***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 
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    Input: Background The optimal dose infusion of 0.125 % bupivacaine via a femoral catheter after total knee replacement ( TKR ) has not been defined . This study examined various dose infusions of bupivacaine to determine the analgesic quality in patients receiving a continuous femoral nerve block ( CFNB ) . Methods Patients were r and omized to receive a single-injection femoral nerve block ( SFNB ) or CFNB performed with 20 ml of 0.125 % bupivacaine , followed by a continuous infusion of 0.125 % bupivacaine in four groups ( n = 20 per group ) : 1 ) 0 ml/h ( SFNB ) , 2 ) 2 ml/h , 3 ) 4 ml/h , and 4 ) 6 ml/h . The pain intensity at rest and on knee movement was assessed using a visual analog scale ( VAS ) for the first 2 postoperative days . The cumulative bolus use of IV patientcontrolled analgesia ( PCA ) with a morphine-ketorolac combination  was evaluated . Results A lower cumulative bolus of IV PCA was noted in all CFNB groups compared to SFNB on postoperative days ( PODs ) 1 and 2 , respectively ( P < 0.05 ) . Lower VAS scores at rest were observed in the 4 ml/h and 6 ml/h groups than in the SFNB group on PODs 1 and 2 , respectively , but only on POD 2 in the 2 ml/h group ( P < 0.05 ) . Lower VAS scores on movement were noted in the 4 ml/h than the SFNB group on PODs 1 and 2 , but only on POD 1 in 6 ml/h ( P < 0.05 ) . Conclusions The minimum effective infusion rate of 0.125 % bupivacaine for CFNB after TKR appears to be 4 ml/h according to the VAS pain scores Background : The authors tested the hypotheses that , compared with an overnight continuous femoral nerve block ( cFNB ) , a 4-day ambulatory cFNB increases ambulation distance and decreases the time until three specific readiness-for-discharge criteria are met after tricompartment total knee arthroplasty . Methods : Preoperatively , all patients received a cFNB ( n = 50 ) and perineural ropivacaine 0.2 % from surgery until the following morning , at which time they were r and omly assigned to either continue perineural ropivacaine or switch to perineural normal saline . Primary endpoints included ( 1 ) time to attain three discharge criteria ( adequate analgesia , independence from intravenous analgesics , and ambulation of at least 30 m ) and ( 2 ) ambulatory distance in 6 min the afternoon after surgery . Patients were discharged with their cFNB and a portable infusion pump , and catheters were removed on postoperative day 4 . Results : Patients given 4 days of perineural ropivacaine attained all three discharge criteria in a median ( 25th–75th percentiles ) of 25 ( 21–47 ) h , compared with 71 ( 46–89 ) h for those of the control group ( estimated ratio , 0.47 ; 95 % confidence interval , 0.32–0.67 ; P < 0.001 ) . Patients assigned to receive ropivacaine  ambulated a median of 32 ( 17–47 ) m the afternoon after surgery , compared with 26 ( 13–35 ) m for those receiving normal saline ( estimated ratio , 1.21 ; 95 % confidence interval , 0.71–1.85 ; P = 0.42 ) . Conclusions : Compared with an overnight cFNB , a 4-day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 53 % after tricompartment total knee arthroplasty . However , the extended infusion did not increase ambulation distance the afternoon after surgery . ( Clinical Trials.gov No. NCT00135889 . Although the analgesic effects of periarticular multimodal drug injection ( PMDI ) after TKA have been well documented , there is little information about additional pain relieving effects of PMDI incorporated to contemporary multimodal pain control protocol s which have been proved to provide excellent analgesia . We performed a parallel-group , r and omised , controlled study to determine whether PMDI provides additional clinical benefits on contemporary multimodal analgesic protocol s including preemptive analgesics , continuous femoral nerve block , and IV-PCA . Eighty-seven patients were r and omized to a PMDI group ( n=45 ) or to a No-PMDI group ( n=42 ) .  Pain level and opioid consumption were compared as primary outcomes . The incidences of narcotic and ropivacaine related side effects and complications , functional recovery , and satisfaction were also compared . The PMDI group experienced less pain during the operation night and the 1st postoperative day and showed lower opioid consumption over 24h after surgery . However , the PMDI group had a higher VAS pain score on the 1st postoperative day than during the operation night . No group differences in side-effects and complication incidences , functional recovery , and satisfaction were found . This study demonstrates that PMDI provides additional pain relief and reduces opioid consumption only during the early postoperative period in patients managed by the contemporary pain management protocol following TKA STUDY OBJECTIVE To investigate the effects of single-injection femoral nerve block ( FNB ) in postoperative pain after total knee replacement ( TKR ) and anterior cruciate ligament ( ACL ) reconstruction . DESIGN Prospect i ve , r and omized , double-blind study . PATIENTS 96 ASA physical status I , II , and III patients , scheduled for TKR or ACL reconstruction . INTERVENTIONS All patients received a st and ard spinal anesthetic , then were r and omly divided into three treatment groups as follows : Group B ( n = 30 ) received an FNB with 40 mL of 0.25 % bupivacaine containing epinephrine , 1:200,000 ; Group R ( n = 32 ) received an FNB with 40 mL of 0.25 % ropivacaine ; and Group C ( n = 28 ) received no FNB . MEASUREMENTS The following clinical outcomes were assessed at up to 6 hours ( T1 ) , 6 to 10 hours ( T2 ) , and 10 to 24 hours ( T3 ) after spinal anesthesia was given : visual analog scale ( VAS ) for pain , both at rest and on movement ( no or mild pain , moderate pain , or severe pain ) ; morphine use ; sensory block in the femoral , obturator , and lateral femoral cutaneous nerve dermatomes ; and motor block of the femoral and obturator nerves . MAIN RESULTS Except for VAS during rest and on movement at time T3 , there were more Group C patients who experienced moderate or severe pain than those who had no pain or mild pain , when compared with Groups R and B. Sensory block in the femoral and lateral femoral cutaneous nerve dermatomes did not differ between Groups R and B at any times . However , sensory block in the obturator nerve dermatome was lower in Group R than Group B only at T3 . We observed a lower , significant use of morphine at T2 when comparing Groups R and B with Group C. No Group R patient and about 30 % of Group B patients remained with motor block of femoral and obturator nerves at T3 . Except for frequency of nausea , which was highest in Group C , the frequency of other side effects was similar among the three groups . CONCLUSIONS Femoral nerve block using 0.25 % ropivacaine or 0.25 % bupivacaine is an effective method of postoperative analgesia after TKR and ACL reconstruction , particularly for the first 10 hours after spinal anesthesia Total knee arthroplasty ( TKA ) may result in severe pain , and single-injection femoral nerve blocks ( SFNB ) have been demonstrated to have a limited duration of analgesia . Continuous femoral nerve blocks ( CFNB ) can prolong the analgesic duration of SFNB . We prospect ively r and omized 36 patients undergoing TKA to CFNB versus SFNB  and evaluated the effect on hospital length of stay ( LOS ) as the primary outcome within a st and ardized clinical pathway . Secondary outcomes included visual analog scale ( VAS ) pain scores , opioid consumption , and long-term functional recovery at 12 wk . Mean VAS resting scores were significantly lower among patients who received CFNB versus SFNB : first day ( 1.7 vs 3.3 [ P = 0.002 ] ) and second day ( 0.9 vs 3.2 [ P < 0.0001 ] ) after surgery . Mean maximal VAS scores during physical therapy were significantly lower among patients who received CFNB versus SFNB : first day ( 4.7 vs 6.3 [ P = 0.01 ] ) and second day ( 3.9 vs 6.1 [ P = 0.0005 ] ) after surgery . Mean oxycodone consumption was significantly lower among patients who received CFNB versus SFNB : 15 mg versus 40 mg ( P = < 0.0001 ) on the first day after surgery ; 20 mg versus 43 mg ( P = 0.0004 ) on the second day after surgery . There was no difference in hospital LOS ( 3.8 vs 3.9 days ) or long-term functional recovery ( 117 ° versus 113 ° knee flexion at 12 wk ) between the two groups . The lack of effect provided by increased duration of analgesia  ( from CFNB ) after TKA may now have minimal impact on hospital LOS and long-term functional recovery in the contemporary healthcare environment within the United States The objective of this prospect i ve , r and omized , double-blind study was to determine if preoperative administration of a femoral nerve block reduces the amount of morphine needed for postoperative analgesia after total knee arthroplasty ( TKA ) . Forty-two patients undergoing TKA were r and omly assigned to receive either a femoral nerve block ( 0.50 % bupivacaine hydrochloride with epinephrine 1:200,000 ) or matching placebo . Results showed postoperative morphine use was significantly lower in patients who received the nerve block ( 25.5 vs 37.5 mg , P = .016 ) ; however , the 2 groups had similar pain scores and rehabilitative outcomes . In general , a preoperative femoral nerve block is a safe and effective adjunct for decreasing morphine use for post-TKA analgesia Epidural analgesia remains the “ gold st and ard ” of pain relief after total knee replacement . However , peripheral nerve block is gaining popularity because the incidence of side effects may be reduced . Our study tests this postulate . Sixty patients were prospect ively r and omized to receive either epidural infusion or combined continuous femoral and sciatic nerve blocks . Ropivacaine 2 mg/mL plus sufentanil 1 & mgr;g/mL was given either epidurally or through the femoral nerve catheter , and ropivacaine 0.5 mg/mL was given through the sciatic nerve catheter using elastomeric infusers ( delivering 5 mL/h for 55 h ) . The primary outcome measure was the total incidence of side effects ( urinary retention and moderate to severe degrees of dizziness , pruritus , sedation , and nausea/vomiting on the first postoperative day ) . Intensity of motor blockade , pain at rest and on mobilization , and rehabilitation indices were also registered for 72 h. One or more side effects were present in 87 % of patients in the epidural group whereas only 35 % of patients in the femoral and sciatic block groups were affected on the first postoperative day ( P = 0.0002 ) . Motor blockade was more intense in the operated limb on the day of surgery and the first postoperative day in the peripheral nerve block group ( P = 0.001 ) , whereas the non-operated limb was more blocked in the epidural group on the day of surgery ( P = 0.0003 ) . Pain on mobilization was well controlled in both groups and there were no differences in the length of hospital stay . Rehabilitation indices were similar . The results demonstrate a reduced incidence of side effects in the femoral/sciatic nerve block group than in the epidural group on the first postoperative day Continuous femoral " 3-in-1 " nerve blocks are commonly used for analgesia after total knee arthroplasty ( TKA ) . There are conflicting data as to whether additional sciatic blockade is needed . Our routine use of both continuous femoral ( CFI ) and sciatic ( CSI ) peripheral nerve blocks was changed because of concerns that sciatic blockade , and its motor consequences in particular , might obscure diagnosis of perioperative sciatic nerve injury . The revised protocol includes placing single-shot blocks and perineural catheters at both sites , but infusing local anesthetic postoperatively only in the CFI . CSI is reserved for patients having poorly controlled posterior knee or calf pain . A sample group of 12 patients treated with this protocol was followed . Ten of 12 patients required use of the CSI . Within 1 h of a 5 - 10 mL CSI bolus of 0.2 % ropivacaine and beginning an infusion of the same drug at 5 mL/h , patients ' median pain by verbal analog scale decreased from 7.5 to 2.0 ( mean scores from 7.3 to 2.4 ) . It was possible to maintain this level of analgesia until the third postoperative day when catheters were discontinued . Our experience suggests that , in most patients , adequate analgesia after TKA can not be 
    Output:
    
Pain was also less in each FNB subgroup : single-shot FNB , continuous FNB and continuous FNB + sciatic block , compared with PCA .
Available evidence was insufficient to allow determination of the comparative safety of the various analgesic techniques .
AUTHORS ' CONCLUSIONS Following TKR , FNB ( with or without concurrent treatments including PCA opioid ) provided more effective analgesia than PCA opioid alone , similar analgesia to epidural analgesia and less nausea/vomiting compared with PCA alone or epidural analgesia .
The review also found that continuous FNB provided better analgesia compared with single-shot FNB .
RCTs were insufficient to allow definitive conclusions on the comparison between FNB and local infiltration analgesia or oral analgesia