Therapeutic Modalities Review

1. Therapeutic Modalities Review

2. Basic Principles of Electricity and Electrical Stimulating Currents

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

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

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

6. 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)

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. Therapeutic Uses of Electrical Stimulation of Sensory Nerves – Asymmetric Biphasic Currents (TENS) • Gate Control Theory • Descending Pain Control • Opiate Pain Control

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

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

29. Therapeutic Ultrasound

30. 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

31. 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

32. 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

33. 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

34. 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”

35. 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

36. 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.

37. Transducer or Applicator • Matched to individual units and not interchangeable • Houses a piezoelectric crystal • Quartz • Lead zirconate or titanate • Barium titanate • Nickel cobalt

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

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

40. 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

41. 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

42. 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

43. 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

44. 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

45. Amplitude, Power, & Intensity • Amplitude • 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

46. Thermal vs. Non-Thermal Effects • 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

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

48. 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

49. 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

50. 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