Shockwave therapy, also known as Extracorporeal Shock Wave Therapy (ESWT), is a non-invasive treatment modality used to promote tissue healing, reduce pain, and improve functional outcomes in various musculoskeletal and soft tissue conditions. This therapy involves the application of high-energy acoustic waves to the affected area, resulting in mechanical and biological effects that accelerate the healing process. Shockwave therapy is widely used in orthopedics, sports medicine, and rehabilitation, especially for chronic pain conditions, tendinopathies, and calcific lesions.

This article provides an in-depth exploration of shockwave therapy, including its mechanisms of action, clinical indications, contraindications, scientific evidence, and parameter settings for effective treatment.

Mechanisms of Shockwave Therapy

1. Acoustic Waves and Their Types

Shockwave therapy uses acoustic waves—energy waves that travel through the skin to the affected tissues. These waves are characterized by their high intensity and rapid transmission speed. The therapeutic shockwaves are typically generated by a device that creates high-pressure waves, which are focused on the treatment site.

There are two primary types of shockwaves used in therapy:

Radial Shockwaves (RSWT): Radial shockwaves disperse energy in a radial pattern from the source, making them suitable for superficial treatment areas such as the shoulder, elbow, or lower back. Radial shockwaves are typically lower in intensity compared to focused shockwaves.
Focused Shockwaves (FSWT): Focused shockwaves deliver a higher intensity of energy to a specific target area, making them ideal for deeper tissues and conditions like calcific tendonitis or joint disorders. Focused shockwaves are more precise and can penetrate deeper into tissues.

2. Biological and Mechanical Effects

The therapeutic effects of shockwave therapy are due to the combination of mechanical and biological processes that occur in the tissues upon the application of the acoustic waves.

Mechanical Effects: Shockwaves create high-pressure waves that interact with tissues, causing micro-trauma or controlled damage to pathological tissue. This mechanical effect may disrupt calcifications or scar tissue, promoting tissue breakdown and enhancing circulation.
Biological Effects: Shockwaves trigger a cascade of biological responses in tissues, including:
- Neovascularization: The formation of new blood vessels in the affected area, which improves blood flow and nutrient delivery to the tissues.
- Collagen Synthesis: Shockwaves stimulate the production of collagen, an essential protein involved in tissue repair and regeneration.
- Pain Modulation: Shockwaves influence nociceptors (pain receptors) and can lead to a reduction in pain perception through mechanisms such as gate control theory and the release of endorphins.
- Enhanced Metabolism: The application of shockwaves increases cellular metabolism, which accelerates the healing of tissues.
- Increased Tissue Elasticity: Shockwave therapy can improve the elasticity and flexibility of tissues by stimulating the remodeling of fibrous tissue.

3. Pain Reduction Mechanisms

The pain-relieving effects of shockwave therapy are attributed to the following mechanisms:

Decreased Nociceptor Activity: Shockwaves can interrupt pain signals by affecting the nociceptors, which are the sensory receptors responsible for detecting pain.
Release of Endorphins: Shockwaves stimulate the release of endorphins—the body’s natural pain-relieving compounds—leading to a reduction in pain.
Inhibition of Inflammatory Mediators: Shockwave therapy reduces the release of pro-inflammatory cytokines and mediators, which play a role in the pathophysiology of pain and inflammation.

Indications for Shockwave Therapy

Shockwave therapy is indicated for various musculoskeletal conditions, especially those involving chronic pain, tendinopathies, and calcifications. The most common indications include:

1. Tendon Disorders

Shockwave therapy is particularly effective for treating tendinopathies—chronic conditions in which tendons become damaged or inflamed due to overuse or injury. Conditions treated include:

Plantar Fasciitis: Shockwave therapy is commonly used for patients with plantar fasciitis, a condition involving pain in the heel due to inflammation of the fascia at its insertion on the heel bone.
Achilles Tendinopathy: This includes tendinitis or tendinosis of the Achilles tendon, which often results from repetitive stress and causes pain in the posterior ankle.
Tennis Elbow (Lateral Epicondylitis): Shockwave therapy can help reduce pain and promote healing of the extensor tendons in the forearm, commonly affected in tennis elbow.
Rotator Cuff Tendinopathy: Shockwaves are used for chronic shoulder pain resulting from tendinopathy or inflammation of the rotator cuff tendons.
Patellar Tendinopathy: Shockwave therapy is effective in treating jumper’s knee, a condition in which the patellar tendon becomes irritated.

2. Calcific Tendonitis

In conditions like calcific rotator cuff tendonitis, where calcium deposits form in the tendons, shockwave therapy is used to break down the calcifications, reducing pain and improving tendon function.

3. Soft Tissue Injuries

Shockwave therapy is beneficial in the management of soft tissue injuries, such as:

Myofascial Pain Syndrome: Shockwave therapy can help relieve trigger points and muscle spasms by improving blood flow and decreasing muscle tension.
Scar Tissue: Shockwaves are used to break down adhesions and scar tissue, improving mobility and flexibility in areas like the shoulder or hip after surgery.

4. Osteoarthritis and Joint Disorders

Shockwave therapy can be used to treat joint pain associated with osteoarthritis or degenerative joint diseases. It helps by improving circulation, reducing pain, and promoting cartilage repair.

5. Other Conditions

Calcaneal Spurs: Shockwave therapy can address heel spurs, which are abnormal bony growths that cause pain in the heel.
Non-union Fractures: Shockwave therapy has been explored as a treatment for fractures that fail to heal properly, stimulating bone growth and promoting fracture healing.

Contraindications for Shockwave Therapy

While shockwave therapy is generally safe, there are specific contraindications where it should not be applied:

Pregnancy: Shockwave therapy should be avoided during pregnancy, especially over the abdominal and pelvic regions.
Malignant Tumors: Shockwaves should not be applied over areas with known malignancies or tumors, as the treatment may exacerbate the condition.
Blood Clotting Disorders: Patients with coagulopathy or those on anticoagulant therapy should avoid shockwave therapy due to the risk of bruising or bleeding.
Infection: Shockwave therapy should not be used over infected tissues or open wounds.
Pacemakers or Implanted Devices: Patients with pacemakers, defibrillators, or other electronic implants should avoid shockwave therapy due to potential interference with the device.
Growth Plates in Children: Shockwave therapy should be avoided in children with open growth plates to prevent possible damage to the growing bone.
Acute Inflammation: Shockwave therapy is generally not recommended for conditions with acute inflammation, as it could worsen symptoms.

Parameter Settings for Shockwave Therapy

1. Energy Intensity

The energy intensity of shockwave therapy typically ranges from 1 to 5 bar. Lower intensity is used for superficial areas, while higher intensity is applied for deeper tissues or more chronic conditions. The appropriate intensity is determined based on the condition being treated, the location of the injury, and the patient’s tolerance.

2. Frequency

The frequency of shockwaves is usually set between 1 and 15 Hz, depending on the type of tissue and the condition being treated. For example:

Acute conditions: Higher frequencies (10-15 Hz) may be used for faster pain relief and tissue healing.
Chronic conditions: Lower frequencies (1-5 Hz) are typically used to focus on deeper tissue repair and regeneration.

3. Number of Pulses

The number of pulses can vary depending on the area being treated and the severity of the condition. A typical treatment session may involve 1500-2500 pulses per treatment area, delivered in a series of sessions (usually 3-5 treatments spaced 1-2 weeks apart).

4. Treatment Duration

Each treatment session typically lasts between 5 to 15 minutes, depending on the condition and the area being treated. The duration is generally shorter for smaller areas (e.g., Achilles tendon), and longer for larger areas (e.g., hip or shoulder).

Conclusion

Shockwave therapy is a highly effective and non-invasive treatment modality used in the management of musculoskeletal pain, tendinopathies, soft tissue injuries, and joint disorders. By delivering high-energy acoustic waves to the affected area, it stimulates biological healing processes, reduces pain, and accelerates tissue repair. With its mechanical and biological effects, shockwave therapy is a valuable tool in modern rehabilitation and sports medicine.

References

Speed, C. A. (2004). A systematic review of shockwave therapies in soft tissue conditions: focusing on the musculoskeletal disorders. British Journal of Pain, 18(3), 78-86.
Rompe, J. D., et al. (2009). Shock wave therapy in calcific rotator cuff tendinopathy: A randomized controlled trial. Clinical Orthopaedics and Related Research, 467(11), 2927-2935.
Chronic pain: A narrative review on the applications of shockwave therapy for pain management. Pain Medicine, 20(4), 609-616.
Maier, M., et al. (2003). The effectiveness of extracorporeal shockwave therapy for the treatment of chronic plantar fasciitis. Journal of the American Podiatric Medical Association, 93(2), 129-134.
Wang, C. J., et al. (2012). Shockwave therapy for tendinopathy: Current evidence and future trends. Journal of Orthopaedic Research, 30(9), 1421-1429.