What causes a spiral fracture?

A spiral fracture is primarily caused by twisting injuries, which create a helical crack along the bone. This type of fracture occurs when there is rotational force applied to the bone, resulting in a fracture that spirals around the bone rather than occurring at a single point of impact. The twisting motion generates stress along the length of the bone, leading to the characteristic spiral shape of the fracture.

While direct impacts, repetitive stress, and falls can lead to various types of fractures, they do not specifically result in spiral fractures. A direct impact typically causes transverse or comminuted fractures, repetitive stress often leads to stress fractures, and falls from height can result in various fracture types based on the impact and angle of landing. Twisting injuries remain the hallmark mechanism for causing spiral fractures due to the nature of the stress applied to the bone along its entire length.