Novel Microcurrent Treatment is More Effective than Conventional Therapy for Chronic Achilles Tendinopathy

Summary

Background

The healing processes of tendon tissue are not well understood and the difficulty in clinical management of its pathology reflects this. Previous in vitro studies have demonstrated that application of microcurrent can promote protein production (collagen) in fibroblasts and tenocytes. In vivo studies, using animal models, have demonstrated that tendon and ligament tissue responds particularly well to this application. Thus the purpose of this study was to evaluate functional outcome in patients presenting with chronic pathology in the Achilles tendon, following application of microcurrent compared with conservative management.

Method

A prospective comparative study was undertaken using a blocked randomisation method. Subjects were allocated either to group A and exposed to current clinical management or to group B, the experimental microcurrent regime. Classification and subsequent evaluation of pathology were assessed employing clinical assessment tests, self-assessment and assessment by diagnostic ultrasound. Baseline characteristics were similar in both groups. Subjects were assessed at three, six and 12 months after entry into the study.

Forty-eight subjects, 24 in each group, completed the study. A statistical analysis was performed, calculating the differences between the two groups and between each interval assessment. Categorical variables were compared between the two groups using the chi-squared test. The Mann-Whitney test was performed to assess changes in ordinal variables.

Results

Statistically significant differences were found in favour of group B, the experimental group, in four out of the five clinical markers used at the 0.1% level of significance.

Conclusion

The application of microcurrent treatment to patients presenting with chronic Achilles tendon pathology can make a significant contribution to improvement of the condition.

Introduction

The use of electricity, electrical stimulation, and electromagnetic fields is not new in medicine. Studies have shown, for example Akai et al (1988), Lee et al (1993) and Dunn et al (1988), that by externally imposing an electrical field or electrical current the electrical potentials present in and between cells, in soft tissues, may promote biological and physiological changes of these tissues. Indeed there is strong experimental evidence to suggest that tendon repair can be significantly affected by electrical stimulation with intensities at a micro-current level. The work of Stanish et al (1985), Nessler and Mass (1985) and Fujita et al (1992) are of particular relevance.

Microcurrent is understood to be distinct from other forms of therapeutic electrical stimulation because the current intensity is significantly less than that of other forms of electrotherapy, such as transcutaneous electrical nerve stimul-ation or Faradic units. Microcurrent applications are believed to be effective by influencing and modifying cellular processes and activity. Employing different levels of current, frequency and polarity have been shown to have diverse effects upon different cell groups.

In respect to wound healing and the tissue repair process it is believed that not only is the intensity of current crucial to optimise its efficacy but also the polarity is vital to success (Becker and Seldon, 1985). Davis et al (1990) demonstrated that in skin healing, treatments using positive polarity surpassed the controls. Other combinations of negative and negative and positive were worse than untreated controls. This demonstrates that micro-current therapy has a soph-isticated mechanism of action that depends upon many different biological and physiolo-gical actions and inter-actions. This has also been discussed by Bourguignon and Bourguignon (1987) and Dunn et al (1988).

The proposed physiological effects that accelerate healing may be summarised as the following:

• A mechanism that modifies or mimics the normal processes of electro-chemical signal transduction (Chapman-Jones, 1997).

• An amplification of A.T.P synthesis (highlighted by Cheng et al, 1982).

• A change in the acid/base chemical balance in the cell environment (Lee et al, 1993).

There may be four reasons why the cell membrane is implicated in the process:

• An electric field/current is amplified within the membrane making it the most likely site of interaction.

• The cell membrane is a major site of signal transduction.

• Changes to ion flow, especially calcium, will affect cell behaviour.

• The cell membrane is involved in controlling the electrical aspects of the cell, maintaining the potential gradient through the active regulation of ion influx into and out of the cell (Chapman-Jones, 1997).

When microcurrent is applied to a patient via small electrodes the treatments generally produce no noticeable sensory or neuromuscular effect on the patient or practitioner.

Science and scientists have yet to reach agreement upon the aetiology of chronic tendon pathology. The pathophysiology of the tendon with chronic pathology and the healing processes involved are debated in the literature, particularly with reference to the Achilles tendon (Leadbetter et al, 1992; Clement et al, 1984; Blackman et al, 1990). Conservative management regimes have proved to be unreliable, with inconsistent results and a generally low level of success, as highlighted by Williams (1986) and Niesen-Vertommen et al (1992).

Despite the fact that studies have reported augmentation of healing processes following microcurrent stimulation in connective tissue, for example skin (Alvarez et al, 1983), and in a collagen matrix (Dunn et al, 1988) a literature search revealed that there have been no clinical studies which demon-strated the efficacy of the technique for the treatment of tendon pathology in human subjects using non-invasive skin surface application. Only animal models, in vitro cell cultures, and invasive in vivo techniques have been used to demonstrate the effectiveness of microcurrent electrical stimulation (Owoeye et al, 1987; Spielholz, 1986).

It was against this background of cell behaviour modification that the clinical potential of microcurrent stimulation to augment healing in tendons was to be evaluated. It was reasoned that microcurrent electrical stimulation would induce a modification in cell behaviour which would augment healing processes in Achilles tendons with chronic pathology.

The following question was addressed: Do patients exposed to microcurrent return to a normal functional outcome more quickly than those receiving conservative treatment? (Functional outcome was measured as the subject being able to perform activities under-taken prior to the onset of symptoms, evaluated by pain, stiffness and flexibility levels.)