Comparative evaluation of addition of genicular nerve block versus ipack block on post-operative analgesic efficacy of adductor canal block in patients undergoing anterior cruciate ligament repair under spinal anaesthesia.

Anterior cruciate ligament (ACL) is the most commonly damaged ligament in the knee largely affecting young adults. ACL reconstruction is now being largely performed as an out-patient surgery and early rehabilitation is one of the primary goals of this surgery. The achievement of aforementioned goals is largely dependent on an effective analgesic regimen that minimizes the role of systemic analgesics yet provides adequate postoperative pain control, eliminates the need for overnight stay and facilitates early rehabilitation. Antero-medial side of knee is innervated by saphenous nerve, nerve to vastus medialis, medial branch of nerve to vastus intermedius. Antero-lateral side of knee is innervated by nerve to vastus lateralis and lateral branch of vastus intermedius. Posterior division of obturator nerve and terminal branches of sciatic nerve supply the posterior aspect of knee joint. Ultrasound guided (USG) Adductor canal block (ACB) by targeting saphenous nerve and nerve to vastus medialis is ideally suited to provide analgesia without causing quadriceps weakness and has been demonstrated to reduce pain and opioid consumption after major knee surgery. Genicular nerve block (GNB) targets the three genicular nerves (supero-medial, supero-lateral, infero-medial) supplying the anterior knee joint. Recently, USG guided iPACK (infiltration of local anaesthetic between the popliteal artery and the posterior capsule of the knee) by targeting genicular nerves and popliteal plexus has shown to provide motor-sparing posterior knee analgesia. Based on knee innervation, we hypothesise that ACB supplemented with GNB would provide better post-operative analgesia than ACB supplemented with iPACK, in patients undergoing ACL repair under spinal anaesthesia. After obtaining approval from the institutional ethics committee of SGPGIMS and written informed consent from the patients, the study will be conducted over a period of 18 months in patients undergoing ACL repair surgery. A thorough pre-anaesthetic evaluation will be done a night before surgery and procedure (spinal anaesthesia followed by regional anaesthesia) will be explained to the patient. Patients satisfying eligibility criterion will be randomly categorized as under 2 groups as- group A, B . All standard ASA monitors will be attached. Spinal anaesthesia will be administered in sitting position under complete aseptic precautions using 25G Quincke’s spinal needle in L3-L4 interspace using 15mg of Injection heavy bupivacaine (0.5%) with 15mcg of Inj fentanyl as adjuvant. After assessing adequacy of the effect of spinal anaesthesia, patient will be administered USG guided regional anaesthesia according to the group allocation. GROUP A will be given USG guided ACB with 20ml of 0.375% ropivacaine + iPACK block with 20ml 0.375% ropivacaine . GROUP B will be given ( adductor canal block with 20 ml 0.375% ropivacaine + genicular nerve block with 15 ml 0.375% ropivacaine. Injection Dexamethasone (0.1 mg/kg i.v) will be administered as adjuvant to prolong the duration of block. Injection Paracetamol (1gm i.v) will be administered 6 hourly as part of multi-modal analgesia. Gracilis and Semitendinosis hamstring tendon will be used for single bundle ACLR. Primary Objective of the study is mean opioid consumption at the end of 24 hrs. Post operatively, static and dynamic pain assessment will be done at 2hr,4hr,6hr,12hr,18hr,24hr using NRS. Dynamic pain will be assessed by asking the patient to elevate operated limb by 15 degrees. NRS score > 4 will be treated as breakthrough pain and will be treated by administering injection Fentanyl (1mcg/kg,iv). Subsequent to that patient will be observed for 30 minutes and in absence of any pain relief, injection Diclofenac (75 mg iv) will be administered. Patients with NRS score > 4 within first 6 hours of post-operative observation, will be treated as block failure and will be analysed according to “intention to treat” principle. Patient will be requested to complete IKDC form (International knee documentation committee) preoperatively and at 1 month post-operatively.