Analgesic Efficacy of Adding Sciatic Blockade to the 3-in-1 Block Following Total Knee Arthroplasty: A Meta-analysis

Abstract

Background: Total knee arthroplasty (TKA) is one of the most common orthopedic procedures performed. It is also invasive and is associated with severe postoperative pain. The 3-in-1 block has been repeatedly demonstrated to provide effective postoperative analgesia. However, adding sciatic blockade to the 3-in-1 has become a growing practice as a result of residual pain to the posterior knee, although the additional benefit is unknown particularly in light of the potential risks. Purpose: To examine the analgesic efficacy and associated adverse events of adding sciatic blockade to the 3-in-1 block compared to the 3-in-1 alone for postoperative analgesia following TKA. Methods: A meta-analysis was conducted on relevant articles from 1993 to 2010. Methodological rigor was applied to each of the analytical procedures including: evaluation of between-study heterogeneity, pooling effects, subgroup analyses, sensitivity analysis, and assessment of publication bias. Results: Nine studies representing 1827 subjects were included. Pain outcomes were measured with the visual analog scale both at rest (VASr) and dynamic (VASd) and reported as the weighted mean difference (WMD). The addition of sciatic blockade demonstrated improved postoperative analgesia with the greatest effects up to 24 hours postoperatively: early (6-8hr) VASr WMD -2.039 (95% CI: -2.718, -1.360); 12hr VASr WMD -1.491 (95% CI: -2.174, -0.808); 24hr VASr WMD -0.767 (95% CI: -1.114, -0.421); 24hr VASd WMD -0.671 (95% CI: -1.301, -0.041). The 24hr opioid consumption was also lower [WMD -10.237 (95% CI: -20.029, -0.444)]. After 24 hours, effects were small and/or not significant. There was also a statistically significant advantage in maximum knee flexion on POD3 [WMD -7.102 (95% CI: -11.864, -2.339)]. A lack of consistent reporting precluded quantitative analysis on adverse events. Conclusion: Findings support the use of peripheral nerve blocks for postoperative analgesia following TKA. The addition of sciatic blockade appears to offer greater analgesic efficacy than a 3-in-1 block alone but only in the early postoperative period. However, until an accurate estimate of associated adverse events can be unveiled, the addition of a sciatic block cannot be recommended for all patients following TKA. It should, however, be considered in the postoperative period for those patients who continue to experience substantial pain to the posterior aspect of the knee on a case-by-case basis.