Final answer:
On MRI, a fracture is seen as a low signal intensity line with surrounding edema. The internal callus fibrocartilaginous matrix aids in healing within the endosteal region. Low calcium levels can impact bone healing.
Step-by-step explanation:
On MR images, a fracture appears as a fracture line of low signal intensity surrounded by an ill-defined zone of edema. Fracture healing involves several steps, starting with the formation of a hematoma, followed by the development of an internal callus made up of a fibrocartilaginous matrix. This internal callus forms in the endosteal region between the fractured ends of bone. As healing progresses, new bone is formed, and the internal callus becomes ossified, reducing evidence of the fracture on imaging modalities as the healing is complete. A slight swelling may remain on the outer surface of the bone, but this often undergoes remodeling, and with time no external evidence of the fracture remains. It's also noteworthy that low levels of calcium can affect the bone healing process.