Therapeutic Modalities Review

Basic Principles of Electricity and Electrical Stimulating Currents

Electrotherapeutic CurrentsDirect (DC) or MonophasicFlow of electrons always in same directionSometimes called galvanic

Electrotherapeutic CurrentAlternating (AC) or BiphasicFlow of electrons changes directionAlways flows from negative to positive pole until polarity is reversed

Electrotherapeutic CurrentsPulsatile CurrentPulses grouped together and interruptedRussian and interferential currentsMay be bi-directional or uni-directional

Electrical GeneratorsAll are transcutaneous electrical stimulatorsTranscutaneous electrical nerve stimulators (TENS)Neuromuscular electrical stimulator (NMES) = Electrical muscle stimulator (EMS)Microcurrent electrical nerve stimulators (MENS) = Low intensity stimulators (LIS)

Pulse Frequency (CPS, PPS, Hz) Number of pulses or cycles per secondMuscle and nervous tissue respond depending on the length of time between pulses and on how pulses or waveforms are modulatedLow vs. Medium vs. High frequency currents

Electrode PlacementElectrodes may be placed:On or around the painful area Over specific dermatomes, myotomes, or sclerotomes that correspond to the painful areaClose to spinal cord segment that innervates an area that is painful Over sites where peripheral nerves that innervate the painful area becomes superficial and can be easily stimulatedOver superficial vascular structuresOver trigger point locations

Over acupuncture pointsIn a crisscrossed pattern around the point to be stimulated so the area to be treated is central to the location of the electrodesBipolar application resulting in similar physiologic effects beneath each electrodeMonopolar setup both an active and dispersive pad set up causing higher current density at the active electrodeQuadripolar technique

Physiologic Response To Electrical CurrentElectricity can have an effect on each cell and tissue it passes throughType and extent is dependent on the type of tissue, its response characteristics, and the nature of current appliedReactions can be:ThermalChemicalPhysiologic

Can be used to:Creating muscle contraction through nerve or muscle stimulationStimulating sensory nerves to help in treating painCreating an electrical field in biologic tissues to stimulate or alter the healing processCreating an electrical field on the skin surface to drive ions beneficial to the healing process into or through the skin

Therapeutic Uses of Electrically Induced Muscle Contraction High-volt CurrentsMuscle re-educationMuscle pump contractionsRetardation of atrophyMuscle strengtheningIncreasing range of motionReducing Edema

Muscle Re-EducationMuscular inhibition after surgery or injury is primary indication A muscle contraction usually can be forced by electrically stimulating the muscle Provides artificial use of inactive synapsesRestore normal balance to system as ascending sensory info is reintegrated into movement patternsPatient feels the muscle contract, sees the muscle contract, and can attempt to duplicate this muscular response

Muscle Pump ContractionsUsed to duplicate the regular muscle contractions that help stimulate circulation by pumping fluid and blood through venous and lymphatic channels back to the heartCan help in reestablishing proper circulatory pattern while keeping injured part protectedSensory level stimulation has been shown to decrease edema in sprain and contusion injuries

Retardation of AtrophyElectrical stimulation reproduces physical and chemical events associated with normal voluntary muscle contraction and helps to maintain normal muscle function

No specific protocol exists clinician should try to duplicate muscle contraction associated with normal exercise routine

Increasing Range of MotionElectrically stimulating a muscle contraction pulls joint through limited range

Continued contraction of muscle group over extended time appears to make contracted joint and muscle tissue modify and lengthen

The Effect of Non-contractile Stimulation on EdemaSensory level direct current used as a driving force to make charged plasma protein ions in interstitial spaces move in the direction of oppositely charged electrodeCook et al. hypothesized that 1) the electrical field facilitated movement of charged proteins into lymphatic channels2) Electrical field caused indirect stimulation of autonomic nervous system, stimulating release of adrenergic substances, increasing smooth muscle activity and lymph circulation

Therapeutic Uses of Electrical Stimulation of Sensory Nerves Asymmetric Biphasic Currents (TENS)Gate Control TheoryDescending Pain ControlOpiate Pain Control

Provide high frequency sensory level stimulation to stimulate peripheral sensory A fibers and close gateReferred to as conventional, high frequency or sensory-level TENSIntensity is set at a level to cause tingling sensation without muscle contractionPain relief lasts only while stimulation is providedTENS & Gate Control Theory

Intense electrical stimulation of smaller peripheral A and C fibers through input to the CNS causes a release of enkephalins blocking pain at the spinal cord levelCognitive input from the cortex relative to past pain perception also contributes to this mechanismLow-frequency or motor-level TENS is used elicits tingling and muscle contractionProvides pain relief >1 hourTENS & Descending Pain Control

Noxious stimulus causes release of endorphins and dynorphin resulting in analgesiaA point stimulation set-up must be usedendorphin stimulation may offer better relief for deep aching or chronic painIntensity of impulse is a function of pulse duration and amplitudeGreater pulse width is more painfulTENS & Endogenous Opiate Pain Control

Used to treat skin ulcers that have poor blood flowAccelerated healing rate has been notedMechanism of enhanced healing is elusiveCells are stimulated to increase normal proliferation, migration motility, DNA synthesis and collagen synthesis Receptors for growth factor have also shown significant increasesPromotion of Wound Healing

Could be used in fracture prone to non-unionMay accelerate healing via a monophasic currentGetting current into area non-invasively is a challengePromotion of Fracture Healing

Limited evidenceBoth tissues generate strain related electric potentials when stressedSignal tissue growth in presence of stressIncreased fibroblastic activity, cellular proliferation, and collagen synthesis has been notedIncreased histologic repair rates notedPromotion of Healing in Tendons & Ligaments

Interferential CurrentsWhen electrodes are arranged in a square and interferential currents are passed through a homogeneous medium a predictable pattern of interference will occur

Interest on part of clinician impacts perception of the patientPerceptual change is influenced by cognitive and affective factorsWhen active physiologic changes occur that can assist healing processDoes not mean athletic trainer should intentionally deceive patient but should use treatment to have best impact on patients perception of problem and the treatments effectivenessPlacebo Effect of Electrical Stimulation

Treatment will work best if patient has belief in its ability to alleviate the problemPatient needs to be intimately involved in treatmentEducateEncourageEmpower patient to get better

Contraindications for Electrical StimulationPregnancyInfectionCancerous TumorPacemakerHead and genitals

Therapeutic Ultrasound

Therapeutic UltrasoundInaudible, acoustic vibrations of high frequency that produce can produce both non-thermal and non-thermal physiologic effects

Classified as a deep heating modality with the ability to heat tissues to a greater degree in less time as compared to other superficial heating modalities

Penetration vs. AbsorptionUltrasound penetrates through tissue high in water content and is absorbed by tissues with high protein content

Tissues with high protein content possess the greatest potential for heating

Inverse relationship

Penetration vs. AbsorptionAbsorption increases as frequency increasesTissues high in water content decrease absorptionTissues high in protein content increase absorptionTissue absorption rates in descending order BoneNerveMuscleFat

Ultrasound At Tissue InterfacesSome energy scatters due to reflection and refractionAcoustic impedance determines the amount reflected vs. transmitted

Acoustic impedance = tissue density X speed of transmission

The most energy will the transmitted if the acoustic impedance is the same

difference in acoustic impedance = reflected energy

Reflection vs. TransmissionTransducer to air - Completely reflectedThrough fat - TransmittedMuscle/Fat Interface - Reflected and refractedSoft tissue/Bone Interface - ReflectedCreates standing waves or hot spots

Therapeutic Ultrasound GeneratorsHigh frequency electrical generator connected through an oscillator circuit and a transformer via a coaxial cable to a transducer housed within an applicator

Therapeutic Ultrasound Generator Control PanelTimerPower meterIntensity control ( watts or W/cm2)Duty cycle switch (Determines On/Off time)Selector switch for continuous or pulsed *All units should be calibrated and checked regularly.

Transducer or ApplicatorMatched to individual units and not interchangeableHouses a piezoelectric crystalQuartzLead zirconate or titanateBarium titanateNickel cobalt

Transducer or ApplicatorCrystal converts electrical energy to sound energy through mechanical deformation

When an alternating current is passed through a crystal it will expand and contractPiezoelectric Effect

Piezoelectric EffectIndirect or Reverse Effect - As alternating current reverses polarity the crystal expands and contracts producing ultrasoundCrystal vibrates at a selected frequency sound wave generated and passed to tissues

Effective Radiating Area (ERA)That portion of the surface of the transducer that actually produces the sound waveShould be only slightly smaller than transducer surfaceAcoustic energy is contained in a focused cylinderEnergy output and temperature are significantly greater at center as compared to periphery

Treatment Area SizeShould be 2-3 times larger than the ERA of the crystal in the transducerResearch has shown that treating too large an area will not result in the desired increase in tissue heatingBest if used on smaller treatment areas

Frequency of Therapeutic Ultrasound Frequency range of therapeutic ultrasound is 0.75 to 3.3 MHzFrequency is the number of wave cycles per secondMost generators produce either 1.0 or 3.0 MHz

The Ultrasound BeamDepth of penetration is frequency dependent not intensity dependent1 MHz transmitted through superficial layer and absorbed at 3-5 cm3 MHz absorbed superficially at 1-2 cm

Amplitude, Power, & IntensityAmplitudeMagnitude of the vibrations in a wavePowerTotal amount of US energy in the beam (expressed in watts)IntensityRate at which energy is delivered per unit area

Thermal vs. Non-Thermal EffectsThermal effects Tissue heatingNon-Thermal effectsTissue repair at the cellular levelThermal effects occur whenever the spatial average intensity is > 0.2 W/cm2Whenever there is a thermal effect there will always be a non-thermal effect

Thermal Effects of UltrasoundIncreased collagen extensibilityIncreased blood flowDecreased painReduction of muscle spasmDecreased joint stiffnessReduction of chronic inflammation

Set at 1.5 W/cm2 with 1MHz ultrasound would require a minimum of 10 minutes to reach vigorous heatingUltrasound Rate of Heating Per MinuteIntensity W/cm2 1MHz 3MHz0.5 .04C .3C1.0 .2C .6C1.5 .3C .9C2.0 .4C 1.4C

There are no specific guidelines which dictate specific intensities that should be used during treatmentRecommendation is to use the lowest intensity at the highest frequency which transmits energy to a specific tissue to achieve a desired therapeutic effectEveryones tolerance to heat is different get feedback from patient during treatmentAdjust settings to patient toleranceTreatment should be temperature dependent

Set at 1.5 W/cm2 with 3 MHz ultrasound would require only slightly more than 3 minutes to reach vigorous heatingIntensity W/cm2 1MHz 3MHz0.5 .04C .3C1.0 .2C .6C1.5 .3C .9C2.0 .4C 1.4C

Thermal EffectsBaseline muscle temperature is 36-37CMild heatingIncrease of 1C accelerates metabolic rate in tissueModerate heatingIncrease of 2-3C reduces muscle spasm, pain, chronic inflammation, increases blood flowVigorous heatingIncrease of 3-4C decreases viscoelastic properties of collagen

Non-Thermal Effects of UltrasoundIncreased fibroblastic activityIncreased protein synthesisTissue regenerationReduction of edemaBone healingPain modulation

Literature indicates that non-thermal ultrasound may modify cellular functionModulate membrane propertiesAlter cellular proliferationProduce increases in proteins associated with inflammation and repairCould modify inflammatory responseImpact protein functionInduce conformational shift change functionDissociate multimolecular complex change function

Frequency of TreatmentAcute conditions Require more treatment over a shorter period of time (2 X/day for 6-8 days)Consider pulsed ultrasoundCan begin using within 48 hoursChronic conditions Require fewer treatments over a longer period (alternating days for 10-12 treatments)Treatment should continue as long as there is progress

Duration of TreatmentSize of the area to be treatedWhat exactly are you trying to accomplishThermal vs. non-thermal effectsIntensity of treatmentWhat is the desired effect?Size of the Treatment AreaShould be 2-3 times larger than the ERA of the crystal in the transducerIf the area to be treated is larger use shortwave diathermy, superficial hot packs or hot whirlpool

Numbers Represent C Increase Following TreatmentIntramuscular Temp 1 cm below fat layer at 3 cm after 10 min. after 4 minutes

Hydrocollator Pack0.8C-----

1 MHz Ultrasound4.0 C-----

Hot Whirlpool (40.6C)----- 1.1C

3 MHz Ultrasound-----4.0CUltrasound As A Heating Modality(Smith, et al., 1995)(Meyrer et al., 1994)

Direct ContactTransducer should be small enough to treat the injured areaGel should be applied liberallyArea to be treated should be larger than transducerHeating of gel does not increase the effectiveness of the treatment

Immersion TechniqueGood for treating irregular surfacesA plastic, ceramic, or rubber basin should be usedTap water is useful as a coupling mediumTransducer should move parallel to the surface at .3-5 cmAir bubbles should be wiped away

Bladder TechniqueGood for treating irregular surfaces when body part cannot be submerged in waterUses a balloon filled with waterBoth sides of the balloon should be liberally coated with gel

Moving The TransducerStationary technique no longer recommended could result in hot spotsApplicator should be moved at about 4 cm/secLow BNR allows for slower movementHigh BNR may cause cavitation and periosteal irritationMoving the transducer too rapidly decreases the total amount of energy absorbed per unit area

Rapid movement may also cause the athletic trainer to treat too large an area, reducing the ability to achieve the desired treatment temperatureLower BNR tends to allow for more slow movement of the transducerIf the patient complains of pain the intensity should be lowered and the treatment time should be adjustedToo much transducer pressure could impact acoustic transmissivity

Clinical Applications For UltrasoundUltrasound is recognized clinically as an effective and widely used modality in the treatment of soft tissue and bony lesionsThere is relatively little documented, data-based evidence concerning its efficacyMost of the available data-based research is unequivocal

Soft Tissue Healing and RepairEffects on inflammation processCavitation and streaming increases transport of calcium across cell membrane releasing histamineHistamine stimulate leukocytes to clean upStimulates fibroblasts to produce collagenWill liquefy gel-like cellular debrisHeating collagen will increase extensibility in the tissue

Scar Tissue and Joint ContractureIncreased temperature causes an increase in elasticity and a decrease in viscosity of collagen fibers Increases mobility in mature scar When vigorous heating is achieved heated tissues become more extensible

Collagen tissue becomes more yielding when heatedActive exercise is more effective than ultrasound in increasing intramuscular temperatureTemperature increase does not appear to influence range of motionStretching windowTime period of vigorous heating when tissue will undergo greatest extensibility and elongationStretching Connective Tissue

Tissue heated with ultrasound cools at a very rapid rateJoint mobilizations and friction massage should be performed shortly after heating due to the elevated cooling rateStretching should be done immediately following ultrasound heating

Acute and post-acute conditions (non-thermal)Soft tissue healing and repairScar tissueJoint contractureChronic inflammationIncrease extensibility of collagenReduction of muscle spasmsPain modulationIncrease blood flowIncrease protein synthesisTissue regenerationBone healingRepair of nonunion fxInflammation associated with myositis ossificansPlantar wartsMyofascial trigger pointsIndications

Acute & post-acute conditions (thermal)Areas of decreased temperature sensationAreas of decreased circulationVascular insufficiencyThrombophlebitisEyesReproductive organsPelvis immediately following mensesPregnancyPacemakerMalignancyEpiphyseal areas in childrenTotal joint replacementsInfectionContraindications