TISSUE REPAIR ULTRASOUND

dense collagen based tissues

■ ligament ■ tendon ■ fascia ■ joint capsule ■ scar tissue

PULSED SHORTWAVE

wet, ionic, low resistance tissues

■ muscle ■ nerve

■ areas of oedema

haematomas and effusion

LASER superficial vascular tissues

■ open wounds ■ muscle ■ nerve

■ tendon sheath

Figure 3 : Energy absorption profiles of different electrotherapy modalities

stretching and flexibility gains (21,22) may also be of interest. The effects of PSWT appear to be dose dependent in the same way as for US and laser.

The strong similarity in therapeutic effects of the three modalities discussed here are in many ways not surprising. Each energy mode appears to generate an up regulation of cell activity, based on cell membrane level stimulation, almost certainly related to cell mem- brane transport changes. That this reaction can be produced by the three different modalities is a reflection of membrane reactivity to energy - whether mechanical (US) light (laser) or electromagnetic (PSWT). The key clinical issue is that these effects are predomi- nantly generated in different tissues depending on energy absorp- tion profiles. Figure 3 summarises the energy absorption character- istics of the three modalities discussed.

FUTURE DEVELOPMENT AND ISSUES Growth factors and angiogenesis As identified in the previous article (23), there is a growing inter- est in the relationship between several therapies and their influ- ence on the angiogenic components of repair. It has been shown for example that ultrasound, laser and electrical stimulation have a beneficial influence on this process, and it is anticipated that this research area will continue to develop and become a mainstream element of tissue repair enhancement.

Magnetics There are many therapeutic devices available that deliver a mag- netic (as opposed to an electromagnetic) field, and this is claimed to achieve significant benefit in relation to injured and repairing tissues. Some of the results are rather equivocal at the current time, though there is reasonable evidence already to suggest that this energy will achieve similar if not identical results to the main three therapies discussed in this paper. At the present time, it is not clear which energy delivery systems are the most effective (high power, low power, pulsed, continuous etc). Much of the research to date has concentrated on wound healing and fractures, though there is some expansion into soft tissue areas (24,25).

Electrical stimulation and microcurrent therapy The final ‘up and coming’ area for brief consideration is that of ‘microcurrent’ type therapy. There are many variations of this modal- ity, often referred to by various and somewhat obscure names, but

in principle, the therapeutic approach is based on sound bioelectric research. Current flow in the body under ‘normal’ and ‘injured’ con- ditions is at the microcurrent level, and electrotherapy aside, these endogenous currents appear to have a significant effect in relation to modifying and/or driving the tissue repair process (26). The use of an external source of current at these levels is logical and is gen- erating a growing volume of literature (27,28). A quick search of the literature will reveal tens of similar papers, and a web search will provide even more, though some will lack a degree of credibil- ity in the way it is presented. It is considered to be one of the most interesting areas for growth and development in electrotherapy, especially in relation to tissue repair and recovery following injury.

SUMMARY AND CONCLUSIONS In summary, there are currently three mainstream modalities which are evidenced in terms of their capacity to influence tissue repair - ultrasound, laser and pulsed shortwave therapies. They appear to have a common mode of action, though their effects are predomi- nantly achieved in different tissues according to differential absorption. Other therapies, including microcurrent type electrical stimulation and magnetic therapy are becoming stronger in their evidence base, and it is anticipated that they will join the list of effective modalities at some point in the future. The responses of the tissues appear to be both modality and dose specific, and there- fore electrotherapy, when correctly applied does have the capacity to enhance tissue repair. Applied at ‘other than ideal’ doses will most likely achieve no significant therapeutic benefit, as in fact would be case for any other therapeutic intervention.

THE AUTHOR Prof Tim Watson is a professor of physiotherapy and director of research at the University of Hertfordshire. He completed a degree in biomedical sciences followed by a PhD on the bioelectric correlates of musculoskeletal injury and repair. His main research areas are elec- trotherapy (mainly ultrasound, pulsed shortwave and microcurrent) and tissue repair. Author correspondence t.watson@herts.ac.uk For more information about Professor Watson’s work visit www. electrotherapy.org

References 1. Karu TI. Photobiological fundamentals of low power laser therapy. The Journal of Quantum Electronics 1997;23(10):1703-1717 2. Hill J, Lewis M et al. Pulsed short-wave diathermy effects on human fibroblast proliferation. Archives of Physical Medicine and Rehabilitation 2002;83(6):832-836 3. Al Mandil M and Watson T. An Evaluative Audit of Patient Records in Electrotherapy with Specific Reference to Pulsed Short Wave Therapy (PSWT). 2006 in press 4. Watson T. The role of electrotherapy in contemporary physiotherapy prac- tice. Manual Therapy 2000;5(3):132-141 5. Wilkin LD, Merrick MA et al. Influence of therapeutic ultrasound on skele- tal muscle regeneration following blunt contusion. International Journal of Sports Medicine 2004;25(1):73-77 6. Markert CD, Merrick MA et al. Nonthermal ultrasound and exercise in skeletal muscle regeneration. Archives of Physical Medicine and Rehabilitation 2005;86(7):1304-1310 7. Sparrow K J, Finucane SD et al. The effects of low-intensity ultrasound on medial collateral ligament healing in the rabbit model. American Journal of Sports Medicine 2005;33(7):1048-1056

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