***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: We conducted a r and omized , double-blind trial to evaluate the early and late analgesic effect of preoperative wound infiltration with bupivacaine 0.25 % ( 40 mL ) compared to placebo ( NaCl 0.9 % , 40 mL ) in patients undergoing major surgery . Forty-one patients scheduled for elective hysterectomy during general anesthesia were included . The pain management focused on pain prevention , including preoperative administration of nonsteroidal antiinflammatory drugs ( NSAIDs ) , and peroperative administration of opioids . Postoperatively patients received buprenorphine and /or acetaminophen on dem and . A significant difference between treatments was evident in the 3-day postoperative trial period . With identical pain scores in the two groups , the requested total amount of buprenorphine  was greater in the placebo group ( 2.0 [ 0 - 5.1 ] mg ) ( median and [ range ] ) than in the bupivacaine group ( 0.8 [ 0 - 2.8 ] mg ) ( P < 0.05 ) . The dem and for analgesics occurred earlier in those who received placebo ( 225 min ) than in those who received bupivacaine ( 345 min ) , but did not reach the level of significance . In conclusion , preoperative wound infiltration with bupivacaine improved immediate and late postoperative pain management after hysterectomy compared to placebo . ( Anesth Analg 1996;83:376 - 81 This study tests the null hypothesis that there is no difference between sciatic nerve block ( SNB ) and periarticular anesthetic infiltration ( PI ) as adjuncts to femoral nerve blockade ( FNB ) in total knee arthroplasty in terms of postoperative opioid requirements . Fifty-two patients undergoing total knee arthroplasty were r and omized to receive either ( a ) combined FNB-SNB or ( b ) combined FNB-PI .  Average morphine consumption in the first 24 ( 20 vs 23 mg ) and 48 hours ( 26 vs 33 mg ) showed no significant difference . Visual Analogue Scale scores , knee flexion ( 60 ° vs 67.5 ° ) and extension lag ( 0 ° vs 5 ° ) were comparable . Anesthetic time , surgical time , and length of hospital stay ( 5.5 vs 6 days ) were similar . This study showed no significant difference between the 2 groups . The PI offers a practical and potentially safer alternative to SNB BACKGROUND Pain after total knee arthroplasty ( TKA ) is usually severe . Recently , the usefulness of local periarticular injection analgesia ( PAI ) and peripheral nerve block ( PNB ) has been reported . We report a prospect i ve blinded r and omized trial of PAI versus PNB in patients undergoing primary TKA , in accordance with the CONSORT statement 2010 . METHODS A total of 210 patients undergoing TKA under spinal anesthesia were r and omized to receive PNB group or PAI group . In the PNB group , femoral nerve block and sciatic nerve block were performed . In the PAI group , a special mixture containing ropivacaine , saline , epinephrine , morphine hydrochloride , and dexamethasone was injected into the periarticular soft tissue . Pain intensity at rest was assessed using a numerical rating scale ( NRS : 0 - 10 ) after surgery . Use of a diclofenac sodium suppository ( 25 mg ) was allowed for all patients at any time after surgery , and the diclofenac sodium suppository usage was assessed . The NRS for patient satisfaction at 48 hours after surgery was examined . RESULTS The average NRS for pain at rest up to 48 hours after surgery was low in both groups . Within 48 hours after surgery , the  diclofenac sodium suppository usage was similar in both groups . There were no significant differences in the NRS for patient satisfaction in both groups . CONCLUSIONS The analgesic effects of PAI and PNB are similar . PAI may be considered superior to PNB because it is easier to perform . LEVEL OF EVIDENCE Therapeutic Level 1 Background : Pain is one of the major concerns of patients underwent Total Knee Arthroplasty ( TKA ) ; appropriate pain management is a key factor in patient 's early physical fitness to move , physiotherapy , and most importantly , patient satisfaction . Objectives : In this study the analgesic effect of single injection femoral nerve block ( SFNB ) was compared with local infiltration analgesia ( LIA ) . Patients and Methods : Forty patients who underwent TKA under spinal anesthesia  were r and omized to receive single femoral nerve block ( group F ) or intra-periarticular infiltration ( group I ) . Group F received single injection 20cc ropivacaine ( 10mg/cc ) and in group I , a combination of 300 mg ropivacaine , 30 mg ketorolac and 0.5 mg epinephrine diluted to a volume of 150cc and locally injected in and around the knee joint in 3 stages . Postoperative pain intensity measured by Visual Analog Scale ( VAS ) . Morphine consumption , mobilization time and patients ’ satisfaction evaluated as well . Results : Group I had significantly lower morphine consumption in the first postoperative day ( 10 vs. 12.5 mg , P-value < 0.05 ) . Within 6 hours postoperatively , VAS score was statistically lower in group I compared to group F ( 3 vs. 4 , P-value < 0.05 ) . However , within 12 hours it was statistically higher in group I than group F ( 6 vs. 5 , P-value < 0.05 ) . Other parameters were not statistically different in two groups . Conclusions : Both methods LIA and SFNB provided excellent pain relief and lower morphine consumption following TKA . LIA is a surgeon-controlled analgesic technique , which can be used to enhance patients ’ satisfaction and reduce the pain in the very early postoperative period by surgeon independently Background Pain management after TKA remains challenging and the efficacy of continuously infused intraarticular anesthetics remains a controversial topic . Questions / purpose sWe compared the side effect profile , analgesic efficacy , and functional recovery between patients receiving a continuous intraarticular infusion of ropivacaine and patients receiving an epidural plus femoral nerve block ( FNB ) after TKA . Methods Ninety-four patients undergoing unilateral TKA were prospect ively r and omized to receive a spinal-epidural analgesic infusion plus a single-injection FNB or a spinal anesthetic plus a continuous postoperative intraarticular infusion of 0.2 % ropivacaine . All patients were blinded to their treatment with placebo saline catheters . Blinded coinvestigators collected data concerning side effect profiles ( nausea , hypotension ) , analgesic efficacy ( VAS pain scores , narcotic usage ) , and functional recovery ( timed up and go test , quadriceps strength , WOMAC scores , Knee Society scores , early postoperative ambulatory ability , in-hospital falls ) . All complications and adverse events were recorded . Results The frequency of nausea and hypertension was not different between the study groups . During the first 12 and 24 postoperative hours , the mean maximum VAS pain scores were higher in the ropivacaine group than in the epidural group ( first 12 hours : 3.93 versus 1.14 , respectively , p < 0.0001 ; 12–24 hours : 3.52 versus 1.93 , respectively , p = 0.008 ) . After 24 hours , pain scores were similar between groups . Narcotic consumption was significantly higher in the ropivacaine group on the day of surgery , but overall in-hospital narcotic usage was similar between groups . There were no clinical ly important differences in functional recovery between groups at any time point , but patients in the epidural group were more likely to have knee buckling ( 32.7 % versus 6.7 % , p = 0.002 ) and delayed ambulation ( 16.3 % versus 0.0 % , p = 0.006 ) than patients in the ropivacaine group , though not in-hospital falls . No infections occurred in either group , and the frequency of complications was not different between groups . Conclusions A continuous intraarticular infusion of ropivacaine can be recommended as a safe , effective alternative to epidural analgesia plus single-injection FNB after TKA . Improved analgesic efficacy in the group that received epidural analgesia plus single-injection FNB must be weighed against the disadvantage of a higher likelihood of knee buckling and delayed ambulation with that treatment approach . Level of Evidence Level I , therapeutic study . See Instructions for Authors for a complete description of levels of evidence Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more Background The ideal local anesthetic regime for femoral nerve block that balances analgesia with mobility after total knee arthroplasty ( TKA ) remains undefined . Questions / purpose sWe compared two volumes and concentrations of a fixed dose of ropivacaine for continuous femoral nerve block after TKA to a single injection femoral nerve block with ropivacaine to determine ( 1 ) time to discharge readiness ; ( 2 ) early pain scores and analgesic consumption ; and ( 3 ) functional outcomes , including range of motion and WOMAC scores at the time of recovery . Methods Ninety-nine patients were allocated to one of three continuous femoral nerve block groups for this r and omized , placebo-controlled , double-blind trial : a high concentration group ( ropivacaine 0.2 % infusion ) , a low concentration group ( ropivacaine 0.1 % infusion ) , or a placebo infusion group ( saline 0.9 % infusion ) . Infusions were discontinued on postoperative Day ( POD ) 2 . The primary outcome was time to discharge readiness . Secondary outcomes included opioid consumption , pain , and functional outcomes .  Ninety-three patients completed the study protocol ; the study was halted early because of unanticipated changes to pain protocol s at the host institution , by which time only 61 % of the required number of patients had been enrolled . Results With the numbers available , the mean time to discharge readiness was not different between groups ( high concentration group , 62 hours [ 95 % confidence interval [ CI ] , 51–72 hours ] ; low concentration group , 73 hours [ 95 % CI , 63–83 hours ] ; placebo infusion group 65 hours [ 95 % CI , 56–75 hours ] ; p = 0.27 ) . Patients in the low concentration group consumed significantly less morphine during the period of infusion ( POD 1 , high concentration group , 56 mg [ 95 % CI , 42–70 mg ] ; low concentration group , 35 mg [ 95 % CI , 27–43 mg ] ; placebo infusion group , 48 mg [ 95 % CI , 38–59 mg ] , p = 0.02 ; POD 2 , high concentration group , 50 mg [ 95 % CI , 41–60 mg ] ; low concentration group , 33 mg [ 95 % CI , 24–42 mg ] ; placebo infusion group , 39 mg [ 95 % CI , 30–48 mg ] , p = 0.04 ) ; however , there were no important differences in pain scores or opioid-related side effects with the numbers available . Likewise , there were no important differences in functional outcomes between groups . Conclusions Based on this study , which was terminated prematurely before the desired sample size could be achieved , we were unable to demonstrate that varying the concentration and volume of a fixed-dose ropivacaine infusion for continuous femoral nerve block influences time to discharge readiness when compared with a conventional single-injection femoral nerve block after TKA . A low concentration of ropivacaine infusion can reduce postoperative opioid consumption but without any important differences in pain scores , side effects , or functional outcomes . These pilot data may be used to inform the statistical power of future r and omized trials . Level of Evidence Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence In this prospect i ve r and omized study , patients undergoing total hip ( THA ) or knee arthroplasty ( TKA ) were r and omized to either a study group receiving periarticular injections or a control group receiving patient-controlled analgesia with or without femoral nerve block ( TKA patients ) . All patients received a comprehensive multimodal perioperative protocol .  Pain , recovery of functional milestones , and overall satisfaction were assessed . The THA study group demonstrated significantly lower average pain scores and higher overall satisfaction than the control group . There was no significant difference in pain scores between the study and control groups in the TKA cohort . Both study groups demonstrated lower narcotic usage and side effects as well as improved early functional recovery . Periarticular injection with a multimodal protocol was shown to safely provide excellent pain control and functional recovery and can be substituted for conventional pain control modalities Background The postoperative analgesic potential of periarticular anesthetic infiltration ( PAI ) after TKA is unclear as are the complications of continuous femoral nerve block on quadriceps function . Questions / purpose sWe asked ( 1 ) whether PAI provides equal or improved postoperative pain control in comparison to a femoral nerve block in patients who have undergone TKA ; and ( 2 ) if so , whether PAI improves early postoperative quadriceps control and facilitates reh 
    Output:
    
The primary outcomes were cumulative i.v .
There were no clinical differences in functional outcomes or rates of complications .
Local infiltration analgesia provides similar postoperative analgesia after total knee arthroplasty to femoral nerve block .