Hip fractures and avascular necrosis are the leading causes of hip joint replacement in India, and the incidence is multiplying. Pain following THR surgery is a significant concern, and it could be as high as 81%, as reported by previous studies, with the mean persistent post-surgical pain rate being around 16.5%. [1] Adequate analgesia with minimal side effects allows for early postoperative mobility, optimal functional recovery, and decreased postoperative morbidity [2]. Despite being a frequently performed surgical procedure, there is high variability in the peri-operative anaesthetic and analgesic management for total hip arthroplasty [3, 4].

    There is strong evidence supporting the effectiveness of intrathecal morphine for pain relief after total hip arthroplasty, with no significant increase in the risk of respiratory depression with dose between 50 mcg to 100 mcg even in elderly and patients with risk of apnea.[5] The incidence of postoperative nausea and vomiting (PONV) after intrathecal morphine is dose dependent and dose less than equal to 100 µg  provide sufficient analgesia without increasing the risk of PONV. [5,6] PROSPECT guidelines for THR surgery recommend consideration of 100 mcg of intrathecal morphine administration if the procedure is being done in spinal anaesthesia. [4]

        The ESPB is a regional block that targets both the dorsal and ventral roots of the spinal nerve, offering analgesia for both somatic and visceral pain. This technique facilitates the extensive distribution of local anaesthetics in a craniocaudal direction, effectively blocking multiple dermatomes. [4] Recently, some case studies suggested that the sacral erector spinae plane block (ESPB) also called as sacral multifidus block, was found to be an effective technique for providing postoperative pain relief in patients undergoing femoral fracture surgery via a posterolateral approach. [4] But this technique has not been extensively studied for adult patients undergoing hip surgeries. There is paucity of literature comparing sacral ESPB and ITM which has quality of recovery (QoR15) as the primary outcome in THR surgery. Hence, we plan to compare effect of sacral ESP block with intrathecal morphine in the quality of recovery at 24hr after THR surgery.