Post Market Clinical Follow Up of LEGION™ Primary TKS With VERILAST™

Inclusion Criteria: * Subject requires primary TKA and has elected to use the LEGION™ Primary TKS with VERILAST™. * Subject requires primary TKA due to degenerative joint disease (primary osteoarthritis, post-traumatic arthritis, avascular necrosis, rheumatoid arthritis). * Subject is of legal age to consent, agrees to consent to and to follow the study visit schedule (as defined in the study protocol and informed consent form), by signing the EC approved informed consent form. * Routine radiographic assessment is possible. * Subject plans to be available through ten (10) years postoperative follow-up. * Subject is 18-75 years of age at the time of surgery. Exclusion Criteria: * Age \> 75 years at the time of surgery. * Subjects with immunosuppressive disorders. * Subject has severe pronation of the ipsilateral foot or any other relevant clinical condition contributing to abnormal ambulation (including but not limited to ankle fusion, ankle arthroplasty, previous hip fracture, ipsilateral hip arthritis resulting in flexion contracture). * Subject has undergone a previous major surgery to the study knee (including osteotomy, fracture fix, medial or lateral ligament surgery). * Subject has active infection or sepsis (treated or untreated). * At the time of enrollment, subject has one or more of the following arthroplasties that are not fully healed and well-functioning, as determined by the Investigator: * Ipsilateral or contralateral primary total hip arthroplasty or hip resurfacing arthroplasty. * Contralateral primary total knee or unicondylar knee arthroplasty. * Subject has presence of malignant tumor, metastatic, or neoplastic disease. * Subject has conditions that may interfere with the TKA survival or outcome (i.e., Paget's or Charcot's disease, muscular atrophy, uncontrolled diabetes, moderate to severe renal insufficiency or neuromuscular disease). * Subject has any acute or chronic morbidity of vascular origin that, in the opinion of the Investigator, is likely to compromise successful treatment or compliance to follow-up visits. * Subject has inadequate bone stock to support the device (severe osteopenia, family history of severe osteoporosis or osteopenia). * Subject has an emotional or neurological condition that would pre-empt their ability or willingness to participate in the study. * Subject has a Body Mass Index (BMI) \>40.0. * Subject requires revision TKA. * Subject is expected to require bilateral TKA within 1 year following study knee replacement. * Subject does not understand the language used in the Informed Consent Form. * Subject is enrolled in another clinical study at the same time.