title: Single-dose intra-articular morphine after arthroscopic knee surgery: a meta-analysis of randomized placebo-controlled studies.
abstract: OBJECTIVE
  The purpose of this quantitative meta-analysis is to appraise the efficacy and side effects of intra-articular morphine in patients undergoing arthroscopic knee surgery.
  
  
  METHODS
  The comprehensive literature search, using Medline (1966 to 2013), the Cochrane Central Register of Controlled Trials, and EMBASE databases, was conducted to identify randomized placebo-controlled trials that used single-dose intra-articular morphine for postoperative pain. The relative risk (RR), standardized mean difference (SMD), and their corresponding 95% confidence intervals (CIs) were calculated using statistical software.
  
  
  RESULTS
  Twenty-six articles were included in the meta-analysis. The acute postoperative visual analog scale (VAS) pain scores of the morphine group compared with the control group were significantly lower (SMD, -1.16; 95% CI, -1.79 to -0.53; P = .0003). The number of patients requiring supplementary analgesia was also significantly reduced (RR, 0.80; 95% CI, 0.70 to 0.93; P = .008), and there was a significant difference in the time to first analgesic request (SMD, 1.47; 95% CI, 0.49 to 2.44; P = .003) when the morphine group was compared with the placebo group. However, there was no significant difference in side effects between the morphine group and the control group (RR, 0.93; 95% CI, 0.67 to 1.28; P = .65).
  
  
  CONCLUSIONS
  The key findings of the present study were that the administration of single-dose intra-articular morphine at the end of arthroscopic knee surgery provided better pain relief, reduced the need for supplementary analgesics, and lengthened the time interval before the first request for additional analgesic medication, all with short-term side effects similar to those of the saline placebo.
  
  
  METHODS
  Level II, meta-analysis of Level I-II studies.
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Hunan Province, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zeng
authors.forename: Shu-guang
authors.initials: SG
authors.lastname: Gao
authors.forename: Ling
authors.initials: L
authors.lastname: Cheng
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Yu-sheng
authors.initials: YS
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Tu
authors.forename: Jian
authors.initials: J
authors.lastname: Tian
authors.forename: Mai
authors.initials: M
authors.lastname: Xu
authors.forename: Fang-jie
authors.initials: FJ
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Li-cheng
authors.initials: LC
authors.lastname: Wei
authors.forename: Guang-hua
authors.initials: GH
authors.lastname: Lei
mesh_terms: D001182:Arthroscopy / Q000009:adverse effects*; D006801:Humans; D007270:Injections, Intra-Articular; D007719:Knee Joint / Q000601:surgery*; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy* / Q000209:etiology
chemical_list: D009020:Morphine