modalities exam 3

therapeutic ultrasound

provides heat to soft tissues via mechanical energy

--> can also provide non-thermal effects by knocking around tissue

ultrasound unit

- oscillating circuit with duty cycle selector

- sound head/transducer contains crystal that converts electrical energy into mechanical acoustical energy

- power meter (how much sound is delivered)

- coaxial cable carries electrical energy from generator to crystal

electrical generator

ultrasound produced by converting electrical energy into acoustical energy

electrically stimulates crystal in transducer head (crystal vibrates)

Reverse piezoelectric effect

mechanically deforming a crystal by introducing an electrical current

piezoelectric effect

production of an electrical charge with deformation of a crystal

results in compression and expansion of crystal, resulting in vibrational activity that ultimately creates the ultrasound

what describes the size and quality of an ultrasound crystal?

- effective radiating area (ERA)

- beam non-uniformity ratio (BNR)

--> better scores = better crystals

--> BEST = ERA that is same size as sound head (highest) and BNR of 1:1

effective radiating area (ERA)

surface area of crystal that emits significant mechanical energy; always smaller than actual size of crystal

*ERAs close to actual size of transducer are generally better quality crystals

*Intensity = watts / ERA

beam non-uniformity ratio (BNR)

US energy not consistent as it is emitted from sound head (areas of high and low intensity)

BNR is ratio of highest intensity found in US beam compared with average intensity indicated on power meter

*acceptable = 6:1 (lower is better to reduce hot spots)

*ideal is 1:1

*ex: set 1.0 W/cm2, but get a 10 W/cm2 spike = ratio is 10:1

ultrasound - conducting media

- air is poor conductor

- commercial ultrasound gel/gel pads are superior (helps fill in gaps between skin and US head)

- water is not a good conducting medium

thermal effects of US

heat created by mechanical agitation of molecules

temperature increases cause:

- increased metabolic activity (increased local blood flow and can aid in tissue repair process)

- increased collagen elasticity

- analgesic and antispasmodic responses are not as good as other modalities

1-4 degrees celsius increase in tissue temperature is possible

*always wait until inflammatory process is over to do ultrasound!

thermal effects - degrees and their effects

1 degree Celsius = increased metabolism

2-3 degrees Celsius = decreased pain/spasm, increased blood flow, reduces chronic inflammation

4 degrees Celsius = increased collagen elasticity and extensibility

non thermal effects of US

stabile cavitation: cyclic expansion and contraction of gas bubbles, facilitating fluid movement and membrane support

acoustical streaming: movement of fluid along cell membranes by mechanical pressure of waves, facilitating fluid movement and increased membrane permeability; proposed to increase fibroblastic activity (granulation tissue)

ultrasound - frequency

operates from 1-3 MHz

inverse relationship between frequency of US and depth of penetration into tissue

--> 1 MHz dissipates 50% at depth of 5cm, while 3 MHz at 1 cm

ultrasound - intensity

thermal --> continuous wave with high intensities (1-2 W/cm2)

non thermal --> pulsed wave with lower intensities

*higher frequencies concentrate energy in superficial tissues

*consider depth of target tissue (deeper = low frequency and high intensity)

**fleshier body part = higher intensity, lower frequency

ultrasound - duty cycle

- 'on' time / 'total time'

- pulsed US minimized both thermal and non-thermal effects

ultrasound - duration

depends on size of treatment area, treatment goals, frequency and intensity (intensity and duration are inversely proportional)

*should NOT cover area larger than 3x ERA

- increased tissue density = faster heating (bones & nerves have high absorption, muscles/ligs/tendons have moderate absorption, skin/adipose have low absorption)

- incrased frequency provides faster heating

dosage for US

calculate increases per minute based on chose intensity and frequency for treatment goal

*ex: vastus intermedius to increase tissue extensibility = 1 MHz @ 2 W/cm2 for 10 mins

direct ultrasound

- loss of consistent skin contact can damage crystal (needs coupling medium)

- sound head should always be moving (3-4 cm/sec); faster movements decrease effects

indirect ultrasound

- either water or gel-filled bladder used as coupler

- commonly used for small/irregular areas to maintain appropriate contact

with immersion coupling water should be warm and de-gassed...

--> sound head held 0.5-1 inch from skin and kept moving

--> bubbled wiped off

--> sound head held parallel to tissues

dosage should be increased because of energy dissipation (ex: chronic LisFrac injury)

clinical indications of ultrasound

- localized areas/deep heat

- chronic inflammation (2 deg.)

- fibrosis and adhesions (4 deg.)

- adhesive joint capsulitis/contracures (4 deg)

contraindications of ultrasound

malignancy, pregnancy, acute sepsis, metal joint replacements, eyes/heart/genitalia, epiphyseal plates, CNS

phonophoresis

driving topical medication into tissue

medications: hydrocortisone, salicylates, anesthetics, etc.

treatments: usually 3-4, but up to 10 in a row

precautions: corticosteroids on tendons

ultrasound - combination treatments

E-stim, infrared thermotherapy, cryotherapy

diathermy

high frequency electromagnetic energy used to generate thermal and non-thermal effects at moderate depth in tissues (~2 in)

short wave diathermy

power output = 80-200+ watts

- frequencies and wavelengths we usually use: 27.12 MHz (11 meters)

- continuous vs pulsed

diathermy - electrical (capacitative) technique

patient is part of circuit

rotation/oscillation of dipoles

--> as poles change, ions rotate, causing tissue resistance/friction = heat

increased dipoles = increased capacitance (more energy needed to stimulate)

*muscles/tendons/deeper tissues need more dipoles than fat

*good for superficial (gate control)

diathermy - capacitive electrodes

- condenser field (two air space electrodes)

- causes molecules to vibrate in tissues (generates heat)

- greatest heating occurs near electrodes (greater current density)

*NOT during acute phase

diathermy - magnetic (inductance) technique

inductance field places patient in electromagnetic field of electrodes

inductance coil has AC current passive through it (current produces magnetic field perpendicular to coil; induces eddy currents in tissue)

greatest heating in tissue with low impedence (muscles/deeper tissues)

eddy currents

backwards current causing friction and heat

inductance electrodes

drum electrodes

- flat and house in drum(s), penetration of 3-5 cm

cable electrodes

- pancake and wrap-around

SW diathermy application

15-30 minutes

no metal within 4ft and no moisture

cosine and inverse square laws

diathermy - thermal effects

increased tissue temp, blood flow, metabolism, pain threshold

decreased muscle spasm

diathermy - non-thermal effects

theories for tissue repair

- repolarization of cells

- reactivation of sodium pump

diathermy - indications

moderate depth, large pathologies

- increased circulation, decreased pain/spasm

diathermy - contraindications

metal, pacemakers, pregnancy, infection, acute pathologies, malignancy, joint effusion, anesthesia/hypoesthesia

pulsed electromagnetic field (PEMF)

low frequency (

micro-wave diathermy

frequencies and wavelengths

- 915 MHz (33 cm)

- 2456 MHz (12 cm)

less penetration and less safe than SW

applicators = circular and rectangular

infrared modalities examples

cryotherapies, hot & cold baths, whirlpools, paraffin baths, hydrocollators, infrared lamps, fluid therapy, vapocoolant sprays

energy transfer types

conduction: direct contact

convection: medium movement

radiation: through medium

conversion: energy change

cryotherapy

superficial (2-5 cm)

sensations stages:

- cold

- aching/stinging

- warmth/pins and needles

- anesthesia/analgesia

tx time: 5-45 min

relief time: 2x tx time

penetration: up to 5 cm

effectiveness: up to hours

thermal mass

the ability of a material to absorb and store heat energy

cold lake will have more thermal mass, therefore a lesser chance of changing the water's temperature

ice bags

increased effectiveness:

- direct contact

- may cover

- compression (reduces resistance)

- remove air

- crushed ice is best

*good for gate control

commercial cryopacks

8 deg. F (much colder than ice), protective layer needed if using

cryocompression

combines cold and compression (px control + reduces swelling)

ice massage

strokes, 5-15 min

ice immersion

intense cryotherapy

tx time: 5-20 min

tx temp: 50-60 deg for appendage, 65-80 deg for torso

dependent position (ideally, above heart)

can be used with whirpool to eliminate thermoplane

vapocoolant spray

superficial, stimulates A fibers, with 3-4 strokes going distal to proximal

spray then stretch

cryokinetics

cold & exercise; increases JROM strength, function ?

contraindication motions: tissue extensibility, ballistic movements

ex: ice for 10 mins then just walk/do simple movements as pain is controlled

effects of cryotherapy

decreased metabolism (secondary ischemia), pain, spasm, circulation, sensation

cryotherapy indications

pain (acute/chronic), edema/effusion (add compress/elevation), spasm

cryotherapy contraindications

cold allergies, vasospastic disorders (raynaud's), rhematoid, circulatory insufficiencies, anesthesia, large/superficial nerves

hunting response

cold-induced vasodilation theory

30 min/cryotherapy

- 4-6 mins of cold induced vasodilation

- 15 mins of vasoconstriciton

**repeats back and forth for ~2 hrs, then vasoconstricts after that

infrared thermotherapy

tx time: 20-30+ min

penetration: up to 2 cm

effectiveness: short lived

*vasodilation with heat = more blood coming and going, hence why we use it for longer

hot pack only lasts as long as you have it on (gate control)

infrared thermotherapy modalities

hot packs, warm baths, paraffin baths, infrared lamps, fluidotherapy

target heat for thermotherapy

104 deg F

hot packs

~20 mins, 160-170 deg (no bacteria survives here)

moist (better heat transfer) v dry; pad on patient rather than patient on pad (heat rises)

temperature

-

bath temperatures

• 104° - 113° = Very Hot

• 98° - 104° = Hot

• 96° - 98° = Warm

• 92° - 96° = Neutral

• 80° - 92° = Tepid

• 65° - 80° = Cool

• 55° - 65° = Cold

•

paraffin bath

- intense heat (risk of burns)

- techniques

--> dip and hold

--> dip and wrap

~20 mins @ ~125 deg

*lower specific heat = slower energy transfer than water

works well for irregular surface (hands/feet), and for things like plantar fasciitis, carpal tunnel, tendon strains, etc.

infrared lamp

fluidotherapy

~20 min

110-125 deg (dry heat -- crushed corn husk)

benefits: exercise during tx, non-dependent position, massage

effects of thermotherapy

increased metabolism, collagen elasticity, inflammatory response

decreased muscle spasm/pain

thermotherapy indications

pain, spasm, non-acute swelling, JROM limitations

thermotherapy contraindications

acute injury, circulatory impairments, anesthesia, eyes/genital regions, pregnancy/menstruation, poor thermal control/hot environment

contrast therapy

theory = "vaso pump"

if used => probably not acute, and probably 3:1 or 4:1 (hot:cold)

great for pitting edema

cryo or thermo therapy?

trauma:

- acute: cryo

- non acute: thermo or cryo (personal preference)

muscle soreness: thermo

flexibility: thermo

severe pain/spasm: cryo