A number of factors, including aging, trauma, obesity, limb misalignments like varus tilt, inflammatory diseases, ligament instability, and genetics, can contribute to knee osteoarthritis (KOA), which causes cartilage degradation and mechanical damage. Meniscal damage increases cartilage wear, which accelerates the progression of KOA. Using finite element analysis (FEA), this study examines the effects of overweight and knee misalignment on the distribution of stress in the menisci of osteoarthritic and healthy human knees. To simulate biomechanical behavior under different loading forces, two comprehensive three dimensional (3D) virtual models of the bones, ligaments, cartilages, and menisci of normal (healthy) and osteoarthritic knees with varus misalignment were created using Ansys Workbench and imaging data. The osteoarthritic models had a 10° varus inclination and reduced elasticity in affected areas. Resulted equivalent (von Mises) stress maps showed that osteoarthritic knees had more stress in certain areas, especially under loads exceeding 800 N. The medial meniscus in knees with osteoarthritis showed signs of damage that were linked to varus misalignment and increased load. Both factors significantly increase the amount of stress on the menisci and cartilage, which speeds up the breakdown of cartilage and damage to the menisci, thus promoting the progression of KOA. Stress values and damage patterns align with clinical observations and previous studies, confirming the model’s accuracy and usefulness for biomechanical assessment of knee joint health.