they all utilize water for the generation of focused shockwaves. The difference, however, is the moment at which the shockwaves are formed.
Radial Shock Waves (RSWT): Meanwhile, radial shock waves have a lower intensity and are generated upon acceleration of a projectile, using compressed air through a tube which has an extremity connected to an applicator. Radial devices create shock waves by using compressed air to move a projectile quickly. The projectile then transfers its energy to the applicator, which transmits the shock wave through the skin. The intensity is greatest at the applicator and then decreases as it moves deeper into the body. Radial shockwaves are not generated in water. Instead, they are generated upon acceleration of a projectile, using compressed air through a tube which has an extremity connected to an applicator. The fundamental differences between the two types of shockwave therapy, as illustrated in Fig. 1 of this manuscript, are as follows. First and foremost, focused shockwaves reach their maximal energy deeper in body tissues whereas radial shockwaves have a more superficial aspect.

Some research points out that it may be equivocal to refer to RSWT as an actual shockwave therapy because, technically, such devices do not generate “real” shockwaves. RSWT does not have the regular physical features of shockwaves, such as short rise time, a high peak pressure and non-linearity.

Energy Flux Density (EFD)

Energy Flux Density (EFD) is the parameter referred to by professionals based on the flow of shockwave energy through an area with perpendicular orientation to the direction of propagation. The unit of measurement is given in mJ/mm2. ESWT has been previously classified based on EFD with low (<0.08 mJ/mm2), medium (<0.28 mJ/mm2) and high (<0.60 mJ/mm2) treatment intensities. It should be taken into consideration that there is no consensus in the classification regarding EFD since the literature shows different energy parameters reported in various studies. Despite this observation, clinicians typically resort to energy ranges from 0.001 to 0.4 mJ/mm2. Lower and medium EFD trigger the release of nitric oxide (NO), which is beneficial due to its antalgic, angiogenetic and anti-inflammatory effects in clinical settings. Higher EFD intensity is usually recommended for the treatment of pseudoarthrosis, for example, and yields about 72% success rate.

Reaction Phases of ESWT on Tissue

From previous research, 4 reaction phases of ESWT on tissue have been proposed, as follows: physical, physicochemical, chemical, and biological.

Firstly, in the physical phase, shockwaves cause a positive pressure to generate absorption, reflection, refraction, and transmission of energy to tissues and cells. Additionally, it appears that cavitation increases the permeability of cell membranes and ionization of biological molecules.
Secondly, in the physicochemical phase, the physical stimulus leads to biochemical reactions. Interestingly, a study reported that low-energy ESWT also stimulates a polarity shift in the macrophage phenotype from M1 to M2. This is particularly valuable for the inflamed cellular microenvironment from a standpoint of the regenerative potential of ESWT, because the macrophage expresses two major phenotypes. These are M1 and M2, and may depend on the given chemical signal. Since M1 is usually stimulated by microbial agents, it takes on a pro-inflammatory role. Conversely, the M2 macrophage is produced by the T-helper type 2 (Th2) immune response and exhibits an anti-inflammatory property, typically characterized by an increase in the biosynthesis of interleukins IL-4, IL-5, IL-9 and IL-13. The type 2 response is known to be directly involved in regenerative processes after injury and macrophages elicit their protective role mainly by the promotion of angiogenesis via the release of cytokines and growth factors. The M2 macrophage has also shown stimulation of cell proliferation and repair through polyamine and collagen synthesis in addition to other tissue remodeling functions, releasing IL-10 and IL-4. In addition to the aforementioned cellular effects, many studies on ESWT for musculoskeletal infirmities have been performed with focused shockwaves, generating promising results.

The Biological Effects of ESWT

It has been hypothesized that the biological effects of ESWT are a consequence of mechanotransduction, a phenomenon which relies on the action of ultrasonic vibrations on tissues, which then lead to regeneration and healing. So far, there are two principal hypotheses proposed to explain the analgesia induced by SW treatment. One of them suggests that SWs degenerate nerve fibers from small immunoreactive neurons, therefore decreasing the concentration of pro-inflammatory mediators. The second mechanism is theorized to cause analgesia via hyperstimulation, indicating that SWs trigger the release of endorphins and other analgesic molecules by activating the descending inhibitory system. To elaborate, conditioned pain modulation remains an experimental paradigm, dependent on the state of the descending inhibitory system function. This means that in a standard nociceptive system, for instance, the amount of pain generated by a primary nociceptive stimulus will be reduced during and after the presentation of a second nociceptive stimulus.

Other studies performed on animals, however, suggest that ESWT may have an influence on pain transmission to the brainstem by acting on substance P, calcitonin gene gene-related peptide (CGRP) expression in the dorsal root ganglion, and on neurovascular sprouting. In a rat model of Achilles Tendinopathy (AT), there was evidence indicating that ESWT triggered the release of tenocyte-derived growth factors and increased expression of transforming growth factor β1 (TGF-β1) and insulin-like growth factor 1 (IGF-1) in response to treatment. In regards to tendinopathy, there is another important molecule produced via the effects of shockwaves, which is lubricin. This mucinous glycoprotein is particularly important for tendinous structures as it facilitates tendon gliding. Lubricin expression is upregulated by both mechanical and biochemical stimuli. Elaborating further, the elevated expression of TGF-β1 mediated by SW has also been found to stimulate the expression of lubricin, contributing to healing in tendinopathy. These observations supported the long hypothesized effect of ESWT in stimulating the expression of lubricin in tendons, prompting researchers to carry on with additional investigations. Zhang and colleagues explored the effects of shockwaves in tendons and septa of rats in 2011. The researchers learned that increased lubricin deposition in tendons and septa following the application of ESWT may convey beneficial effects. Their conclusion was derived from the observation that the expression of the endogenous lubricant was associated with facilitated movement among gross structures and collagen fascicles.

Common Applications of Shockwave Therapy

Shockwave therapy has a wide range of applications, primarily in the treatment of musculoskeletal conditions. Some common uses include:

Plantar Fasciitis: Shockwave therapy is frequently used to treat foot and ankle conditions like plantar fasciitis. A 2018 study found that ESWT lowered pain intensity and improved quality of life and function in patients with plantar fasciitis and other tendon issues.
Achilles Tendinopathy: Another common application is for Achilles tendinopathy, both of which can cause significant discomfort and mobility issues if left untreated.
Tennis Elbow (Lateral Epicondylitis): Shockwave therapy has also been FDA-approved as a treatment for lateral tennis elbow and plantar fasciitis, giving patients hope.
Shoulder Pain: Patients often seek this therapy as an alternative to surgery for conditions like tennis elbow, shoulder pain, and heel issues.
Tendon Injuries: If you’ve sustained an injury to a tendon, elbow, or hamstring, your doctor might recommend shockwave therapy. Any type of tendinopathy can put you out of work for weeks at a time.
Erectile Dysfunction (ED): University of Utah Health offers shockwave therapy as an option for patients suffering from ED. Shockwave therapy for ED is still considered an experimental treatment option. During the treatment, a small wand-like device uses targeted sound waves to stimulate penile tissue and encourage blood flow, which can also speed up the healing process.
Bone Conditions: ESWT has been studied in the treatment of fractures, delayed bone healing, and osteonecrosis or avascular necrosis.
Other Musculoskeletal Conditions: ESWT is a treatment option for various conditions affecting the following:musclestissuesjoints bonesother parts of the musculoskeletal system

Benefits of Shockwave Therapy

Non-Invasive: Shockwave therapy does not require any incisions. It is a noninvasive treatment option for various conditions that affect the musculoskeletal system. Shockwave therapy is praised for being a non-invasive option with minimal side effects.
Avoidance of Surgery: Along with helping to avoid surgery and treating conditions surgery can’t fix, ESWT also can help patients 18 and older avoid repeated steroid injections, which we can cause increased breakdown of the tissue long term. It’s non-surgical. You can continue to live your life while you receive shockwave therapy for plantar fasciitis, bursitis, or tennis elbow instead of setting aside time for a lengthy surgical recovery.
Stimulates Natural Healing: Shockwave therapy can offer such help, jump-starting the body’s ability to regenerate new tissue. The healing processes that shockwave therapy stimulates are completely natural functions that your body can handle all on its own.
Pain Reduction: It also decreases your pain by directly stimulating your nerves at the site of the injury. Extracorporeal shockwave therapy uses shock waves to help with healing, pain reduction, and repair processes. ESWT uses shock waves to help reduce pain and encourage healing or repair in the treatment area.
Quick Return to Activity: One of the greatest benefits of shockwave therapy is a quick return to activity, typically on the same day or the next day. Athletes sometimes receive shockwave therapy to help with pain recovery during a match or competition and return to play. Athletes and active people like shockwave therapy because it requires little to no recovery time. Unlike surgery, there is no downtime associated with shockwave therapy.
Potential for Long-Term Relief: It promotes natural tissue regeneration and provides long-term relief.
May Help Tough Cases Heal: Cases of tendon injuries that don’t respond to such treatment, though, may frustrate both physicians and patients. Plantar fasciitis, as one example, is a chronic condition that can be difficult to treat and causes patients a lot of pain. It often requires more than NSAIDS and rest but is also usually not severe enough to require surgery. Shockwave therapy offers a middle-ground treatment that might help the soft tissues regenerate.

Risks and Side Effects

Shockwave therapy is generally a safe procedure with few risks and side effects. However, it is important to understand the potential risks and side effects of shockwave therapy before proceeding with treatment. Most side effects of shockwave therapy are mild and will resolve on their own over time. It is also important to take steps to prevent side effects from occurring in the first place. With appropriate use, it generally does not lead to severe complications.

Common Side Effects: In fact, the most common side effect is a temporary increase in pain or discomfort in the area that was treated. Some of the typical side effects a person experiences may include:minor or moderate pain or discomfortskin discolorationmild bruisingtinglingnumbnessswellingnerve irritationdizzinessinflammation throbbingYou might notice slight bruising or odd sensations in the spot where you were treated. This effect should be limited to numbness and mild swelling as the area heals, though.
Rare but Serious Side Effects: Rare but serious side effects can occur in some cases. These may include skin burns, nerve damage, and tissue damage. If you experience any severe side effects, it is important to seek medical attention right away.
Pain and Discomfort: While ESWT is non-invasive, it can still be uncomfortable. In particular, high-intensity versions of the treatment are known to cause discomfort. Some patients report significant pain during the procedure, which may deter them from completing the full treatment plan.
Soreness and Bruising: It is not uncommon to feel a bit sore afterward and have some bruising at the treatment area.
Limited Suitability: Shockwave therapy isn't suitable for everyone.

Contraindications: When to Avoid Shockwave Therapy

Health experts do not recommend ESWT in certain cases. In some situations, high energy doses are inadvisable, though low energy doses may be more suitable. Your doctor probably won't recommend shockwave therapy, for instance, when soft tissue is torn beyond repair. That could increase the soft tissue damage in this case. Your doctor also won't consider shockwave therapy when an injury clearly needs surgery instead of a noninvasive treatment.

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ESWT, or specifically high energy ESWT, may be inappropriate when a person has:

a serious infection
complete tendon rupture
bleeding or blood clotting disorders
cancerous tissue in the treatment area
cancer that has spread
multiple myeloma
lymphoma
It may also be inappropriate for pregnant people.
In addition, high energy ESWT is unsuitable when certain structures, such as a growth, a plate, or the spine, are present in the treatment area.
Shockwave treatment also shouldn’t be used:Close to the womb during pregnancyOn malignant tumors or nearby tissuesNear the brain or spineNear the lungsOn a patient with any type of bleeding disorder

Before receiving shockwave therapy, it is important to discuss any underlying medical conditions or medications you are taking with your shockwave therapy provider.

Factors Influencing Effectiveness

According to a 2023 review, health experts consider ESWT an effective treatment. However, its effectiveness can depend on a person’s condition, the protocols healthcare professionals use, and other factors. Variable Effectiveness: While some patients see great improvement, others experience little to no relief from ESWT. Conditions like cellulite, for example, often require the therapy to be combined with other treatments to be fully effective.

What to Expect During Shockwave Therapy

A shockwave therapy regimen typically includes six separate treatments, but treatment protocols could change as more research becomes available. This procedure is performed in an exam room and does not require anesthesia. Most patients feel results right away and need only two or three treatments over six to 12 weeks for complete healing and lasting symptom resolution. The beauty of ESWT is that if it is going to work, it likely will start working immediately after the first treatment. So, if you don’t start seeing results right away, we can investigate other potential causes of your symptoms.

The Procedure

During the procedure, your urologist will move a wand-like device around different areas of your penis. Urologists at U of U Health use DUOLITH®devices, which emit gentle pulses that trigger increased blood flow. During shockwave therapy, your provider will spread a gel on your skin, like what is used during an ultrasound. After setting up the machine, the doctor will touch the shockwave probe to your injured area and apply the therapy. Every application of sound waves will sound like a click. We will position you so that we can get to the problem area and keep you comfortable, and then apply a water-based gel to your skin. We will move the handheld applicator over the area while it releases pressure waves, slowly increasing the pulses until we reach your therapeutic level.

Pain Management

During the shockwave procedure itself, we may use a local anesthetic to dull the sensations of the vibrations. Shockwave therapy can be uncomfortable, especially since it focuses on an already injured spot. But providers will control the energy to a level of pain that you can tolerate. No local anesthesia is used.You customize the treatment to each patient’s personal pain tolerance. I tell patients we are trying to reach a five out of 10 on the pain scale. We will start out at a low level and increase it until we reach your personal five, at which point we’ll hold steady at the therapeutic range for about 2,000 pulses. The process takes about 15 minutes.

Post-Treatment Care

Once the treatment is complete, you will be able to return home. You should be able to safely drive yourself home. If you experience pain, your doctor will recommend over-the-counter (OTC) medications, such as acetaminophen or ibuprofen for pain relief. After the procedure, it is best to avoid anti-inflammatory medications, such as Advil because stimulating the inflammation cascade is part of the healing process activated by ESWT.

Duration of Treatment Effects

Most people who get shockwave therapy for ED will often see benefits within one to three months. The initial results (within the first several weeks) can be dramatic. You may initially have a decrease in pain that returns after one to two weeks. You may need more than one session to treat your condition.

Cost and Insurance Coverage

Since shockwave therapy is a fairly new ED treatment that is not covered by insurance plans, your urologist may recommend other ED treatment options first. Insurance may not cover ESWT costs. Doctors may not consider it a medically necessary treatment. Someone can check with their insurance provider to see if ESWT meets their coverage criteria. That’s not to say it’s out of reach for the average patient-even when paying out of pocket, we do what we can to make sure this is an affordable treatment option for our patients who want it.

Choosing a Qualified Provider

The best way to minimize the risks associated with shockwave therapy is to choose a qualified provider. It is important that you were prescribed this treatment by a licensed professional and that you only receive shockwave therapy from a qualified clinician. Before receiving shockwave therapy, it is important to discuss any underlying medical conditions or medications you are taking with your shockwave therapy provider.

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