How Is Therapeutic Ultrasound Used for Inflammation?

Inflammation is the body’s natural response to injury, often causing pain, swelling, and reduced function. To manage these symptoms, physical therapists may use therapeutic ultrasound, which employs high-frequency sound waves to interact with bodily tissues. This treatment is intended to address inflammation at a cellular level, helping to facilitate recovery in specific soft-tissue injuries.

How Therapeutic Ultrasound Addresses Inflammation

Unlike diagnostic ultrasound which creates images, therapeutic ultrasound uses sound waves between 0.8 and 3.0 MHz to produce physiological effects deep within injured tissues. The primary mechanisms are thermal and non-thermal, and both approaches aim to modify the inflammatory process and accelerate tissue repair.

The thermal effects are generated when sound wave energy is absorbed by tissues and converted into heat. This deep heating, which can penetrate up to five centimeters below the skin, increases blood flow to the targeted area. Enhanced circulation delivers more oxygen and nutrients for tissue repair while also helping to flush out waste products. This process can help resolve chronic inflammatory states and increase the flexibility of collagen-rich tissues, which may have become stiff.

Non-thermal effects are achieved without a significant increase in tissue temperature and are driven by mechanical processes. One such process is cavitation, which involves the formation and vibration of microscopic gas bubbles in the tissue fluids. This vibration, along with a related effect called acoustic streaming, alters the permeability of cell membranes to stimulate cellular repair and regulate inflammatory cells.

Conditions Commonly Treated with Ultrasound

Therapeutic ultrasound is applied to a range of musculoskeletal conditions, particularly those involving inflammation of soft tissues. It is frequently used for tendinopathies, which involve the inflammation or micro-tearing of tendons. Conditions like tennis elbow, Achilles tendonitis, and rotator cuff tendonitis are common targets for this treatment.

Bursitis, the inflammation of the fluid-filled sacs that cushion joints, is another condition where ultrasound is often applied. In areas like the shoulder and hip, the therapy can reduce the inflammatory response in the bursa, alleviating pain and improving joint movement. For muscle strains and ligament sprains, ultrasound is used after the initial, acute phase of injury to accelerate healing and reduce the formation of stiff scar tissue.

The therapy is also used as part of a larger treatment plan for certain chronic joint conditions like osteoarthritis. It may be used to manage pain and stiffness by warming the tissues around the joint and improving blood flow. This can provide temporary relief and make it easier for individuals to participate in prescribed exercises.

What to Expect During Ultrasound Therapy

A therapeutic ultrasound session is a straightforward and non-invasive procedure performed by a physical or occupational therapist. After inspecting the skin for open wounds or infections, the therapist applies a conductive gel to the skin over the area that requires treatment. This gel eliminates air pockets between the skin and the machine, allowing the sound waves to be transmitted effectively.

The therapist then uses a handheld applicator, known as a transducer, which is connected to the ultrasound machine. This transducer is moved slowly and continuously in small, circular patterns over the gel-covered skin. Keeping the sound head in constant motion prevents any single point from overheating.

Patients do not feel significant sensations during the procedure, though some report a slight feeling of warmth in the treatment area. A session is brief, lasting between five and 10 minutes for each targeted area. Depending on the condition, a therapist may recommend sessions several times a week for a few weeks to achieve the desired outcome.

Factors Influencing Treatment Success

The effectiveness of therapeutic ultrasound is influenced by several factors. The treatment approach for acute inflammation, which often focuses on non-thermal effects, differs from that for chronic conditions, where deep heating may be more beneficial. A therapist must select the correct treatment parameters, including frequency, intensity, and mode—either continuous for thermal effects or pulsed for non-thermal.

The success of the therapy is also connected to its role within a comprehensive rehabilitation program. Ultrasound is most often used as an adjunctive therapy, complementing treatments like therapeutic exercise and manual therapy. Patient adherence to the full rehabilitation plan is a significant contributor to recovery, and individual response can vary based on factors like tissue type.

Certain situations are considered contraindications where the treatment should not be applied. A thorough evaluation by a healthcare professional is necessary to determine if the therapy is an appropriate and safe option. It should not be used in the following circumstances:

• Over areas with active tumors, infections, or impaired circulation
• Over the abdomen or low back of pregnant women
• Near pacemakers
• Over the growth plates of children