IRCT20121204011662N15 IRCT 2020-12-03 Shiraz University of Medical Sciences Survey the effect of mixture of two anesthetic drugs on control of postoperative pain of opioid dependent patients undergoing orthopedic ankle surgery. Survey the effect of Ketodex on postoperative pain management of opioid-dependent patients undergoing orthopedic ankle surgery. 2020-12-05 anticipated 60 Complete https://irct.ir/trial/51842 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Randomization description: Patients will be randomly allocated into two groups by block randomization. In this technique, a permutation block of size 4 will be made for patients of two groups A & B. In each block, equal numbers for two groups will be considered in alternative positions. Then 15 blocks of size 4 will be selected randomly and patients will be allocated randomly and equally into three groups according to these permutation block, Blinding description: For blindness, All of the drugs solution (ketodex and normal saline) of this study will be prepared in 50 ml syringes that are similar and equal in shape, by a nurse of anesthesia who is aware of patients' grouping. These syringes will have labels A or B. An anesthesiologist who will use these syringes will not aware of the content of these syringes, and just will use syringes with label A for patients in group A and syringes with label B for patients in group B. Patients and all medical staffs who will collaborate in data gathering, will not be aware of the content of these syringes. 3 Acute pain. Intervention 1: Intervention group: patients in group A, Ketodex infusion (Ketamine 0.1mg/Kg/min and Dexmedetomidine 0.1 mic/Kg/min ) will be started through a 50 ml syringe with the label A after induction of anesthesia till the end of surgery. Intervention 2: Control group: after induction of anesthesia, patients in group B will received intravenous infusion of the normal saline through a 50 ml syringe with the label B till end of surgery. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is There is no further information