title: Continuous adductor canal blocks are superior to continuous femoral nerve blocks in promoting early ambulation after TKA.
abstract: BACKGROUND
  Femoral continuous peripheral nerve blocks (CPNBs) provide effective analgesia after TKA but have been associated with quadriceps weakness and delayed ambulation. A promising alternative is adductor canal CPNB that delivers a primarily sensory blockade; however, the differential effects of these two techniques on functional outcomes after TKA are not well established.
  
  
  OBJECTIVE
  We determined whether, after TKA, patients with adductor canal CPNB versus patients with femoral CPNB demonstrated (1) greater total ambulation distance on Postoperative Day (POD) 1 and 2 and (2) decreased daily opioid consumption, pain scores, and hospital length of stay.
  
  
  METHODS
  Between October 2011 and October 2012, 180 patients underwent primary TKA at our practice site, of whom 93% (n = 168) had CPNBs. In this sequential series, the first 102 patients had femoral CPNBs, and the next 66 had adductor canal CPNBs. The change resulted from a modification to our clinical pathway, which involved only a change to the block. An evaluator not involved in the patients' care reviewed their medical records to record the parameters noted above.
  
  
  RESULTS
  Ambulation distances were higher in the adductor canal group than in the femoral group on POD 1 (median [10(th)-90(th) percentiles]: 37 m [0-90 m] versus 6 m [0-51 m]; p < 0.001) and POD 2 (60 m [0-120 m] versus 21 m [0-78 m]; p = 0.003). Adjusted linear regression confirmed the association between adductor canal catheter use and ambulation distance on POD 1 (B = 23; 95% CI = 14-33; p < 0.001) and POD 2 (B = 19; 95% CI = 5-33; p = 0.008). Pain scores, daily opioid consumption, and hospital length of stay were similar between groups.
  
  
  CONCLUSIONS
  Adductor canal CPNB may promote greater early postoperative ambulation compared to femoral CPNB after TKA without a reduction in analgesia. Future randomized studies are needed to validate our major findings.
  
  
  METHODS
  Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Seshadri C
authors.initials: SC
authors.lastname: Mudumbai
authors.forename: T Edward
authors.initials: TE
authors.lastname: Kim
authors.forename: Steven K
authors.initials: SK
authors.lastname: Howard
authors.forename: J Justin
authors.initials: JJ
authors.lastname: Workman
authors.forename: Nicholas
authors.initials: N
authors.lastname: Giori
authors.forename: Steven
authors.initials: S
authors.lastname: Woolson
authors.forename: Toni
authors.initials: T
authors.lastname: Ganaway
authors.forename: Robert
authors.initials: R
authors.lastname: King
authors.forename: Edward R
authors.initials: ER
authors.lastname: Mariano
mesh_terms: D000368:Aged; D000701:Analgesics, Opioid / Q000627:therapeutic use; D000704:Analysis of Variance; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D004434:Early Ambulation; D005260:Female; D005267:Femoral Nerve; D006801:Humans; D007902:Length of Stay; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects / Q000379:methods*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid
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