Using Ultrasound For Scar Treatment


laser treatmentScar tissue is persistent once formed and may become an impediment to bodily motion or cause marked disfiguration. Advances in treating scars with refined ultrasound equipment and techniques have been used to literally alter the tissue itself and provide some relief. When skin is treated with ultrasound, the local area is heated and physiological changes occur within scars.

History Of Ultrasound Technology For Therapeutic Use

In World War II, submarines began using sonar systems to navigate. It was discovered that the high intensity ultrasound waves they utilized were actually heating the nearby fish and killing them. Medical scientists were intrigued and began to study how heat from ultrasound waves worked to heal tissue.

Techniques from these experiments have been used by therapists since that time to address a variety of medical problems. Currently, more than a million treatments using ultrasound occur in the United States every single year.

How A Therapeutic Ultrasound Machine Works

Ultrasound equipment uses inaudible high-frequency mechanical sound waves that are converted to acoustic sound wave within the machinery. As these waves pass through the body, they lose energy due to collisions with the molecules within the tissue.

The amount of targeted energy that reaches the treatment site depends upon both the frequency, focus, and intensity of the emitted waves as well as the type of tissue that it passes through. When calculating the settings on the machine for any given scar treatment plan, both of these variables must be considered.

Most machines are set to deliver waves at a frequency of one to three MHz. Lower frequency waves will penetrate deeper into tissue but are less focused. At 1 MHz, ultrasound waves go 3-5 cm below the skin. Scar tissue that sits on the surface of the skin generally requires a frequency of 3 MHz to concentrate the energy where it is most needed.

Acoustic impedance is calculated by multiplying the density of the tissue and the speed at which waves travel through it. Tissues that are high in water content allow the waves to travel through them at a higher rate of speed. This means that wave speed is higher through fat cells that are high in water content and slower through skeletal muscles which have very little water in them.

The person performing the ultrasound for scar treatment must be sure to keep the device moving. If it stays in one position too long, standing waves may form and damage the surrounding tissue. A series of pulsed waves helps prevent this from happening.

Gels are used to prevent reflection of the waves away from the desired location. Gels have different impedance and different types may be selected depending upon the area of the old wound as well as the diameter of the device itself. A skilled therapist will factor in all of these conditions to create a mix that will heal rather than harm.

The Physiological Effects Of Ultrasound Waves on Scar Tissue

An ultrasound treatment delivers high levels of heat into the area that is targeted. The effects are both thermal (heat-induced) and non thermal. Each of these works on scar tissue in a different way.

Thermal effects can trigger increased blood flow into a region. They reduce muscle spasms and consequently increase the ability of collagen to extend, or relax. There is also a local response in inflammation within the cell which triggers repair cells to arrive on the scene.

Non-thermal effects are quite complex. They include responses known as cavitation and acoustic micro streaming. It is thought that these effects may be more important for healing than the thermal effects.

Cavitation occurs when gas bubbles within the interstitial fluid expand and contract. This causes increased flow within the liquid contained between the cells of the tissue. The more stable and rhythmic the flow induced by cavitation is, the more beneficial the treatment will be. Irregular pulses can damage surrounding tissues so it is imperative that the treatment last long enough to become stable.

Acoustic micro streaming forces the liquid to move in one direction as it passes by the cellular material within the tissue. This occurs because the ultrasound waves make mechanical pressure changes within the treated area and force the tissue to move in a single direction. As the fluid passes the cells, it changes the membranes that surround them and causes them to become more permeable. This allows materials to enter the cells themselves to signal them to begin repairs within the area.

One of the ultimate results of these mechanical inducements to change are production and attraction of more fibroblasts. Fibroblasts are young cells that produce collagen. It is this collagen that the body will use to reorganize and repair the scar tissue.

The increased number of fibroblasts in the area require oxygenation that can only be delivered by blood. This is how the thermal effects of an ultrasound treatment plan for scar tissue works together with the non-thermal effects. It is also used for newly formed wounds to help them heal with minimal scarring.

As mentioned above, the thermal effect of ultrasound treatment also allow the collagen to stretch. When a severe injury occurs, the scar tissue may be so tightly bound by the collagen used in its repair that movement is restricted. Applied heat allows the existing collagen to begin to relax for greater mobility. Over time and with continued treatment, the configuration of scar tissue will permanently change and debilitating effect will disappear.


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