In patients undergoing total knee arthroplasty (TKA), sciatic nerve block (SNB) plus femoral nerve block (FNB) was more effective for pain relief and had fewer adverse effects than local infiltration analgesia (LIA) plus FNB, according to a study published in the Journal of Orthopaedic Surgery and Research.1
Adequate pain control after TKA is necessary to enable early mobilization after surgery, which helps reduce hospital length of stay and the risk for complications such as deep vein thrombosis.2 FNB is commonly used for regional anesthesia after TKA, but does not provide sufficient pain control in all patients.3
LIA, which has few adverse effects and does not weaken the quadriceps muscle, is increasingly used as an effective adjunct to FNB after TKA.4 Because the knee joint receives innervation from the sciatic nerve, SNB is also used in combination with FNB postoperatively. However, the optimal method for managing pain after TKA has been unclear until recently. Here, researchers compared the efficacy and safety of LIA plus FNB vs SNB plus FNB for pain control after TKA in a meta-analysis of available evidence.
A total of 273 patients from 4 randomized controlled trials (RCTs) and 2 non-RCTs were included for analysis. All 6 studies included pain assessments at 12, 24, and 48 hours. At 12 and 24 hours, SNB combined with FNB was significantly more effective at managing pain, as measured by the visual analog scale (VAS) score, than LIA plus FNB (At 12 h: standard mean difference [SMD], -0.303 [95% CI, -0.543 to -0.064; P =.013]; at 24 h: SMD, -0.395 [95% CI −0.636 to -0.154; P =.001]). No differences in VAS scores between the groups were found at 48 hours.
Morphine consumption (4 studies) was reduced in the SNB plus FNB group compared with the LIA plus FNB group at 24 hours (SMD, -0.330; 95% CI, -0.606 to -0.055; P =.019), but not at 48 hours. Hospital lengths of stay (6 studies) were similar for both groups.
A total of 5 studies evaluated nausea and vomiting, which were significantly less common with SNB plus FNB than with LIA plus FNB.
Summary and Clinical Applicability
Although FNB is commonly used to manage pain after TKA, this method does not provide adequate pain control in all patients. LIA or SNB combined with FNB may be effective in patients with inadequate response to FNB alone, but the efficacy of these techniques has not been compared until recently.
“FNB-combined SNB provides superior pain relief and less morphine consumption within the first 24 h compared with FNB-combined LIA in [TKA]. In addition, there were fewer side effects associated with SNB. Because the sample size and the number of included studies were limited, a multicenter RCT is needed to identify the effects of the two kinds of methods and further work must include range of motion analyses and functional test,” the investigators concluded.
Only a small number of studies were included, some of which were not RCTs or had methodological issues.
- Ma LP, Qi YM, Zhao DX. Comparison of local infiltration analgesia and sciatic nerve block for pain control after total knee arthroplasty: a systematic review and meta-analysis. J Orthop Surg Res. 2017;12(1):85. doi: 10.1186/s13018-017-0586-z
- Tripuraneni KR, Woolson ST, Giori NJ. Local infiltration analgesia in TKA patients reduces length of stay and postoperative pain scores. Orthopedics. 2011;34(3):173. doi: 10.3928/01477447-20110124-11
- Choy WS, Lee SK, Kim KJ, Kam BS, Yang DS, Bae KW. Two continuous femoral nerve block strategies after TKA. Knee Surg Sports Traumatol Arthrosc. 2011;19(11):1901-1908. doi: 10.1007/s00167-011-1510-4
- Tran J, Schwarzkopf R. Local infiltration anesthesia with steroids in total knee arthroplasty: A systematic review of randomized control trials. J Orthop. 2015;12(Suppl 1):S44-S50. doi: 10.1016/j.jor.2015.01.017