Low-Intensity Pulsed Ultrasound (LIPUS) is a non-invasive therapy that uses mechanical sound waves to stimulate the body’s natural healing processes. It is applied to the skin over an injury to promote tissue regeneration by sending painless mechanical forces through tissue. This activates cellular activity and enhances biological functions that contribute to healing, accelerating recovery without surgical intervention.
Understanding LIPUS Technology
LIPUS technology is distinct from high-intensity ultrasound used for tissue destruction or diagnostic ultrasound used for imaging. Its characteristics are a low intensity, around 30 mW/cm², and a pulsed delivery method. These parameters ensure the effects are non-thermal, meaning it does not generate significant heat and relies on mechanical stimulation for its therapeutic effects.
The sound waves are delivered in short, repeated bursts, with a frequency of 1.5 MHz and a pulse width of 200 microseconds, repeated at 1 kHz. This configuration is engineered to stimulate biological activity at a cellular level. The mechanical energy creates subtle, localized pressures within the tissue, which is the basis of its mechanism of action.
Key Therapeutic Uses of LIPUS
The most established therapeutic use for LIPUS is in orthopedics for enhancing bone fracture healing. It is used for fractures that have difficulty healing, such as delayed unions (slower than expected healing) and non-unions (failure to heal). Daily LIPUS treatments can accelerate the healing of fresh fractures and improve outcomes for these challenging cases, including fractures of the tibia and distal radius.
Beyond bone healing, LIPUS has been investigated for treating soft tissue injuries. Research has explored its use for conditions like tendinopathies and for accelerating the repair of ligaments and cartilage. It is also used to manage injuries at the bone-tendon junction, and for dental applications like supporting bone healing after oral surgeries.
The Biological Impact of LIPUS
The therapeutic effects of LIPUS are rooted in its ability to influence cellular behavior through mechanotransduction. This is the mechanism by which cells convert mechanical stimuli into biochemical responses. The low-intensity sound waves generate mechanical forces that activate specific signaling pathways within cells, leading to a cascade of biological events that support tissue repair.
At the molecular level, LIPUS upregulates the production of growth factors and proteins instrumental in healing. It can increase the expression of vascular endothelial growth factor (VEGF), which promotes the formation of new blood vessels (angiogenesis). The mechanical forces also stimulate the production of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2), which play a part in bone formation.
This technology also influences the behavior of stem cells, encouraging them to migrate to the injury site and differentiate into specialized cells like osteoblasts, which build new bone. It can also modulate inflammatory responses. By activating these various pathways, LIPUS helps amplify the body’s own repair mechanisms at multiple stages of the healing process.
The LIPUS Treatment Process
LIPUS therapy is straightforward and can often be administered by the patient at home using a small, portable device. Treatment begins with applying a coupling gel to the skin over the injury site. The device’s transducer head is then placed directly against the skin over the injury.
A single, painless session lasts about 20 minutes and is performed once a day. This daily regimen continues for several weeks or months, depending on the injury’s severity. For fractures, the device is used with standard treatments like cast immobilization.
Safety Profile and Observed Results
LIPUS is a non-invasive treatment with a strong safety profile. Because it operates at a low intensity and in a pulsed manner, it avoids thermal effects that could damage tissue. The most common side effect is minor skin irritation at the application site, with no significant adverse events consistently found in clinical studies.
Clinical results have shown that LIPUS can accelerate healing times for certain types of fresh fractures and improve the success rate in non-union fractures. There are specific situations where LIPUS is not recommended. These contraindications include application:
- Over cancerous tumors
- Near electronic implants such as pacemakers
- Over the open growth plates of bones in children and adolescents
- During pregnancy