Proximal, Mid, and Distal Adductor Canal Block for Pain Control After Total Knee Arthroplasty

The goal of this clinical trial is to learn which level of adductor canal block (proximal, mid, or distal) gives the best pain relief after total knee replacement while preserving leg muscle strength. The study includes adults aged 18-75 having knee replacement under spinal anesthesia. The main question is: Does the block level change how much opioid (tramadol) patients need in the first 24 hours after surgery? Participants will be randomly assigned to one of three groups and receive an ultrasound-guided block with 30 mL of 0.25% bupivacaine before surgery. Pain, opioid use, numbness, muscle function, walking ability, side effects, and recovery quality will be assessed for 48 hours after surgery.

Inclusion Criteria: * Age 18 to 75 years * American Society of Anesthesiologists (ASA) physical status I-III * Scheduled for elective unilateral total knee arthroplasty * Surgery planned under spinal anesthesia * Cognitively able to use a patient-controlled analgesia (PCA) device * Willing to participate and provided written informed consent Exclusion Criteria: * Refusal to participate * Allergy to local anesthetics or history of local anesthetic toxicity * Allergy to tramadol or other study analgesics * Coagulopathy * Inability to appropriately discontinue anticoagulant therapy * Infection at the injection site * Pre-existing motor or sensory deficit in the operative limb * Peripheral neuropathy * Significant diabetes-related neuropathy * Chronic opioid use * Regular analgesic or opioid use due to a chronic pain syndrome * Advanced hepatic failure * Advanced renal failure * Severe cardiac disease * Psychiatric illness or cognitive impairment preventing pain assessment * Substance or alcohol dependence * Pregnancy or breastfeeding * Body mass index (BMI) \> 40 kg/m² * Revision knee arthroplasty * Bilateral knee arthroplasty * Contraindication to spinal anesthesia