Comparison of Anterior Sciatic Nerve Block and Adductor Magnus Muscle Plane Block for Anterior Cruciate Ligament Surgery

Overview

Anterior cruciate ligament (ACL) reconstruction is frequently associated with moderate-to-severe postoperative pain despite its arthroscopic nature, owing to the complex sensory innervation of the knee involving the femoral, sciatic, and obturator nerves. Multimodal analgesic strategies, particularly peripheral nerve blocks, are therefore widely used to improve postoperative pain control and reduce opioid consumption. Although anterior sciatic nerve block can be combined with adductor canal block in the supine position, its application may be technically challenging because of the deep localization of the sciatic nerve. Recently, adductor magnus muscle plane block has emerged as a potentially easier alternative by indirectly targeting the terminal branches of the sciatic nerve through fascial plane spread. In this study, we compared the efficacy of anterior sciatic nerve block and adductor magnus muscle plane block, both combined with adductor canal block.

This single-center, prospective, randomized clinical trial included 90 patients aged 18-45 years with ASA physical status I-II who underwent arthroscopic anterior cruciate ligament reconstruction under spinal anesthesia. Patients were randomly allocated into three groups to receive either adductor canal block alone (Group C), adductor canal block combined with anterior sciatic nerve block (Group ASB), or adductor canal block combined with adductor magnus muscle plane block (Group AMB). Randomization was performed using a computer-generated sequence with concealed allocation through sealed opaque envelopes. Although the anesthesiologist performing the blocks was aware of group allocation, all postoperative assessments were conducted by an independent blinded investigator. All regional blocks were ultrasound-guided and performed preoperatively by the same experienced anesthesiologist using standardized techniques and local anesthetic volumes. Procedural characteristics, including block performance time, needle visibility, needle passes, and sonographic visibility of target structures, were systematically recorded. Sensory blockade was assessed at predefined intervals using cold-warm discrimination tests across multiple nerve distributions. All patients received standardized spinal anesthesia with hyperbaric bupivacaine, as well as a multimodal postoperative analgesic regimen including intravenous paracetamol, dexketoprofen, and fentanyl-based patient-controlled analgesia. Postoperative pain scores at rest and during movement were evaluated at multiple time points during the first 24 hours, while cumulative fentanyl consumption, time to first PCA demand, and rescue analgesic requirements were recorded. Opioid-related adverse events, including nausea, vomiting, constipation, pruritus, dry mouth, and urinary retention, were also documented. In addition, postoperative motor function of the tibialis anterior and quadriceps femoris muscles was assessed using a three-point qualitative motor scale at predefined postoperative intervals up to 48 hours.