Spray vs EMLA Cream on Pain During Intra-articular Injection

All participants are randomly allocated to the spray group, EMLA group and placebo group. In spray group, participants receive an application of placebo cream at the needle electrode insertion site 60 minutes before needle insertion, and a self adhering dressing is placed over the site. After 60 minutes, the dressing and cream are removed from the site, then the insertion site is sprayed using ethyl chloride spray (Walter Ritter GmbH and Co., Hamburg, Germany) from a distance of 30 cm for 5 seconds or until the skin was blanched, then intra-articular injection of shoulder is performed. Immediately after injection, participants are asked to fill out the visual analog scale for injectional pain, five point Likert scale for satisfaction about the topical anesthesia. In EMLA group, participants receive an application of EMLA cream at the needle electrode insertion site 60 minutes before needle insertion, and a self adhering dressing is placed over the site. After 60 minutes, the dressing and cream are removed from the site, then the insertion site is sprayed using placebo spray (Evain Eau Minerale Naturelle, a pure water spray with hydrocarbon propellant), then intra-articular injection of shoulder is performed. Immediately after injection, participants are asked to fill out the same scales. In placebo group, participants receive a placebo cream and placebo spray.