American Academy of Professional Coders (AAPC) Practice Exam

What causes a spiral fracture?

1. Direct impact on the bone

2. Twisting stress along the length of the bone

3. Compression of the bone

4. Loss of blood supply to the bone

The correct answer is: Twisting stress along the length of the bone

A spiral fracture occurs as a result of twisting stress applied to the length of the bone. This unique fracture pattern is distinguished by its helical appearance, which reflects the rotational force that causes the bone to break in a circular or spiral manner. When a bone is subjected to a twisting motion, it can experience torsional forces that exceed its structural integrity at certain points, leading to the fracture. This is particularly common in athletic injuries or accidents where sudden twisting movements occur, such as in sports or falls. The other causes listed, such as direct impact, compression, and loss of blood supply, lead to different types of fractures. A direct impact typically results in a transverse or comminuted fracture depending on the force and angle of impact. Compression can cause wedge fractures in vertebrae, particularly in conditions like osteoporosis. Lastly, loss of blood supply can lead to conditions such as avascular necrosis, but this does not directly result in a specific type of fracture like a spiral fracture.