Plantar fasciitis (PF) is a common cause of heel pain, characterized by irritation of the plantar fascia, the thick band of tissue connecting the heel bone to the toes. This condition often causes a sharp, stabbing pain, especially with the first steps in the morning or after periods of rest. Extracorporeal Shockwave Therapy (SWT) is a non-invasive method utilizing acoustic waves to stimulate the body’s natural healing processes. As a non-surgical option, SWT promotes tissue regeneration and reduces chronic pain, but many worry the high-energy waves might worsen their existing heel pain.
Understanding Post-Treatment Discomfort
A temporary increase in pain or soreness immediately following a shockwave session is a common and expected reaction, which does not signify that the plantar fasciitis is getting worse. This transient discomfort is part of the therapy’s intended mechanism, which involves delivering controlled microtrauma to the damaged tissue. This mechanical stimulation triggers a local inflammatory response, which is necessary to jump-start the body’s repair cycle.
The acoustic waves stimulate the formation of new blood vessels, a process called neovascularization, which enhances the supply of oxygen and nutrients to the chronically injured area. Simultaneously, the shockwaves can desensitize nerve endings, providing a longer-term reduction in pain signals. This acute, post-treatment tenderness usually peaks within 24 to 48 hours and then rapidly subsides. This profile of short-lived, localized soreness is distinctly different from the chronic, persistent pain experienced with long-standing plantar fasciitis.
Commonly reported side effects include mild swelling, temporary skin redness, or slight bruising (ecchymosis) at the treatment site. These superficial responses are normal indicators of the mechanical energy interacting with the tissue and are generally self-limiting. The therapist can adjust the intensity of the acoustic pulses to keep the discomfort tolerable while still delivering a therapeutic dose.
Factors That Can Lead to a True Setback
While temporary soreness is expected, a genuine setback, where the condition is truly exacerbated, is rare and almost always linked to specific technical errors or patient contraindications. The energy settings used during the procedure are a critical factor, as administering excessively high energy flux density or too many pulses can damage healthy tissue. Incorrect focus or aiming the acoustic waves at the wrong anatomical structure could also lead to injury rather than healing.
The application of SWT to an area with a recent corticosteroid injection is a significant contraindication that can lead to complications. Corticosteroids weaken the plantar fascia tissue, and the addition of high-energy acoustic waves shortly after injection substantially increases the risk of a rupture. Healthcare providers must screen carefully for underlying conditions before starting treatment. Precautions that must be respected include:
- Certain blood clotting disorders.
- The use of anticoagulation medications.
- The presence of a known malignancy in the treatment area.
A true setback can also occur if the patient’s heel pain was misdiagnosed before treatment began. For instance, treating a calcaneal stress fracture (an overuse injury to the heel bone) with high-intensity shockwaves could worsen the fracture. Since the therapeutic effect relies on stimulating soft tissue healing, applying this mechanical force to a bony injury can have detrimental consequences.
Recognizing Serious Complications and Next Steps
Distinguishing between expected temporary discomfort and a serious complication requires vigilance for specific physical signs that deviate from the normal post-treatment soreness. A serious complication is indicated by symptoms that persist beyond the first few days or are immediately severe and disabling. Red flags include the sudden onset of severe, sharp localized pain that does not diminish or the inability to bear weight on the treated foot immediately following the session.
Other signs warranting immediate contact with your specialist include:
- The development of a large, dark hematoma or severe bruising that rapidly expands.
- Any change in sensation, such as persistent numbness or tingling (dysesthesia), suggesting nerve irritation or damage.
- Signs of skin breakdown or a localized skin infection at the probe application site.
If any of these severe symptoms occur, the treating physician or physical therapist should be contacted immediately for an evaluation.