DJO Global Empowr Knee Replacement for Knee Osteoarthritis

Inclusion Criteria: Controls: 1. At least 50 years of age. 2. Subjects who provide signed and IRB approved informed consent for gait analysis data collection Retrospective subjects: 1. Subjects who had primary total knee replacement with either Stryker Triathlon Total Knee System or Biomet Vanguard Complete Knee System. 2. Subjects at least 50 years of age at the time of the surgery. 3. Subjects who previously provided signed and informed consent for gait analysis data collection under approval of the Sun Health Institutional Review Board 4. Cases that followed product labeling. Prospective subjects: 1. Subjects who are eligible for DJO Global's Empowr total knee replacement. 2. Subjects at least 50 years of age at the time of the surgery. 3. Subjects who are willing to provide signed and IRB approved informed consent for gait analysis data collection. 4. Cases that followed product labeling. Exclusion Criteria: Controls: 1. Controls with any musculoskeletal injury or disorder. 2. Controls that are pregnant or planning on becoming pregnant. 3. Controls with a BMI\>40 Retrospective subjects: 1. Subjects with inflammatory arthritis or psoriatic arthritis at the time of surgery. 2. Subjects that are pregnant or planning on becoming pregnant. 3. Subjects with a BMI\>40 4. Subjects who had an active infection or suspected latent infection in or about the joint at the time of surgery. 5. Subjects whose bone stock was compromised by disease, infection or prior implantation which could not provide adequate support and/or fixation of the prosthesis. 6. Subjects who had any mental or neuromuscular disorders which created an unacceptable risk of prosthesis instability, prosthesis fixation failure, or complication in postoperative care. 7. Subjects with severe instability of the knee joint secondary to the absence of collateral ligament integrity and function. Prospective subjects: 1. Subjects with inflammatory arthritis or psoriatic arthritis at the time of surgery. 2. Subjects that are pregnant or planning on becoming pregnant. 3. Subjects with a BMI\>40 4. Subjects who had an active infection or suspected latent infection in or about the joint at the time of surgery. 5. Subjects whose bone stock was compromised by disease, infection or prior implantation which could not provide adequate support and/or fixation of the prosthesis. 6. Subjects who had any mental or neuromuscular disorders which created an unacceptable risk of prosthesis instability, prosthesis fixation failure, or complication in postoperative care. 7. Subjects with severe instability of the knee joint secondary to the absence of collateral ligament integrity and function.