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Diathermy – A Great Solution for the Pain

A large number of doctors recommend Diathermy as a physiotherapeutic treatment that applies a high-frequency electric current on the body tissues to produce heat. 

“Deep-heating agents, also called diathermies, include ultrasound, shortwave, and microwave. Therapeutic ultrasound is a method of stimulating the tissue beneath the skin’s surface using very high-frequency sound waves. Shortwave and microwave diathermy uses high-frequency electromagnetic energy to generate heat.”1 

The heat helps ease pain and boost blood circulation. This treatment is highly recommended for joint and muscle problems. It can also be used to treat arthritis, arthralgia, sciatica, and neuralgia.

Diathermy Frequencies

“Diathermy, from the Greek words dia meaning ‘“through’” and therma meaning “heating,” is the application of shortwave (frequency of about 3–300 MHz) or microwave (frequency of 300 MHz to 300 GHz) electromagnetic energy and ultrasound (acoustic vibration with a frequency of 0.8–3.0 MHz) to produce heat and other physiological changes within tissues. Both shortwave and microwave radiation are nonionizing. Shortwave diathermy devices have been allocated the three frequency bands centered on 13.56, 27.12, and 40.68 MHz,19 of which the 27.12-MHz band is the most commonly used modality. Microwave diathermy devices operate at three frequencies: 433.92, 915, and 2045 MHz.”

Depending on the frequency, Diathermy figures in two or more categories. “Diathermy is a form of electromagnetic wave generation with frequency ranges that can be categorized as either microwave or shortwave. Shortwave diathermy is also described as either continuous shortwave diathermy (CSWD) or pulsed shortwave diathermy (PSWD). Diathermy involves the generation of oscillating electromagnetic fields (EMF) that are comprised of both electrical and magnetic fields. Variations in the strength of these fields are dependent upon several factors including the frequency of the unit and characteristics of the applicator.”3 

Diathermy as a Therapeutic Treatment for Certain Conditions

“The use of diathermy is an adjunct procedure to produce tissue heat that may be used with conventional methods of treatment in the following conditions:

  1. Secondary muscle spasms in musculoskeletal disease
  2. Relief of pain resulting from muscle spasm
  3. For joints where there are some acute chronic inflammatory processes
  4. To improve range of motion and relieve joint stiffness associated with collagen diseases
  5. Chronic periarthritis
  6. Fibrositis or myofibrositis
  7. Epicondylitis
  8. Subacute or subchronic bursitis
  9. To increase blood flow and improve circulation
  10. Chronic inflammatory pelvic diseases 

The use of diathermy for therapy or treatment is based upon the absorption characteristics of radiofrequency electromagnetic fields in tissues for therapeutic heating of tissues. It is also based on the physiologic responses produced and the mechanisms by which they are achieved. An elevation of tissue temperature into the range of 40’C. to 450C. is considered necessary for therapy to be effective.”4 

Therapy Duration and Intensity

“The usual and accepted length of time for a treatment with short wave diathermy is from twenty to forty minutes. In conventional diathermy the milliamperage indicates the amount of current flowing. However, in short wave diathermy the dose or intensity of current is determined mainly by the patient’s tolerance. In treating a pathological condition with heat, it is important to visualize the process in the tissues and not to use diathermy to the exclusion of other methods of treatment. In many instances, short wave diathermy is a valuable adjunct to other forms of therapy. In the various types of arthritis, adequate treatment is essential. The various physical agents are important adjuncts to treatment, and physical agents alone should not be relied upon in the treatment of this disease. Rest is of prime importance in most instances. Foci of infection should be eliminated, anemia and lowered metabolism should be corrected, and if the patient is obese, weight reduction is important.”5


“Tissue heated to 40-45°C exhibits a mild inflammatory reaction mediated primarily by the release of histamine and the prostaglandins lU. These alter directly vascular smooth muscle tone and the contractility of the endothelial cells, thus raising the hydrostatic pressure of blood within the capillaries. This, in turn, increases the rate at which fluid filters into the extravascular space to cause swelling.

Heat reinforces acute inflammation, promoting further edema with exacerbation of pain and loss of function. Pulsed shortwave diathermy is used more appropriately in this situation. Sub-acute or chronic conditions respond favorably to heating, SWD being reported effective in conditions such as chronic sinusitis, bicipital and supraspinatus tendinitis and epicondylitis when applied by the inductance and as lessening symptoms of traumatic arthritis. 

Local heating clearly provokes vasodilation. Deep heating causes arterioles, capillaries and venules to dilate either by direct action or in response to decreased oxygen tension and increasing metabolite concentration in surrounding tissue. Lymph vessels also respond to heating and the rate of interstitial fluid drainage increases with temperature. Generally, blood flow to active organs rises during heating whilst that to inactive organ falls. This effect is more marked in some tissues than in others.”6 

Shortwave Diathermy

“In general, the tissue response to SWD (Shortwave diathermy) compares closely with that from other methods of heating, and the common indications and contraindications are similar to those for superficial heating. Those differences which do however exist originate in the patterns of heating generated by the diathermies, which are unlike those produced by more superficial heating. Diathermy heats both the deep and superficial layers of tissue whilst the effect of superficial heating is most marked in the skin and subcutaneous tissues. The physiological response also depends upon the magnitude of the rise in temperature, rate of rise, volume of tissue heated and the efficiency of the homeostatic mechanisms active in dissipating heat.”7

The effects of SWD. “It is generally accepted that the major physiological effects of CSWD (Continuous Short-wave Diathermy) are related to an induced increase in tissue temperature, which may induce vasodilatation, the elevation of pain threshold, reduction in muscle spasm, acceleration of cellular activity, and increased soft tissue extensibility.”8

Microwave Diathermy

“Microwave diathermy is a form of electromagnetic energy that uses its conversion to thermal energy, which is produced by increased kinetic energy of molecules within the microwavefield; radiation is absorbed selectively by water, and muscle should be heated preferentially. Fourteenth Federal Communications Commission-approved frequencies for therapeutic microwave are 915 MHz and 2,450 MHz. The lower frequency has the advantage of increased depth of penetration but also the disadvantages of greater beam dispersion and the requirement of larger applicators [14].Microwaves do not penetrate tissue as deeply as short-wave diathermy and ultrasound. Shortwave therapy is generally preferred over microwave because it has a more predictable heat distribution pattern.”9

Shortwave and Microwave Diathermy in the management of nerve injuries. “During the last few years, shortwave and microwave diathermy has been proven effective in the management of skeletal muscle injuries. However, only a few randomized controlled studies have focused on diathermy in the treatment of peripheral nerve injuries, primarily CTS (carpal tunnel syndrome). The efficacy of diathermy is related to the increase in heat in the deep tissue. The effect includes an increase in vasodilatation and soft tissue elasticity, amelioration of local blood flow, and reduction of muscle spasms. This mechanism might be relevant in the treatment of CTS, given that the positive effect of diathermy on local ischemia plays a pivotal role in the pathogenesis of CTS.”10  

Contraindications to Diathermy

“It is important to keep the contraindications for diathermy in mind. The local application of high-frequency currents is contraindicated in the case of certain acute inflammatory processes such as acute non-draining cellulitis and acute infectious arthritis, or any condition in which there is a tendency to hemorrhage, such as a gastric ulcer; over areas in which the appreciation of heat has been impaired or lost, as in the case of certain peripheral nerve injuries; through the abdomen, pelvis or lower part of the back during pregnancy; during menstruation or thirty-six hours before or after menstruation, and over areas where a malignant growth is suspected.”11 

Diathermy Therapy Products

  • Diathermy machines
  • Accessories for Diathermy machines
  • Applicator cables
  • Cabinets
  • Coil applicators
  • Condenser applicators



(1, 2, 10) Role of shortwave and microwave diathermy in peripheral neuropathy. Fu, T., Lineaweaver, W.C., Zhang, F. & Zhanf, J. Sage Journals. 

(3) Diathermy: A Literature Review of Current Research and Practices. Cacolice, P.A., Scibek, J.S. & Martin, R. Orthopaedic Practice. 2013. 

(4) Clinical Applications Of Microwave Radiation: Hypothermy and Diathermy. Davis, J.B. Bull. New York Academy of Medicine. 1979. 

(5, 11) Clinical Application Of Short Wave Diathermy.  Zeiter, W.J. Cleveland Clinic Journal of Medicine. 1940. 

(6, 7) Continuous short-wave (radio-frequency) diathermy. Goats, G.C. British Association Of Sports and Exercises Medicine. 1989. 

(8) Effectiveness of thermal and athermal short-wave diathermy for the management of knee osteoarthritis: a systematic review and meta-analysis. Laufer, Y, & Dar, G. Elsevier. 2012. 

(9) Microwave Diathermy for Treating Nonspecific Chronic Neck Pain. A randomized, Controlled Trial. Andrade, J., Fernández, E., Llorent, R., González, M. & Delgado, A. 2013. 


María Laura Márquez
13 October, 2018

Written by

María Laura Márquez, general doctor graduated from The University of Oriente in 2018, Venezuela. My interests in the world of medicine and science, are focused on surgery and its breakthroughs. Nowadays I practice my more:

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