Shockwave Therapy (ESWT) — Complete Clinical Overview

What Is Shockwave Therapy?

Types of Shockwaves

Mechanism of Action

1. Mechanical Effects

• Rapid positive pressure causes energy absorption, reflection, refraction, and transmission in tissue
• Destroys calcific deposits in tendons (e.g., calcific tendinopathy of the shoulder) by physical disintegration
• Induces microcavitation: formation and collapse of microbubbles generating microshear forces that stimulate cell membranes

2. Cellular & Molecular Effects

• ATP release → activates extracellular signal-regulated kinase (ERK) pathways → enhances cell proliferation and wound healing
• Nitric oxide (NO) release → downstream analgesic, anti-inflammatory, and angiogenic effects
• Alteration of ion channels in cell membranes
• Upregulation of growth factors:
  • TGF-β1 and IGF-1 → increased collagen synthesis
  • VEGF → neovascularization
  • BMP-2 → bone healing/osteogenesis
• Increased IL-6, IL-8, MMP-2, MMP-9 → matrix remodeling
• Increased glycosaminoglycans and tenocyte proliferation
• Osteoprogenitor cell differentiation → bone remodeling

3. Analgesic Effects

• Stimulation of nociceptive C-fibers → hyperstimulation → temporary nerve block (hyper-stimulation analgesia)
• Gate-control theory: activates large afferent fibers inhibiting pain transmission
• Depletion of Substance P → reduced neurogenic inflammation
• Reduced calcitonin gene-related peptide (CGRP) at nerve endings

4. Angiogenesis & Tissue Repair

• Promotes neovascularization via VEGF and NO
• Activates endogenous stem cells (CD31/CD34-positive endothelial precursors)
• Stimulates collagen remodeling and tendon repair

Indications

Tendon Pathologies

• Calcific tendinopathy of the shoulder (highest evidence)
• Lateral epicondylopathy (tennis elbow)
• Plantar fasciitis / plantar fascopathy (strong evidence)
• Achilles tendinopathy
• Patellar tendinopathy (jumper's knee)
• Greater trochanteric pain syndrome (gluteal tendinopathy)
• Hamstring, adductor, peroneal, distal biceps tendinopathies
• Rotator cuff tendinopathy (non-calcific)

Bone Pathologies

• Delayed fracture healing / non-union
• Stress fractures
• Avascular necrosis (osteonecrosis) of the femoral head
• Osteochondritis dissecans
• Medial tibial stress syndrome
• Osgood-Schlatter disease

Muscle/Soft Tissue

• Myofascial pain syndrome / trigger points
• Muscle strain (without fiber discontinuity)

Urological

• Erectile dysfunction (low-intensity ESWT)
• Peyronie's disease (limited evidence per urology guidelines)

Wound Healing

• Chronic diabetic foot ulcers
• Pressure ulcers
• Burns (2nd degree)

Other Emerging

• Cardiac ischemia (low-intensity, research stage)
• Neurological conditions (post-stroke spasticity)
• Dupuytren's disease

Note: ESWT is typically indicated after failure of conservative treatment (rest, physiotherapy, NSAIDs for 3–6 months).

Contraindications

Absolute Contraindications (All Energy Levels)

Additional Absolute Contraindications for High-Energy Focused ESWT

Relative / Important Considerations

• Current NSAID use or anticoagulant use (warfarin, heparin) — increased bleeding risk
• Corticosteroid injection within 6 weeks at the same site
• Blood thinning medications
• Skull bones, vertebral bodies, ribs — exercise caution with focused high-energy

Note: Cancer itself in a different/remote area is NOT an absolute contraindication. Similarly, chronic infection in wound care is increasingly showing benefit — guidelines may evolve.

Clinical Application Protocol

Before Treatment

1. Confirm indication and failure of prior conservative treatment
2. Screen for contraindications (imaging to confirm diagnosis — ultrasound or X-ray)
3. Informed consent — explain: onset of effect after 4–12 weeks, potential temporary increase in pain, bruising
4. Identify anatomical target by palpation ± ultrasound guidance

Treatment Parameters

During Treatment

• Patient positioned comfortably exposing the target area
• Ultrasound gel applied to skin
• Applicator held perpendicular to tissue surface
• Energy titrated to patient tolerance (biofeedback guides dosing)
• For trigger points: "referred pain recognition" confirms correct localization

After Treatment

• Avoid NSAIDs for 1–2 weeks post-treatment (inflammation is part of the healing response)
• Patients should expect temporary soreness for 24–48 hours
• No immobilization required; gradual return to activity
• Reassess at 4–6 weeks; repeat treatment cycle if partial response

Side Effects (Generally Mild, Transient)

• Local pain during/after treatment
• Skin redness, petechiae, or bruising
• Transient swelling
• Rare: hematoma, nerve irritation

Clinical Images

Key Takeaway Summary

Shockwave Therapy in Avascular Necrosis (AVN) of the Femoral Head

Understanding the Problem — Why AVN Needs ESWT

• Impaired angiogenesis (no new vessels reach the necrotic zone)
• Osteoblast-osteoclast imbalance (resorption exceeds formation)
• Bone marrow edema (BME) → increased intraosseous pressure → further ischemia
• Mesenchymal stem cell (MSC) dysfunction → impaired bone regeneration

How ESWT Works in AVN — Specific Mechanisms

1. Angiogenesis (New Blood Vessel Formation)

• Upregulates VEGF (Vascular Endothelial Growth Factor) → stimulates new capillary sprouting into the necrotic zone
• Releases nitric oxide (NO) → vasodilation + angiogenic signaling
• Mobilizes CD31/CD34+ endothelial progenitor cells from bone marrow → they migrate to the necrotic area and form new vessels
• High-energy ESWT specifically upregulates localized NO to promote angiogenesis in bone, which is why high energy is required for bone lesions

2. Osteogenesis (New Bone Formation)

• Stimulates BMP-2 (Bone Morphogenetic Protein-2) → drives osteoprogenitor differentiation into osteoblasts
• Upregulates TGF-β1 → bone matrix synthesis and collagen deposition
• Promotes MSC proliferation and osteoblast differentiation → direct bone repair in necrotic zone
• Studies of femoral heads removed at hip replacement show histological evidence of new bone formation and neovascularization after ESWT

3. Bone Marrow Edema (BME) Reduction

• Mechanical effect reduces intraosseous pressure
• Anti-inflammatory signaling reduces local edema
• Meta-analysis (Tan 2025, PMID 38896858): ESWT significantly improves BME in early ONFH (OR 4.35, 95% CI 1.32–14.37, P=0.02)

4. Pain Modulation

• C-fiber hyperstimulation → analgesia
• Substance P depletion → reduced neurogenic pain
• Gate-control mechanism

MRI Evidence of ESWT Response in AVN

Clinical Evidence — What the Data Shows

Meta-Analysis: Mei et al. 2022 (PMID 34058957) — 9 studies, 409 patients

Systematic Review: Tan et al. 2025 (PMID 38896858) — 9 studies, 716 patients

Network Meta-Analysis: Zhai et al. 2024 (PMID 39234503) — 11 RCTs

• ESWT significantly reduced VAS vs. core decompression + bone grafting (MD -2.84, P significant)
• SUCRA ranking for HHS: ESWT alone ranked 3rd (58.3%), ESWT + injectable medication ranked 2nd (72.2%)
• Recommendation: ESWT alone for long-term/chronic patients; ESWT + injectable medication for acute/short-term onset

Long-Term Study (8–9 year follow-up)

ESWT vs. Other Treatments in AVN

Stage-Specific Guidance

Key principle: ESWT cannot reverse established collapse (Stage III–IV). It is most effective as early intervention to halt progression before structural failure.

Treatment Protocol for AVN

• Device: High-energy focused ESWT (not radial) — required to penetrate deep to the femoral head (6–10 cm)
• Energy density: 0.25–0.40 mJ/mm²
• Impulses: 2,000–4,000 per session
• Sessions: 3–5 sessions, 1 week apart
• Localization: Fluoroscopy or ultrasound guidance to target the necrotic zone precisely
• Coupling: Ultrasound gel over the hip
• Avoid NSAIDs for 2 weeks post-treatment
• Follow-up MRI at 3–6 months to assess BME response

Summary