N of 1, two contemporary arm, randomised controlled clinical trial for bilateral epicondylitis: a new study design.

Objective: To investigate the use of a novel study design in analysis of bilateral elbow pain.

Design: N of 1, two contemporary arm, open label, randomised controlled clinical trial.

Setting: A clinical epidemiologist at a university hospital in Pavia, Italy.

Participants: Two elbows with epicondylitis.

Interventions: Autologous platelet lysate versus "wait and see" strategy.

Main Outcome Measures: Visual analogue scale for pain on elbow extension and resisted wrist extension.

Results: Over six months' follow-up, the patient experienced bilateral improvement in pain, but higher in the treated arm, with a drop in visual analogue scale for pain from 28 to 4 for right (control) arm (drop of 24 points) and from 67 to 10.5 for left (treated) arm (drop of 56.5 points).

Conclusions: Platelet lysate might (or might not) work. Competing interests and lack of blinding might be relevant issues in the interpretation of trial results. However, the new study design can be applied to a number of conditions such as bilateral sport or trauma injuries, bilateral otitis, or any condition affecting chiral organs or limbs.