Background: Resection and modular endoprosthesis replacement have revolutionized the surgical management of primary tumors at the distal femur, offering patients improved functional outcomes and enhanced quality of life. This review article provides a comprehensive analysis of current surgical techniques, oncological principles, and functional outcomes associated with this approach. We discuss indications for limb-salvage surgery, preoperative planning, and the intricacies of distal femoral resection. Additionally, we evaluate the design evolution, biomechanical properties, and survivorship of modular endoprostheses. Key factors influencing long-term success, including implant failure, infection, and local recurrence, are thoroughly examined. The review also highlights rehabilitation protocols and their role in optimizing postoperative recovery. By synthesizing recent advancements and clinical evidence, this article aims to guide orthopedic oncologists in making informed decisions for managing primary distal femoral tumors while balancing oncological control and functional preservation.