Abstract: To address the problems of high maximum stress, severe bone tissue damage, and excessive implant mass associated with tibial intramedullary stems in total knee arthroplasty, this study proposes a novel high-performance tibial intramedullary stem with both structural safety and clinical practicality. Using Altair Inspire software, topology optimization, geometric reconstruction, and multi-condition strength verification were conducted under five typical clinical loading conditions, including standing and knee flexion at different angles. The results show that the optimized structure significantly reduces implant stress, interfacial bone stress, and locally excessive strain, while achieving structural lightweighting and reducing the extent of invasion into bone tissue. These improvements satisfy the design requirements of optimizing interfacial stress distribution, reducing structural weight, and minimizing tissue damage. These findings provide a theoretical basis and technical support for the development of high-performance tibial intramedullary stems.