***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : Although peripheral nerve blocks decrease pain after total knee arthroplasty , the population -level impact of nerve blocks on arthroplasty re source utilization is unknown . Methods : We conducted a population -based cohort study using linked administrative data from Ontario , Canada . We identified all adults having their first primary knee arthroplasty between 2002 and 2013 . Using propensity scores to adjust for measureable confounders , we matched nerve block patients to a patient who did not receive a block . Within the matched cohort , we estimated the independent association of blocks with outcomes ( length of hospital stay [ primary ] ; and readmissions , emergency department visits , and falls [ secondary ] ) . Results : One hundred seventy-eight thous and two hundred fourteen patients were identified ; 61,588 ( 34.6 % ) had a block . The mean hospital stay was 4.6 days with a block compared to 4.8 without . After matching , there was a statistically significant decrease in the length of stay in the block group ( relative risk , 0.98 ; 95 % CI , 0.97 to 0.99 ; P < 0.001 ) . Blocks were associated with a significant decrease in readmissions ( relative risk , 0.87 ; 95 % CI , 0.79 to 0.88 ; P < 0.001 ) but not emergency department visits ( relative risk , 1.02 ; 95 % CI , 0.98 to 1.05 ) or falls ( relative risk , 1.37 ; 95 % CI , 0.90 to 2.08 ) . The association of blocks with length of stay after 2008 was inconsistent ; overall , they were associated with longer stays ; however , single-shot blocks were associated with shorter stays , while continuous techniques prolonged the length of stay . Conclusions : Nerve blocks in total knee arthroplasty patients were associated with statistically significant reductions in length of stay and readmissions , but not emergency department visits or falls . The significance of these findings at the patient level and in contemporary practice requires further exploration in prospect i ve r and omized studies at low risk of indication bias BACKGROUND We studied the efficacy of local infiltration analgesia in surgical wounds with 0.2 % ropivacaine ( 50 mL ) , ketorolac ( 15 mg ) , and adrenaline ( 0.5 mg ) compared with that of local infiltration analgesia combined with continuous infusion of 0.2 % ropivacaine as a method of pain control after total hip arthroplasty . We hypothesized that as a component of multimodal analgesia , local infiltration analgesia followed by continuous infusion of ropivacaine would result in reduced postoperative opioid consumption and lower pain scores compared with infiltration alone , and that both of these techniques would be superior to placebo . METHODS In this prospect i ve , double-blind , placebo-controlled study , 105 patients were r and omized into three groups : Group I , in which patients received infiltration with ropivacaine , ketorolac , and adrenaline followed by continuous infusion of 0.2 % ropivacaine at 5 mL/hr ; Group II , in which patients received infiltration with ropivacaine , ketorolac , and adrenaline followed by continuous infusion of saline solution at 5 mL/hr ; and Group III , in which patients received infiltration with saline solution followed by continuous infusion of saline solution at 5 mL/hr . All patients received celecoxib , pregabalin , and acetaminophen perioperatively and patient-controlled analgesia ; surgery was performed under general anesthesia . Before wound closure , the tissues and periarticular space were infiltrated with ropivacaine , ketorolac , and adrenaline or saline solution and a fenestrated catheter was placed . The catheter was attached to a pump prefilled with either 0.2 % ropivacaine or saline solution set to infuse at 5 mL/hr . The primary outcome measure was postoperative opioid consumption and the secondary outcome measures were pain scores , adverse side effects , and patient satisfaction . RESULTS There were no differences between groups in the administration of opioids in the operating room , in the recovery room , or on the surgical floor . The pain scores on recovery room admission and discharge and the floor were low and similar between groups . There were no differences in the incidence of adverse side effects among groups . Patient satisfaction with pain management was similar in all groups . CONCLUSIONS Local infiltration analgesia alone or followed by continuous infusion of ropivacaine as part of multimodal analgesia provides no additional analgesic benefit or reduction in opioid consumption compared with placebo following total hip arthroplasty . LEVEL OF EVIDENCE Therapeutic level I. See Instructions for Authors for a complete description of levels of evidence Background : The analgesic effect of perioperative low doses of intravenous lidocaine has been demonstrated after abdominal surgery . This study aim ed to evaluate whether a continuous intravenous low-dose lidocaine infusion reduced  postoperative pain and modified nociceptive pain threshold after total hip arthroplasty . Methods : Sixty patients participated in this r and omized double-blinded study . Patients received lidocaine 1 % ( lidocaine group ) with a 1.5 mg/kg−1 intravenous bolus in 10 min followed by a 1.5 mg · kg−1 · h−1 intravenous infusion or saline ( control group ) . These regimens were started 30 min before surgical incision and stopped 1h after skin closure .  Lidocaine blood concentrations were measured at the end of administration . In both groups , postoperative analgesia was provided exclusively by patient-controlled intravenous morphine . Pain scores , morphine consumption , and operative hip flexion were recorded over 48 h. In addition , pressure pain thresholds and the extent of hyperalgesia around surgical incision were systematic ally measured at 24 and 48 h. Results : In comparison with the placebo , lidocaine did not induce any opioid-sparing effect during the first 24 h ( median [ 25–75 % interquartile range ] ; 17 mg [ 9–28 ] vs. 15 mg [ 8–23 ] ; P = 0.54 ) . There was no significant difference regarding the effects of lidocaine and placebo  on pain score , pressure pain thresholds , extent in the area of hyperalgesia , and maximal degree of active hip flexion tolerated . Mean plasma lidocaine concentration was 2.1 ± 0.4 & mgr;g/ml . Conclusion : Low dose perioperative intravenous lidocaine  after total hip arthroplasty offers no beneficial effect on postoperative analgesia and does not modify pressure and tactile pain thresholds Background : The authors tested the hypotheses that after hip arthroplasty , ambulation distance is increased and the time required to reach three specific readiness-for-discharge criteria is shorter with a 4-day ambulatory continuous lumbar plexus block ( cLPB ) than with an overnight cLPB . Methods : A cLPB consisting of 0.2 % ropivacaine was provided from surgery until the following morning . Patients were then r and omly assigned either to continue ropivacaine or to be switched to normal saline . Primary endpoints included ( 1 ) time to attain three discharge criteria ( adequate analgesia , independence from intravenous analgesics , and ambulation ≥ 30 m ) and ( 2 ) ambulatory distance in 6 min the afternoon after surgery . Patients were discharged with their cLPB and a portable infusion pump , and catheters were removed on the fourth postoperative day . Results : Patients given 4 days of perineural ropivacaine ( n = 24 ) attained all three discharge criteria in a median ( 25th–75th percentiles ) of 29 ( 24–45 ) h , compared with 51 ( 42–73 ) h for those of the control group ( n = 23 ; estimated ratio = 0.62 ; 95 % confidence interval , 0.45–0.92 ; P = 0.011 ) . Patients assigned to receive ropivacaine  ambulated a median of 34 ( 9–55 ) m the afternoon after surgery , compared with 20 ( 6–46 ) m for those receiving normal saline ( estimated ratio = 1.3 ; 95 % confidence interval , 0.6–3.0 ; P = 0.42 ) . Three falls occurred in subjects receiving ropivacaine ( 13 % ) , versus none in subjects receiving normal saline . Conclusions : Compared with an overnight cLPB , a 4-day ambulatory cLPB decreases the time to reach three predefined discharge criteria by an estimated 38 % after hip arthroplasty . However , the extended infusion did not increase ambulation distance to a statistically significant degree Background and Objectives : High-volume local infiltration analgesia ( LIA ) is widely applied as part of a multimodal pain management strategy in total hip arthroplasty ( THA ) . However , method ological problems hinder the exact interpretation of previous trials , and the evidence for LIA in THA remains to be clarified . Therefore , we evaluated whether intraoperative high-volume LIA , in addition to a multimodal oral analgesic regimen , would further reduce acute postoperative pain after THA . Methods : Patients scheduled for unilateral , primary THA under spinal anesthesia were included in this r and omized , double-blind , placebo-controlled trial receiving high-volume ( 150 mL ) wound infiltration with ropivacaine 0.2 % with epinephrine ( 10 & mgr;g/mL ) or saline 0.9 % . A multimodal oral analgesic regimen consisting of slow-release acetaminophen 2 g , celecoxib 400 mg , and gabapentin 600 mg was instituted preoperatively . Rescue analgesic consisted of oral oxycodone .  Pain was assessed repeatedly the first 8 hrs after surgery using the 100-mm visual analog scale . The primary end point was pain during walking ( 5 m ) 8 hrs after surgery . Secondary end points were pain at rest , pain on 45 degrees of passive flexion of the hip with the leg straight , and cumulative consumption of oxycodone .  Results : A total of 120 patients were included .  Pain during walking ( median [ interquartile range ] [ 95 % confidence interval ] ) was low in the ropivacaine versus the placebo group ( 20 [ 14 - 38 ] [ 0 - 93 ] vs 22 [ 10 - 40 ] [ 0 - 83 ] ) and did not differ significantly ( P = 0.71 ) . Consumption of rescue oxycodone  ( 5 mg [ 0 - 10 mg ] [ 0 - 24 mg ] vs 10 mg [ 0 - 15 mg ] [ 0 - 29 mg ] ) did not differ ( P = 0.45 ) . Conclusions : Intraoperative high-volume LIA with ropivacaine 0.2 % provided no additional reduction in acute pain after THA when combined with a multimodal oral analgesic regimen consisting of acetaminophen , celecoxib , and gabapentin and is therefore not recommended Background Optimal postoperative pain management is important to ensure patient comfort and early mobilization . Methods In this double-blind , placebo- and active-controlled , r and omized clinical trial , we evaluated postoperative pain following knee replacement in patients receiving placebo , etoricoxib ( 90 or 120 mg ) , or ibuprofen 1800 mg daily for 7 days . Patients ≥18 years of age who had pain at rest ≥5 ( 0–10 Numerical Rating Scale [ NRS ] ) after unilateral total knee replacement were r and omly assigned to placebo ( N = 98 ) , etoricoxib 90 mg ( N = 224 ) , etoricoxib 120 mg ( N = 230 ) , or ibuprofen 1800 mg ( N = 224 ) postoperatively . Co- primary endpoints included Average Pain Intensity Difference at Rest over Days 1–3 ( 0- to 10-point NRS ) and Average Total Daily Dose of Morphine over Days 1–3 . Pain upon movement was evaluated using Average Pain Intensity Difference upon Knee Flexion ( 0- to 10-point NRS ) . The primary objective was to demonstrate analgesic superiority for the etoricoxib doses vs. placebo ; the secondary objective was to demonstrate that the analgesic effect of the etoricoxib doses was non-inferior to ibuprofen . Adverse experiences ( AEs ) including opioid-related AEs were evaluated . Results The least squares ( LS ) mean ( 95 % CI ) differences from placebo for Pain Intensity Difference at Rest over Days 1–3 were -0.54 ( -0.95 , -0.14 ) ; -0.49 ( -0.89 , -0.08 ) ; and -0.45 ( -0.85 , -0.04 ) for etoricoxib 90 mg , etoricoxib 120 mg , and ibuprofen , respectively ( p < 0.05 for etoricoxib vs. placebo ) . Differences in LS Geometric Mean Ratio morphine use over Days 1–3 from placebo were 0.66 ( 0.54 , 0.82 ) ; 0.69 ( 0.56 , 0.85 ) ; and 0.66 ( 0.53 , 0.81 
    Output:
    
Results Multimodal analgesia emphasizing nonsteroidal anti-inflammatory agents and acetaminophen is associated with decreases in perioperative opioid use for THA and TKA .
Regional analgesia , including  peripheral nerve blocks and local infiltration analgesia  , is also associated with decreased perioperative opioid use for THA and TKA .
Emerging topics in post-arthroplasty analgesia include ( 1 ) the value of nonsteroidal anti-inflammatory drugs , ( 2 ) the use of peripheral nerve catheters and extended-release local anesthetics to prolong the duration of opioid-free analgesia , and ( 3 ) novel peripheral nerve blocks , exemplified by the IPACK ( interspace between the popliteal artery and posterior capsule of the knee ) block for TKA .
Conclusions The use of multimodal analgesia with regional techniques may decrease perioperative opioid use for patients undergoing THA and TKA .