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Background and Aims iPACK block is a novel regional method providing analgesia to the posterior part of the knee without causing motor block in knee surgeries. In this study, we aimed to compare the postoperative analgesic efficacy of iPACK block using different doses of local anaesthetics.

Methods 119 patients aged 18-80 years, ASA I-III, undergoing total knee arthroplasty(TKA) surgery under spinal anaesthesia were included in this prospective randomized controlled study registered with the Clinical Trials(NCT05963139). The patients were divided into 4 groups using a computer software. All groups received an adductor canal block(ACB) with 15ml of 0.25%bupivacaine. iPACK block; 10ml of 0.25%bupivacaine in Group-1, 15ml of 0.25%bupivacaine in Group-2, 20ml of 0.25%bupivacaine in Group-3 and no iPACK block in Group-4 as control group. NRS score, morphine consumption, and nausea-vomiting were evaluated at 1,4,8,12,24 and 48hours postoperatively. Time to first mobilization, length of hospital stay, breakthrough opioid need, patient and surgeon satisfaction, muscle strength measured preoperatively and at discharge, WOMAC Osteoarthritis index, ROM, and complications were recorded.

Results In Groups-2&3, the NRS scores at the 4th&8th hours were significantly lower than in Group-4(p=0.026,p=0.009,respectively). In Group-3, morphine consumption at the 8th&12th hours was significantly lower than in Groups-1&2&4(p=0.018,p=0.004,respectively). The presence of nausea-vomiting at the 12th&24th&48th hours was significantly higher in Group-4 compared to Groups-2&3(p=0.026,p=0.026,p=0.032,respectively). Patient and surgeon satisfaction were significantly lower in Group-4 compared to the other groups(p=0.001,p=0.001,respectively).

Conclusions We believe that iPACK block with 20ml of 0.25%bupivacaine provides more ideal postoperative analgesia with lower pain scores, thereby reducing opioid side effects without causing complications in knee arthroplasties.