LIPUS is a form of mechanical energy which is transmitted through & into the living tissue as acoustic pressure waves above the human audible range.
Hypothesis: Micro-mechanical strains produced in biological tissues >Biochemical events >stimulate Fracture healing
EFFECTS: 1. causes Osteoblasts, Fibroblasts & Monocytes induced cell proliferation-differentiation >Bone-formation.
2. Angiogenesis- through release of TGF-β, b-FGF, IL-8, PGE2 & VEGF.
3. decrease in Pro-inflammatory cytokines like IL-6, TNF-α.
Timing of Use: ~Useful in Inflammatory & Repair phase
~does not affect remodelling phase of fracture-healing.
Mechanism of Action: not clear
Different Hypothesis:-
- Motion caused by pulsed waves of LIPUS at both fractured ends; the motion occurs at nanometric scale
>to stimulate molecular & cellular pathways involved in healing. - Cavitation & Acoustic Sreaming: Pulsating sounds from LIPUS
>Accumulation of Gas Bubbles within Cells & tissues>creats a CAVITY to support Acoustic streaming
CAVITY–> Stable & Unstable - Stable Cavitation
>Turbulence/Circular flow of tissue around bubbles>Increases cell-permeability>Rise in BP at the site of injury>Increased gas-exchange & nutrient-delivery - Unstable Cavitation
>Burst of bubbles>Energy released>Stimulate surrounding tissues
USES: 1. Delayed Union, 2. Non-union, 3. Osseointegration of Implants.
DNB Orthopaedics Q&A 