The femur is the strongest bone in the human body. It can withstand up to 1,750 pounds per square inch (psi) of force. This is equivalent to the weight of a small car.

The femur is made of a dense type of bone tissue called cortical bone. Cortical bone is composed of tightly packed Haversian systems, which are cylindrical structures that contain blood vessels and nerves. The Haversian systems are surrounded by a matrix of collagen and calcium phosphate. This matrix gives cortical bone its strength and hardness.

The femur is also supported by a number of muscles and ligaments. These structures help to protect the femur from injury.