=====A Review of Low-Intensity Pulsed Ultrasound for Therapeutic Applications=====

====Abstract====
Ultrasound therapy has a long history of novel applications in medicine. Compared to high-intensity ultrasound used for tissue heating, low-intensity ultrasound has drawn increasing attention recently due to its ability to induce therapeutic changes without biologically significant temperature increase. Low-intensity pulsed ultrasound (LIPUS) is a specific type of ultrasound that delivers at a low intensity and outputs in the mode of pulsed waves. It has minimal thermal effects while maintaining the transmission of acoustic energy to the target tissue, which is able to provide noninvasive physical stimulation for therapeutic applications. LIPUS has been demonstrated to accelerate the healing of fresh fracture, nonunion and delayed union in both animal and clinical studies. The effectiveness of LIPUS for the applications of soft-tissue regeneration and inhibiting inflammatory responses has also been investigated experimentally. Additionally, research has shown that LIPUS is a promising modality for neuromodulation. The purpose of this review is to provide an overview of the recent developments of LIPUS for therapeutic applications, based on the papers that report positive effects, and to present the findings on the understanding of its mechanism. Current available LIPUS devices are also briefly described in this paper.

====Commentary====

=== Effects===
  * thermal - since 1920s
  * non-thermal: acoustic cavitation, biological signaling
  * Intensity
    * diagnostic 0.05-0.5 W/cm2
    * high intensity 0.2-100 W/cm2 up to 10K  --> thermal effects
    * low intensity --> non-thermal effects
      * **LIPUS: 1-3 MHz, 0.02-1 W/cm2 SATA (Spatial average, Temporal average) @ 5-20 mins a day
**

=== Biological Effects of LIPUS===

  * through "non-thermal effects mostly include microbubbles and microjets induced by cavitation, acoustic streaming and mechanical stimulation etc."
  * biological effects:
    * regulate cell proliferation and differentiation
    * anti-inflammatory effect
    * neuromodulation

===Tendon Healing===

====Source=====

Jiang, X., Savchenko, O., Li, Y., Qi, S., Yang, T., Zhang, W., & Chen, J. (2019). A Review of Low-Intensity Pulsed Ultrasound for Therapeutic Applications. IEEE Transactions on Biomedical Engineering, 66(10), 2704–2718. https://doi.org/10.1109/TBME.2018.2889669

====See also====
  * [[md:flexor_tendon|Flexor Tendon Injuries]]

====Meta====
  * created: 2021-05-18