ULTRASOUND THERAPY

ULTRASOUND THERAPY

Ultrasonography is a deep heating modality that uses high-frequency acoustic vibrations; the frequencies employed are above the human audible spectrum, that is, they are greater than 17,000 Hz.

Therapeutic Ultrasonography uses a frequency range of 0.8-1.0 MHz Ultrasonographic energy is generated by the piezo-electric effect; electrical energy is applied to a crystal, causing the crystal to vibrate at a high frequency and thereby produce ultrasound.

Ultrasound is delivered by continuous or pulsed waves (the goal being to produce nonthermal effects, such as streaming and cavitation) and provides a high heating intensity.

Ultrasonographic energy is absorbed and transformed into heat energy as it propagates through tissue. The therapeutic dose is computed by the power output (total W) and the size of the ultrasonographic head.

The usual initial dose is 1 W/cm2 and is adjusted to patient tolerance,

as well as to the treatment goals. The practitioner must select the wave form (continuous or pulsed), intensity, and duration.

The patient should experience a comfortable heating or no sensation at all. The treatment time is 5-10 minutes, taking into account the patient's tolerance and comfort.

After the skin is cleansed, a coupling agent, such as an ultrasonographic gel, is required to provide effective conduction between the ultrasonographic head/transducer and the skin surface. To avoid hot spots, the ultrasonographic head must be continuously moved over the treatment site.

THERAPEUTIC ULTRASONOGRAPHY BIOLOGIC EFFECTS

• Temporary analgesia

• Increased peripheral blood flow

• Increased vascularity with associated hyperemia/inflammatory response

• Increased cell membrane permeability

• Peripheral nerve conduction changes (reversible conduction block with high-intensity ultrasonographic exposure)

• Relief of muscle spasms

The following factors influence the propagation of ultrasound in biologic tissue:

• Transmission

• Absorption

• Refraction

• Reflection

Therapeutic Ultrasonography is ideal for providing deep heat to large joints. For example, it is effective in treating the shoulder or hip, because a standing wave is produced as a result of the curved reflection of the glenoid or the acetabulum; this effect concentrates heat energy at the articular surfaces of the joint.

In combination with a physical therapy program utilizing range of motion (ROM) and stretching activities, the localized, intra-articular heating produced by Ultrasonography greatly facilitates the mobilization of joint adhesions or capsular restrictions caused by tightness or scarring.

Ultrasonography is also used to treat osteoarthritis, tendinitis, and bursitis. Ultrasonographic deep heating has not been found to be effective for the preventive management of post eccentric exercise, delayed-onset muscle soreness.

As mentioned above, the nonthermal effects of ultrasonography include cavitation, which disrupts chemical and cellular bonds, thereby assisting with the treatment of fibrous tissue, scar tissue, and joint capsule adhesions.

A form of ultrasonography known as phonophoresis is used to diffuse a topical medication, such as a steroid, analgesic, or anesthetic in a gel, into the subcutaneous tissue.

ADDITIONAL INDICATIONS FOR ULTRASONOGRAPHY

• Joint contracture

• Joint adhesions

• Calcific bursitis

• Hematoma resolution

• Neuromas

• Fibrosis

• Phantom limb pain

• Myofascial pain

• Reflex vasodilatation

• Ulcer debridement

PRECAUTIONS

Precautions to be noted in the use of therapeutic ultrasonography are the same as those for most other deep heating modalities.

Although the literature for physical therapy and for physical medicine has differing opinions, therapeutic ultrasonography can be used over metal implants with caution and with constant motion of the ultrasonographic head.

CONTRAINDICATIONS

Additional contraindications for the use of ultrasonography include conditions in which the application of deep heat would require direct exposure of the eye, pregnant uterus, spine, Laminectomy sites, brain, heart, or known ischemic areas, which can result in detrimental cavitation and heating of those tissues.