A stress fracture is primarily caused by which of the following?

A stress fracture is primarily caused by repetitive low-impact forces that lead to micro-damage in the bone structure over time. This gradual accumulation of stress results in a fracture that typically occurs in weight-bearing bones, such as those in the legs and feet. Unlike a traditional fracture, which often results from a single traumatic incident or high-energy trauma, a stress fracture develops from the bone's inability to repair itself quickly enough in response to consistent, moderate stress.

The phrase "repetitive low-impact forces" encapsulates activities such as running or jumping, where the body faces repeated stress without adequate rest for recovery. Over time, as these low-level stresses continue, the bones can become weakened, leading to a stress fracture.

In contrast, a single high-impact event usually results in acute fractures rather than stress fractures, which are chronic in nature. High-energy trauma refers to more significant forces, like those sustained from a car accident, which also are unlikely to cause stress fractures due to their sudden and pronounced nature. Severe osteoporosis, while it may make bones more susceptible to all types of fractures, is typically associated with spontaneous fractures rather than specifically stress-related injuries.