To assess the efficacy of lidocaine iontophoresis on myofascial trigger-point pain.
University athletic training facility.
Randomized, double-blind, placebo-controlled, repeated-measures.
Twenty-three subjects with sensitive trigger points over the trapezius.
Placebo iontophoresis treatment without current or lidocaine, control treatment using distilled water and normal current dose, medicated treatment using 1% lidocaine and normal current dose.
Main Outcome Measure:
Trigger-point pressure threshold assessed with an algometer.
ANOVA revealed a significant difference among treatments (F 2,40 = 7.38, P < .01). Post hoc comparisons revealed a significant difference in pressure threshold between the lidocaine treatment and the control (P = .01) and placebo (P = .001) treatments. Effect sizes of .28 and .39, respectively, were found for these comparisons.
Although the data revealed significant differences between treatments, the small effect sizes and magnitude of the pressure-sensitivity deviation scores suggest that iontophoresis with 1% lidocaine is ineffective in treating trigger points.