1. Hip bone, also called ilium, is flush with the lower edge of the fourth lumbar vertebra, forms the pelvic entrance together with pubic bone and sacrum, and forms the hip joint downward with ischium, ulna and femoral head. It is the largest load-bearing joint of human body.

2. Ilium can protect the hollow organs in pelvic cavity, and it is also an important link to connect the upper and lower limbs of human trunk and maintain the stability of body structure. After the hip joint is formed, people can stand, walk and run.

3. Ilium is prone to fracture under the action of great external force, such as car accident, falling injury, crushing injury, etc. After iliac bone fracture, blood vessels are easy to rupture, leading to massive bleeding. Because the iliopsoas artery is close to the inner edge of ilium, it is easy to damage the blood vessels here in the case of trauma.