Pregabalin, Celecoxib, Total Knee Arthroplasty and Intrathecal Morphine (PCTKA)

• 24-hour cumulative morphine consumption [ Time Frame: Participants will be followed for the duration of hospital stay, an expected average of 2 weeks ] [ Designated as safety issue: Yes ]
  • The time to first morphine requirement will be recorded
  • The cumulative morphine consumption will be recorded at the end of surgery and 2-h, 6-h, 10-h, 24-h, and 48-h postoperatively
  • Visual analog scale (VAS) pain scores at rest will be assessed at the night before surgical date, before starting anesthesia, at the end of surgery, and 2-h, 6-h, 10-h, 24-h and 48-h postoperatively
  • Visual analog scale (VAS) pain scores when on movement will be assessed at the end of surgery, and 2-h, 6-h, 10-h, 24-h and 48-h postoperatively
  
  

• Anxiety scores (VAS), patients' satisfaction [ Time Frame: Participants will be followed for the duration of hospital stay, an expected average of 2 weeks ] [ Designated as safety issue: Yes ]
  • Anxiety scores will be assessed at the night before surgical date, before starting anesthesia, at the end of surgery, and 2-h, 6-h, 10-h, 24-h and 48-h postoperatively;
  • 24-h and 48-h patients' satisfaction (0-10,0=dissatisfied and 10= very satisfied)
  
  

A single-dose spinal anesthesia combining with morphine for total knee arthroplasty (TKA) is a simple, economical anesthetic technique commonly used in our hospital. Still some patients could not get effective postoperative pain control. Pregabalin, an anticonvulsant, has been shown to reduce acute pain after molar extraction, laparoscopic cholecystectomy, and reduce postoperative morphine requirement after total hip arthroplasty, and celecoxib, a selective cyclo-oxygenase (COX) - 2 inhibitor, with perioperative prescription is successfully reduces pain score and opioid consumption after TKA under spinal anesthesia alone. However, no clinical study has yet investigated whether preoperative single-dose of pregabalin, celecoxib or in combination compared to placebo can improve analgesic efficacy of intrathecal morphine after TKA. The primary objective of this study was to evaluate whether these medications could reduce pain scores at rest / when movement and morphine requirement after TKA under spinal anesthesia with intrathecal morphine. Secondary outcome assessed include adverse effects, anxiety score and patients' satisfaction score.