This study presents a three-dimensional finite element analysis of a femoral bone-implant system designed for post-amputation prosthetic integration. The use of prostheses with implants that directly interact with the bone is currently a trend in modern biomedicine. In the development of such prostheses, preliminary modeling plays a huge role. The primary focus is on evaluating the effect of varying internal dry sliding friction coefficients, which characterize the evolving contact interaction between the implant and the bone during different stages of rehabilitation. A detailed 3D model of the human femur, the implant, and a segment of the prosthesis was developed, incorporating realistic anatomical geometry and material properties. The system was subjected to a simplified vertical loading condition, simulating the static weight-bearing scenario of an 80 kg patient in a standing posture. Simulations revealed a significant dependence of stress magnitudes and localization patterns on the friction coefficient at the bone-implant interface. The results provide insight into how micro-stiffness at the interface influences mechanical load distribution, especially critical during early postoperative stages when bone-implant fusion is incomplete. As the interface conditions evolve through the healing process, the biomechanical response of the system changes markedly. These findings offer valuable guidance for clinical rehabilitation protocols, informing load management strategies and improving long-term outcomes for patients undergoing limb prosthesis implantation.