TC-A Registration Study

Inclusion Criteria: * Male or female subjects, aged between 50 and 75 years inclusive of Chinese ethnicity. * Subject presents with primary osteoarthritis, rheumatoid arthritis, post-traumatic arthritis or avascular necrosis of knee joint requiring primary total knee replacement with the PS knee system. * Subject who is able to give voluntary, written informed consent to participate in the study and from whom consent has been obtained by signing and dating an EC-approved consent form. * Subject who is able to understand this clinical study, co-operates with the investigational procedures and is willing to return to the hospital for all the required post-operative follow-ups for up to 12 months. * Life expectancy of subject is over 2 years. Exclusion Criteria: * Bilateral knee disease with the anticipated need for bilateral knee implant during study participation (i.e., within the next 12 months). * Subject has known or suspected metal sensitivity. * Subject is known to have insufficient femoral or tibial bone stock resulting from conditions such as cancer, distal femoral/proximal tibial osteotomy, significant osteoporosis or metabolic bone disorders, which cannot provide adequate support and/or fixation to the prosthesis. * Subject is severely obese (BMI\>35). * Subject has hip arthritis and/or replacement. * Subject had an active infection or sepsis (treated or untreated) * Subject has conditions that may compromise implant stability or postoperative recovery (i.e., Paget's or Charcot's disease, vascular insufficiency, muscular atrophy, uncontrolled diabetes, moderate to severe renal insufficiency or neuromuscular disease). * Subject has an emotional or neurological condition that would affect their ability or willingness to participate in the study (e.g. mental illness, mental retardation). * Subject is immunosuppressed, has an autoimmune disorder, or an immunosuppressive disorder. For examples, subject is on immunosuppressive therapy (corticosteroid hormones in large amounts, cytotoxic drugs, antilymphocytic serum or irradiation in large doses) or has acquired immunodeficiency syndrome (AIDS). * Subject is a woman who is pregnant or lactating，or intends to become pregnant during the course of the study. * Subject is known to be at risk for lost to follow-up, or failure to return for scheduled visits. * Subject was enrolled in another investigational drug, biologic, or device study in the last 12 months. * Known alcohol and/or drug abuse