Shockwave Therapy (ESWT): How It Works and When It’s Needed

Shockwave therapy (eswt)

Extracorporeal Shock Wave Therapy (ESWT) represents one of the most widely used instrumental therapies in orthopedics and physiotherapy over the last twenty years. These are high-energy acoustic waves that, applied externally to the area to be treated, are capable of stimulating biological tissue repair processes, reducing pain, and promoting the reabsorption of calcifications.

Originally introduced in medicine in the 1980s for breaking up kidney stones (lithotripsy), shockwaves have found increasing application in the musculoskeletal field since the 1990s. Today, they are successfully used in the treatment of numerous tendon, bone, and soft tissue pathologies: from plantar fasciitis to calcific tendinitis of the shoulder, from epicondylitis to heel spur.

Their effectiveness is supported by a growing number of scientific studies and international guidelines, which recommend their use as a conservative therapeutic option before resorting to surgery. However, not all indications have the same level of evidence, and the treatment must always be prescribed and supervised by a doctor or physical therapist capable of evaluating the individual clinical case.

What Shockwaves Are: The Physical Principle

Shockwaves are acoustic impulses characterized by a very high pressure peak (up to 100 MPa), reached in very short times (a few nanoseconds), followed by a negative pressure phase. This characteristic distinguishes them from traditional therapeutic ultrasounds, which generate continuous low-energy sinusoidal waves.

How They Are Generated

Shockwaves can be generated by three main mechanisms:

• Electrohydraulic: an electrical discharge produces a spark that vaporizes the surrounding water, generating the shockwave. This is the principle used in classic lithotripsy.
• Electromagnetic: an electromagnetic field accelerates a metallic membrane, which transmits the impulse to the surrounding medium.
• Piezoelectric: piezoelectric crystals rapidly expand under electrical stimulation, producing the acoustic wave.

Regardless of the generating mechanism, the result is a mechanical impulse that propagates through the tissues until it reaches the target area, where it exerts its biological effects.

Key Treatment Parameters

The main parameters that define a shockwave treatment are:

• Energy Flux Density (EFD): expressed in mJ/mm², it indicates the energy transferred per unit of surface area. Treatments are distinguished as low energy (< 0.08 mJ/mm²), medium energy (0.08-0.28 mJ/mm²), and high energy (> 0.28 mJ/mm²).
• Number of impulses: the total number of “shots” administered per session, generally between 1500 and 4000.
• Frequency: the number of impulses per second (Hz), typically between 1 and 15 Hz.
• Pressure: expressed in bar, it indicates the maximum pressure reached by the wave.

Focal vs. Radial Shockwaves: The Differences

Shockwaves are high-pressure acoustic impulses (up to 100 MPa) that propagate through tissues in nanoseconds, distinguished from ultrasound by rapid pressure peaks followed by negative phases. One of the most important distinctions concerns the type of shockwave used. There are two main categories, with different characteristics and indications.

Focal Shockwaves

Focal shockwaves (or “true” shockwaves) concentrate energy at a precise point in depth (the focus). Thanks to focusing systems, energy is channeled into a restricted area, reaching high energy densities. They are particularly indicated for deep structures and for pathologies such as pseudoarthrosis and calcific tendinitis.

Radial (or Ballistic) Shockwaves

Radial shockwaves (rESWT) are generated by a pneumatically accelerated projectile that strikes a metallic applicator. The energy spreads radially from the surface, decreasing with depth. They are easier to use, less expensive, and suitable for superficial and widespread pathologies.

Comparative Table: Focal vs. Radial

In clinical practice, many centers have both types, and the professional chooses the most suitable one based on the pathology, the depth of the structure to be treated, and the patient’s response.

Biological Mechanism of Action

The effect of shockwaves is not simply “mechanical.” The acoustic impulse triggers a cascade of biological responses at the cellular and tissue level, which represent the true therapeutic mechanism.

Mechanotransduction

When the shockwave passes through tissues, it generates compression and traction forces that are perceived by cells through membrane mechanoreceptors. This mechanical stimulus translates into intracellular biochemical signals (mechanotransduction), which activate genes involved in tissue repair.

Neoangiogenesis

One of the most studied and documented effects is the stimulation of new blood vessel formation (neoangiogenesis) in the treated area. Increased local vascularization improves the supply of oxygen and nutrients, promoting the healing of chronically suffering tissues. Histological studies have shown a significant increase in neoangiogenesis markers (VEGF, eNOS) in tissues treated with shockwaves.

Pain Modulation

Shockwaves exert an analgesic effect through several mechanisms:

• Hyperstimulation of nerve fibers: the intense mechanical stimulus causes a kind of “overload” of nociceptors, resulting in reduced pain transmission (gate control theory).
• Reduction of Substance P: studies have shown a decrease in the concentration of Substance P (a pain neurotransmitter) in treated tissues.
• Local denervation: at high energies, shockwaves can cause temporary denervation of free nerve endings, with an analgesic effect.

Stimulation of Tissue Repair

Shockwaves promote cell proliferation and differentiation, stimulating collagen production by fibroblasts and favoring the remodeling of tendon and bone tissue. In bone, they stimulate osteoblast activity, promoting callus formation in pseudoarthrosis.

Effect on Calcifications

In calcific tendinitis, shockwaves act through a dual mechanism: on the one hand, they fragment calcium deposits through direct mechanical effect, and on the other hand, they stimulate biological reabsorption through macrophage activation and increased local vascularization.

Anti-inflammatory Effect

Paradoxically, despite causing an initial acute inflammatory reaction, shockwaves lead in the medium term to a modulation of the chronic inflammatory response, favoring the transition from stagnant inflammation to an active reparative process. This is particularly relevant in chronic tendinopathies, where the problem is not so much the excess of inflammation as its chronicity and the tissue’s inability to complete healing.

Main Indications

Shockwaves are indicated in numerous musculoskeletal pathologies. Below are the main ones, divided by level of scientific evidence.

Indications with Strong Evidence

• Plantar fasciitis: this is the indication with the most supporting studies. Shockwaves (both focal and radial) are recommended in chronic forms resistant to conservative treatment for at least 6 months. Success rates reported in the literature range from 60% to 80%.
• Calcific tendinitis of the shoulder: high-energy focal shockwaves represent the first-choice treatment for symptomatic rotator cuff calcifications. Complete or partial reabsorption of calcification is achieved in 60-90% of cases.
• Chronic lateral epicondylitis (tennis elbow): indicated in forms refractory to conservative therapy. Evidence shows significant effectiveness in reducing pain and improving function in the medium to long term.

Indications with Good Evidence

• Heel spur: often treated concurrently with plantar fasciitis, with positive results on pain reduction.
• Chronic Achilles tendinitis: both in insertional and mid-tendon forms. Good results in chronic forms unresponsive to conservative treatment.
• Pseudoarthrosis and delayed union: high-energy focal shockwaves stimulate bone callus formation. They represent an alternative to surgical revision in selected cases, with success rates of 60-80%.
• Supraspinatus tendinitis and rotator cuff tendinopathies without calcification.
• Trochanteric pain syndrome (greater trochanteric pain syndrome): shockwaves have proven effective in treating gluteal tendinopathies and trochanteric bursitis.

Indications with Emerging Evidence

• Groin pain and adductor tendinopathies: growing evidence, especially in chronic forms in athletes.
• Patellar chondropathy and patellar tendinopathy: used as part of an integrated rehabilitation program.
• Myofascial pain syndrome and trigger points: radial shockwaves have proven effective in treating myofascial trigger points, with effects comparable to or superior to infiltrative therapy.
• Post-stroke spasticity: a more recent application, with promising results in reducing spastic muscle tone.
• Osteonecrosis of the femoral head (early stages): positive preliminary evidence with high-energy focal shockwaves.

Contraindications

Like any treatment, shockwave therapy also has contraindications that must be carefully evaluated by the doctor or physical therapist before starting therapy.

Absolute Contraindications

• Pregnancy: treatment should not be administered to pregnant women, due to the theoretical risk of effects on the fetus.
• Neoplasms in the treatment area: stimulation of cell growth and vascularization could theoretically promote tumor progression.
• Pacemakers or implantable cardiac defibrillators: shockwaves can interfere with the functioning of cardiac devices, altering their programming or causing malfunctions.
• Open growth plates (growing epiphyses): in children and adolescents, treatment should not be applied near growth plates, due to the risk of damage to bone growth.
• Coagulation disorders and anticoagulant therapy: the risk of hematoma and bleeding is increased. Patients on oral anticoagulants (warfarin, NOACs) or with hemorrhagic diathesis should not be treated without first consulting the prescribing doctor.

Relative Contraindications

• Antiplatelet therapy (aspirin, clopidogrel): the risk is lower than with anticoagulants, but should be evaluated on a case-by-case basis.
• Local or systemic infections: shockwaves should not be applied to infected tissues.
• Peripheral neuropathies in the treatment area: can amplify pain or cause nerve damage.
• Treatment on superficial bony prominences without adequate soft tissue coverage: risk of periostitis.
• Metallic prostheses in the treatment area: case-by-case evaluation, as energy could concentrate at the interface between metal and bone.

It is essential to communicate all health conditions, medications in use, and the presence of implanted devices to the professional before starting treatment.

How a Session Takes Place

Preparation

Before treatment, the professional performs a thorough clinical evaluation to confirm the indication and precisely identify the area to be treated. In some cases, especially for focal shockwaves, ultrasound guidance is used to identify the target (e.g., a calcification or an area of tendinopathy).

The skin in the treatment area is covered with a contact gel (the same used for ultrasounds), which ensures optimal transmission of acoustic waves from the handpiece to the underlying tissues.

Treatment Procedure

The handpiece is placed on the area to be treated, and the professional starts administering the impulses. Typical parameters are:

The intensity is generally increased gradually during the session, starting from low levels to allow the patient to adapt to the sensation. The professional can adjust the parameters in real-time based on the patient’s tolerance and clinical response.

Standard Protocol

A complete treatment cycle generally includes:

• Number of sessions: 3 to 5 (in some cases up to 6-8)
• Interval between sessions: 5-7 days (to allow tissues to complete the biological response before the next stimulation)
• Re-evaluation: after completing the cycle, a period of 4-12 weeks is awaited to evaluate the full effect of the treatment, as the biological processes triggered by shockwaves continue to produce effects even after the sessions end.

What to Do After the Session

• Relative rest: avoid intense efforts on the treated area for 24-48 hours.
• Local ice: can be applied in case of post-treatment pain or swelling.
• Avoid anti-inflammatories (NSAIDs): in the 4-6 hours following treatment, as the acute inflammation triggered by shockwaves is part of the therapeutic mechanism and should not be suppressed.
• Continue light activity: unless otherwise indicated, normal daily activities and walking can be performed.

Side Effects and Pain During Treatment

Pain During the Session

One of the aspects that most concerns patients is pain during treatment. It is important to know that:

• Shockwaves cause a certain degree of pain during administration, especially in the first sessions and at high intensities.
• Pain is generally tolerable with radial waves and at low-medium energy.
• For high-energy focal shockwaves, local anesthesia or sedation may be necessary.
• Pain tends to decrease in subsequent sessions, as tissues respond to treatment.
• A certain degree of discomfort is considered physiological and necessary: the pain biofeedback is even used by the professional to precisely identify the area to be treated (the point of maximum pain, which corresponds to the lesion, is sought).

Side Effects

Shockwaves are considered a safe treatment with generally mild and transient side effects:

• Skin redness: in the treated area, resolves spontaneously within a few hours.
• Local swelling: mild transient edema, resolves in 1-2 days.
• Post-treatment pain: soreness in the treated area may persist for 24-72 hours. This is a normal reaction.
• Ecchymosis or petechiae: small subcutaneous hemorrhages, more frequent with high-energy focal waves. Resolve spontaneously in 1-2 weeks.
• Temporary numbness: a slight transient hypoesthesia in the treated area.

Rare Complications

• Tendon rupture: extremely rare, described in anecdotal cases in already severely degenerated tendons. The risk is minimized by correct patient selection and parameters.
• Nerve damage: possible only in case of direct application on superficial nerve structures.
• Deep hematomas: rare, more likely in patients with coagulation disorders.

Scientific Evidence

The scientific literature on shockwaves has significantly expanded in the last two decades. Below is a summary of the evidence for the main indications.

Plantar Fasciitis

Plantar fasciitis is the most studied indication. Several systematic reviews and meta-analyses (including those published in The Lancet, BMJ, and Foot &038; Ankle International) confirm the effectiveness of shockwaves in chronic forms (duration longer than 6 months) resistant to conservative treatment. The American College of Foot and Ankle Surgeons guidelines recommend shockwaves as a Level B therapeutic option. The best results are obtained with medium-high energy protocols and at least 3 sessions.

Calcific Tendinitis of the Shoulder

Calcific tendinitis of the rotator cuff represents perhaps the indication with the most solid evidence. High-quality randomized controlled trials (Level 1 evidence) have shown calcification reabsorption rates of 60-90% and significant clinical improvement compared to placebo. High-energy focal shockwaves produce superior results compared to low-energy ones. The treatment is recommended by European and international guidelines.

Epicondylitis

For chronic lateral epicondylitis, the evidence is conflicting but overall positive. Some meta-analyses show significant medium-to-long-term benefit, while others report modest results. More recent evidence suggests that shockwaves are particularly effective in chronic forms (duration longer than 6 months) that have not responded to at least two lines of conservative treatment. Association with an eccentric exercise program seems to improve results.

Achilles Tendinopathy

For chronic Achilles tendinitis, evidence supports the use of shockwaves in both insertional and mid-tendon forms. Randomized studies have shown a significant reduction in pain and improved function compared to placebo. The insertional form, often associated with posterior heel spur, responds particularly well to treatment.

Pseudoarthrosis

Pseudoarthrosis and delayed union represent a classic indication for high-energy focal shockwaves. Studies with long-term follow-up report consolidation rates of 60-80%, with better results in hypertrophic pseudoarthrosis compared to atrophic ones. The treatment is considered a valid alternative to surgical revision in selected cases.

Other Indications

For trochanteric pain syndrome, groin pain, and patellar chondropathy, evidence is growing but less consolidated. Good quality studies support the use of shockwaves in these conditions, but further research is needed to define optimal protocols and patient selection criteria.

Costs and Number of Sessions

How Much a Cycle of Shockwave Therapy Costs

Treatment costs vary based on several factors:

Indicative costs per single session in Italy (2025-2026):

For a complete cycle of 3-5 sessions, the total cost therefore ranges between 150 and 800 euros, depending on the type and chosen facility.

National Health Service

In some Italian regions and for specific indications (particularly pseudoarthrosis and calcific tendinitis of the shoulder), shockwaves can be provided under the National Health Service (SSN) agreement, with only the co-payment (ticket) required. It is advisable to check with your local health authority (ASL) for access conditions and waiting times, which can be significant.

How Many Sessions Are Needed

The number of sessions required depends on the pathology and individual response:

• Plantar fasciitis: 3-5 sessions (appreciable results after 4-12 weeks from completion)
• Calcific tendinitis of the shoulder: 3-4 sessions (calcification reabsorption can take up to 6 months)
• Epicondylitis: 3-5 sessions
• Achilles tendinopathy: 3-5 sessions
• Pseudoarthrosis: 3-4 high-energy sessions (consolidation can take 3-6 months)
• Trochanteric pain syndrome: 3-5 sessions

It is important to remember that results are not immediate: the biological processes triggered by shockwaves (neoangiogenesis, tissue remodeling, calcification reabsorption) take weeks or months to fully manifest. The definitive evaluation of treatment effectiveness should not be made before 3-6 months after completing the cycle.

Frequently Asked Questions (FAQ)

Frequently Asked Questions

What conditions are typically treated with Shockwave Therapy?

Shockwave therapy is commonly used for various musculoskeletal conditions affecting tendons, bones, and soft tissues. It effectively addresses chronic issues such as plantar fasciitis, calcific tendinitis of the shoulder, epicondylitis, and Achilles tendinopathy. The therapy aims to stimulate healing and reduce pain in these affected areas.

What are the main differences between focal and radial shockwave therapy?

Focal shockwaves deliver high-energy pulses precisely to a deep, targeted area, making them suitable for specific conditions like calcifications or deep-seated tendinopathies. Radial shockwaves, conversely, spread energy over a broader, more superficial area, often used for larger muscle groups, trigger points, and more diffuse conditions. The choice between them depends on the specific condition and treatment goals.

Are there any situations where Shockwave Therapy should not be used?

Yes, there are specific contraindications for shockwave therapy. Absolute contraindications include pregnancy, malignancy in the treatment area, and growth plates in children. Relative contraindications may involve certain blood clotting disorders or the presence of pacemakers, requiring careful consideration by a medical professional.

What can a patient expect during a typical Shockwave Therapy session?

During a session, a physical therapist or doctor will apply a gel to the treatment area, then use a handheld device to deliver acoustic waves. The procedure usually lasts 5-10 minutes, with the intensity adjusted based on patient comfort and the specific condition. Following the session, patients can typically resume normal activities, though some mild soreness may occur.

Sources and Scientific References

1. Charles R et al. (2023). The effectiveness of shockwave therapy on patellar tendinopathy, Achilles tendinopathy, and plantar fasciitis: a systematic review and meta-analysis. Front Immunol. 14:1193835. DOI | PubMed
2. Schroeder AN et al. (2021). Extracorporeal Shockwave Therapy in the Management of Sports Medicine Injuries. Curr Sports Med Rep. 20:298-305. DOI | PubMed
3. Perveen W et al. (2024). Effects of extracorporeal shockwave therapy versus ultrasonic therapy and deep friction massage in the management of lateral epicondylitis: a randomized clinical trial. Sci Rep. 14:16535. DOI | PubMed
4. Xue X et al. (2024). Effect of extracorporeal shockwave therapy for rotator cuff tendinopathy: a systematic review and meta-analysis. BMC Musculoskelet Disord. 25:357. DOI | PubMed
5. Rhim HC et al. (2025). Recommendations for use of extracorporeal shockwave therapy in sports medicine: an international modified Delphi study. Br J Sports Med. 59:1287-1301. DOI | PubMed