The research demonstrates a novel three-dimensional finite element analysis to analyze biomechanical changes in a femur with implant. The method uses principal stress projections to determine trabeculae trajectories in the femur. Visual comparisons of the projections of the femurs show areas of cortical and cancellous changes due to changes in tensile and compressive stresses, revealing areas of stress shielding. The method also includes a bone remodeling algorithm to simulate bone adaptation. In the experiment, a patient-specific femur model with inhomogeneous material properties was created from CT scans. Models of femurs with implants varying in type and size were also created. Maximum load during walking was simulated with realistic muscle forces, and stress projections of the femur model were compared to trabecular trajectories of a real femur for validation. Bone remodeling was also simulated to investigate changes in projections over time. High correlation was found between the principal stress projections of the computational model and trabeculae trajectories of a real femur. Changes in projections were evident for implant models, suggesting stress shielding and bone remodeling. The analysis provides an effective method for planning implants that are ideal for patients and for designing future implants that preserves the biomechanics of the femur to maintain its physiology.