Explain about ultra sound physiotherapy
Reading File
Finding Sources
Finding Sources
Searching the Web
ultrasound physiotherapy mechanism effects clinical applications 2024
Finding Sources
Finding Sources
Searching PubMed
"therapeutic ultrasound" physiotherapy
Reading File
Reading File
Reading Web Page
https://ckphysio.co.uk/blog/therapeutic-ultrasound-and-physi…
Here is a thorough explanation of ultrasound physiotherapy:
Ultrasound Physiotherapy (Therapeutic Ultrasound)
What Is It?
Therapeutic ultrasound is a physical therapy modality that uses high-frequency sound waves (typically 0.5 to 5 MHz) to deliver mechanical energy into body tissues. It has been in clinical use since the 1950s and is distinct from diagnostic ultrasound - it produces no images. The transducer head (treatment probe) is moved over the skin with a coupling gel, directing sound energy into deeper structures.
Physical Principles
- Sound waves are generated by a piezoelectric crystal in the transducer
- Frequency used: 1 MHz for deep tissues (up to 5 cm), 3 MHz for superficial tissues (1-2 cm)
- Intensity is measured in Watts/cm² (W/cm²)
- Delivered in either continuous or pulsed mode
Mechanisms of Action
Therapeutic ultrasound works through two distinct mechanisms:
1. Thermal Effects (Continuous Mode)
- Sound wave energy is absorbed by tissues, generating heat
- Increases tissue temperature by 1-4°C
- Effects include: increased blood flow, increased tissue extensibility, reduced muscle spasm, decreased joint stiffness, and faster enzymatic reactions
- Best suited for chronic conditions (e.g., chronic inflammation, scar tissue)
2. Non-Thermal (Mechanical) Effects (Pulsed Mode)
- Acoustic streaming - movement of fluids along acoustic pressure gradients, increasing cell membrane permeability
- Stable cavitation - formation and oscillation of tiny gas bubbles in tissues; these vibrate rhythmically, creating microstreaming around cells
- Inertial (transient) cavitation - violent bubble collapse generating shock waves (less common at therapeutic levels)
- These effects stimulate fibroblast activity, enhance tissue repair, and improve cell membrane function
- Best suited for acute inflammation where heating is undesirable
Phonophoresis (Sonophoresis)
A specialized technique that uses ultrasound to drive topical medications (e.g., dexamethasone, hydrocortisone, lidocaine) across the skin into deeper tissues. The acoustic streaming effect increases membrane permeability, enhancing drug delivery. This is particularly useful for localized anti-inflammatory treatment.
- Pulsed ultrasound is used in acute cases (avoids temperature increase)
- Continuous ultrasound is used in chronic cases (thermal benefits added)
- Dose: typically 1-2 W/cm² for 5-10 minutes
- - Pfenninger and Fowler's Procedures for Primary Care, p. 1598
Equipment Parameters
| Parameter | Typical Range |
|---|---|
| Frequency | 1 MHz (deep) / 3 MHz (superficial) |
| Intensity | 0.5 - 3.0 W/cm² |
| Duty cycle (pulsed) | 20%, 50%, or 100% |
| Treatment duration | 5-10 minutes |
| Mode | Continuous (thermal) or Pulsed (non-thermal) |
Clinical Indications
- Superficial periarticular disorders - bursitis, tendinitis, ligament sprains
- Joint contracture and adhesive scars - capsule tightness, post-surgical scars
- Plantar fasciitis - moderate evidence from a 2024 systematic review (Alhakami et al., PeerJ, PMID: 38529309)
- Myofascial pain / trigger points - large effect found in a 2024 systematic review
- Calcific tendinitis - historically a strong indication; ultrasound has been shown to reduce calcium deposit size
- Neuromas and reflex sympathetic dystrophy
- Muscular strains, fibrosis, spasm, myositis (limited evidence)
- Temporomandibular joint disorders (TMD) - supported by systematic review (Ansari et al., Cranio, PMID: 35315745)
- Soft tissue healing - post-surgical or post-injury recovery
- Plantar warts
Absolute and Relative Contraindications
| Contraindication | Notes |
|---|---|
| Tumors / malignancy | May accelerate growth |
| Pregnancy | Contraindicated over abdomen and pelvis |
| Thrombophlebitis | Risk of embolism |
| Cardiac disease / pacemaker | Avoid over cervical ganglia, cardiac area |
| Hemorrhagic or infected areas | Risk of spread |
| Unhealed fracture sites | May disrupt healing |
| Epiphyseal plates in children | Risk of growth plate damage |
| Spinal cord | Neural sensitivity |
| Post-radiation areas | Wait at least 6 months |
| Eyes | High sensitivity |
| Allergy to coupling gel/medication | Relevant in phonophoresis |
- Pfenninger and Fowler's Procedures for Primary Care
Modes of Delivery
Continuous Mode
- Sound wave output is uninterrupted
- Produces both thermal and non-thermal effects
- Used for chronic conditions - scar tissue, chronic tendinopathy, joint stiffness
Pulsed Mode
- Interrupted output (e.g., on 2 ms / off 8 ms = 20% duty cycle)
- Primarily non-thermal effects
- Used for acute inflammation, edema, acute injuries
Current Evidence and Limitations
The evidence base for therapeutic ultrasound is mixed and condition-specific:
- Plantar fasciitis - A 2024 systematic review (PMID: 38529309) supports its use for pain and functional disability
- Myofascial pain - A 2024 systematic review found large effects for trigger point treatment
- Low back pain - NICE guideline NG59 states: "Do not offer ultrasound for managing low back pain with or without sciatica"
- Osteoarthritis - NICE guideline NG226 (2022) recommends against it, citing insufficient evidence. A 2024 systematic review (Luo et al.) showed moderate effects for knee OA with pulsed ultrasound, but NICE has not revised guidance
- Endothelial function - A 2025 meta-analysis (PMID: 40745908) shows therapeutic ultrasound improves endothelial function
- Neck pain - A 2025 network meta-analysis (PMID: 40244434) compared biophysical agents; ultrasound showed moderate benefit
Key limitation: there is significant variation in treatment protocols across studies (frequency, intensity, duration, mode), making comparisons difficult.
Comparison: Therapeutic Ultrasound vs. Shockwave Therapy
| Feature | Therapeutic Ultrasound | Shockwave Therapy |
|---|---|---|
| Energy type | Continuous or pulsed sound waves | High-energy acoustic pulses |
| Mechanism | Thermal + gentle tissue stimulation | Mechanical microtrauma, triggers healing |
| Sensation | Generally painless, gentle warmth | Can be uncomfortable (2-5/10 pain scale) |
| Evidence | Weak to moderate (condition-dependent) | Moderate to strong (NICE-supported) |
| Best for | Myofascial pain, soft tissue | Plantar fasciitis, Achilles, tennis elbow |
Safety
When used correctly by a qualified physiotherapist, therapeutic ultrasound at standard clinical settings is considered safe. The key safety principle is keeping the transducer head moving continuously during treatment - holding it stationary can cause localized heating and tissue damage ("hot spots"). Coupling gel must ensure good acoustic contact to prevent energy reflection at the skin surface.
Summary: Therapeutic ultrasound is a well-established physiotherapy modality with clear thermal and non-thermal mechanisms. It is best supported for myofascial pain, plantar fasciitis, calcific tendinitis, and as part of phonophoresis. Its use for low back pain and osteoarthritis is not recommended by major guidelines. A skilled clinician should match the mode (continuous vs. pulsed), frequency, and intensity to the specific condition and stage of injury.
This is a shared conversation. Sign in to Orris to start your own chat.