physiobia

What is Short-wave diathermy?

A short-wave diathermy(SWD)  current medical purpose frequency used is 27.12 MHz and the Wavelength – is 11m. In SWD, the current is generated in a machine circuit, which is in turn coupled to a patient (resonator) circuit used to treat the patient.

In Short -, diathermy produces one million impulses per second, each with a duration of 0.001 ms, beyond the range used for nerve stimulation.  No discomfort or muscle contractions are produced when such a current is passed through the body. This type of current is alternating which does not have the danger of chemical burns on the body of the patient. Consequently, it is possible to pass through the tissue currents of a much greater intensity than can be used with low-frequency currents. The intensity of the current can be great enough to produce a direct heating effect on the tissues, similar to the heating effect of the current on any other conductor, and the term ‘diathermy ‘means ‘through heating’.

History of short-wave diathermy

The term “diathermy” has its roots in the Greek words dia meaning “through,” and therme meaning “heat.” Together, they describe the idea of “heating through tissues.” This simple yet powerful concept became the foundation of one of the most significant developments in electrotherapy.

In the early 1900s, a German physician named Dr. Karl Franz Nagelschmidt forever changed the course of physical medicine. In 1908, he discovered that high-frequency alternating current could be safely used to generate heat deep within body tissues. This heating effect helped relieve pain, stiffness, and muscle tension — marking the beginning of a new era in therapeutic treatment.

Dr. Nagelschmidt built his first machines using spark-gap oscillators, which produced frequencies of around 1 megahertz (MHz) — quite advanced for his time. His remarkable work gained recognition when he presented his findings at the 1910 Congress of Physical Medicine in Berlin, an event now remembered as the official birth of medical diathermy.

As technology advanced, researchers sought ways to make diathermy more effective and safer. This led to the invention of Short Wave Diathermy (SWD) in the 1920s, a technique that used radiofrequency energy with much shorter wavelengths — typically between 10 and 100 meters.

To prevent interference with radio transmissions, an international agreement standardized the medical frequency at 27.12 MHz (with a wavelength of about 11 meters). This advancement allowed therapists to heat deeper tissues more uniformly than the earlier longwave methods, making SWD an even more valuable tool in clinical care.

By the 1930s, Short Wave Diathermy had become a popular treatment across physiotherapy and rehabilitation centers. It was especially effective for conditions like joint stiffness, muscle spasms, and chronic inflammation.

In the 21st century, Short Wave Diathermy remains an essential component of physiotherapy and rehabilitation. It continues to help patients by reducing pain, relaxing muscles, improving circulation, and accelerating tissue healing.

How short-wave diathermy is applied? 

 In short-wave diathermy, the transfer of electrical energy to the patient occurs via an electrostatic or electromagnetic field. There are therefore two methods of application; the condenser/capacitor field and the endothermy method”. 

Capacitor field method.

In this method, the electrode is placed on each side of the part to be treated and separated from the skin by insulating material. The electrodes act as the plates of a capacitor, while the patient’s tissues together with the insulating material separate them from the electrodes from the dielectric. When the current is applied in short-wave diathermy, rapidly alternating charges are set up on the electrode, giving rise to a rapidly alternating electric field between them. The electric field influences materials that lie within it

Differential heating of the tissues.

This is used for superficial tissue rather than deep tissues because the electric field in short-wave diathermy tends to spread between the electrodes so the density is usually greatest close to the electrodes. The lines of force pass more easily through the material of high than the low dielectric constant of about 80.