High tibial osteotomy is a joint-preserving surgical technique for realigning the lower limb in patients with knee osteoarthritis and varus deformity, aiming to reduce medial knee loading and slow osteoarthritis progression. Knee contact force predictions via musculoskeletal models are affected by tibiofemoral alignment and knee contact locations. However, previous models assumed the entire varus deformity within the knee joint, neglecting bone deformities in the tibia and femur. This thesis aimed to (i) assess the accuracy of modeling tibiofemoral malalignment as a whole joint varus deformity, and (ii) analyze the effects of real high tibial osteotomy, which corrects tibial varus only, compared to a hypothetical correction involving both tibia and femur, on medial and lateral knee contact forces.