Pain relief after total knee arthroplasty (TKA) may be greater when femoral nerve block (FNB) is combined with sciatic nerve block (SNB) than when it is combined with local infiltration analgesia (LIA).1
While previous research indicates that FNB plus SNB provides superior pain management for TKA, adding SNB to FNB may increase the occurrence of adverse effects such as weakness of the quadriceps, leading to postoperative falls.2 “Furthermore, there is a risk of peripheral nerve injury, which has an incidence of 0.024% in patients who receive SNB.3 Sciatic nerve injury is also a common complication following TKA and its incidence is 1.3 to 2.2%,” the researchers noted.4,5 “Therefore, LIA combined with FNB was suggested to achieve comparable pain control.”
Yixuan Zhang from Henan University in Kaifeng, China, and colleagues, conducted a systematic review and meta-analysis of studies available in Embase, Medline, PubMed, ScienceDirect, web of science, and Cochrane Library that were published online in English between 1966 and 2017.
Out of 310 studies initially reviewed, the researchers identified 5 studies (n=240; 3 randomized controlled trials [RCTs], 2 non-RCTs) that met the eligibility criteria: study participants subjected to TKA; studies comparing SNB+FNB with FNB+LIA; and reported study outcomes included: “visual analog scale (VAS) scores, morphine consumption, length of stay and postoperative adverse effects, including the risk of nausea, vomiting and falls.”
The researchers found significant differences in pain relief and adverse effects between groups:
- Pain scores assessed using VAS at 12 hours: standardized mean difference (SMD) −0.337; 95% confidence interval (CI), −0.593 to −0.081; P =.010)
- VAS score at 24 hours: SMD −0.337; 95% CI, −0.612 to −0.061; P =.017
- Morphine equivalent consumption at 24 hours: SMD −0.371; 95% CI, −0.627 to −0.114; P =.005)
- Incidence of nausea: RD 0.215; 95% CI, 0.078-0.353; P =.002)
- Incidence of vomiting: RD 0.143; 95% CI, 0.026-0.260; P =.017
“The present meta-analysis indicated that SNB combined with FNB had an analgesic effect that was superior to that of LIA combined with FNB at 24 and 48 hours following TKA,” the researchers wrote.
FNB combined with SNB was also associated with less morphine consumption at 12 hours and 24 hours, as well as with a lower risk of nausea and vomiting.
However, the researchers noted that their quality of evidence was low to very low. “Our confidence in the effect estimate is limited, and the true effect may be substantially different from our estimates.”
“Further studies should focus on surgeries that are known to be associated with significant postoperative pain, particularly surgeries where improved pain control may deliver significant clinical benefits through reduced morbidity, or cost-effectiveness benefits through faster rehabilitation and discharge,” they concluded.
- Only 5 studies with relatively small sample sizes were included in the analysis
- Due to the insufficient data available, the researchers could not perform a meta-analysis on functional outcome
- The varying doses of anesthetics and pain management regimes varied between studies, which may have influenced results
- The short duration of follow-up may have led to an underestimation of complications
- Publication bias in the meta-analysis may have influenced results
- Zhang Z, Yang Q, Xin W, Zhang Y. Comparison of local infiltration analgesia and sciatic nerve block as an adjunct to femoral nerbe block for pain control after total knee arthroplasty: a systematic review and meta-analysis. Medicine. 2017;96(19):pe6829. doi:10.1097/MD.0000000000006829
- Cappelleri G, Ghisi D, Fanelli A, et al. Does continuous sciatic nerve block improve postoperative analgesia and early rehabilitation after total knee arthroplasty? A prospective, randomized, double-blinded study. Reg Anesth Pain Med. 2011;36:489-492.
- Auroy Y, Benhamou D, Bargues L, et al. Major complications of regional anesthesia in France: the SOS Regional Anesthesia Hotline Service. Anesthesiology. 2002;97:1274-1280.
- Schinsky MF, Macaulay W, Parks ML, et al. Nerve injury after primary total knee arthroplasty. J Arthroplasty. 2001;16:1048-1054.
- Horlocker TT, Cabanela ME, Wedel DJ. Does postoperative epidural analgesia increase the risk of peroneal nerve palsy after total knee arthroplasty? Anesth Analg. 1994;79:495-500.