title: Impact of peripheral nerve block with low dose local anesthetics on analgesia and functional outcomes following total knee arthroplasty: a retrospective study.
abstract: OBJECTIVE
  While the safety and efficacy of peripheral nerve blocks for postoperative pain management has been established in several well controlled prospective trials, the local anesthetic (LA) concentration and volume used in these studies was associated with a significant increase muscle weakness due to motor nerve block. The purpose of the present retrospective study of patients undergoing total knee arthroplasty was to assess the relative analgesic efficacy and functional outcomes of the low concentration, low volume of LA used in peripheral nerve blocks for postoperative pain management.
  
  
  METHODS
  Twenty-four months of deidentified patient data were extracted from an electronic medical record system. All patients received opioids with or without continuous femoral and sciatic nerve block infusions for postoperative analgesia. Pain (resting and with activity), cumulative opioid and LA use were primary endpoints, participation in physical therapy (PT), muscle strength deficits and length of hospital stay (LOS) were secondary endpoints.
  
  
  RESULTS
  Postoperative pain and opioid use were significantly lower in patients with peripheral nerve blocks (n = 1,329) than those with opioids alone (n = 439). There was no detectable decrease in strength associated with nerve blocks, while a significantly greater proportion of patients with nerve blocks were able to participate in PT on postoperative day 1 (96.4% vs 57.1%). These differences were not due to the impact of the surgeon per se, but whether or not the surgeon used nerve blocks for pain management. There was a small but statistically significant decrease in the average LOS in patients with blocks.
  
  
  CONCLUSIONS
  This analysis supports the use of low concentration, low volume of LA based peripheral nerve blocks for postoperative pain management.
authors.affiliation: Department of Anesthesiology, University of Pittsburgh Medical Center, Pennsylvania, 15213, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Division of Acute Interventional Perioperative Pain and Regional Anesthesia, University of Pittsburgh Medical Center, Pennsylvania, 15213, USA.
authors.forename: Jacques E
authors.initials: JE
authors.lastname: Chelly
authors.affiliation: Department of Anesthesiology, University of Pittsburgh Medical Center, Pennsylvania, 15213, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Williams
authors.affiliation: Department of Anesthesiology, University of Pittsburgh Medical Center, Pennsylvania, 15213, USA.|Department of Medicine (Division of Gastroenterology Hepatology and Nutrition), University of Pittsburgh, Pittsburgh, Pennsylvania, 15213, USA.|Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213, USA.|Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gold
mesh_terms: D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D059408:Pain Management / Q000379:methods*; D010149:Postoperative Pain / Q000188:drug therapy* / Q000209:etiology; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000779:Anesthetics, Local
keywords: Acute Pain; Analgesic; Knee Pain; Narcotics; Regional Pain