The aim of this clinical trial is to evaluate the efficacy of adding magnesium sulfate to bupivacaine in ultrasound-guided transmuscular quadratus lumborum block for postoperative analgesia in adult patients underdoing hip arthroplasty. The main questions it aims to answer are: * Does Magnesium sulphate lower Pain score (VAS) postoperatively. * Does Magnesium sulphate lowerTotal opioid consumption postoperatively. and What side effects do participants have when taking Magnesium sulphate? Researchers will compare Magnesium sulphate to a placebo (a look-alike substance that contains no drug) to see if Magnesium sulphate works to lower pain score. Participants will: * Take with have ultrasound-guided transmuscular quadratus lumborum block after surgery using bupivacaine with Magnesium sulphate or with placebo * Followed up 48 hours postoperatively to monitor pain score or any reported side effect.