A comparative randomized controlled study of modified 4 in 1 block versus IPACK plus adductor canal block for post-operative analgesia in total knee arthroplasty.

Background and Aims: Postoperative analgesia for Total Knee Arthroplasty (TKA) is paramount for early mobilisation and rehabilitation. The newer motor sparing peripheral nerve blocks for analgesia for TKA are 4 in 1 block, modified 4 in 1 block, infiltration between popliteal artery and capsule of the knee (IPACK) block along with adductor canal block (ACB). We hypothesised that Modified 4 in 1 block is as efficient as the already proven technique of combined IPACK and ACB in providing post-operative analgesia to the patients of TKA. Methods: Seventy patients fulfilling the inclusion criteria posted for TKA surgery were randomised into two groups: Modified 4 in 1 block group (Group - M) and combined IPACK + ACB group (Group - I). After thorough preoperative evaluation and with mimimum standard monitoring the patients received sub-arachnoid block followed by the desired peripheral nerve block as per the group. After the surgery the visual analog scale (VAS) pain score was compared at 3, 6, 12, 24 hours postoperatively and tabulated. Results: The mean pain scores between both the groups was comparable at 3 hours, 6 hours and 24 hours. But at 12 hours after the surgery, VAS was less in Group-M in comparison to Group-I, Haemodynamic parameters were comparable between both the groups. None of the patients in both the groups showed any complications like muscle weakness in the post-operative period. Conclusion: Modified 4 in 1 block is a new and novel technique for the TKA surgeries and is comparable with already established combined IPACK+ACB technique for providing adequate postoperative analgesia after TKA.