**1. Introduction**

Mechanical stimulation of bone cells modulates a myriad of molecular signalling pathways involved in osteogenesis. There are distinct forms of mechanical forces, such as centrifuge force,

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gravitational force, electromagnetic force, hydrostatic force and acoustic force. Acoustic forces comprise a modality of mechanical load that can be represented basically by three different types of acoustic waves: ultrasound wave, shock wave and radial pressure wave. Those waves may be applied to patients suffering from orthopaedics disorders, especially those related to osteogenesis; for instance, delayed union, nonunion, osteoporosis and acute fractures.

The application of mechanical devices for medical purposes is termed mechanotherapy. Accordingly, the use of acoustic devices, which is a category of mechanical devices, for medical purposes will be termed here acoustic therapy and will be further divided into three subcate‐ gories: low-intensity pulsed ultrasound stimulation (LIPUS), extracorporeal shock wave therapy (ESWT) and radial pressure wave therapy (RPWT). This chapter discusses the physical phenomena, biological events and clinical indications of acoustic therapy on bone tissue (**Table 1**).



**Table 1.** Abbreviations used throughout text.

gravitational force, electromagnetic force, hydrostatic force and acoustic force. Acoustic forces comprise a modality of mechanical load that can be represented basically by three different types of acoustic waves: ultrasound wave, shock wave and radial pressure wave. Those waves may be applied to patients suffering from orthopaedics disorders, especially those related to

The application of mechanical devices for medical purposes is termed mechanotherapy. Accordingly, the use of acoustic devices, which is a category of mechanical devices, for medical purposes will be termed here acoustic therapy and will be further divided into three subcate‐ gories: low-intensity pulsed ultrasound stimulation (LIPUS), extracorporeal shock wave therapy (ESWT) and radial pressure wave therapy (RPWT). This chapter discusses the physical phenomena, biological events and clinical indications of acoustic therapy on bone tissue (**Table**

osteogenesis; for instance, delayed union, nonunion, osteoporosis and acute fractures.

ActR activin receptor MCP monocyte chemoattractant protein ALP alkaline phosphatase MIP macrophage-inflammatory protein

ATP adenosine triphosphate mTOR mechanistic target of rapamycin Bax Bcl-2-associated X protein NADPH nicotinamide adenine dinucleotide

CDK cyclin-dependent kinase PPARγ2 peroxisome proliferator-activated

c-jun Jun proto-oncogene Rac Ras-related C3 botulinum toxin substrate

cox cyclooxygenase RANKL receptor activator of nuclear factor kappa

CXCR C-X-C chemokine receptor RANTES regulated upon activation, normal T-cell-

Dlx distal-less homeobox Ras portmanteau of "rat" and "sarcoma"

egr early growth response rhBMP-2 recombinant human BMP-2

phosphate

receptor γ2

PTHr parathyroid hormone receptor

B

B ligand

RANK receptor activator of nuclear factor kappa

expressed and secreted

PGE2 prostaglandin E2

**Abbreviations Meanings Abbreviations Meanings**

AT1 angiotensin II type 1 receptor Msx Msh homeobox

BMP bone morphogenetic protein NO nitric oxide

cbfa core binding factor subunit alpha-1, also known as Runx2

c-fos FBJ murine osteosarcoma viral oncogene homolog

c-myc avian myelocytomatosis viral oncogene homolog

BMPR bone morphogenetic protein receptor NOS nitric oxide synthase Ca2+ calcium ion OPG osteoprotegerin

**1**).

28 Advanced Techniques in Bone Regeneration
