Shockwave therapy

Background

  • Used since 1940s to promote healing process
  • Thermal and non-thermal effects
  • Ultrasound waves generated from vibrating crystals in the head of device
  • Soundwaves pass through the skin and cause vibrating effect in the tissues
  • Thermal effects not felt
  • Coupling medium needed to conduct soundwaves
  • Motion of probe necessary to prevent heating effects

Thermal effects

  • U/S is absorbed by the underlying tissues leading to heat generation
  • The higher the frequency, the greater the absorption
  • Heat is dissipated by the local blood flow of the tissue
  • Benefits include pain relief, decreased joint stiffness, increased blood flow

Transmission of wave

Non Thermal effects

  • Stimulation of soft tissue regeneration
  • Stimulation of soft tissue repair
  • Stimulation of blood flow

What would you use U/S on ?

  • Any soft tissue injury, not on bone due to lack of absorbsion

Contraindications

Absolute contraindications

  • Application in foetal region
  • Bleeding tissue
  • Application over eyes & testes

Local contraindication

  • Malignancy
  • Active implants - pacemakers
  • Active epiphysis

Precautions

  • Circulation insufficiency
  • Devitalised tissue - post radiotherapy
  • Anaesthetic if a thermal dose is being used
  • Subcutaneous major nerve and bony prominances
  • Continuous ultrasound is unwise over metal implants
  • Acute infections
  • Heamophilliacs not covered by replacement factor
  • All tissues impede the passage of sound waves
  • To minimise steel/air interface, a coupling medium is used (U/S gel)
  • Critical angle for u/s at the skin surface is 15 degrees or more

Dosage basics

  • Depends on size of the lesion
  • The greater the surface area the greater the time
  • Treatment time= 1min of u/s per size of treatment head
    Thermal effects - High intensity in continuous mode (>0.5Wcm2)
    Non thermal effects- Lower intensity pulse mode
    • 1:1=50% of the time on
    • 1:2=33% of the time on
    • 1:4=20% of the time on
      The more acute the tissue, the greater ratio used ie. 1:4

Dosage Depth

Frequency used relates to depth of lesion

  • 1MHz:> 3cm depth
  • 3MHz: 0-3cm depth
    If deep use 1 MHz

Dosage Pulses

  • Acute 1:4 or 1:3 (20% or 25%)
  • Subacute 1:3 or 1:2 or 1:1 ( 25% or 33% or 50%)
  • Chronic- 1:2 or 1:1 or continuous (33% or 50% or 100%)

Dosage Intensity

  • Acute 0.1-0.3 Wcm2
  • Subacute- 0.2-0.5 Wcm2
  • Chronic- 0.3-0.8 Wcm2