Therapeutic Modalities - ULTRASOUND

Ultrasound(US) is a sound wave that has a frequency greater than 20 KHz.
It is generated by applying an alternate current to a piezoelectric
crystal (found in the transducer in the sound head). This crystal
contracts and expands at the same frequency at which current changes
polarity. The sound field generated by this crystal in turn makes the
molecules in the sound field vibrate and oscillate.
The crystal commonly used in US units is synthetic plumbium
zirconium titanate (PZT), lead zerconate.

Therapeutic ultrasound has a frequency range of 0.75 and 5.0 MHz.
Most modalities have 1 MHz and 3 MHz sound head

Ultrasound energy is absorbed mostly in tissues with high collagen
content (bone, periosteum, cartilage, ligaments, capsules, tendons, fascia,
scar tissue and tissue interface i.e. bursa & synovium).


Physiological effects of Ultrasound:
1. Enhance inflammatory response and tissue repair
2. Heat soft tissue

Common uses for pulsed non-thermal ultrasound
· Facilitate healing in the inflammatory and proliferative phase
following soft tissue injury (tendonitis, bursitis, acute soft tissue
injuries)
· Bone healing

Common use for continuous ultrasound:
· Prior to stretching at tight structure (tendon, capsule, ligaments,
fascia, scar)
· Pain control in chronic pain
· Chronic inflammatory conditions

CONTRAIDICATIONS
· Undiagnosed pain
· Cancer
· Active tuberculosis
· Psoriasis
· Decreased circulation
· Infection
· Pregnancy
· Central nervous system tissue
· Joint cement (cannot use continuous mode, but may use pulsed
mode 50% or less)
· Plastic components
· Pacemakers
· Thrombophlebitis
· Uncontrolled bleeding or blood-thinning medication (coumadin)
· Eyes
· Reproductive organs
· Heart

PRECAUTIONS
· Acute inflammation (use non-thermal settings only)
· Epiphyseal plates (use pulsed, low intensity <0.5w/cm2)>