Treatment of calcifying tendinitis of the shoulder by acetic acid iontophoresis: a double-blind randomized controlled trial

OBJECTIVE: To assess the effects of acetic acid iontophoresis on the treatment of calcifying tendinitis of the shoulder. DESIGN: Double-blind randomized controlled trial. SETTING: Ambulatory academic hospital in Quebec, Canada. PARTICIPANTS: Thirty-six subjects with a calcifying tendinitis of the shoulder. INTERVENTIONS: Subjects were randomized into 1 of 2 groups: physiotherapy during 6 weeks (10 sessions) plus acetic acid iontophoresis for the treatment group (n=18) and sham acetic acid iontophoresis for the control group (n=18). MAIN OUTCOME MEASURES: The Shoulder Pain and Disability Index (SPADI), shoulder range of motion (ROM); and radiologic evaluation of shoulder calcifications. RESULTS: Nine patients dropped out, leaving 27 assessable subjects for analysis. Interim analysis showed that, in both groups, treatment led to improvement, as measured by the SPADI score (P=.004), ROM of the shoulder for abduction (P<.001), internal rotation (P=.001), external rotation (P<.001), and the mean number of calcifications per subject (P=.010). Although no formal significant intervention effects (P=.13) were found for the primary endpoint (SPADI), exploratory analyses suggest a greater improvement in the treatment group (P=.001) than in the control group (P=.33). CONCLUSIONS: Despite a trend toward greater improvement in the SPADI score in the treatment group, the use of acetic acid iontophoresis and physiotherapy for the treatment of calcifying tendinitis of the shoulder did not result in better clinical and radiologic effects than those observed in subjects treated by physiotherapyalone.