Sciatic-femoral nerve block versus unilateral spinal anesthesia for outpatient knee arthroscopy: a meta-analysis

Because of the short hospital stay involved in outpatient knee arthroscopy, anesthesiologists should provide an effective and safe anesthesia scheme. Unilateral spinal anesthesia is a conventional choice for outpatient knee arthroscopy, and combined sciatic-femoral nerve block also permits successful results. This study aimed to compare sciatic-femoral nerve block with unilateral spinal anesthesia for outpatient knee arthroscopy.

We screened randomized controlled trials (RCTs) that compared sciatic-femoral nerve block (SFB) with unilateral spinal anesthesia (USA) from EMBASE, MEDLINE and the Cochrane Library. Ten statistic parameters, such as time-to-readiness for discharge (TRD, minutes), time to first spontaneous urination (minutes), time to perform (PT, minutes), Visual Analogue Scale (VAS) for postoperative (24 hours) pain, patients' satisfaction, and total anesthesia time (TAT, minutes) were considered in this study. RevMan 5.2 and Stata 12.0 softwares were used for data analysis.

There were 7 RCTs including 402 total patients which met our criteria. Compared with the USA group, in the SFB group TRD (mean difference [MD]=-38.8; 95% CI [-63.7, -14.0]; P=0.002) and time to first spontaneous urination (MD=-78.2; 95% CI [-92.7, -63.7]; P<0.00001) were shorter, TAT (MD=100.2; 95% CI [30.3, 170.1]; P=0.005) and PT (MD=4.0; 95% CI [2.4, 5.6]; P<0.00001; I2=97%) were longer in the SFB group. For the two groups, no statistically significant differences were observed in patients' satisfaction (MD=3.2; 95% CI [0.3, 31.8]; P=0.33).

SFB provided faster bladder function recovery and faster discharging from hospital, hence it could be a good alternative to USA for outpatient knee arthroscopy.