Ultrasound Therapy For Wound Healing 

Ultrasound is quite a common word and is, more often than not, pictured as being used as an imaging tool. You may have heard it being used in particular with regards to pregnancies and diagnosing other medical conditions. With the introduction of ultrasound therapy, ultrasounds can be used for treatments and wound healing.

Whenever we sustain any type of injury on our bodies, our bodies immediately activate a complex wound-healing system to treat that wound. This involves limiting any further damage, stopping bleeding, and promoting the rebuilding of any injured tissue. This is an intricate process which can take several weeks, depending on the size of the injury. 

The ultrasound works by releasing electrical impulses which travel as waves through the surfaces of the body. These waves travel through the body tissues and can get absorbed by them thus, promoting faster wound healing.¹

How the body heals

Getting injured is a common occurrence. The extent of the injury can range from a small cut on your finger to a much larger and deeper wound in your body. No matter the size of the injury, our bodies will start to heal that wound. In minor injuries, no external interference is necessary but for larger injuries, it is advised to seek professional medical help.

The first step in wound healing is to stop the bleeding and this is done by initiating the clotting system to essentially “plug up” the wound and prevent any further blood loss.² After that, the injured area undergoes inflammation, an immunological response,  to kill any bacteria and keep the wound clean. The next step is filling the wound with new blood vessels, tissue, and cells, usually accompanied by a scab. Lastly, the repaired wound would need time to strengthen and regain its original flexibility.²

Understanding ultrasound therapy

You are probably wondering how exactly an ultrasound works in promoting healing in the body. The ultrasound machine releases electrical currents that travel to the ultrasound probe (or ultrasound wand, transducer) which contains crystals which then vibrate. This vibration forms mechanical waves which penetrate the skin and are then transferred to your body's tissues.¹ Your body tissues absorb this energy which could reduce swelling, improve blood flow to the injured area, and promote wound healing.

The type of wound obtained will determine the duration and intensity of your ultrasound therapy. Injuries which are more extensive may require a higher intensity of ultrasound therapy over a longer period of time. The ultrasound can also be aimed towards deeper body tissues without affecting the tissues nearer the surface, if the injury is deeper within the body. Parts of the body, such as muscle or bone, contain a high amount of protein and can absorb energy waves more efficiently than fat, which contains a high amount of water. This means that since muscle and bone absorb most of the energy waves, they will have lower penetration within the body and fat will have a higher penetration. 

One type of ultrasound therapy is called mechanical ultrasound. This uses mechanical waves to form a difference in pressure within the fluid of the tissue. These pressure differences create bubbles which can then burst on contact with a solid entity in the body and create shockwaves. This form is commonly used to treat kidney stones.

Another form is thermal ultrasound, in which the vibrations formed by the probe cause the body tissues to heat up. This form is commonly used to treat pain.

One of the types of ultrasound used in wound healing is a low-frequency, non-contact ultrasound.³ This device emits a lower frequency than usual and does not actually touch the body surface. The probe emits a sterile, saline (contains dissolved salts)  mist which can transfer the energy waves to the body. The mist particles are of roughly equal size to properly transfer the energy. This ultrasound can promote wound healing mainly by proper cleaning of the wound. A more traditional method would be an ultrasound probe which comes into direct contact with the body after a gel is applied to the skin, which helps to transfer the energy waves. 

Clinical applications and efficacy 

There are many different medical conditions which can benefit from ultrasound therapy. Some of these conditions are: 

• Soft tissue injuries: soft tissues include muscle, fat, blood vessels, nerves etc.
• Diabetic foot ulcers: these are painful, open wounds which occur on the bottom of the feet due to uncontrolled and severe diabetes. 
• Char-cot fractures: this is also a complication from severe and uncontrolled diabetes, which can lead to fractures in the foot. 
• Pressure ulcers/sores: these ulcers or sores are formed by putting prolonged pressure on one area of the body and they are most common in people who have trouble moving, in conditions such as paralysis or old age. 

Some of the more traditional wound healing methods used are based on debridement of the wound.⁴ This is a process where wounds are cleaned of any dead skin or foreign material which may have entered the wound. This reduces the chances of contracting an infection and helps the wound to heal properly. Debridement can be done with or without surgery, depending on the extent of the injury. Wound healing can then be promoted by various ointments, bandages or negative pressure. 

Some advantages that ultrasound therapy has over more conventional methods of wound healing are: 

• It is relatively painless as compared to physical debridement of any wounds
• Ultrasound waves can penetrate deep into the body tissue without affecting the body surface.
• Ultrasound waves can provide an antiseptic effect as well which can help to kill any bacteria and thus, promote wound healing.
• It can help to reduce any swelling or pain which is present
• It can also stimulate the formation of blood vessels and collagen

It can help in wound closure.

Practical considerations and implementations 

Ultrasound therapy can be useful in a variety of patients and most people can benefit from it. However, there are some instances in which it is not possible to have ultrasound therapy, including: 

• If you are pregnant 
• If the wound is over the eyes or spine 
• If the wound has been infected
• If there are any underlying broken bones
• If you have a pacemaker 
• If you have a malignant tumour 
• If you have a reduced amount of blood flow to the area, for example, if you develop a blood clot 

Before you start your ultrasound therapy sessions, a healthcare professional will likely check that you do not possess any of the contraindications listed. 

During the procedure, the part of your body which needs ultrasound therapy will need to be exposed and the probe will be passed over that area multiple times for roughly ten minutes. It is a relatively quick procedure and it is painless. 

However, as with any procedure, there are some small risks of side effects and these may include:⁵

• If the probe is left in contact with your skin for too long it may cause a minor burn on your skin. This is why the probe is constantly moved around. This is more common in thermal ultrasounds.
• Some minor internal bleeding may occur due to mechanical waves being transferred to your body from the ultrasound probe. This is more common in mechanical ultrasounds.
• Rapid changes in pressure may cause a disruption in cellular activity which is called microplosion.

Conclusion 

Ultrasound has been used for years as an imaging modality but now it is also becoming used as a treatment modality. It is being used in various disorders but most commonly for pain relief and to promote wound healing. 

The body's healing system is quite complex and intricate, enabling it to efficiently heal minor wounds. At times, larger and deeper wounds might need medical intervention with medical or surgical procedures or even ultrasound therapy. Ultrasound therapy works by converting electrical impulses from the ultrasound device to either mechanical waves (mechanical ultrasound) or vibrations which can generate heat (thermal ultrasound) These vibrations can penetrate more in high water-content parts of the body, such as fat, and they generally have a low penetration in high protein-content parts, such as muscle.

Ultrasound therapy can be preferred over other options because it is a relatively painless and quick procedure. You will probably have a few appointments with your healthcare provider, depending on the extent of the injury and the probe will be passed over the affected area several times, for around ten minutes. It can also penetrate deep within the body without harming the surface skin. However,  some side effects may occur, such as minor burns on the skin or internal bleeding. This therapy cannot be used on pregnant women or wounds which overlap the spine and eye. 

This is an emerging and innovative mechanism which will be further improved and researched to provide even quicker and painless relief in wound healing.