Phonophoresis

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Phonophoresis

Definition

Phonophoresis is a procedure that delivers drugs through the skin (transdermally) through the use of ultrasound. Phonophoresis is sometimes called sonophoresis.

Purpose

Ultrasound has been used to as a treatment for musculoskeletal disorders for almost 40 years. The application of low-frequency sound waves (ultrasound) to the skin increases the permeability of the skin and raises the temperature 7-9 °F (4-5 °C) up to 3 in (8 cm) below the skin surface within a localized area. In phonophoresis, drugs are applied to the skin before ultrasound treatment. The idea is that the ultrasound waves disrupt the lipid (fat) layer in the cell membrane of the skin cells on the surface of the body. These cells create the strongest barrier to drug penetration. The theory behind phonophoresis is that ultrasound creates a channel in the cell membrane and drives the drug through the barrier and deeper into the tissue. Phonophoresis is used to treat pain caused by musculoskeletal disorders, mainly arthritis and sports injuries. Some insurance companies consider phonophoresis an investigational or alternative treatment and do not cover its cost.

Precautions

Phonophoresis is non-invasive and involves minimal risks. It should not be performed over areas where the skin is broken or over a fracture. Allergic reactions can also occur to drugs used during phonophoresis.

Description

The skin is cleaned and the medication is applied. The medication is usually in the form of a cream. Drugs used during phonophoresis are usually nonsteroidal anti-inflammatory drugs such as ibuprofen, steroid drugs, or local anesthetics.

The area to be treated is then exposed to either pulsed or continuous ultrasound. Pulsed treatments tend to be preferred for acute injuries and continuous treatment for chronic conditions. Treatment continues for five to eight minutes, after which the skin is cleaned again.

Preparation

No special preparation is needed before phonophoresis.

Aftercare

After washing the skin, no special aftercare is needed, No disability or delayed recovery is expected from this treatment.

Complications

No complications are expected with this procedure.

Results

Few large, well-designed, controlled studies of phonophoresis exist. The ones that do use a variety of different drugs and show mixed results. Some steroid drugs appear to penetrate the skin and move into deep tissue layers. However a controlled study of the nonsteroidal anti-inflammatory drug ibuprofen showed no greater improvement among individuals who received plain ultrasound and those who received phonophoresis (ultrasound plus the drug). The authors concluded that any improvement seen by patients in either treatment group was from the heating effects of the ultrasound rather than from penetration of the drug. Because there is no clear-cut benefit of phonophoresis over ultrasound treatment alone, many insurers will not pay for the procedure.

Health care team roles

Phonophoresis is almost always performed by a physical therapist or sports medicine technician in an outpatient setting.

KEY TERMS

Permeability— The degree to which materials such as drugs or ions pass through a barrier such as skin or cell membranes.

Transdermal— Across the skin.

Resources

PERIODICALS

Meidan, V.M. and B.B. Michniak. "Emerging Technologies in Transdermal Theraputics" American Journal of Therapy. 4(July-August 2004): 312-316.

Cagnie, Barbara et al. "Phonophoresis versus Topical Application of Ketoprofen: Comparison Between Tissue and Plasma Levels." Physical Therapy. 83(August 2003): 707-713.

Koznoglu, Erkan, et al. "Short Term Efficacy of Ibuprofen Phonophoresis Versus Continuous Ultrasound Therapy in Knee Osteoarthritis." Swiss Medical Weekly. 2003:133:333-338.