Optetrak Posterior Stabilized Versus Optetrak Hi-Flex

Inclusion Criteria: 1. Patient is indicated for total knee replacement with a posterior stabilized device. 2. Patient is between the ages of 50 and 80 years old 3. Patient has a Body Mass Index (BMI) \< 35.0 using the following method (or comparable method) • BMI = Weight (lbs.) ÷ Height (in.)2 x 703 4. Patient is skeletally mature. 5. Patient is willing to participate by complying with pre and postoperative visit requirements, over at least a 1-year period, including completion of studyrequired questionnaires. 6. Patient is willing and able to review and sign a study Informed Consent. Exclusion Criteria: 1. Patient has a Body Mass Index (BMI) \> 35.0 using the following method (or comparable method) • BMI = Weight (lbs.) ÷ Height (in.)2 x 703 2. Patient is skeletally mature 3. Patient is willing to participate by complying with pre and postoperative visit requirements, over at least a 1-year period, including completion of study required questionnaires. 4. Patient is willing and able to review and sign a study Informed Consent.