title: Which analgesic mixture is appropriate for periarticular injection after total knee arthroplasty? Prospective, randomized, double-blind study.
abstract: OBJECTIVE
  Although the analgesic effect of periarticular injection after total knee arthroplasty (TKA) has been well documented, the gold standard for drug combination has not yet been established. In this study, the analgesic effects of six different drug combinations were compared.
  
  
  METHODS
  A total of 256 patients undergoing TKA for primary osteoarthritis were randomized into one of six groups: a control group (saline solution, epinephrine, and cefazolin, n = 42), Group 1 (ropivacaine, n = 43), Group 2 (ropivacaine + morphine, n = 43), Group 3 (ropivacaine + ketorolac, n = 42), Group 4 (ropivacaine + morphine + ketorolac, n = 43), and Group 5 (ropivacaine + morphine + ketorolac + methylprednisolone, n = 43). Pain level assessed by visual analogue scale (VAS) and opioid consumption were primary outcomes. The incidence of complications, range of motion (ROM), C-reactive protein (CRP) value, and the amount of post-operative blood drainage were also compared.
  
  
  RESULTS
  Patients in Groups 4 and 5 complained less pain than the control group for the first 12 h after surgery, and the patients in the other groups showed less pain only during the initial 6 h after surgery. Groups 4 and 5 also showed less opioid consumption than the control group during the 24 h period after surgery. Patients in Group 5 showed no significant difference in VAS score and opioid consumption compared with Group 4, but they had lower CRP value and greater ROM than any other groups at post-operative day 2 and day 4.
  
  
  CONCLUSIONS
  The combination of ropivacaine, morphine, and ketorolac showed a significantly stronger and sufficiently synergistic analgesic effect without adding methylprednisolone in periarticular injection after TKA. The clinical relevance of the study is that the combination of ropivacaine, morphine, and ketorolac can be a good option for periarticular injection following TKA in terms of synergistic analgesic effect and efficiency of drug combination.
authors.affiliation: Department of Orthopaedic Surgery, Hallym University Hospital, 77, Sakju-ro, Chuncheon-si, Gangwon-do, 200-704, Korea.
authors.forename: Tae Woo
authors.initials: TW
authors.lastname: Kim
authors.forename: Sang Jae
authors.initials: SJ
authors.lastname: Park
authors.forename: Se Hyeok
authors.initials: SH
authors.lastname: Lim
authors.forename: Sang Cheol
authors.initials: SC
authors.lastname: Seong
authors.forename: Sahnghoon
authors.initials: S
authors.lastname: Lee
authors.forename: Myung Chul
authors.initials: MC
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000008:administration & dosage; D000700:Analgesics / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007270:Injections, Intra-Articular; D020910:Ketorolac / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010149:Postoperative Pain / Q000188:drug therapy*; D011446:Prospective Studies; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000700:Analgesics; D009020:Morphine; D000077212:Ropivacaine; D020910:Ketorolac