The Analgesic Efficacy of Ultrasound Guided Adductor Canal Block Versus 4 in 1 Block in Patients Undergoing Knee Surgeries: A Comparative Randomized Double Blinded Study .

Knee surgeries are associated with severe postoperative pain. Improper pain management affects patients' psychological status with prolongation of hospital stay time and rehabilitation period, with the possibility of progression of the acute pain to chronic pain (McCartney CJ, Nelligan K., 2014). Many Pain management options following these surgeries are available: non-opioid analgesics, opioids and regional anesthesia techniques (epidural and peripheral nerve block). Multi-modal analgesia is considered the best option for pain management in knee surgeries. As non-opioid analgesics alone are not effective enough while opioids alone are associated with many risk factors: nausea, vomiting, decrease intestinal motility and respiratory depression with possibility of addiction (Goode VM, Morgan B, et al, 2019). Regarding the functional anatomy of the nerve supply to knee joint: The knee is innervated by genicular branches from the nerve to vastus medialis, saphenous nerve, sciatic nerve and the posterior division of obturator nerve. The skin around the knee is supplied by the cutaneous branches from the femoral nerve and the saphenous nerve (Ritesh Roy, Gaurav Agarwal, et al, 2018). The widespread use of ultrasound to advance peripheral nerve block techniques over the past decade has led to enormous growth in the utilization and efficiency of regional anesthesia (Cozowicz, Crispiana & Poeran, et al, 2015). The adductor canal block (ACB) is an interfascial plane block performed in the middle third of the medial side of the thigh. The adductor canal bounded anteriorly by the sartorius muscle, posteriorly and medially by the adductor longus and magnus muscles, and laterally by the vastus medialis muscle. It contains the femoral vein and artery, the saphenous nerve and the nerve to the vastus medialis, both are sensory branches of the femoral nerve. In some individuals, the obturator sensory branch (also a femoral nerve branch) can be affected by local anesthetic infiltration into this area. It can be noted that this block affect sensory branches and avoid blocking the majority of motor branches. The block is most commonly performed using ultrasound guidance (Thiayagarajan MK, Kumar SV,et al 2019). Ultrasound guided 4-in-1 block technique: a new single injection technique described by Roy R, Agarwal G, et al, 2018 for the combined 4 nerves (saphenous nerve, obturator nerve, nerve to vastus medialis and sciatic nerve) with a single injection point is located at the adductor hiatus where descending genicular artery branches from superficial femoral artery. Bupivacaine is a long-acting amide local anesthetic (max. dose 2.5 mg/kg). Symptoms contributed to local anesthetic toxicity include tinnitus, perioral tingling, visual disturbances and dizziness (Shafiei FT, McAllister RK, Lopez J, 2022)