In general terms, combination therapy involves the simultaneous application of ultrasound (US) with an electrical stimulation therapy. Most commonly used applications are US with Transcutaneous Electrical Nerves Stimulation (TENS), US with IFT and US with Electrical stimulation of any form including Iontophoresis In Europe, Diadynamic Currents are frequently utilised, but in the UK, US is most often combined with bipolar Interferential Therapy (IF).

There is a significant lack of published material in this area. And much of the information herein is anecdotal or based on the experience of those who use the modality frequently. Broadly, the effects of the combined treatment are those of the individual modalities. There is no evidence at present for any additional effects which can only be achieved when the modalities are used in this particular way.

Therapeutic Ultrasound is the high frequency modality which produces thermal and nonthermal effects. Thermal effects include increase tissue metabolism, collagen elasticity, and capillary blood flow and reduce skeletal muscle spasm and non-thermal effects include acoustic streaming and cavitation enhancing inflammatory response, , increase in protein synthesis, membrane alterations and tissue repair. It is well absorbed in tissues rich in collagen content.

Various electrical stimulation approaches like Transcutaneous Electrical Stimulation (TENS) - High TENS and Low TENS, Neuromuscular Electrical Stimulation (NMES), Interferential current therapy (IFT), Pulsed Electrical Stimulation, noninvasive interactive neurostimulation, etc. are used for pain relief in musculoskeletal conditions like osteoarthritis.

Combination therapy is simultaneous application of two different modalities at the same site where production, application and therapeutic effects of both modalities can be achieved at the same time. During such an application, enhancing effect of one over the other modality is seen. Few studies have concluded that combination therapy is more effective than application of individual modality in relieving pain.