Intraarticular Application of Opioids versus Glucocorticoids versus Placebo in Gonarthritis

INTERVENTION: Single injection of Morphine 3 mg or Dexamethasone 4 mg or Placebo during needle arthroscopy. Rearthroscopy after 7 days. CONDITION: Gonarthritis in inflammatory rheumatic disease ; Musculoskeletal Diseases ; Gonarthritis PRIMARY OUTCOME: Improvement of VAS pain of at least 20 mm on a 0‐100 scale. SECONDARY OUTCOME: Impovement of a numeric pain scale, sleep quality, global daily activity, knee mobility with Lysholm and Gilquist Score, Western Ontario McMaster Universities Osteoarthritis (WOMAC) index, relief of pain on a numeric scale from 0‐3. INCLUSION CRITERIA: 1. Age 19‐70 2. Gonarthritis with sonographically evident effusion in inflammatory rheumatic disease 3. Visual analogue score (VAS) pain >30 mm 4. Body weight 50‐90 kg 5. Written informed consent