This study aims to compare the effectiveness of duloxetine after total knee arthroplasty in Central sensitization patient. Central sensitization plays an important role in the chronic pain experienced by osteoarthritis patients.Elimination of the nociceptive input from the damaged joint by total joint arthroplasty was not always followed by a complete resolution of symptoms. Patients with high levels of preoperative pain and low pain thresholds had a higher risk of persistent pain after total knee arthroplasty (TKA), which has been interpreted as evidence of central sensitization. Thus, the presence of central sensitization before surgery in Osteoarthritis patients may be an important contributing factor to postoperative pain versus adequate analgesia. Preclinical models of central sensitization suggest that duloxetine is effective in the treatment of persistent pain. Investigators will compare the pain following TKA of central sensitization patients in duloxetine group (n=50) with those in non-duloxetine group (n=84). Investigators will classify the central sensitization patients by central sensitization inventory and divide the central sensitization patients in to 2 groups (duloxetine and non-duloxetine group) randomly. Investigators checks the visual assessment scale at preoperative, postoperative 1, 2,6,12 weeks. All participants will receive postoperative pain control after TKA using the same pain control regimen except duloxetine.

Both groups of participants will receive pain control regimens as follows:

Preemptive analgesia : celebrex celecoxib, Lyrica Pregabalin, Patient controlled analgesia (postoperation 28 hours), During admission : celebrex 200mg#1, Ircodon 5mg 2Tablets#2, Ultracet 2T#2 (Postoperation 1 week) Discharge medication: celebrex 200mg 1Capsule#1 x 5 weeks, Ultracet 2T#2 x 1 week

Drug generic names: celecoxib (celebrex), Pregabalin (Lyrica), acetaminophen/tramadol (ultracet ER), oxycodone (Ircodon)

Inclusion Criteria:

• Patients for total knee arthroplasty
• having medicare insurance
• CSI(Central sensitization inventory)> 40 (Central sensitization patient )

Exclusion Criteria:

• Rheumatoid arthritis
• Other inflammatory arthritis
• Neuropsychiatric patients
• Allergy or intolerance to study medications
• Patients with an ASA(American society of anesthesiologist) classification of IV (angina, congestive heart failure, dementia, cerebrovascular accident)
• Chronic gabapentin or pregabalin use (regular use for longer than 3 months)
• Chronic opioid use (taking opioids for longer than 3 months)
• Alcohol, drug abuser
• Narcotics addiction