Causes

There are a number of ways you can break a leg, including:

• Falls. A simple fall can fracture one or both of the lower leg bones. However, the thighbone is unlikely to be broken without more significant trauma.
• Motor vehicle accidents. All three leg bones can break during a motor vehicle accident. Fractures can occur when your knees become jammed against the dashboard during a collision.
• Sports injuries. Hyperextending your leg during contact sports can cause a broken leg. So can a direct blow — such as from a hockey stick or an opponent's body.
• Child abuse. In children, a broken leg may be the result of child abuse, especially when such an injury occurs before the child can walk.
• Overuse. Stress fractures are tiny cracks that develop in the weight-bearing bones of your body, including your shinbone. Stress fractures are usually caused by repetitive force or overuse, such as running long distances. But they can also occur with normal use of a bone that's been weakened by a condition such as osteoporosis.