Total knee arthroplasty is associated with significant postoperative pain, which can delay rehabilitation and prolong hospital stay if inadequately managed. Epidural analgesia is commonly used after TKA, and addition of opioids such as morphine may enhance analgesic efficacy. This prospective, randomized, double-blind study will be conducted on 62 adult patients, ASA physical status I–III, scheduled for unilateral TKA under combined spinal–epidural anaesthesia . These patients will be enrolled and randomly allocated into two equal groups. All patients will receive continuous epidural infusion of 0.2% ropivacaine for 24 hours postoperatively. After 24 hours, patients in Group A will receive a single epidural dose of morphine 3 mg added to 0.2% ropivacaine ,total volume 6 ml , while Group B will receive normal saline added to 0.2% ropivacaine total volume 6 ml. The epidural catheter will then be removed. Postoperative monitoring will include vital parameters, numeric rating scale (NRS) pain scores, and rescue analgesic consumption for 24 hours following the epidural injection. The primary outcome is total rescue analgesic consumption over 24 hours. The secondary outcome is postoperative pain intensity assessed using the NRS.