Ultrasound Therapy PDF

 Definition: Sound waves are mechanical longitudinal waves consisting of series of compression (molecules are squeezed together) and rarefaction (molecules are spread out). 2. Ultrasound (US) is an inaudible, acoustic, high frequency vibration energy which exceeds the upper limit of...

 Definition: Sound waves are mechanical longitudinal waves consisting of series of compression (molecules are squeezed together) and rarefaction (molecules are spread out). 2. Ultrasound (US) is an inaudible, acoustic, high frequency vibration energy which exceeds the upper limit of normal human hearing range (20 Hz – 20,000 Hz). 3. The US frequencies used in Physical Therapy are 0.75 OR 3 MHz. Ultrasound is a DEEP HEATING MODALITY with a penetration of 2 – 5 cm. At 3 cm depth and after 10 minutes Hot US (0.75 packs MHz) 0.8 °C 4 °C  Selective heating modality Collagen content Joint Muscle Tendon Ligament Mensci Bones capsule 1.Ultrasound generator consists of; a. High frequency electrical generator: produce electric current at the required frequency. (0.75 MHz OR 3 MHZ) b. Coaxial cable: transmitting the high frequency electric current to the transducer. c. Transducer housed in the ultrasound head which is made of; i. Piezoelectric crystal. ii.Backing (dampening material). iii.Matching metal surface.  Transducer is a device that converts energy from one type to another, i.e., converts electric energy to sound energy and vice versa.  Transducer US transducer converts electric energy into mechanical sound waves by changing its thickness in response to passage of electric current. It is made of a piezoelectric crystal (2-3 mm in thickness) that is made of quartz crystal or synthetic ceramic crystals (lead zirconate titanate OR barium titanate). Piezoelectricity: 1. Piezoelectricity is a natural phenomenon found in some mineral crystals like quartz. 2. These crystals have the ability to convert induced mechanical deformation into electric current and vice versa. 3. So, they can change their thickness in response to passing an alternating electric current through them.  Indirect (Reverse) Direct Piezoelectricity  Indirect Direct (Reverse) is the generation of an is the change of the alternating electric crystal thickness when current on the crystal an alternating electric when it is compressed orcurrent pass through expanded. the crystal. Piezoelectric effect Ultrasound waves production: 1. The high frequency electric current is transmitted through the coaxial cable to the piezoelectric crystal. 2. The crystal is attached to a metal backing material (from the back) and fused to a metal front through which ultrasound waves are transmitted to the tissue. 3. The crystal will deform (expand and compress) in response to the passage of electric current. Ultrasound waves production: 4. As the back of the crystal is attached to a metal backing material, the deformation of the crystal will move the metallic front in a vibratory manner with the preset frequency. 5. This vibration produces series of compression and rarefaction (ultrasound waves) in the adjacent tissues. 1.Acoustic energy depends on molecular collision for transmission. So, molecules in the conducting medium will oscillate with minimal displacement. 2.Ultrasound waves can travel in solids, liquids and gases with different velocities and acoustic impedances, but CANNOT travel in vacuum.  Reflection Refraction US interaction Absorption and penetration Shear forces Reflection: 1. Reflection occurs if there is mismatch in the acoustic impedance of the two media. 2. The percentage of reflection depends on the acoustic impedance of the two media. 3. With greater difference in acoustic impedance between the two media at the interface, greater percentage of waves will be reflected at the interface and less percentage will pass through the tissue.  Material Acoustic impedance (Ω) Air 213 Fatty tissue 1.4  106 Muscle 1.7  106 Bone 5.1  106 Water 1.5  106 Steel 47  106 Reflection: 4. To minimize reflection: a. The impedance of the two media must be close to each other. b.This can be achieved by using suitable coupling medium. c. As the steel – air impedance is very high, the presence of even small air bubbles in the conducting medium will reflect the waves to the US head and may cause damage to the head.  Interface Energy reflected (%) Water – Soft tissue 0.2 % Soft tissue – Fat 1% Soft tissue – Bone 15 – 40 % Soft tissue – Air 99.9 % Steel – Air 99.9 % Refraction: 1.It occurs when the US waves strike the skin with angle other than 90º. 2.To prevent refraction, make sure that the head is perpendicular on the skin. Attenuation, Absorption and Penetration: 1.Attenuation means reduction of the intensity of US waves as it passes through the tissue. 2.Attenuation depends on absorption and scattering. So, the greater energy absorption by the tissue, the less penetration of US waves.  0.75 MHz Wave frequency 3 MHz Penetration depends on; Collagen Tissue property Fluid  Shearing effect: 1. It is the transformation of US from the longitudinal form to transverse form at the periosteum. 2. There are two types of waves that can travel in the tissue;  There are two types of waves transmission in tissue 1.Longitudinal waves: A. Travel through both solids and liquids. B. In biological tissue, they travel in soft tissues only. C. Molecular displacement occur in the same direction of wave travel. 2. Transverse waves: A. Travel in solids only. B. Molecular displacement occur in perpendicular direction. Thermal Physiological effects Non- thermal  Continuous mode Produce thermal effect Produce selective deep heating Decrease as it pass in the tissue. Tissue temperature should be increased 4-5 °C for 5 minutes  Increase metabolism. ↑ 1 °C Increase blood flow. Increase healing rate. Help in treatment of chronic inflammation. ↑ 2-3 Reduce muscle spasm. °C Relief pain.. ↑ 4 °C Increase collagen tissue extensibility and decrease joint stiffness. Above 45 °C May cause tissue damage. Cavitation Micro- streaming Non-thermal effects The non-thermal effects stimulate cell membrane and increase cell activity which results in; 1. Increase Ca++ uptake by cells. 2. Increase cell membrane permeability. 3. Release histamine-like substance. 4. Increased blood flow. 5. Stimulation of fibroblast activity. 6. Increased protein synthesis. 7. Increased tissue regeneration. 8. Increase macrophages activity. 9. Increased bone healing and repair of nonunion fractures.  Unstable Stable OR cavitation Cavitation transient cavitation Cavitation is the formation of gas-filled bubbles inside the tissue, which expand and compress in response to ultrasound waves. Stable cavitation; Unstable cavitation;  It occurs at therapeutic  It is violent large excursion doses of US. in bubble volume resulting  The bubbles expand in bubble implosion OR and compress in collapse. response to pressure  It releases huge amounts of changes. energy which cause local  It increases fluid flow tissue damage. around the bubbles and  Unstable cavitation occurs produce the acoustic with high intensity, low streaming. frequency ultrasound.  Micro-streaming It is the unidirectional movement of fluids along the boundaries of cell membranes. It is produced by the mechanical pressure of US.  ↑ membrane permeability Increased membrane permeability to Na+ and Ca++ ions which changes cell membrane Na+ potential and increases cell metabolism, & Ca++ protein synthesis and secretion of growth hormones. Remove waste products  Therapeutic effects: 1. Break down adhesion and scar tissues: a. US waves break down adhesions through; i. Depolymerization of mucopolysaccharides, mucoproteins and glycoproteins. ii. Decreasing the viscosity of hyaluronic acid in adhesions. b. It increases collagen tissue extensibility secondary to increased tissue temperature. c. It improves scar quality, making it stronger and more elastic. d. It should be used before applying ROM exercises.  Therapeutic effects: 2.Wound healing: a. Low intensity pulsed US enhances wound and fracture healing through; i. Increasing intracellular Ca++. ii.Stimulating collagen production by fibroblasts. iii.Stimulates myofibroblasts contraction which increases wound strength. iv.Stimulates angiogenesis. v.Improving local blood flow. Therapeutic effects: 3. Chronic edema: a. It removes chronic edema through increasing circulation and removal of waste products.  Therapeutic effects: 4.Pain control: a.Direct effect: i. Increases pain threshold. ii.Decreases pain transmission. iii.Stimulates tactile skin receptors which blocks pain through gate control theory.  Therapeutic effects: 4.Pain control: b. Indirect effect: i. US treats the problem presented, and hence removes the source of pain; ✓ Removing waste products. ✓ Increasing capillary permeability. ✓ Reducing edema. ✓ Improving cell function and tissue healing. ✓ Decreasing muscle spasm. ✓ Breaking down adhesions. Indications: 1. Joint stiffness and soft tissue contractures; a. Frozen shoulder. b. Myofascial pain syndrome and Fibromyalgia. c. Trigger points. d. Scar tissue. 2. Soft tissue injuries, e.g., sprains, strains, contusions and muscle tear. 3. Acute and chronic inflammatory conditions, e.g.,; a. Tendinitis, bursitis and capsulitis. b. Nerve root impingement and neuritis, e.g., Carpal tunnel syndrome and sciatica. Indications: 4. Musculoskeletal disorders; a. Degenerative disorders, e.g., osteoarthritis and spondylosis. b. Rheumatoid disorders, e.g., rheumatoid arthritis. 5. Muscle spasm. 6. Tissue healing; a. Open wounds and ulcers. b. Fracture healing. 7. Pain relief. 8. Herniated intervertebral disc.  Contraindications: 1. Absolute contra-indications; a. Loss or impaired sensation. b. Ischemia and poor circulation. c. Deep Vein Thrombosis (DVT) and thrombophlebitis. d. Neoplasm and after deep x-ray therapy. e. Acute infections and open infected wounds. f. Metal implants. g. Over the eyes and reproductive organs. h. Exposed spinal cord, e.g., cervical and thoracic spine. i. Near areas of bone overgrowth. j. Epiphyseal cartilage plate.  Contraindications: 2.Relative contra-indications; a.Unreliable patients. b.Near pacemakers. c.Over the abdomen and lumbar region of a pregnant woman. d.Hemorrhagic areas.  Phonophoresis is the introduction of drugs through the skin using mechanical force of ultrasound. Increase permeability of >>>>>>>>>>>> Push small molecules through the skin to deeper tissues. Up to 6 cm deep Drug penetration is affected by; Skin thickness and composition Hydration Vascularity  Safe Advantage Local high of drug painless Phonophores concentration is Non- invasive  Molecular size Skin Factors permeability affecting phonophoresis Frequency Intensity Drugs used with phonophoresis: 1. Hydrocortisone. 2. Non-steroidal anti-inflammatory drugs (NSAID). 3. Lidocaine. 4. Salicylates.