title: Patient-controlled bolus femoral nerve block after knee arthroplasty: quadriceps recovery, analgesia, local anesthetic consumption.
abstract: BACKGROUND
  Continuous femoral nerve block (cFNB) induces quadriceps muscle weakness, but patient-controlled femoral nerve block (PCFNB) can provide analgesia with lower consumption of local anesthetics compared to cFNB. We hypothesized that cFNB followed by PCFNB leads to accelerated recovery of quadriceps weakness after total knee arthroplasty compared to cFNB alone. Secondary outcomes were local anesthetic consumption, pain, and mobilization.
  
  
  METHODS
  Fifty-six subjects received post-operative cFNB for 24 h and then randomized to receive either cFNB (basal infusion of 6 ml/h using a dummy bolus button; n = 27) or PCFNB (bolus infusion of 3 ml with a lockout time of 30 min and no basal infusion; n = 29) using 0.08% levobupivacaine for the subsequent 24 h in a double-blind manner (registration: UMIN000010105). Quadriceps strength was assessed using a hand-held dynamometer. The percentage change from baseline was compared between groups.
  
  
  RESULTS
  Quadriceps strength at 48 h was 47.3 ± 18.3% in the cFNB group and 49.7 ± 15.7% in the PCFNB group (95% confidence interval -7.0-11.9%, P = 0.61). Local anesthetic consumption during the post-operative period was significantly lower in the PCFNB group compared to the cFNB group (102 ± 10.8 ml vs.146 ± 4.6 ml; P < 0.001). No significant differences were found in any of the other outcomes, including pain scores at rest and during knee rehabilitation.
  
  
  CONCLUSIONS
  Continuous femoral nerve block followed by PCFNB does not improve quadriceps strength recovery time compared to cFNB alone after total knee arthroplasty, but similar analgesic effects were demonstrated with reduced levobupivacaine consumption.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Osaka University Graduate School of Medicine, Suita, Japan. sakayline@gmail.com.
authors.forename: N
authors.identifier: http://orcid.org/0000-0003-4332-4681
authors.initials: N
authors.lastname: Sakai
authors.affiliation: Department of Pharmacy, Osaka University Medical Hospital, Suita, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakatsuka
authors.affiliation: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tomita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016058:Analgesia, Patient-Controlled; D000779:Anesthetics, Local / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee; D044963:Biopsy, Fine-Needle; D002045:Bupivacaine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D004311:Double-Blind Method; D005260:Female; D005267:Femoral Nerve; D006801:Humans; D000077554:Levobupivacaine; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D009407:Nerve Block / Q000379:methods*; D010149:Postoperative Pain / Q000517:prevention & control*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D020127:Recovery of Function
chemical_list: D000779:Anesthetics, Local; D000077554:Levobupivacaine; D002045:Bupivacaine