A Randomized Comparison of the Efficacy of the IPACK Block Versus the Popliteal Plexus Block for Posterior Knee Analgesia, in Patients Undergoing a Total Knee Arthroplasty and Receiving a Continuous Distal Femoral Triangle Block

Inclusion Criteria: * Adults aged 18-85 years. * Scheduled for elective unilateral primary total knee arthroplasty for knee osteoarthritis. * American Society of Anesthesiologists (ASA) physical status I-III. * Ability to understand and use the 0-10 Numeric Rating Scale (NRS) for pain assessment. * Ability to understand and use the intravenous patient-controlled analgesia (PCA) device. * Ability to complete the Quality of Recovery-15 (QoR-15) questionnaire. * Ability to provide written informed consent. Exclusion Criteria: * Revision or bilateral total knee arthroplasty. * Patient refusal or inability to provide informed consent. * Contraindication to peripheral nerve block, including infection at the needle insertion site or clinically significant coagulation abnormalities. * Known allergy or contraindication to the local anesthetics or analgesic medications used in the study protocol. * Pre-existing clinically significant sensory or motor neurological deficit affecting the operative lower limb. * Chronic opioid use or opioid dependence that could interfere with postoperative opioid consumption assessment. * Inability to understand or operate the PCA device. * Cognitive impairment or communication difficulty preventing reliable assessment of pain, motor function, or QoR-15. * Any medical condition that, in the investigator's judgment, would make participation unsafe or interfere with assessment of the study outcomes.