iPACK block (local anesthetic infiltration of the interspace between the popliteal artery and the posterior knee capsule) added to the adductor canal blocks versus the adductor canal blocks in the pain management after total knee arthroplasty: a systematic review and meta-analysis

BACKGROUND: Several studies have suggested that the addition of iPACK block (the popliteal artery and the posterior knee capsule have been given interspace local anesthetic infiltration) might get better analgesia than adductor canal block (ACB) only after total knee arthroplasty (TKA). This paper compiles all available evidence on the effect of two analgesia regimens (ACB and iPACK + ACB) involving all sides. METHODS: We searched in eight major databases for all clinical trials discussing the effect of two analgesia regimens after TKA. Statistical analyses were conducted by Stata and RevMan Software. In addition, we performed GOSH analysis, subgroup analysis, meta-regression analysis to study the source of heterogeneity. Publication bias was checked using Egger’s test. Trim-and-fill analysis was applied in terms of sensitivity analysis of the results. RESULTS: There are fourteen eligible studies for our meta-analysis. There are significant differences between the two groups in VAS score at rest and with activity, and the VAS scores were lower in the ACB + iPACK Group (VAS scores at rest: 95%CI [− 0.96, − 0.53], P < 0.00001. VAS scores with activity: 95%CI [− 0.79, − 0.43], P < 0.00001). A differential was discovered to support the ACB + iPACK Group when comparing the two groups on postoperative cumulative morphine consumption (95%CI: [− 0.52, − 0.14], P: 0.0007). The patients in the group of ACB + iPACK performed better in the postoperative range of knee movement (95%CI: [5.18, 10.21], P < 0.00001) and walking distance (95%CI: [0.15, 0.41], P < 0.00001). There were significant differences between the patients in the ACB + iPACK Group and ACB Group on the TUG test of POD1 and POD2. We found that patients' hospital stays in the ACB + iPACK Group were significantly shorter than in the ACB Group (95%CI: [− 0.78, − 0.16], P: 0.003). No difference was found between the patients in the ACB + iPACK Group and ACB Group on postoperative quadriceps muscle strength and the incidence of PONV. CONCLUSION: The addition of iPACK lowers postoperative VAS scores, cumulative morphine consumption, and hospital stays. Meanwhile, the addition of iPACK improves postoperative patients’ activity performance without extra side effects. iPACK combined with ACB proves to be a suitable pain management technique after TKA.