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  • Randomised controlled trial evaluating the short-term analgesic effect of topical diclofenac on chronic Achilles tendon pain: a pilot study

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Rehabilitation medicine
Research
Randomised controlled trial evaluating the short-term analgesic effect of topical diclofenac on chronic Achilles tendon pain: a pilot study
  1. Erin Rebecca Bussin1,
  2. Brian Cairns2,3,
  3. Jim Bovard4,
  4. Alexander Scott1
  1. 1 Physical Therapy, University of British Columbia, Vancouver, Canada
  2. 2 Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
  3. 3 Health Science and Technology, Aalborg Universitet, Aalborg, Denmark
  4. 4 Family Practice, University of British Columbia, Vancouver, Canada
  1. Correspondence to Professor Alexander Scott; ascott{at}mail.ubc.ca

Abstract

Objectives To determine if a topically applied non-steroidal anti-inflammatory drug (diclofenac) can provide short-term pain relief for chronic Achilles tendinopathy (CAT), in order to inform the development of a new rehabilitation protocol.

Design and setting Pilot double-blind, cross-over randomised controlled trial providing participants with tertiary care. The study was conducted at a single research centre in Vancouver, BC.

Participants Sixteen adults with unilateral CAT and three adults with bilateral CAT participated.

Interventions Participants received two successive treatments (10% diclofenac gel or placebo gel) in random order over a 3-day period. There was a 1-week washout period between the treatments. Allocation was by simple randomisation, and the participants as well as the assessing/treating researcher were blinded to treatment allocation.

Outcome measures The primary outcome measure was pain level (0–10) during tendon loading (hopping). Secondary outcome measures included pain at rest, pressure pain threshold of the Achilles tendon and symptom improvement.

Results Nineteen adults participated in the study, and all were included in the analysis. Diclofenac gel significantly reduced the average pain during tendon loading (p<0.001) and at rest (p=0.031). The average baseline hopping pain was 4.8/10 (95% CI 3.92 to 5.68) and was reduced to 3.1/10 (2.35–3.85) by diclofenac. Pain at rest was decreased and pressure pain threshold increased with diclofenac treatment, but not with placebo gel. There were no observed or reported side effects of either treatment.

Conclusions In this small, short-term study, diclofenac was able to improve symptoms and reduce pain during tendon loading in participants with CAT, whereas placebo gel was not. A future study of diclofenac as a supplement to rehabilitation, with longer follow-up and powered to detect a difference between diclofenac and placebo, is indicated.

Trial registration ISRCTN60151284, http://www.isrctn.com/ISRCTN60151284

Ethics UBC Clinical Research Ethics Board approval was obtained for this research. The certificate number of the ethics certificate of approval to conduct research is H15-00999.

  • Chronic pain
  • Achilles tendon
  • Tendinopathy
  • Diclofenac
  • Achilles tendinopathy

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2016-015126

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    Footnotes

    • Contributors ERB drafted the study protocol, piloted study procedures, recruited and consented participants, carried out interventions and data collection, contributed to the statistical analysis and drafted the manuscript. AS, JB and BC assisted in developing the protocol and study procedures and in editing the manuscript.

    • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. Medisca (Burnaby, Canada) supplied the gel base as an in-kind contribution, but they played no role in the design or execution of the study and had no access to the data at any time. Diclofenac was purchased from a commercial pharmacy (Northmount, West Vancouver, Canada) and compounded by them for a fee. ERB was supported in part by a Graduate Student Initiative award from UBC, and Dr AS was supported in part by the Michael Smith Foundation of Health Research. The drug and study supplies and facility usage for the Centre for Hip Health and Mobility were paid through internal (UBC) unrestricted research funds allocated to Dr AS’s tendinopathy research program.

    • Competing interests None declared.

    • Ethics approval UBC Clinical Research Ethics Board.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Data are available by contacting the corresponding author at alex.scott@ubc.ca.