Phonophoresis is a therapeutic technique that uses ultrasound waves to enhance the delivery of topical medications through the skin into underlying tissues. This non-invasive method is common in physical therapy for targeted treatment of various musculoskeletal conditions. By combining ultrasonic energy with medication, phonophoresis delivers drugs directly to an affected area to improve their local effect.
The Phonophoresis Process
The process integrates two primary components: therapeutic ultrasound and a medicated gel or cream. A therapist first applies the topical medication to the skin over the injured area. An ultrasound gel is then applied over the medication, serving as a coupling agent to help transmit the sound waves efficiently.
The core mechanism involves ultrasound waves creating microscopic vibrations in the skin and deeper tissues. These vibrations are thought to increase the permeability of the skin’s outer layer, a concept sometimes called sonoporation. This increased permeability helps push medication molecules more deeply into the target tissues than simple topical application alone.
During a typical session, which lasts between five and ten minutes, the therapist moves the ultrasound transducer in slow, continuous circular motions over the treatment site. Patients usually feel a mild warming sensation on their skin as the sound waves generate thermal energy. The procedure is painless and serves as a non-invasive alternative to injections for delivering certain medications.
Medical Applications and Medications
Phonophoresis is most frequently used to treat localized inflammation and pain in muscles, ligaments, and joints. It is commonly applied for musculoskeletal conditions such as tendinitis, bursitis, and tenosynovitis, where inflammation is a primary concern. The technique is also used for managing symptoms of carpal tunnel syndrome and certain forms of osteoarthritis.
The medications administered via phonophoresis are typically anti-inflammatory drugs and anesthetics. Corticosteroids, such as hydrocortisone and dexamethasone, are frequently used to reduce inflammation in the target tissue. Nonsteroidal anti-inflammatory drugs (NSAIDs), like diclofenac and salicylates, are another class used to manage pain and swelling. In some cases, local anesthetics like lidocaine are used to provide direct pain relief.
Safety and Contraindications
While generally considered safe, phonophoresis has potential side effects, which are typically mild. Some individuals may experience skin irritation or sensitivity from the medication or the ultrasound gel. There is also a minor risk of thermal burns if the ultrasound transducer is held stationary for too long or the intensity is set too high, though this is rare when performed by a qualified therapist.
Specific situations, known as contraindications, exist where phonophoresis should not be used. The treatment should not be applied over areas with open wounds, active skin infections, or known tumors. It is also contraindicated for use over electronic implants like pacemakers or areas with vascular abnormalities.
Phonophoresis is not recommended for use on pregnant women, particularly over the abdominal or low back regions. Caution is also advised in patients with healing fractures, as the ultrasound may interfere with the healing process.