Therapeutic Modalities Review

Basic Principles of Electricity and Electrical Stimulating Currents

Electrotherapeutic Currents Direct (DC) or Monophasic Flow of electrons always in same direction Sometimes called galvanic

Electrotherapeutic Current Alternating (AC) or Biphasic Flow of electrons changes direction Always flows from negative to positive pole until polarity is reversed

Electrotherapeutic Currents Pulsatile Current Pulses grouped together and interrupted Russian and interferential currents May be bi-directional or uni-directional

Electrical Generators All are transcutaneous electrical stimulators Transcutaneous 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 second Muscle and nervous tissue respond depending on the length of time between pulses and on how pulses or waveforms are modulated Low vs. Medium vs. High frequency currents

Electrode Placement Electrodes may be placed: On or around the painful area Over specific dermatomes, myotomes, or sclerotomes that correspond to the painful area Close 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 stimulated Over superficial vascular structures Over trigger point locations

Over acupuncture points In a crisscrossed pattern around the point to be stimulated so the area to be treated is central to the location of the electrodes Bipolar application resulting in similar physiologic effects beneath each electrode Monopolar setup  both an active and dispersive pad set up causing higher current density at the active electrode Quadripolar technique

Physiologic Response To Electrical Current Electricity can have an effect on each cell and tissue it passes through Type and extent is dependent on the type of tissue, its response characteristics, and the nature of current applied Reactions can be: Thermal Chemical Physiologic

Can be used to: Creating muscle contraction through nerve or muscle stimulation Stimulating sensory nerves to help in treating pain Creating an electrical field in biologic tissues to stimulate or alter the healing process Creating 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 Currents Muscle re-education Muscle pump contractions Retardation of atrophy Muscle strengthening Increasing range of motion Reducing Edema

Muscle Re-Education Muscular 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 synapses Restore normal balance to system as ascending sensory info is reintegrated into movement patterns Patient feels the muscle contract, sees the muscle contract, and can attempt to duplicate this muscular response

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

Retardation of Atrophy Electrical 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 Motion Electrically 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 Edema Sensory level direct current used as a driving force to make charged plasma protein ions in interstitial spaces move in the direction of oppositely charged electrode Cook et al. hypothesized that 1) the electrical field facilitated movement of charged proteins into lymphatic channels 2) 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 Theory Descending Pain Control Opiate Pain Control

TENS & Gate Control Theory Provide high frequency sensory level stimulation to stimulate peripheral sensory Aβ fibers and “close gate” Referred to as conventional, high frequency or sensory-level TENS Intensity is set at a level to cause tingling sensation without muscle contraction Pain relief lasts only while stimulation is provided

TENS & Descending Pain Control Intense electrical stimulation of smaller peripheral Aδ and C fibers through input to the CNS causes a release of enkephalins blocking pain at the spinal cord level Cognitive input from the cortex relative to past pain perception also contributes to this mechanism Low-frequency or motor-level TENS is used  elicits tingling and muscle contraction Provides pain relief >1 hour

TENS & Endogenous Opiate Pain Control Noxious stimulus causes release of β–endorphins and dynorphin resulting in analgesia A point stimulation set-up must be used β–endorphin stimulation may offer better relief for deep aching or chronic pain Intensity of impulse is a function of pulse duration and amplitude Greater pulse width is more painful

Promotion of Wound Healing Used to treat skin ulcers that have poor blood flow Accelerated healing rate has been noted Mechanism of enhanced healing is elusive Cells are stimulated to increase normal proliferation, migration motility, DNA synthesis and collagen synthesis Receptors for growth factor have also shown significant increases

Promotion of Fracture Healing Could be used in fracture prone to non-union May accelerate healing via a monophasic current Getting current into area non-invasively is a challenge

Promotion of Healing in Tendons & Ligaments Limited evidence Both tissues generate strain related electric potentials when stressed Signal tissue growth in presence of stress Increased fibroblastic activity, cellular proliferation, and collagen synthesis has been noted Increased histologic repair rates noted

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

Placebo Effect of Electrical Stimulation Interest on part of clinician impacts perception of the patient Perceptual change is influenced by cognitive and affective factors When active  physiologic changes occur that can assist healing process Does not mean athletic trainer should intentionally deceive patient but should use treatment to have best impact on patient’s perception of problem and the treatment’s effectiveness

Patient needs to be intimately involved in treatment Treatment will work best if patient has belief in its ability to alleviate the problem Patient needs to be intimately involved in treatment Educate Encourage Empower patient to get better

Contraindications for Electrical Stimulation Pregnancy Infection Cancerous Tumor Pacemaker Head and genitals

Therapeutic Ultrasound

Therapeutic Ultrasound Inaudible, 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. Absorption Ultrasound 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. Absorption Absorption increases as frequency increases Tissues high in water content decrease absorption Tissues high in protein content increase absorption Tissue absorption rates in descending order Bone Nerve Muscle Fat

Ultrasound At Tissue Interfaces Some energy scatters due to reflection and refraction Acoustic 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. Transmission Transducer to air - Completely reflected Through fat - Transmitted Muscle/Fat Interface - Reflected and refracted Soft tissue/Bone Interface - Reflected Creates “standing waves” or “hot spots”

Therapeutic Ultrasound Generators High 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 Panel Timer Power meter Intensity 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 Applicator Matched to individual units and not interchangeable Houses a piezoelectric crystal Quartz Lead zirconate or titanate Barium titanate Nickel cobalt

Transducer or Applicator Crystal converts electrical energy to sound energy through mechanical deformation

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

Piezoelectric Effect Indirect or Reverse Effect - As alternating current reverses polarity the crystal expands and contracts producing ultrasound Crystal 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 wave Should be only slightly smaller than transducer surface Acoustic energy is contained in a focused cylinder Energy output and temperature are significantly greater at center as compared to periphery

Treatment Area Size Should be 2-3 times larger than the ERA of the crystal in the transducer Research has shown that treating too large an area will not result in the desired increase in tissue heating Best if used on smaller treatment areas

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

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

Amplitude, Power, & Intensity Magnitude of the vibrations in a wave Power Total amount of US energy in the beam (expressed in watts) Intensity Rate at which energy is delivered per unit area

Thermal vs. Non-Thermal Effects Tissue heating Non-Thermal effects Tissue repair at the cellular level Thermal effects occur whenever the spatial average intensity is > 0.2 W/cm2 Whenever there is a thermal effect there will always be a non-thermal effect

Thermal Effects of Ultrasound Increased collagen extensibility Increased blood flow Decreased pain Reduction of muscle spasm Decreased joint stiffness Reduction of chronic inflammation

Ultrasound Rate of Heating Per Minute Intensity W/cm2 1MHz 3MHz 0.5 .04°C .3°C 1.0 .2°C .6°C 1.5 .3°C .9°C 2.0 .4°C 1.4°C Set at 1.5 W/cm2 with 1MHz ultrasound would require a minimum of 10 minutes to reach vigorous heating

Treatment should be temperature dependent There are no specific guidelines which dictate specific intensities that should be used during treatment Recommendation is to use the lowest intensity at the highest frequency which transmits energy to a specific tissue to achieve a desired therapeutic effect Everyone’s tolerance to heat is different – get feedback from patient during treatment Adjust settings to patient tolerance Treatment should be temperature dependent

Intensity W/cm2 1MHz 3MHz 0.5 .04°C .3°C 1.0 .2°C .6°C 1.5 .3°C .9°C 2.0 .4°C 1.4°C Set at 1.5 W/cm2 with 3 MHz ultrasound would require only slightly more than 3 minutes to reach vigorous heating

Thermal Effects Baseline muscle temperature is 36-37°C Mild heating Increase of 1°C accelerates metabolic rate in tissue Moderate heating Increase of 2-3°C reduces muscle spasm, pain, chronic inflammation, increases blood flow Vigorous heating Increase of 3-4°C decreases viscoelastic properties of collagen

Non-Thermal Effects of Ultrasound Increased fibroblastic activity Increased protein synthesis Tissue regeneration Reduction of edema Bone healing Pain modulation

Literature indicates that non-thermal ultrasound may modify cellular function Modulate membrane properties Alter cellular proliferation Produce increases in proteins associated with inflammation and repair Could modify inflammatory response Impact protein function Induce conformational shift  change function Dissociate multimolecular complex  change function

Frequency of Treatment Acute conditions Require more treatment over a shorter period of time (2 X/day for 6-8 days) Consider pulsed ultrasound Can begin using within 48 hours Chronic 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 Treatment Size of the Treatment Area Size of the area to be treated What exactly are you trying to accomplish Thermal vs. non-thermal effects Intensity of treatment What is the desired effect? Size of the Treatment Area Should be 2-3 times larger than the ERA of the crystal in the transducer If the area to be treated is larger use shortwave diathermy, superficial hot packs or hot whirlpool

Ultrasound As A Heating Modality Numbers Represent °C Increase Following Treatment Intramuscular Temp 1 cm below fat layer at 3 cm after 10 min. after 4 minutes Hydrocollator Pack 0.8°C ----- 1 MHz Ultrasound 4.0 °C ----- Hot Whirlpool (40.6°C) ----- 1.1°C 3 MHz Ultrasound ----- 4.0°C (Smith, et al., 1995) (Meyrer et al., 1994)

Direct Contact Transducer should be small enough to treat the injured area Gel should be applied liberally Area to be treated should be larger than transducer Heating of gel does not increase the effectiveness of the treatment

Immersion Technique Good for treating irregular surfaces A plastic, ceramic, or rubber basin should be used Tap water is useful as a coupling medium Transducer should move parallel to the surface at .3-5 cm Air bubbles should be wiped away

Bladder Technique Good for treating irregular surfaces when body part cannot be submerged in water Uses a balloon filled with water Both sides of the balloon should be liberally coated with gel

Moving The Transducer Stationary technique no longer recommended  could result in hot spots Applicator should be moved at about 4 cm/sec Low BNR allows for slower movement High BNR may cause cavitation and periosteal irritation Moving the transducer too rapidly decreases the total amount of energy absorbed per unit area

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

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

Soft Tissue Healing and Repair Effects on inflammation process Cavitation and streaming increases transport of calcium across cell membrane releasing histamine Histamine stimulate leukocytes to “clean up” Stimulates fibroblasts to produce collagen Will liquefy gel-like cellular debris Heating collagen will increase extensibility in the tissue

Scar Tissue and Joint Contracture Increased 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

Stretching Connective Tissue Collagen tissue becomes more yielding when heated Active exercise is more effective than ultrasound in increasing intramuscular temperature Temperature increase does not appear to influence range of motion Stretching window Time period of vigorous heating when tissue will undergo greatest extensibility and elongation

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

Indications Pain modulation Increase blood flow Increase protein synthesis Tissue regeneration Bone healing Repair of nonunion fx Inflammation associated with myositis ossificans Plantar warts Myofascial trigger points Acute and post-acute conditions (non-thermal) Soft tissue healing and repair Scar tissue Joint contracture Chronic inflammation Increase extensibility of collagen Reduction of muscle spasms

Contraindications Acute & post-acute conditions (thermal) Areas of decreased temperature sensation Areas of decreased circulation Vascular insufficiency Thrombophlebitis Eyes Reproductive organs Pelvis immediately following menses Pregnancy Pacemaker Malignancy Epiphyseal areas in children Total joint replacements Infection