Sciatic nerve block may represent an effective complement to femoral nerve block for total knee arthroplasty, particularly in patients at high risk for postoperative opioid use, according to a systematic literature review published in Journal of Anesthesia.
Researchers conducted a meta-analysis of prospective randomized studies comparing femoral plus sciatic nerve blocks vs femoral nerve block alone for total knee arthroplasty.
They assessed pain score at rest and movement 4, 12, 24, 48, and/or 72 hours after surgery; patient-controlled opioid consumption; incidence of nausea; and length of hospital stay. A total of 514 adult patients from 10 studies were included.
Four outcomes were improved by the nerve block combination vs femoral block alone: pain score at 4 hours (P <.001), pain score at movement at 12 hours (P =.02), opioid consumption at 24 hours and 48 hours (P =.006 and P <.001, respectively), and postoperative nausea (P =.032; 3 studies).
Length of hospital stay was comparable in both groups. Compared with single injection, continuous sciatic nerve block reduced pain scores at rest at 24 hours and at 48 hours (P <.001 for both; n=79; 3 studies), but not at 12 hours.
Among the study’s limitations, study authors cited significant heterogeneity in certain subgroup analyses as well as differences in patients’ baseline characteristics and a small sample size.
“This meta-analysis provides evidence-based supports for the benefits of sciatic nerve block as a complement to femoral nerve block in total knee arthroplasty,” concluded the review authors, adding, “The combination sciatic-femoral nerve block appears to be the optimal choice for patients [at] high risk [for] postoperative opioids consumption or acute pain after total knee arthroplasty.”
Zorilla-Vaca A, Li J. The role of sciatic nerve block to complement femoral nerve block in total knee arthroplasty: a meta‐analysis of randomized controlled trials [published online March 8, 2018]. J Anesth. doi: 10.1007/s00540-018-2480-1