ELECTROTHERAPY

ELECTROTHERAPY AND TISSUE REPAIR

By Prof Tim Watson, MCSP, PhD

Electrotherapy is one form of intervention that has the capacity to influence the processes associated with tissue repair. Some modalities are more effective at achieving this than others, and there are differences in the type of tissue that respond to the different modalities. Numerous elec- trotherapy modalities have significant clinical effects, but not primarily on tissue repair, and they are excluded from this review for this reason.

Evidence for the relationship between electrotherapy and tissue repair is continuously updated and thus, this is the story at it stands at the moment. The latter section of this paper considers some of the emerging issues.

Special note: This article in the original format is fully referenced throughout, however due to space limitations we have focused on referencing the newest or most significant aspects of research. We have uploaded the original version as a word file on www.sportex.net - under Issue 29 of sportEX medicine. This article is accessible by everyone regardless of your online subscription status.

CAPACITY FOR ELECTROTHERAPY TO INFLUENCE TISSUE REPAIR It is evident from published research that some electrotherapy modalities have the capacity to influence the repair process in what might be considered to be a ‘direct’ mode of action. These primari- ly include ultrasound, pulsed shortwave therapy and therapeutic laser. Full information on these and other interventions can be found in standard texts, review papers and various online resources (eg. www.electrotherapy.org). Modalities such as interferential ther- apy, TENS and other neuromuscular electrical stimulation (NMES) do not appear to have a direct effect on tissue repair, though research in these areas continues and the evidence may change in future.

BASIC ELECTROTHERAPY MODE OF ACTION Model of electrotherapy Electrotherapy modalities follow a very straightforward model (see Figure 1). In principle, the model identifies that the delivery of energy from a device is the starting point of the intervention. The energy entry to the tissues results in a change in one or more phys- iological events. Some are very specific whilst others are multifac- eted. The capacity of the energy to influence physiological events

is key to the processes - this physiological shift generates the so- called therapeutic effect.

The clinical application of the model is best achieved by what appears to be a reversal of this process. Start with the patient and their problems, identified from the clinical assessment. Once the problems are known, the treatment priorities can be established and the rationale for the treatment determined. Knowing what it is that is intended to be achieved, generates the target for the interven- tion. Moving one step back through the model, the question then arises - if that is the intended outcome or therapeutic effect, which physiological process(es) need to be stimulated, modified or affect- ed in order for the outcome to be achieved? Once the physiological changes are established, one further step back through the model will enable the determination of the most appropriate modality that can be used to achieve this effect, based on the best available evi- dence. If there is no electrotherapy modality capable of stimulating this/these physiological change(s) in the tissue in question, then electrotherapy has no place in the management of this particular patient.

Having identified the modality that is best able to achieve the effects required, the next clinical stage is to make a ‘dose’ selec- tion. There is a substantial and growing body of evidence that the same modality can be applied at different doses and the results will not be the same. An obvious example might be laser therapy. Applied at low dose, laser has effects that are harnessed by thera- pists when treating a variety of open wounds and musculoskeletal tissue problems. Applied at a higher dose, the same light energy is used by the surgeon as a means to ablate tissue. The energy form might be the same, but the dose is different and the outcome is easily distinguished.

This fundamental model used to explain electrotherapy could be THEORY

deliver physiological energy

effects

theraputic effects

PATIENT Figure 1 : A simple model of electrotherapy

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TREATMENT DELIVERY DOSE CALCULATION