60 patients undergoing total knee arthroplasty (TKA) for knee osteoarthritis (OA) were randomized to undergo TKA using either a microelectromechanical navigation system for femoral intramedullary alignment (MEMS-FEAO; n=30) or conventional femoral intramedullary alignment osteotomy (FIAO; n=30). Outcomes of interest included intraoperative blood loss, drainage volume, operative time, hip-knee-ankle angle (HKAA), mechanical medial proximal tibial angle (mMPTA), femoral varus/valgus angle (FPVA), femoral flexion angle (FPFA), and total blood loss. The intraoperative outcomes between the two groups were similar. The MEMS-FEAO group showed significantly better HKAA alignment and FPFA compared to the FIAO group, with significantly lower HKAA lower deviations. Both groups showed significant improvements in mMPTA values from baseline but there were no between-group differences. The use of MEMS-FEAO can be a helpful tool to improve prosthesis placement and alignment in patients undergoing TKA.