• Patients will be evaluated in blinded fashion for lower extremity CRPS at pre-op, 1, 3, and 6 months postsurgery based initially on telephone interviews. [ Time Frame: 6 months post-surgery ] [ Designated as safety issue: Yes ]
• The degree of active and passive knee flexion and the number of days required until obtaining 90º of active knee flexion will be recorded by the physical therapist twice daily until discharged from the hospital. [ Time Frame: 4 days ] [ Designated as safety issue: Yes ]

• Patients will be evaluated in blinded fashion for lower extremity CRPS at pre-op, 1, 3, and 6 months postsurgery based initially on telephone interviews. [ Time Frame: 6 months post-surgery ]
• The degree of active and passive knee flexion and the number of days required until obtaining 90º of active knee flexion will be recorded by the physical therapist twice daily until discharged from the hospital. [ Time Frame: 4 days ]

The Department of Anesthesiology is conducting a clinical trial to evaluate if pregabalin given prior to and for several days after Total Knee Arthroplasty (TKA) will reduce the prevalence of Complex Regional Pain Syndrome (CRPS) at late postoperative times. The prevalence of complex regional pain syndrome (CRPS) following total knee arthroplasty (TKA) is 13% at 6 months post-surgery. CRPS is a painful debilitating condition, with 4 main classes of symptoms : sensory, including burning, allodynia, and hyperalgesia in the affected limb; vasomotor, including temperature asymmetry and skin color changes; edema and sudomotor, including sweating; and movement disorders and dystrophy, including decreased range of motion, motor dysfunction (weakness, tremor, dystonia) and changes in hair, nails or skin.

The Department of Anesthesiology is conducting a clinical trial to evaluate if pregabalin given prior to and for several days after Total Knee Arthroplasty (TKA) will reduce the prevalence of Complex Regional Pain Syndrome (CRPS) at late postoperative times. The prevalence of complex regional pain syndrome (CRPS) following total knee arthroplasty (TKA) is 13% at 6 months post-surgery. CRPS is a painful debilitating condition, with 4 main classes of symptoms : sensory, including burning, allodynia, and hyperalgesia in the affected limb; vasomotor, including temperature asymmetry and skin color changes; edema and sudomotor, including sweating; and movement disorders and dystrophy, including decreased range of motion, motor dysfunction (weakness, tremor, dystonia) and changes in hair, nails or skin.

Gabapentin and the related more potent compound pregabalin have been shown to reduce postoperative pain in animal models. Pregabalin also reduces neuropathic pain in rats. In patients, gabapentin has been administered before surgery to treat postoperative pain. In addition, pregabalin has been given postoperatively to reduce dental pain after molar extraction. Gabapentin has been used for many years in patients with neuropathic pain, including reflex sympathetic dystrophy. More recently, pregabalin has also been shown to be efficacious in the treatment of neuropathic pain. However, no clinical study has investigated whether perioperative administration of gabapentin or pregabalin can reduce persistent long-term pain syndromes e.g. CRPS.Subjects between the ages of 21 and 80 will be recruited after obtaining an Informed Consent.

• Placebo Comparator: Half of the patients will receive PO placebo for 14 days
• Experimental: PO pregabalin 300 mg 2 hours prior to surgery, and 150 mg twice a day for 10 postoperative days. Pregabalin will be tapered to 75 mg twice daily between days 11 to 12 and then to 50 mg twice daily between days 13 to 14 post operatively and then stopped.

Inclusion Criteria:

1. History of osteoarthritis
2. Subjects who can understand and communicate in English.

Exclusion Criteria:

1. Younger than 21 years or older than 80 years.
2. American Society of Anesthesiologists physical status IV.
3. Prior usage of gabapentin (or pregabalin) will not be an exclusionary criterion; however, patients will have been withdrawn from these medications for at least 7 days before surgery.
4. Patients with a history of neuropathic pain conditions.
5. Patients who are currently enrolled in another investigational study.
6. Pre-existing heart conditions

7. Patients on thiazolidinedione class of anti-diabetic medications (eg. rosiglitazone, pioglitazone).

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