Dexmedetomidine is often used for sedation procedures. It has also been shown to have a pain-protective effect. Researchers predicted that using dexmedetomidine for sedation in total knee arthroplasties performed under spinal anesthesia would reduce the frequency of rebound pain and pain scores.

Randomization will take place before the patient enters the operating room. After spinal anesthesia is applied, 0.4 mcg/kg sedadomide loading will be done for 10 minutes in the sedation group, and then 0.4 mcg/kg/h sedadomide infusion will continue until the end of the surgery. Patients selected for the control group will be given the same amounts of saline. At the end of the surgical procedure, saline and sedadomide infusions will be stopped. All patients will undergo an adductor canal block under USG guidance in the recovery room. 50 mg of buvacin will be given to the block area. Patients will be fitted with a patient control analgesia device, which only provides bolus application and provides 20 mg of madol in each bolus. Postoperatively, sudden onset severe withdrawal pain outside the normal course of pain starting within 48 hours will be followed and Vas-bromage monitoring will be done at 0, 1, 2, 4, 8, 12, 24, 36, 48 hours.

Inclusion Criteria:

• Total Knee arthroplasty American Society of Anesthesiologist score of 1-3 Age 18-85 Elective total knee arthroplasty under spinal anesthetic.

Exclusion Criteria:

• Situations in which spinal anesthesia is contraindicated
• Advanced organ failure states(cardiac,hepatic,respiratuar or renal)
• Pregnancy
• BMI > 40 kg/m^2
• Do not want to participate in the study
• Younger than 18 or older than 85
• Have bilateral total knee arthroplasty or resurgery
• Develop an unexpected intraoperative surgical complication