Background and Purpose
In microcurrent therapy (MCT), low-intensity electric current is applied to promote tissue healing and relieve symptoms. MCT is used with recalcitrant skin and bone lesions, but little is known about its effects on tendinopathy, and optimal treatment parameters are uncertain. Two studies were conducted to ascertain whether varying (i) current intensity and (ii) waveform and treatment duration affect outcomes of MCT for chronic tennis elbow.

Methods
Two trials compared the effects of different MCT parameters on pain and function, grip strength, and sonographically graded tendon structure and hyperaemia. Trial 1 compared monophasic MCT of intensity 50 and 500 μA applied for 35 h; trial 2 compared devices delivering approximately 25 μA but with different waveforms and durations of 15 and 189 h, respectively. Treatment was applied over 3 weeks. Assessments were at baseline and 3, 6 and 15 weeks.

Results
For each trial, n = 31. In trial 1, 50 μA was more effective than 500 μA, with 93% of participants ‘much better’ or ‘fully recovered’ at 15 weeks, compared with 47% in the 500 μA group. Tendon structural normalization was superior at 50 μA, but no significant differences were found in other outcomes. In trial 2, success rates for the two groups at 15 weeks were 75% and 73%, respectively, but group improvements did not differ significantly on any measure. Pooled analysis of data from both trials showed that, immediately following treatment, blood flow had fallen in the subgroup with high baseline scores and risen in the subgroup with low scores. Low baseline score correlated significantly with treatment success.

Conclusion
Monophasic MCT of peak current intensity 50 μA applied for tens of hours may be effective in reducing symptoms and promoting tendon normalization in chronic tennis elbow. Hyperaemia may help predict treatment outcome. A full-scale trial of the therapy is warranted.