This study aims to compare two groups of post-orthopedic patients who received a standard regimen, namely ketorolac 30mg, to the second group, which was given the standard regimen and adjuvant magnesium sulfate 30mg/kgBW 1 hour preoperatively. If it is proven useful, it is hoped that pain will be more controlled, reduce pain complications, reduce treatment costs, and reduce the duration of hospital stays.

The study design used was a randomized controlled trial (RCT) with double blinds. Double blind because neither the patient, the lead investigator, nor the investigator on record knew the drug or placebo that was administered. Research subjects were selected consecutively in patients who will undergo lower extremity surgery at the Cipto Mangunkusumo National Central General Hospital. Forty-eight research subjects will be divided into two groups, namely the group given Intravenous Magnesium Sulfate 30 mg/kgBW and the group given a placebo. Research subjects were randomized by type of surgery using randomization software by research assistants. The results of randomization were not known to the patient, the principal investigator, or the researcher taking notes.

This study aims to determine the effect of adding 30 mg/kg body weight of intravenous MgSO4 to 30 mg of ketorolac on the degree of pain and the need for opioids after lower extremity surgery.

Inclusion Criteria:

• Patients undergoing lower extremity orthopedic surgery under general anaesthesia.
• Patients aged 18-60 years.
• Physical status ASA 1-3
• Willing to participate in research.

Exclusion Criteria:

• Patients who are hemodynamically unstable.
• Patients with decreased renal function
• Patients with skeletal muscle disorders.
• Patients with Ketorolac allergy
• Patients with morphine allergy