Bone fracture is a medical condition in which a bone is broken or cracked. It can be caused by a traumatic injury, such as a fall or a car accident, or it can be caused by a medical condition, such as osteoporosis. Bone fractures can range from minor cracks to complete breaks. Treatment for a bone fracture typically involves immobilizing the affected area with a cast or splint, and in some cases, surgery may be necessary.