title: The analgesic effects of proximal, distal, or no sciatic nerve block on posterior knee pain after total knee arthroplasty: a double-blind placebo-controlled randomized trial.
abstract: BACKGROUND
  The analgesic efficacy of sciatic nerve block (SNB) after total knee arthroplasty (TKA) is unclear. Proximal and distal SNB are each reported to provide posterior knee analgesia, whereas others suggest that posterior knee pain is not important after TKA. This prospective, randomized, double-blind, parallel-arm, placebo-controlled trial examined whether proximal or distal SNB provides superior analgesia in the posterior knee compared with no SNB after TKA.
  
  
  METHODS
  Sixty patients undergoing TKA were randomized to single-shot SNB using either the infragluteal (Proximal group) or popliteal (Distal group) technique, or no SNB (Placebo group). All patients received spinal anesthesia and continuous-femoral nerve blockade. A blinded observer assessed posterior and anterior knee pain at 2, 4, 6, 8, 12, and 24 h postoperatively. The primary outcome was moderate-to-severe posterior knee pain at 4 h postoperatively; secondary outcomes included SNB procedural time, needle passes, and discomfort.
  
  
  RESULTS
  Fifty-three patients were analyzed. The proportion of patients (Proximal:Distal:Placebo) who experienced moderate-to-severe posterior knee pain was 18%:22%:89% (P<0.00001) at 2 h, 24%:28%:72% (P<0.01) at 4 h, and 12%:17%:78% (P=0.00003) at 6 h postoperatively. For the anterior knee, the proportion of patients reporting moderate-to-severe pain was 6%:11%:44% (P=0.02) at 2 h, 6%:6%:39% (P=0.012) at 4 h, and 12%:6%:44% (P=0.017) at 6 h postoperatively. Moderate-to-severe pain did not differ between groups beyond 6 h. Both proximal and distal SNB reduced rest pain in the posterior and anterior knee up to 8 h postoperatively compared with no SNB. The popliteal technique required shorter procedural time, fewer needle passes, and produced less discomfort.
  
  
  CONCLUSIONS
  Proximal and distal SNB each reduce posterior and anterior knee pain after TKA compared with no SNB.
authors.affiliation: From the Departments of Anesthesia, St. Michael's Hospital (F.W.A.), and Toronto Western Hospital (V.W.S.C., A.K., S.A., R.B.), and the Department of Surgery, Toronto Western Hospital (R.G.), University of Toronto, Toronto, Ontario, Canada.
authors.forename: Faraj W
authors.initials: FW
authors.lastname: Abdallah
authors.forename: Vincent W S
authors.initials: VW
authors.lastname: Chan
authors.forename: Rajiv
authors.initials: R
authors.lastname: Gandhi
authors.forename: Arkadiy
authors.initials: A
authors.lastname: Koshkin
authors.forename: Sherif
authors.initials: S
authors.lastname: Abbas
authors.forename: Richard
authors.initials: R
authors.lastname: Brull
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000188:drug therapy*; D011182:Postoperative Care; D012584:Sciatic Nerve; D016896:Treatment Outcome