Wound Ultrasound – Therapy for Chronic Wounds

What is Wound Ultrasound?

Wound ultrasound refers to the therapeutic use of ultrasound waves in the treatment of wounds, particularly chronic or non-healing wounds. High-frequency sound waves are applied directly or indirectly to the wound tissue to accelerate healing, reduce infection, and improve overall wound outcomes. It is used in modern wound care as a standalone or complementary treatment option.

Mechanism of Action

Wound ultrasound uses sound waves at frequencies typically ranging from 20 kHz to 3 MHz. Depending on the frequency range, two main categories are distinguished:

• Low-frequency ultrasound (20–100 kHz): Penetrates deeper into tissue, promotes wound debridement through cavitation (formation and implosion of microbubbles), and has strong antimicrobial properties.
• High-frequency ultrasound (1–3 MHz): Acts more superficially, gently warms the tissue, and promotes circulation and cellular regeneration.

The key biological effects of wound ultrasound include:

• Stimulation of fibroblast activity and collagen synthesis
• Improvement of local microcirculation
• Reduction of bacteria and biofilm within the wound (antimicrobial effect)
• Promotion of angiogenesis (formation of new blood vessels)
• Reduction of wound oedema and inflammatory responses

Indications

Wound ultrasound is primarily used for the following wound types:

• Chronic wounds: e.g., diabetic foot ulcers, venous or arterial leg ulcers, pressure ulcers (decubitus)
• Postoperative wound healing disorders
• Traumatic wounds with delayed healing
• Infected wounds with biofilm burden

Treatment Procedure

Wound ultrasound is administered by trained medical professionals. An ultrasound applicator is either placed directly on the wound or applied in a non-contact manner through a water bath or coupling gel. Each treatment session typically lasts 3 to 10 minutes, depending on the wound size and device used. Multiple sessions per week over several weeks are common.

Contact Method

In the direct contact method, the transducer is applied to the wound surface using a sterile coupling medium. This method is well suited for deep and irregularly shaped wounds.

Non-Contact Method (MIST Therapy)

In non-contact ultrasound therapy, also known as MIST Therapy (Mist Ultrasound Therapy), ultrasound energy is delivered to the wound surface via a fine saline mist. This approach is particularly gentle and is suitable for highly sensitive or painful wounds.

Benefits and Clinical Evidence

Clinical studies demonstrate that wound ultrasound can significantly accelerate wound healing in chronic wounds. Particularly in venous leg ulcers and diabetic foot lesions, positive outcomes have been observed regarding wound size reduction and tissue regeneration. Wound ultrasound is considered a safe and well-tolerated procedure with minimal side effects.

Contraindications and Precautions

Despite its good tolerability, there are situations in which wound ultrasound should not be used or should be applied with caution:

• Application over cartilage or bone structures directly beneath the wound
• Malignant wounds or proximity to tumours
• Pregnancy in the abdominal or pelvic area
• Use over implanted electronic devices (e.g., cardiac pacemakers)
• Active thrombosis in the treatment area

References

1. Wound Healing Society: Clinical Practice Guidelines for Chronic Wound Care (2023). Wound Repair and Regeneration.
2. Voigt J, Wendelken M, Driver V, Alvarez OM. Low-frequency ultrasound (20–40 kHz) as an adjunctive therapy for chronic wound treatment. International Wound Journal, 2011.
3. Ennis WJ et al. Ultrasound therapy for recalcitrant diabetic foot ulcers. Advances in Skin and Wound Care, 2005.