shortwave diathermy

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SHORTWAVE DIATHERMYDr.prashanth kumar1st yr pg in orthopaedics

Diathermy is a therapeutic treatment commonly prescribed for muscular and joint associated pains.

The term diathermy means through heating or producing deep heating directly in the tissues of the body.

Dia through (also means two) thermy heat or temperature

It simulates the circulation, relieve pain, enhances rate of recovery of healing the tissue.



Before injury, the dipole molecules of the body tissue are arranged on the basis of polarity .

When the tissue is damaged the dipoles distribution become irregular and deviates from polarity based arrangement .Under the influence of an electric field , they rotate according to the polarity of their charge in the direction of the field lines and get rearranged and tends to acquire its previous stage of polarity


As the subcutaneous layer is fatty , direct delivery of heat to the deep layers of tissue is not possible.

Diathermy involves uneven and uncontrolled delivery of heat therefore sometimes instead of the target tissue , surrounding tissue gets affected

Subcutaneous layer

Diathermy uses an electric current to produce heat deep inside a targeted tissue. It can reach areas as deep as two inches from the skins surface.

The diathermy machine does not apply heat directly to the body. Instead, the current from the machine allows the body to generate heat from within the targeted tissue.

As the heat increases, it promotes blood flow. It can also help improve flexibility in stiff joints and connective tissue.


Intense heat delivered provides pain relief and better flexibility

Reduces inflammation

Improves circulation

Accelerate healing






SHORT WAVE DIATHERMYDef.: SWD is a modality that produces deep heating via conversion of electromagnetic energy to thermal energy.The pattern of heat produced depend on:Freq. used. type of SWD unit. water content of the tissues.

Shortwave diathermy current freq. 10 100 MHz(The shortest radiofrequency wave is used in therapeutic diathermy.) the commonly used in medical work having freq. of 27.12 MHz with wavelength of 11 meters

Modalities: ether continuous or pulsed (PSWD).PSWD: application of series of short pulses of SWD so that short periods of SWD interrupted by gaps where there is no SWD. The pt. receives lower dose of SWD energy if compared with continuous SWD applied of the same time. The tissues will receive lower thermal load.

SWD: produce both deep and sup. Tissue heating, under certain controlled conditions its applied for 20 min at the max tolerable dose

Types of Shortwave DiathermyInduction Field

Capacitive Field

Induction Field DiathermyPlaces the patient in the electromagnetic fieldCurrent flowing within the coil produces a rotating magnetic fieldMagnetic field produces eddy currents in the tissuesEddy currents cause friction that produce heatSelectively heats muscleAlso referred to as: Magnetic field diathermy

Capacitive Field DiathermyUses the patients tissues as a part of the circuitThetissueselectrical resistance produces heatSelectively heats skin


Also referred to as condenser field diathermy

TYPES OF ELECTRODESFlexible pads: consist of metal electrode encased in rubber and produce an electrostatic field.

Space plates: consist of a rigid metal electrode encased ina Perspex cover electrostatic field.

Coil or cable electrode consists of awire with plugs at either end creates electromagnetic field.

The monode : flat, rigid coil encased in plastic cover electromagnetic field.

The diplode : or drum electrode, consists of a flat coil electrode encased in a Perspex cover with two wings electromagnetic field

FACTORS INFLUENCE FIELD DISTRIBUTION IN S.W.DSpacing :allows the lines of force in the electrostatic field to diverge before entering the tissues. This prevents concentration of heat in the superficial tissues and ensures more heating through the part.Spacing provided by:wrapping flexible pads in towel.flat felt spacing pads between pad electrode and skinair when using space plates.

Normal spacing even field distribution.

Increased spacing deep field concentration.

Decreased spacing superficial concentration

Electrode size:if the electrodes are too small than the diameter of treated part line of force will be concentrated superficially.If the electrodes are markedly larger the line of force will be lost in the air.Ideally, the electrodes should be slightly larger than the area treated.

To concentrate heat on one aspect of the part the electrode should be unequal in size (smaller one placed over the area where concentration of heat is required).You can produce concentration of heat by using equal size electrodes but with unequal spacing (25 mm over concentrated area and more than 30 mm on other electrode).


Coplanar application to structures on one aspect of the body. If the spacing is less than 25 mm more concentration in the treat superficial tissue. If spacing Increases more depth achieved.The distancebetween adjacent ends mustbe greater than the sum of skin electrode distance (A+B) otherwise the line of force willpass directly between Electrodes rather than tissues

Contra planar applicationsTwo flexible pads, two spaceplatesor flexiblepadwitha spaceplateareused.It is essential to put a cotton towel between the two limbs to any absorb perspiration.

Cross-fire application:Forthetreatmentof sinuses,space plates positioned after half diagonally,oftreatment time the positions are alternate.this ensures that the all the sinses membranesare heated.Care must be taken to avoid direct placement over the eye ,uterinedisorders such as dysmenrrohea.

Application using a coil electrode:1.The coil wound evenly firmly2 Pancake application

Application using diplode:Adjust wings of diplode parallel to the skin of the treated area, electromagnetic field will produce.

PHYSIOLOGICAL EFFECTSThe principal effect of SWD on the body is the production of heat in the tissues due to the rise of temperature.1. Increased metabolism:Heating tissues accelerates chemical changes such as metabolism, so oxygen and food stuffs are used up.With increased metabolism, there will be increased output of waste products.

Increased blood supply:As a result of increased output of waste products such as metabolites, which act on the walls of the capillaries and arterioles, these tissues dilate.In addition, heat has direct effect on blood vessels, causing vasodilatation.Heat also produces stimulation of superficial nerve endings, causing reflex dilatation of the arterioles.

. General rise of temperature:As blood passes through the heated tissues, it also becomes heated and carries the heat to other body parts.Rise of temperature induces muscle relaxation and increases the efficiency of muscle action.

. Fall in blood pressure:The generalized vasodilatation reduces the peripheral resistance to blood flow. Heat also reduces blood viscosity, which helps in the reduction of blood pressure.

. Increased activity of sweat glands:If a general rise of temperature occurs, there will be increased activation of the sweat glands.

Therapeutic UsesEffect on Inflammation

Assist in removal of Waste ProductsAll these effects bring about resolution of inflammation

. Effect on Bacterial Infection Inflammation is normal response of Body to bacteria

Heating the tissue auguments these changes so reinforces body's normal mechanism to of dealing with infecting organisms Ex. Boils, Carbuncles, Abscesses

. Reducing Healing time Increased Blood supply More Nutritive MaterialMore O2 supply

. Relief of Pain Sedative Effect Removal of Waste Products Resolution of Inflammation Counter irritation

Effect on Muscle Tissue Muscle relaxation Relief of Muscle Spasm

Musculoskeletal Disorders Degenerative Joint DisordersEx. OA and RA Sprain Strain Hematoma Muscle & tendon Tears Capsule Lesions


Inflammatory Conditions Boils Carbuncles Sinusitis Pelvic Conditions Infected Surgical Incisions

DANGERSBurnsConcentration of electric fieldExcess currentImpaired blood flowHypersensitive skinLeads touching skinScaldsElectric shockOverdosePrecipitation of gangreneFaintnessGiddiness

ContraindicationsMetal implants or metal jewelry (be aware of body piercings)Cardiac pacemakersIschemic areasPeripheral vascular diseasePerspiration and moist dressings: The water collects and concentrates the heat.Tendency to hemorrhage, including menstruation.PregnancyFeverSensory lossCancerDeep X rayTumoursUnreliable patientsAreas of particular sensitivity:Epiphyseal plates in childrenThe genitalsSites of infectionThe abdomen with an implanted intrauterine device (IUD)The eyes and faceApplication through the skull


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