 In total knee replacement operations, the surgeon uses techniques and instruments to guide the operation and ensure that all parts of the prosthesis the artificial knee surfaces are placed into the correct position. There are many techniques a surgeon can use to achieve accuracy in the operation. This study will compare the Principal Investigators present precision-guided technique and instrumentation methods with a newly developed technique that uses a computer-based stereotactic guidance system. The purposes of the study are: 1. to learn whether the use of the different guidance systems results in differences of accuracy of the placement of the prosthesis; 2. to compare the length of time it takes an experienced joint replacement specialist to complete the operation using the different guidance systems; 3. to learn whether there are advantages of either system in terms of the function and recovery of patients over the first year after surgery; and, 4. to provide the manufacturer of the stereotactic guidance system with feedback on the technical ease of use and workflow ease of the system which may be used for training and education purposes andor for planning further refinements to the system. The study will enroll up to 150 patients from Athens Orthopedic Clinic over 2 to 3 years. 