Interferential therapy

Interferential Therapy is a "new-comer" to the field of physical medicine, but it is gradually acquiring a particular identity. As the name implies, a current is generated within the tissues as a result of the interaction of two separate circuits. It can therefore be appreciated that four electrodes are required, two for each circuit. The two currents generated by the unit are medium frequency currents in the 4000 cycle per second range. One of these can be varied so that it is slightly out of phase with the other in such a way that a low frequency beat is generated where the two currents cross within the tissues, and this is equal to the difference between the two medium frequencies. The interferential current produced is an evenly alternating sinusoidal one, without polar effects (Diagram 1). Its frequency can be varied from 0 to 100 or 150, depending on the unit. It is evident that such a current can be made to scan the tissues more deeply, more accurately and more widely than the old sinusoidal current, depending on the way electrodes are placed, to determine where the low frequency current will be produced. Further, it has less superficial sensory effect, provided it is applied correctly. It is undoubtedly an effective therapy for controlling pain.