title: Moderate-to-severe pain after knee arthroscopy is relieved by intraarticular saline: a randomized controlled trial.
abstract: We have previously studied intraarticular (IA) analgesics compared with saline 10 mL in 2 randomized clinical trials. The patients who were given IA saline experienced rapid pain relief. Hypothetically, saline may produce a local analgesic effect by cooling or by diluting IA algogenic substances. This randomized double-blind study compared the analgesic effect of IA saline 10 mL with saline 1 mL, which should be a pure placebo. A soft catheter was left IA in 79 patients. We included 60 patients who developed moderate-to-severe pain within 1 h after knee arthroscopy under general anesthesia. A randomized, double-blind controlled comparison of IA saline 10 mL with saline 1 mL followed. Outcome measures were pain intensity, pain relief, and analgesic consumption. Within 1 h pain intensity decreased in both groups from approximately 50 to approximately 27 on a 0-100 mm visual analog scale. Pain intensity remained low and other pain outcome measures were similar during the 36-h observation period. The patients experienced equally good pain relief after IA injection of saline 10 mL and 1 mL. Our finding of a major placebo effect may have implications for the interpretation of previously published placebo-controlled IA analgesia studies.
  
  
  CONCLUSIONS
  In a randomized controlled trial we showed that pain after knee arthroscopy is modest and short-lived and can successfully be treated with intraarticular saline as placebo.
authors.affiliation: From the *Department of Anesthesia, Rikshospitalet University Hospital and the †Department of Anesthesia, Lovisenberg Diakonale Hospital, Oslo, Norway.
authors.forename: Leiv A
authors.initials: LA
authors.lastname: Rosseland
authors.forename: Knut G
authors.initials: KG
authors.lastname: Helgesen
authors.forename: Harald
authors.initials: H
authors.lastname: Breivik
authors.forename: Audun
authors.initials: A
authors.lastname: Stubhaug
mesh_terms: D000328:Adult; D001182:Arthroscopy / Q000009:adverse effects*; D016009:Chi-Square Distribution; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007270:Injections, Intra-Articular; D007719:Knee Joint / Q000187:drug effects* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D012965:Sodium Chloride / Q000008:administration & dosage*
chemical_list: D012965:Sodium Chloride