This lecture intends to provide general outline about the uses, parameters, precautions and contraindications of therapeutic ultrasound for undergraduate physiotherapy students at Kathmandu University School of Medical Sciences, Nepal. After the lecture, students will explore the evidences about current practices of therapeutic ultrasound in various musculoskeletal pain conditions, critically appraise them and present the evidences to the class.

1. Saurab Sharma, MPT
Lecturer, KUSMS
Therapeutic Ultrasound (US)
MSK III b – Cervical and thoracic
Spine
Electrotherapy
Lecture 4

2. Objectives of session
 At the end of the class, students will be
able to:
 Understand the background of ultrasound
 Explain the transmission, penetration and
absorption of ultrasound
 Explain the effects of ultrasound
 Identify the uses of Ultrasound
 Explain the application of ultrasound
 Identify Precautions and Contraindications
2

3. Introduction
 Most common modality used- 94% (Pope
et al, 1995)
 Initially used for thermal effects, now
used for its non-thermal effects
3

4. Ultrasound Transmission
 Does not pass through air (greatest
steal- air impedance)
 Presence of air between skin and
ultrasound head, means probability of
reflection- 99.9%
 Coupling medium required- water, gel,
oil, cream
 Head position- 90 degrees to skin4

5. Penetration and absorption
 Greater absorption in superficial tissue
than deep
 Half value depth-
 Different for different tissues and
frequencies
 3 MHz- 2 cm
 1 MHz- 4 cm
 Tissue with high protein absorbs more
US
5

6. Effects
 Thermal
 Non-thermal
Increasing protein content
Blood, fat, nerve, muscle, skin, tendon, (cartilage
and bone)
6
Low Ultrasound Absorption
High

7. Effects: Thermal
 Absorbed US generates heat. It
depends on:
 Nature of the tissue: high for protein
 Degree of vascularization
 Frequency of US: more frequency more
absorption
 Insufficient to raise temperature to cause
therapeutic changes
7

8. Effects: Thermal
 Should reduce pain, increase local blood
flow, decrease joint stiffness
 Biologically significant thermal effect can
be achieved by increasing the tissue
temperature to 40 – 45 degrees for at least
5 minutes.
8

9. Effects: Non- Thermal
 Cavitation
 Acoustic streaming
 Stimulates cell activity, membrane
permeability
 Increases protein synthesis
 Increases secretion from mast cells
 Fibroblast mobility changes
 Acceleration of repair
 Standing waves9

10. Effects: Tissue Repair
 Three phases of repair process
1. Inflammation
2. Proliferation/ granulation tissue
formation
3. Remodeling
 Effect of US depends on the phase in
which it is used
10

11. Effects: Tissue Repair:
Phase 1: Inflammation
 Acoustic streaming forces produces
changes in permeability of platelets
membrane causing release of serotonin.
 Serotonin may influence release of other
factors.
 Platelets also contain wound factors
essential for successful repair.
11

12. Effects: Tissue Repair:
Phase 1: Inflammation
 Single dose of US given soon after
injury can stimulate mast cells to release
histamine.
 Changes in permeability of mast cell to
calcium ion, potassium ions etc.
 Calcium ions act as intracellular signal
for appropriate metabolic response.
12

13. Effects: Tissue Repair:
Phase 1: Inflammation
 Cavitation is the physical mechanism
responsible
 Cavitation is the likely to occur at lower
frequency, whereas higher frequency
causes heating
 US causes edema to form and resolve
more rapidly accelerating healing process.
13

14. Effects: Tissue Repair
Phase 2: Proliferative phase of
repair
 US may maximize cell proliferation,
causes migration of cells
 US accelerates the rate of angiogenesis
 Continuous mode- 0.5 w/cm2- 20%
increase in collagen
 Pulse US- 0.5 w/cm2- 30% increase in
collagen
14

15. Effects: Tissue Repair
Phase 2: Proliferative phase of
repair
 Wound contraction is accelerated by US
 Pulsed- 3 MHz, 0.5 w/cm2
 Same degree of contraction can be
achieved by 0.1 w/cm2
15

16. Effects: Tissue Repair
Phase 3: Remodeling phase of
repair
 US changes the types of collagen from
type III to type I
 Increases tensile strength
 Increase scar mobility
 Enhances functional capacity of scar
tissues
16

17. Effects: Tissue Repair
Phase 3: Remodeling phase of
repair
 Best results- when if treated immediately
after injury: 0.1w/cm2 for 3 times/week for 2
weeks causes increased tensile strength
and elasticity
 Increases amount of collagen deposits
 Improves the pattern of deposition like
normal tissue
 Lower intensities are better than higher
17

18. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode
 Duration of treatment
 Hazards18

19. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode
 Duration of treatment
 Hazards19

20. Application of Ultrasound:
Choice of machine
20

21. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode
 Duration of treatment
 Hazards21

22. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode
 Duration of treatment
 Hazards22

23. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency : 1 MHz vs 3 MHz
 Intensity
 Mode
 Duration of treatment
 Hazards23

24. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity: Less vs more
 Mode
 Duration of treatment
 Hazards24

25. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode: Pulsed vs continuous
 Duration of treatment
 Hazards25

26. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode
 Duration of treatment
 Hazards26

27. Application of Ultrasound:
Factors to be considered:
 Choice of machine
 Calibration
 Choice of coupling medium
 Frequency
 Intensity
 Mode
 Duration of treatment
 Hazards27

28. Application of Ultrasound:
28

29. Application of Ultrasound:
29

30. Contraindications, dangers,
precautions
 Consider general contraindications to
Electrotherapy
 Spread of infection to the tissue
 70% alcohol swab reduces infection significantly
 Use it on every patient every time
 Pregnancy- avoid lower thorax, trunk and
pelvic region
 Malignant tissue
 Active epiphysis
 Higher dose US is avoided at fracture sites
30

31. Clinical application:
 Application in acute ankle sprain:
 Aim?
 Site?
 Type of application?
 Parameters/ doses?
 Evidence?
31

32. Objectives of session
 At the end of the class, students will be
able to:
 Understand the background of ultrasound
 Explain the Production, transmission,
penetration and absorption of ultrasound
 Explain the effects of ultrasound
 Identify the uses/ Indications of Ultrasound
 Explain the application of ultrasound
 Identify Precautions and Contraindications
32

33. References
 Kathleen Sluka. Mechanism and Management
of Pain for the Physical Therapist. 2nd Edition.
IASP Press. Wolters and Kluwer. 2016
 Tim Watson. Electrotherapy: Evidence Based
Practice. 2008. Churchill Livingstone. 12th
edition.
 John Low, Ann Reed. Electrotherapy
Explained. Principles and Practice.
Butterworth Heinemann. 3rd Edition.33