 Osteoarthritis OA is the single most common cause of disability in mid and late life. About 27 million people in the United States suffer from this incurable process and 10 million have OA of the knee. Total knee replacement TKR is a reliable treatment option for patients disabled by knee OA who have failed non-operative treatment; 58 of these surgeries are performed on patients 65 years or older. Despite the overall success of TKR in most cases, persistent postsurgical pain PPP of the operated knee remains a common and often difficult to treat postoperative outcome affecting 13-20 of all patients at 6 months post-TKR, which amounts to 65,000-100,000 patientsyear in the USA. Important secondary outcomes of PPP are restricted physical mobility and poor quality of life, especially in older patients. 