Analgesic Impact of Single-Shot Versus Continuous Femoral Nerve Block After Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Introduction Efficient pain management after total knee arthroplasty will accelerate functional recovery and reduce the length of hospital stay. The femoral nerve block is increasingly used in clinical practice owing to its favorable analgesic efficacy. However, the effect of continuous femoral nerve block compared to single-shot femoral nerve block remains controversial. Methods Three databases (Pubmed, Embase and Cochrane Library) were searched for randomized controlled trials up to April 2019. Seven studies with 525 patients were included in this analysis. Results The pooled estimates showed that the continuous femoral nerve block could relieve the pain at rest [standardized mean differences with 95% confidence intervals 1.12 (0.63–1.60), I 2 = 57%, p < 0.00001] and physical therapy [standardized mean differences with 95% confidence intervals 1.05 (0.47–1.63), I 2 = 71%, p = 0.0004] on postoperative day 1 and reduce total morphine consumption on postoperative day 1 [mean differences with 95% confidence intervals 16.15 (13.75–18.54), I 2 = 46%, p < 0.00001] and 2 [mean differences with 95% confidence intervals 7.02 (4.82–9.22), I 2 = 35%, p < 0.00001]. There is no significant difference in pain scores at rest and physical therapy on postoperative day 2 and 3, in Western Ontario and McMaster University Arthritis Index scores ( p = 0.12), the length of hospital stay ( p = 0.94) and the incidence of nausea and vomiting ( p = 0.09). Conclusion We conclude that the continuous femoral nerve block is more effective than single-shot femoral nerve block after total knee arthroplasty, which provides objective evidence of pain management for anesthetists.