Which bone acts as the weight-bearing bone of the lower leg?

The tibia is the correct answer because it is the primary weight-bearing bone of the lower leg. It plays a crucial role in supporting the body’s weight during activities such as walking, running, and standing. The tibia, also known as the shinbone, is larger and more robust compared to the fibula, which is a thinner bone located alongside the tibia and primarily serves as a site for muscle attachment and stabilization rather than weight-bearing.

In contrast, the fibula does not support weight directly as it is situated laterally and does not articulate with the femur at the knee joint. The patella, commonly called the kneecap, is a sesamoid bone that improves the mechanical efficiency of knee extension but does not bear weight itself. Lastly, while the femur is the long bone of the thigh and important in weight-bearing during activities involving the upper leg, it does not reside in the lower leg. Therefore, the tibia's structural characteristics and its position make it the main weight-bearing bone of the lower leg.