The optimal choice of regional anesthesia in total knee arthroplasty: a prospective, double-blind, randomized, placebo-controlled study

BACKGROUND: Rapid advances has led to the widespread use of novel ultrasound-assisted regional anesthesia techniques, such as adductor canal block (ACB) and local infiltration of the interspace between the popliteal artery and the posterior knee capsule (iPACK-block). However, achieving adequate pain relief in patients undergoing total knee arthroplasty (TKA) remains an urgent problem for the anesthesiologist because universal recommendations for the use of blockades or their combinations have not been developed.

OBJECTIVE: Our aim was to evaluate the effectiveness and safety of combinations of various types of iPACK-blocks with single ACB in TKA in achieving analgesia and restoration of knee joint functions.

MATERIALS AND METHODS: A double-blind, randomized, placebo-controlled study of patients undergoing total knee arthroplasty was conducted over a 9-month period. One hundred six participants were divided into 3 groups: I — combination of single ACB + iPACK-block-placebo (n=35), II — combination of single ACB + proximal iPACK block (n=36), and III — combination of single ACB + distal iPACK block (n=35). Pain was assessed by VAS in the back of the knee. Time up and go test was performed. Range of motion in the knee joint (ROM), walking distance, and elevation of the operated limb were assessed. Sensory and motor block, postoperative nausea and vomiting severity, need for opioids, time to first analgesic use, and patient satisfaction were also assessed.

RESULTS: Pain scores and other outcomes were higher in the group with ACB than in the groups with iPACK both at rest and during movement (p=0.000). Pain in the back of the knee was lower in the distal iPACK group (p₁,₃=0.003, p₂,₃=0.032), with no difference in pain between proximal iPACK and single ACB. Moreover, patients who received iPACK performed better in the functional tests on day 1 but not on day 2. In the proximal block group, 5.56±3.82% of cases reported sensorimotor blockade. There were no other adverse events. Patient satisfaction with anesthesia was lower in the ACB group (p=0.000) and no differences in satisfaction was seen in the iPACK blocks.

CONCLUSION: The distal approach in iPACK block is an effective and simple technique to reduce pain in the back of the knee and risk of sensory block. Our findings indicate that combining adductor canal block and distal iPACK block is an optimal technique for achieving postoperative pain relief in patients undergoing total knee arthroplasty.