 We propose to constitute a bank of capsule samples from people with osteoarthritis undergoing primary total knee arthroplasty. It is expected that about 1.3 of people will develop a contracture post arthroplasty. A second sample will be taken from those that require surgery for release of contracture or revision. We will study histological characteristics and compare gene expression between the primary sample and the contracture sample in the same patient. In order to determine whether intrinsic genetic factors influence the develpment of joint contractures in the osteoarthritis population, all specimens will be analyzed for differential gene expression between patients with and without knee contractures post arthroplasty. 