Intraarticular morphine versus dexamethasone in chronic arthritis

Intraarticular morphine inhibits pain after knee surgery without overt toxicity. This study examined intraarticular morphine in chronic arthritis. We undertook a randomized double-blind comparison between intraarticular morphine (3 mg), dexamethasone (4 mg) and saline (3 ml) in 44 patients with chronic inflammatory arthritis or osteoarthritis of the knee. Pain (the primary outcome measure) was assessed at rest and during activity for 6 days using a visual analog scale (VAS) and the McGill pain questionnaire. Before drug injections and on day 6 synovial leukocyte counts (the secondary outcome measure) were taken. During the first 6 h after injection both morphine and dexamethasone significantly reduced VAS and pain rating indices (PRI) in comparison to saline. Both substances also produced a significant reduction of PRI compared to saline during the subsequent 5 days. No patient displayed untoward side effects. Synovial leukocyte counts were lower after morphine than after saline. In conclusion, intraarticular morphine produces analgesia of similar magnitude to dexamethasone and it may have antiinflammatory actions in chronic arthritis.