Talk Description
Aim:
Patients undergoing elective Total Knee Arthroplasty (TKA) experience moderate to severe postoperative pain that significantly impairs early mobilisation, rehabilitation and hospital length of stay. Regional motor-sparing techniques are used to minimise pain and opioid use.
Analgesic efficacy provided by the motor sparing ‘Infiltration between Popliteal Artery and Capsule of the Knee’ (IPACK) block is yet to be established. Recent evidence suggests that motor sparing Adductor Canal (ACB) and IPACK blocks may provide superior analgesia to local infiltration of anaesthetic (LIA) and ACB.
The aim of this study is to determine whether ACB with IPACK block reduces postoperative opioid consumption at 24 and 48 hours post elective TKA, in comparison to ACB +LIA alone.
Methods:
This retrospective cohort study uses a linear regression analysis to determine the postoperative mean oral morphine equivalent daily dosage (OMEDD) at 24 and 48 hours in 130 elective TKAs during a 12-month period (17/12/2021 - 16/12/22) at a regional NSW hospital. Patients either received ACB + IPACK (n=71) or ACB + LIA (n=59).
Ethics approval granted by Greater Western Human Research Ethics Committee (Application ID: 2023/ETH00795).
Results:
This study showed significant reductions in mean post-operative oral morphine equivalent daily dose (OMEDD) in the first 24 hours with IPACK + ACB in comparison to ACB +LIA (IPACK+ AC: Mean= 54.8mg; AC +LIA: Mean= 76.4mg; p= 0.02). At 48 hours, there was no statistically significant reduction in OMEDD.
Discussion:
This is the first study to show OMEDD reduction in the first 24 hours in comparison with ACB + LIA, which is likely a reflection of IPACK block duration and superiority of IPACK + ACB for TKR. A recent study has shown that IPACK can reduce numerical pain scores, however postoperative opioid consumption was not recorded [1]. Another smaller RCT showed reduced opioid use at the end of 48 hours [2]. This study illustrates the efficacy of the IPACK block, reducing opioid-use within the first 24hrs, then returning to baseline use at the 48-hour mark (likely coinciding with the resolution of the block).
Effective pain control is crucial for achieving early mobilization and minimizing postoperative complications [3]. The IPACK block is an effective motor sparing technique which is easy to perform, and has a reduced risk of nerve or vascular injury.
The study has several limitations, such as variability in block performance by different proceduralists, lack of standardisation of local anaesthetics or adjuvants used, and insufficient documentation of periarticular infiltration.
Future research should focus on evaluating the impact of the IPACK block on functional outcomes, dynamic pain scores, and length of stay. Additionally, assessing the performance of local anaesthetic adjuncts and the potential benefits of a dedicated acute pain service, which could perform repeat peripheral nerve blocks to extend the effectiveness seen in this study beyond the initial 24 hours.
This study showed that IPACK + ACB provides superior analgesia in the first 24 hours post TKA and adds to the literature supporting this motor sparing technique. Our findings contribute towards IPACK blocks being considered as a standard of care to reduce patient exposure to opioids and their associated adverse effects.
Conflicts of interest:
Nil.
References:
1. Patterson, M.E. et al. (2020) ‘The effect of the IPACK block on pain after primary TKA: A double-blinded, prospective, randomized trial’, The Journal of Arthroplasty, 35(6). doi:10.1016/j.arth.2020.01.014.
2. Et, T. et al. (2022) ‘Comparison of ipack and periarticular block with adductor block alone after total knee arthroplasty: A randomized clinical trial’, Journal of Anesthesia, 36(2), pp. 276–286. doi:10.1007/s00540-022-03047-6.
3. Martell, J. (2021) ‘Reduction of opioid use with enhanced recovery program for total knee arthroplasty’, Federal Practitioner [Preprint], (38 No. 5). doi:10.12788/fp.0124.