In patients who have sustained a traumatic brain injury with an associated extremity fracture there is often a clinical perception that the rate of new bone formation around the fracture site is increased. Whether this rapidly forming new bone is fracture callus or a variant of heterotopic ossification, a common complication of traumatic brain injury, is the subject of some debate. This review will provide a comprehensive analysis on this topic and will discuss clinical and physiological evidence as well as potential areas for future research in this field.