Topical diclofenac vs placebo for the treatment of chronic Achilles tendinopathy: A randomized controlled clinical trial

• DOI: 10.1371/journal.pone.0247663
• Publication Date: 2021-03-04T18:33:10Z
• Authors: Erin Bussin; Brian Cairns; Tommy Gerschman; Michael Fredericson; Jim Bovard; Alex Scott
• Keywords: Adult; Male; Analysis of Variance; Diclofenac; Science; Administration, Topical; Q; Anti-Inflammatory Agents, Non-Steroidal; R; Pain; Middle Aged; Dermatitis, Contact; 3. Good health; 03 medical and health sciences; 0302 clinical medicine; Double-Blind Method; Chronic Disease; Outcome Assessment, Health Care; Tendinopathy; Medicine; Humans; Research Article

Introduction The application of topical diclofenac has been suggested as a possible treatment for Achilles tendinopathy. Our aim was to answer the question, is topical diclofenac more effective than placebo for the treatment of Achilles tendinopathy?.

Methods 67 participants with persistent midportion or insertional Achilles tendinopathy were randomly assigned to receive a 4 week course of 10% topical diclofenac (n = 32) or placebo (n = 35). The a priori primary outcome measure was change in severity of Achilles tendinopathy (VISA-A score) at 4 and 12 weeks. Secondary outcome measures included numeric pain rating, and patient-reported change in symptoms using a 7 point scale, from substantially worse to substantially better. Pressure pain threshold (N) and transverse tendon stiffness (N/m) were measured over the site of maximum Achilles tendon pathology at baseline and 4 weeks.

Results There were no statistically or clinically significant differences between the diclofenac and placebo groups in any of the primary or secondary outcome measures at any timepoint. Average VISA-A score improved in both groups (p<0.0001), but the improvements were marginal: at 4 weeks, the improvements in VISA-A were 9 (SD 11) in the diclofenac group and 8 (SD 12) in the placebo group, and at 12 weeks the improvements were 9 (SD 16) and 11 (SD13) respectively–these average changes are smaller than the minimum clinically important difference of the VISA-A.

Conclusion The regular application of topical diclofenac for Achilles tendinopathy over a 4 week period was not associated with superior clinical outcomes to that achieved with placebo.