Pain and stiffness due to plantar fasciitis, an inflammatory condition involving the sole of the foot, is relieved by "iontophoresis" treatment with acetic acid, Australian investigators report. Iontophoresis refers to the use of a small electric current to move ionized substances through the skin into tissues. There have been reports that iontophoresis with the steroid dexamethasone or acetic acid benefits patients with plantar fasciitis, Drs. H. R. Osborne and G. T. Allison explain in their study, published in the British Journal of Sports Medicine. However, there have been no comparisons of the two agents. The investigators based at the University of Western Australian in Perth therefore conducted a randomized trial among 31 patients with symptomatic plantar fasciitis for at least 1 month.
The treatments consisted of iontophoresis with 0.4% dexamethasone, 5% acetic acid, or saline "placebo." The patients got six treatments with an iontophoresis drug delivery system, applied to the site of maximum tenderness, over a 2-week period.
Treatment was delivered while the patients also had taping to support the arch of the foot, intended to relieve pressure on the midfoot area of the sole. Patients reported measures of pain and stiffness at the start of the study, after 2 weeks and after 4 weeks, using a 0-10 scale.
At the end of 2 weeks, all three groups reported significant improvement in morning pain and average pain in the preceding week, but acetic acid was the most effective. By the 4-week follow-up visit, the effects of the treatment on pain were diminished, but there was still an overall improvement with acetic acid treatment and to some extent with dexamethasone. In terms of morning stiffness, all three treatments reduced this symptom, but the difference was statistically significant only in the acetic acid and placebo groups. The reduction in stiffness was maintained only among patients treated with acetic acid.
Osborne and Allison conclude, "For the best clinical results at four weeks, taping combined with acetic acid is the preferred treatment option compared with taping combined with dexamethasone or saline iontophoresis."