Long-term Study of The Press Fit Condylar (P.F.C.) Sigma Total Knee Replacement System

Inclusion Criteria: * Patients who have given voluntary written informed consent to participate in this study. * Patients for whom primary Total Knee Replacement is indicated due to degenerative joint disease, including rheumatoid arthritis, osteoarthritis, avascular necrosis, and post-traumatic arthritis, which is causing pain, deformity, or limitation of function uncontrolled by medical treatment. * Patients who, in the opinion of the Investigator, are able to understand this study, co-operate with the investigational procedures and are willing to return to the hospital for all the scheduled post-operative follow-ups. * Male or female patients who are skeletally mature and for whom an appropriate size of device is available. Exclusion Criteria: * Patients scheduled for Revision Total Knee Arthroplasty, or who have had previous surgery to their knee except menisectomy, arthroscopy or synovectomy. * Patients experiencing any condition that may, in the opinion of the Investigator, interfere with the Total Knee Replacement's survival or outcome (e.g. Paget's disease, Charcot's disease, severe osteoporosis, etc.) * Patients who have evidence of active infections which may spread to other areas of the body (e.g. osteomyelitis, pyrogenic infection of the knee joint, overt infection, etc.). * Patients who are currently participating in any other clinical investigation of a device or pharmaceutical. * Patients having non-contained defects in the tibia or femur necessitating bone graft. * Patients with psychosocial disorders that would limit rehabilitation or follow-up. * Subjects with a known history of poor compliance to medical treatment. * Subjects who are known drug or alcohol abusers. * Other contraindications for the use of the P.F.C. ® S Knee System as listed in the package insert.