Nowadays I am writing about electro therapy my name is to provide students user guide for this modalities so that after reading the article of log they can get understanding of the machine they are going to use in their clinical practice. So in this series my next blog is on modality:
Extracorporeal Shockwave Therapy (ESWT): Physics, Uses, Benefits, Evidence, Indications and Contraindications
Introduction
Extracorporeal Shockwave Therapy (ESWT) is a non-invasive physiotherapy modality that delivers mechanical pressure waves into targeted body tissues. It is widely used in musculoskeletal rehabilitation, particularly for chronic tendinopathies, plantar fasciopathy, calcific shoulder conditions, and selected other persistent soft-tissue disorders.
Unlike electrical modalities such as TENS or NMES, ESWT does not primarily work by delivering an electrical current. Instead, it applies mechanical acoustic energy to tissue.
The clinical effects of ESWT are believed to involve mechanotransduction, changes in local cellular signaling, blood-flow-related responses, modulation of pain, and tissue-remodeling processes. However, the exact biological mechanism is complex and varies according to tissue, dose, energy level, and treatment technique. Importantly, evidence for ESWT differs substantially between conditions, so it should not be considered a universal treatment for every musculoskeletal problem. (PubMed)
What Is Extracorporeal Shockwave Therapy?
Extracorporeal means outside the body.
Shockwave refers to a very rapid pressure disturbance that travels through a medium and produces a sudden rise in pressure followed by a negative-pressure phase.
During treatment, a handpiece delivers acoustic/mechanical energy through the skin toward the selected treatment area.
ESWT is commonly divided into:
Focused shockwave therapy (FSWT)
Radial pressure wave therapy (RPWT/RSWT)
Although both are commonly called "shockwave therapy," their physical characteristics are not identical.
Focused shockwaves concentrate acoustic energy toward a target at a selected depth, whereas radial pressure waves spread outward from the applicator and have their greatest energy closer to the skin surface. (PubMed)
Physics Behind ESWT
Understanding the physics helps explain why different ESWT devices can produce different clinical effects.
1. What is a shockwave?
A shockwave is a transient pressure disturbance characterized by an extremely rapid rise in pressure.
In a conventional acoustic wave, pressure changes relatively gradually.
A shockwave has a much steeper pressure front.
In simplified terms:
Rapid pressure rise → high peak pressure → negative-pressure phase → mechanical effects in tissue
The negative phase can contribute to cavitation, where microscopic gas bubbles form and subsequently collapse. Cavitation and mechanical stress are among the physical phenomena associated with shockwave exposure. (PubMed)
2. How are shockwaves generated?
Focused ESWT systems can generate pressure waves using several technologies.
Electrohydraulic generation
A rapid electrical discharge creates a spark in a fluid medium.
This produces a rapidly expanding bubble and pressure disturbance, which can then be reflected and focused toward the target.
Electromagnetic generation
An electrical current produces a magnetic field that rapidly moves a membrane. This movement creates a pressure wave that can be acoustically focused.
Piezoelectric generation
Large numbers of piezoelectric crystals rapidly deform when an electrical voltage is applied. Their combined mechanical movement generates an acoustic pressure wave.
These methods can produce focused acoustic energy at a specific depth. (PubMed)
3. How are radial pressure waves generated?
Radial systems generally use a pneumatic mechanism.
Compressed air accelerates a projectile inside the applicator. The projectile strikes an applicator head, producing mechanical pressure waves that travel into the tissues.
The energy is greatest near the applicator and decreases as the wave propagates deeper.
Therefore, radial pressure waves should not simply be regarded as identical to focused shockwaves delivered at a lower intensity. Their physical characteristics differ. (PMC)
4. Important physical parameters
The therapeutic effect of ESWT depends on several parameters, including:
Energy flux density
Peak pressure
Pulse duration
Rise time
Frequency
Number of impulses
Treatment depth
Treatment area
Type of applicator
Focused versus radial delivery
One important parameter is energy flux density (EFD), which describes the amount of acoustic energy delivered through a unit area.
Higher energy does not automatically mean better treatment. The appropriate dose depends on the condition, tissue, treatment goal, and device.
5. Focused versus radial ESWT
| Feature | Focused ESWT | Radial Pressure Wave |
|---|---|---|
| Energy distribution | Concentrated toward a focal region | Disperses outward |
| Maximum energy | Can occur at a selected depth | Highest near applicator |
| Depth targeting | Greater potential for deeper targets | Generally more superficial |
| Wave generation | Electrohydraulic, electromagnetic or piezoelectric | Usually pneumatic/ballistic |
| Common applications | Deep tendinopathy, calcification and selected bone conditions | Tendinopathies and superficial soft-tissue disorders |
| Physical classification | True focused shockwave/pressure wave | Radial pressure wave |
The distinction is clinically important because device type, energy delivery and treatment depth can influence treatment selection. Current evidence does not establish a universal superiority of focused over radial therapy across musculoskeletal conditions. A recent meta-analysis likewise found no consistent difference in pain or function between the two approaches across the studied disorders, although some low-certainty findings favored one approach for specific outcomes. (PubMed)
How Does ESWT Work?
The biological response to ESWT is usually described as mechanotransduction.
Mechanical forces generated by the treatment are detected by cells and tissues, potentially triggering intracellular signaling and changes in tissue behavior.
Proposed mechanisms include:
1. Mechanotransduction
Mechanical energy produces deformation and stress within cells and extracellular structures.
Cells can convert these mechanical stimuli into biochemical signals.
2. Pain modulation
ESWT may influence peripheral nociceptive mechanisms and pain signaling.
This may help reduce pain in some chronic musculoskeletal conditions.
3. Tissue remodeling
Repeated mechanical stimulation may influence cellular activity and extracellular matrix remodeling.
4. Vascular responses
ESWT may influence local vascular and angiogenic signaling.
5. Effects on calcification
In some calcific tendinopathies, mechanical forces may contribute to fragmentation or remodeling of calcific deposits.
However, biological mechanisms identified in laboratory or experimental studies should not automatically be interpreted as proof of clinical effectiveness. Clinical trials remain necessary to establish whether a particular ESWT protocol improves patient outcomes. (PubMed)
Indications
ESWT is most commonly considered for persistent or chronic musculoskeletal conditions, particularly when appropriate conservative rehabilitation has not produced sufficient improvement.
Common clinical indications include:
1. Plantar Fasciopathy
Plantar fasciopathy is one of the most common indications for ESWT.
Research suggests that ESWT can improve pain and function in some patients with persistent plantar fasciopathy. A 2024 systematic review and meta-analysis found ESWT to be generally tolerable and reported beneficial effects on clinical outcomes, although the optimal treatment parameters remain uncertain. (PubMed)
A separate 2025 systematic review and meta-analysis found ESWT to produce outcomes comparable with several other conservative modalities for plantar fasciitis. (PubMed)
2. Achilles Tendinopathy
ESWT has been studied for chronic Achilles tendinopathy, particularly insertional and mid-portion presentations.
Evidence suggests potential benefit, but outcomes can vary depending on whether ESWT is used alone or combined with an exercise-based rehabilitation program.
Exercise-based tendon loading remains an important component of rehabilitation rather than relying on ESWT alone. (PubMed)
3. Lateral Elbow Tendinopathy
ESWT may be considered for persistent lateral elbow tendinopathy, commonly called tennis elbow.
Evidence from systematic reviews suggests ESWT can improve pain and function in selected patients with upper-limb tendinopathies, although results are not uniformly positive across every study or protocol. (PubMed)
4. Rotator Cuff Tendinopathy
ESWT has been investigated in rotator cuff tendinopathy, including both calcific and non-calcific conditions.
For calcific rotator cuff tendinopathy, ESWT may help reduce pain and improve function, while some protocols may also promote reduction of calcific deposits.
However, recent evidence indicates that ultrasound-guided needling procedures may provide greater improvement for some outcomes than ESWT, so treatment choice should be individualized. (PubMed)
5. Calcific Tendinopathy
Calcific tendinopathy, particularly around the shoulder, is an important indication for ESWT.
The mechanical energy may help alter or fragment calcific deposits and stimulate subsequent biological remodeling.
Evidence supports clinical benefits in selected patients, although treatment parameters and comparisons with procedures such as ultrasound-guided needling remain important considerations. (PubMed)
6. Greater Trochanteric Pain Syndrome
ESWT has also been studied for lateral hip pain associated with gluteal tendinopathy and greater trochanteric pain syndrome.
A 2025 systematic review reported improvements in pain and functional outcomes across studies of hip and pelvic tendinopathies, although protocols varied substantially. (PubMed)
7. Selected Bone-Healing Problems
ESWT has also been used in selected orthopedic situations involving:
Delayed fracture healing
Non-union/pseudoarthrosis
Bone marrow edema
Selected early osteonecrosis
These applications require appropriate medical assessment and are generally more specialized than routine physiotherapy treatment. (PubMed)
Contraindications
Contraindications vary somewhat according to the device, energy level, treatment location and local clinical guidelines.
Important contraindications and precautions include:
Major contraindications
1. Pregnancy over or near the treatment area
Shockwave treatment should not be directed toward the fetus or embryo. (PubMed)
2. Malignancy in the treatment area
ESWT should not be applied directly over malignant tissue or a tumor-containing treatment area. (PubMed)
3. Active local infection
Treatment should generally be avoided over an active infection, including significant local infection or osteomyelitis. (PubMed)
4. Significant bleeding disorders
High-energy ESWT may increase the risk of bleeding or bruising in patients with significant coagulation disorders. (PubMed)
5. Treatment over vulnerable structures
Care should be taken to avoid directing shockwaves unnecessarily over:
Major nerves
Large blood vessels
The lungs
Sensitive neurovascular structures
Treatment location and device characteristics matter when determining the actual level of risk. (PubMed)
6. Skeletal growth plates
Direct application over an active growth plate is generally avoided, particularly in children and adolescents. (PMC)
Anticoagulants: Is ESWT Always Contraindicated?
This is an area where clinical judgment is important.
Anticoagulant or antiplatelet therapy can increase bleeding or bruising risk, particularly with higher-energy treatment.
However, medication use should not automatically be interpreted as an absolute contraindication in every patient or for every device.
The therapist should consider:
The medication
Dose
Bleeding history
Treatment intensity
Treatment site
Patient-specific risk factors
Medication should not be stopped solely for ESWT without appropriate medical advice. (PubMed)
How Is ESWT Applied?
A typical treatment may involve the following steps:
Step 1: Assessment
The clinician identifies the diagnosis, symptom location, tissue involved and suitability for ESWT.
Step 2: Localization
The painful or pathological structure is identified.
Ultrasound or other imaging may be useful in selected cases, especially for deeper or precisely localized structures.
Step 3: Coupling
A suitable coupling medium, commonly ultrasound gel, is placed between the applicator and skin to improve transmission of acoustic energy.
Step 4: Initial low-intensity pulses
Treatment may begin at a lower intensity to allow the patient to adapt.
Step 5: Therapeutic dose
Energy, frequency and number of impulses are adjusted according to the condition, device and patient tolerance.
Step 6: Post-treatment advice
Patients are usually advised to follow an appropriate rehabilitation program and activity modification plan.
ESWT should generally be viewed as one component of rehabilitation rather than an isolated cure.
What Does ESWT Feel Like?
ESWT can be uncomfortable, particularly when the applicator is positioned directly over a highly sensitive tendon or painful structure.
Patients may experience:
Tapping or striking sensations
Sharp discomfort
Aching
Temporary tenderness
Mild redness
Bruising in some cases
The intensity can usually be adjusted according to the patient's tolerance and the treatment protocol.
How Many Sessions Are Usually Needed?
Treatment protocols vary considerably.
A commonly used clinical approach involves approximately 3–5 sessions, often separated by about one week, although some conditions may require different schedules.
The exact number of impulses, energy level and frequency should be selected according to the diagnosis and device rather than following a single universal protocol.
Research continues to investigate the optimal dose and treatment parameters. (PubMed)
Benefits of ESWT
Potential benefits include:
Non-invasive treatment
No surgical incision
Relatively short treatment sessions
Can be used for persistent musculoskeletal conditions
May reduce pain
May improve function
May stimulate tissue remodeling
Can sometimes be combined with exercise therapy
Generally produces only transient adverse effects when appropriately applied
For example, systematic reviews have reported beneficial effects in plantar fasciopathy, selected tendinopathies and calcific shoulder conditions, although the magnitude and certainty of benefit differ between conditions. (PubMed)
Side Effects and Safety
Most reported adverse effects are mild and temporary.
Possible effects include:
Temporary treatment pain
Skin redness
Local tenderness
Mild swelling
Bruising
Temporary increase in symptoms
A systematic review of hip and pelvic tendinopathies reported adverse events such as increased pain and skin irritation, with an overall reported rate of approximately 12% across the included studies. (PubMed)
Severe complications are uncommon when appropriate patient selection and treatment techniques are used.
ESWT and Exercise Therapy
One important point for physiotherapists and patients is that ESWT does not necessarily replace exercise rehabilitation.
For many tendinopathies, progressive loading is an important part of restoring tissue capacity and function.
ESWT may be used as an adjunct to:
Progressive resistance exercise
Tendon-loading programs
Stretching where clinically appropriate
Strengthening
Movement retraining
Activity modification
Education
The best rehabilitation plan depends on the diagnosis and individual patient presentation.
ESWT vs Therapeutic Ultrasound
| Feature | ESWT | Therapeutic Ultrasound |
|---|---|---|
| Primary energy | Mechanical pressure/acoustic energy | High-frequency sound waves |
| Typical treatment sensation | Tapping/pressure, sometimes uncomfortable | Usually mild or minimal sensation |
| Energy characteristics | Can produce very rapid pressure changes | Continuous or pulsed acoustic energy |
| Common use | Chronic tendinopathy, plantar fasciopathy, calcific conditions | Soft-tissue rehabilitation and selected pain conditions |
| Depth | Depends strongly on device | Depends on frequency and tissue characteristics |
| Evidence | Stronger for selected chronic conditions | Evidence varies considerably by condition |
ESWT should not be assumed to be better simply because it delivers higher mechanical energy. The appropriate modality depends on the diagnosis, evidence and clinical objective.
ESWT vs Laser Therapy
Both ESWT and photobiomodulation use physical energy to influence biological processes, but the energy forms are fundamentally different.
ESWT: mechanical/acoustic energy
Laser/PBM: optical energy
Clinical outcomes may overlap in some conditions, but they should not be considered interchangeable treatments.
ESWT vs Corticosteroid Injection
ESWT and corticosteroid injections have different mechanisms and risk profiles.
In plantar fasciitis, systematic-review evidence has compared ESWT with corticosteroid injections and found that outcomes can vary according to follow-up period and treatment parameter. (PubMed)
A treatment decision should therefore consider diagnosis, chronicity, previous treatment, patient preference, potential risks and the available evidence rather than assuming one intervention is universally superior.
Important Clinical Considerations
ESWT treatment outcomes can vary because of differences in:
Diagnosis
Acute versus chronic presentation
Focused versus radial device
Energy level
Number of impulses
Treatment frequency
Treatment location
Patient characteristics
Coexisting pathology
Rehabilitation program
This explains why two studies using "shockwave therapy" may report different outcomes.
Common Myths About ESWT
Myth 1: "Shockwave therapy breaks every painful tissue."
Fact: ESWT does not simply destroy painful tissue. Its effects involve mechanical stimulation and biological responses, and the mechanisms are more complex than tissue destruction.
Myth 2: "More intensity always gives better results."
Fact: Higher energy can increase discomfort and adverse effects, and the optimal dose depends on the clinical condition.
Myth 3: "Radial and focused shockwaves are exactly the same."
Fact: They have different physical characteristics and energy distributions.
Myth 4: "ESWT works immediately."
Fact: Some patients may experience changes in pain relatively early, but biological and clinical improvements can develop over weeks.
Myth 5: "ESWT eliminates the need for rehabilitation exercises."
Fact: For many musculoskeletal disorders, exercise and progressive loading remain important components of rehabilitation.
Frequently Asked Questions
Is ESWT painful?
It can be uncomfortable, particularly over sensitive structures. Treatment intensity can usually be adjusted to improve tolerance.
Is ESWT safe?
When appropriately selected and administered, ESWT is generally considered safe, with most adverse effects being mild and temporary. (PubMed)
How long does an ESWT session take?
Many treatment sessions are relatively short, often around 10–20 minutes depending on the condition, device and treatment area.
Can ESWT cure plantar fasciitis?
It may improve pain and function in some patients with persistent plantar fasciopathy, but it should not be presented as a guaranteed cure. Evidence supports its use in selected patients, while optimal protocols remain under investigation. (PubMed)
Can ESWT be used for Achilles tendinopathy?
Yes, it has been studied extensively for Achilles tendinopathy. It is generally best considered as part of a broader rehabilitation strategy rather than a replacement for progressive tendon loading. (PubMed)
Can ESWT remove calcium from the shoulder?
ESWT may contribute to reduction or resorption of calcific deposits in selected patients with calcific rotator cuff tendinopathy. However, results vary and other interventions, including ultrasound-guided needling, may also be appropriate. (PubMed)
Can ESWT be used during pregnancy?
Treatment should not be directed toward the fetus or embryo, and pregnancy is generally considered a contraindication for ESWT in the relevant treatment region. (PubMed)
Can I exercise after ESWT?
Exercise recommendations depend on the condition and treatment protocol. In many rehabilitation programs, appropriately dosed exercise remains important, but high-load activities may need temporary modification.
Evidence-Based Takeaway
Extracorporeal Shockwave Therapy is a clinically important non-invasive modality that delivers mechanical acoustic energy to targeted tissues.
Its physics involves rapid pressure changes, mechanical stress and, depending on the technology, focused or radial energy delivery.
The biological response may involve mechanotransduction, pain modulation, vascular signaling and tissue remodeling, but no single mechanism completely explains all clinical effects. (PubMed)
Current evidence supports ESWT for several selected musculoskeletal conditions, particularly plantar fasciopathy, certain tendinopathies and calcific rotator cuff tendinopathy. However, treatment effects vary by condition, and the ideal treatment dose and device parameters are not universally established. (PubMed)
Therefore, ESWT should be used as a condition-specific, evidence-informed intervention, preferably integrated with appropriate exercise, education and rehabilitation.
Final Thoughts
ESWT represents an interesting intersection between physics, biomechanics and tissue biology.
Rather than simply "breaking up tissue," shockwave treatment exposes biological tissues to carefully controlled mechanical forces. These forces can produce cellular and tissue responses that may contribute to pain reduction and functional recovery.
For physiotherapists, the key is not simply knowing how to operate a shockwave machine. Effective clinical use requires understanding the diagnosis, physics of the device, treatment parameters, contraindications, patient response and the rehabilitation program surrounding the modality.
When appropriately selected, ESWT can be a useful component of modern musculoskeletal rehabilitation—but it should be used because the clinical indication and evidence support it, not simply because a patient has persistent pain.
Selected References
Auersperg V, Trieb K. Extracorporeal shock wave therapy: an update. EFORT Open Reviews. 2020. (PubMed)
Lippi L, et al. Efficacy and tolerability of extracorporeal shock wave therapy in patients with plantar fasciopathy: a systematic review with meta-analysis and meta-regression. European Journal of Physical and Rehabilitation Medicine. 2024. (PubMed)
Brindisino F, et al. The effectiveness of extracorporeal shock wave therapy for rotator cuff calcific tendinopathy: a systematic review with meta-analysis. Physiotherapy Research International. 2024. (PubMed)
Elgendy MH, et al. Effectiveness of extracorporeal shockwave therapy in treatment of upper and lower limb tendinopathies: a systematic review and meta-analysis. Physiotherapy Research International. 2024. (PubMed)
Xiong Y, et al. Efficacy and safety of extracorporeal shock wave therapy for upper limb tendonitis: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Medicine. 2024. (PubMed)
Simental-Mendía M, et al. Effect of extracorporeal shockwave therapy on plantar fascia thickness in plantar fasciitis: a systematic review and meta-analysis of randomized controlled trials. Archives of Orthopaedic and Trauma Surgery. 2024. (PubMed)
Schmitz C, et al. Efficacy and safety of extracorporeal shock wave therapy for orthopedic conditions. British Medical Bulletin. (PubMed)
The Effects of the Exposure of Musculoskeletal Tissue to Extracorporeal Shock Waves. (PubMed)
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