The Utility of Pericapsular Nerve Group (PENG) Block versus Intrathecal Morphine for Postoperative Analgesia in Anterior Approach Total Hip Arthroplasty: A Multicentre Triple Blinded Randomised Controlled Trial

Hip replacement surgery (total hip arthroplasty) is one of the most common and successful operations performed in Australia, but managing pain afterwards is critical for early recovery and rehabilitation. Currently, many patients undergoing hip replacement via the anterior (front) approach receive a spinal injection of morphine (intrathecal morphine) for pain relief. While effective, this can cause side effects like nausea, itching, and urinary retention. A newer technique called the PENG (pericapsular nerve group) block uses a targeted injection of local anaesthetic around the hip joint capsule. It appears to provide good pain relief with fewer side effects, but its effectiveness for anterior hip replacement specifically has not been well tested in a head-to-head comparison. This multicentre randomised controlled trial is comparing PENG block to intrathecal morphine in adults undergoing elective anterior hip replacement under spinal anaesthesia. The main questions are: which technique provides better pain relief at 3 and 24 hours after surgery, and which has a better side effect profile? Eligible participants are all adults presenting for this specific procedure who can provide informed consent and are able to have spinal anaesthesia.