## 4 Discussion
Cross-sectional equivalent stress contour plots reveal distinct load-bearing patterns between cortical and cancellous bone, which are attributable to their material property disparities. The cortical bone, characterized by a Young's modulus significantly exceeding that of cancellous bone, bears the predominant mechanical load transmitted from the tibial plateau, serving as the primary load-bearing component during physiological activities. Stress visualization demonstrates dense stress concentration bands throughout cortical regions, particularly concentrated in the mid-proximal tibial section. Conversely, cancellous bone, owing to its porous architecture and lower modulus, exhibits minimal dispersed stress distribution. This mechanical load-sharing pattern aligns with structural analyses reported in previous studies, where the cortical bone's dense Haversian systems establish optimized load transmission pathways. Analysis of maximum equivalent strain data reveals progressive strain escalation in the tibia with increasing physiological activity intensity, as loads transmitted through the tibial plateau intensify from standing (0.017%) to running (0.067%). Strain distribution patterns in the intact tibia demonstrate concentrated deformation zones within block-shaped regions of the medial area inferior to the tibial plateau, correlating spatially with high-stress distributions observed in corresponding stress contour maps. This spatial congruence indicates that regions experiencing greater deformation simultaneously bear elevated mechanical stresses. Cross-sectional strain analysis reveals significantly elevated strain values throughout the proximal cancellous bone region, extending from cortical-cancellous junctions to the internal cancellous architecture. This strain distribution pattern aligns with the porous morphological characteristics of cancellous bone. Notably, high-strain regions in cancellous bone exhibit continuity with cortical bone strain concentrations, demonstrating mechanical coupling where cancellous deformation originates from load transmission through cortical bone. These observations validate the effectiveness of modeling cortical-cancellous interactions as a bonded interface in simulating physiological load transfer mechanisms within the finite element framework. According to finite element analysis results of the tibia following HTO surgery, the region with maximum stress concentration was identified at the osteotomized hinge area. The primary purpose of tibial implantation is to replace resected bone mass and optimize lower limb mechanical alignment modification, thereby enhancing physiological load transmission. As the porosity of the tibial implant increased, the peak stress on the tibia progressively elevated, indicating reduced load-bearing capacity in high-porosity implants. Nevertheless, hybrid porous-structured implants demonstrated superior stress distribution across all porosity ranges. Specifically, under 73% porosity conditions, hybrid porous implants achieved optimal mechanical load transfer efficiency without inducing stress concentration in the tibia. Compared to circular and rectangular porous configurations at equivalent porosity levels, the hybrid structure reduced tibial peak stress by 19.97% and 15.33%, respectively. The analysis of stress contour maps across various tibial implants reveals no significant stress concentration within the implant structures. Lower stress values were observed at the cancellous bone interface, whereas higher stresses were concentrated in regions directly interfacing with cortical bone. With increasing porosity, all implant configurations exhibited elevated maximum von-Mises stresses--a phenomenon attributable to reduced material volume in the load-bearing matrix and structural thinning, which amplifies stress intensification in supporting frameworks. Notably, composite porous implants demonstrated superior stress distribution characteristics compared to circular and rectangular porous designs.