4.3. Patient information and randomization (IV and V)

Patients meeting the criteria for inclusion were requested to read through preliminary information about the infiltration procedure and the trial. Patients were informed of the trial option both orally and with a written description of its content and purpose. Where written consent was obtained, patients underwent the investigations and completed the questionnaires. The randomization process took place immediately before the intervention, and was based on a published list of random permutations (Cohran & Cox 1957) with a block size of 16. A person uninvolved in the study placed the assignments in sealed envelopes with running numbers. The envelopes were used in the order provided. On their way to the infiltration procedure, each patient took an envelope to the Department of Radiology, where an authorized nurse filled a tape-covered syringe with the treatment agent indicated therein. The assignments were thus masked to the patient, the physicians and the radiologist giving the injection.