title: Knee strength retention and analgesia with continuous perineural fentanyl infusion after total knee replacement: randomized controlled trial.
abstract: OBJECTIVE
  Despite providing adequate pain relief, a femoral nerve block can induce postoperative muscle weakness after total knee arthoplasty (TKA). Fentanyl has been shown to have peripheral effects but has not been used as a perineural infusate alone after TKA.
  
  
  METHODS
  Sixty patients scheduled for TKA were randomized to one of three blinded groups: a continuous 24 h infusion of either fentanyl 3 μg/ml, ropivacaine 0.1%, or 0.9% normal saline through a femoral nerve sheath catheter at 10 ml/h. The main outcome was maximum voluntary isometric contraction (MVIC) in the quadriceps femoris (knee extension), measured by a handheld dynamometer (Nm/kg). Other variables assessed were preoperative and postoperative visual analog scale (VAS) scores, hamstrings MVIC (knee flexion), active range of motion of the operative knee, distance ambulated, incidence of knee buckling, supplemental morphine usage, postoperative side effects, and serum fentanyl levels.
  
  
  RESULTS
  Quadriceps MVIC values were significantly greater in the fentanyl group compared to the group that received ropivacaine (median values, 0.08 vs. 0.03 Nm/kg; p = 0.028). The incidence of postoperative knee buckling upon ambulation was higher in the ropivacaine group compared to the fentanyl group, although not statistically significant (40% vs. 15 %, respectively; p = 0.077). VAS scores while ambulating were not significantly different between the fentanyl group and the ropivacaine group (p = 0.270). Postoperative morphine consumption, nausea and vomiting, and resting VAS scores were similar among the three groups.
  
  
  CONCLUSIONS
  A continuous perineural infusion of fentanyl produced greater strength retention than ropivacaine post-TKA.
authors: Florida Gulf to Bay Anesthesiology Associates LLC, 1 Tampa General Circle, Suite A327, Tampa, FL, 33606, USA.
authors: Devanand
authors: D
authors: Mangar
authors: Rachel A
authors: RA
authors: Karlnoski
authors: Collin J
authors: CJ
authors: Sprenker
authors: Katheryne L
authors: KL
authors: Downes
authors: Narrene
authors: N
authors: Taffe
authors: Robert
authors: R
authors: Wainwright
authors: Kenneth
authors: K
authors: Gustke
authors: Thomas L
authors: TL
authors: Bernasek
authors: Enrico
authors: E
authors: Camporesi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000008:administration & dosage / Q000627:therapeutic use*; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000627:therapeutic use*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000627:therapeutic use*; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D007260:Infusion Pumps; D007719:Knee Joint / Q000187:drug effects / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use; D009407:Nerve Block / Q000379:methods*; D059408:Pain Management / Q000379:methods; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000701:Analgesics, Opioid; D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D009020:Morphine; D000077212:Ropivacaine; D005283:Fentanyl
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