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Continuous shortwave diathermy is the technique of choice when uniform marked elevation of temperature is required in the deep tissues. This heating can be targeted accurately by using an appropriate applicator positioned correctly. SWD also allows superficial structures to be heated selectively, although for this the various methods of surface heating are usually preferable. Sub-acute or chronic conditions respond best to continuous shortwave diathermy which, when used properly, can be as effective as ultrasound. Acute lesions are better treated with pulsed shortwave diathermy. Continuous shortwave diathermy can help to relieve pain and muscle spasm, resolve inflammatory states and reduce swelling, promote vasodilation, increase the compliance of connective tissue, increase joint range and decrease joint stiffness.

This article discusses some of the basic principles involved in the deposition of microwave power in the tissue. Insight is offered into the characteristics of the instrumentation, its limitations, and the necessary quality control needs.

We conducted a phase I clinical trial of the feasibility of using the Thermotron RF-8, a capacitative heating device utilizing 8-MHz RF, for the treatment of deep-seated and bulky human tumors. Preclinical studies with agar phantoms demonstrated that deep heating can be achieved with this device when the electrode diameters are sufficiently large relative to the thickness of the heated object. In the clinical application of capacitive heating with radiofrequency, excessive heating of subcutaneous tissue has often been a problem. However, this could be minimized by continuous cooling of the subcutaneous fat with a 10 degrees C saline bolus, beginning more than 20 minutes prior to the start of heating. It was often possible to raise the temperature of deep-seated tumors even in obese patients by applying this pre-cooling method. The mean achieved temperature during 30 to 40 minutes of heating was higher than 42 degrees C and 40 degrees C to 42 degrees C in 26% and 50% of 58 tumors treated, respectively. A combination of hyperthermia (four to ten sessions, twice a week) with full-course or a limited dose of radiotherapy resulted in complete tumor remission in 7% of patients, and partial tumor remission in 50% of patients. In the full-course radiotherapy group, 69% of the tumors were judged to show complete or partial regression, and in the low-dose group, 43% of the tumors regressed completely or partially. Histologic examination of many of the tumors that did not regress showed massive necrosis, indicating that tumor size after hyperthermia is not an accurate criterion of the treatment result. Side effects were minimal, and vital sign changes during heating were insignificant. Our data, together with those reported by Japanese investigators, clearly demonstrated that hyperthermia with the Thermotron RF-8 in combination with radiotherapy is useful in treating deep-seated and bulky tumors that fail to respond to conventional treatment modalities.

The effectiveness of spinal manipulation carried out by a non-medical qualified osteopath was compared with that of short-wave diathermy (SWD) and a placebo (detuned SWD) in 109 patients with low back pain. More than half the subjects in each of the 3 treatment groups benefited immediately from therapy. Significant improvements were observed in the 3 groups at the end of 2 weeks' treatment, and these were still apparent at 12 weeks. The outcome of treatment was unrelated to the initial severity or duration of pain or to the trend of pain towards deterioration or improvement. It is, therefore, unlikely that the results simply reflect the natural history of low back pain. Benefits obtained with osteopathy and SWD in this study may have been achieved through a placebo effect.