Nociceptor inputs can trigger a prolonged but reversible increase in the excitability and synaptic efficacy of neurons in central nociceptive pathways, the phenomenon of central sensitization. The degenerative joint disease, osteoarthritis, with characteristic destruction of cartilage and alteration in bone is a very common cause of chronic pain. The degree of pain does not always correlate with the extent of joint damage or presence of active inflammation raising the possibility that there may be a central component to the pain. The central sensitization inventory (CSI) is a new self-report screening instrument to measure the degree of central sensitization, and to help identify patients with central sensitivity syndromes. The aim of this investigation is to evaluate the influence of preoperative central sensitization, which represented by CSI score, on postoperative pain score in osteoarthritis patients undergoing total knee replacement who receiving patient-controlled epidural analgesia.

Inclusion Criteria:

• Aged 20 to 80 years osteoarthritis patients undergoing total knee replacement under spinal anesthesia, and who receiving postoperative epidural PCA

Exclusion Criteria:

• refusal
• coagulopathy
• neurologic deficit
• preoperative opioids medication
• recent analgesics change

osteoarthritis patients undergoing total knee replacement