Final answer:
In the inflammatory stage of bone healing, a fracture hematoma forms initially, followed by capillary growth and phagocytic cleaning. Collagen fibers and spongy bone are produced by fibroblasts and osteoblasts, forming a fibrocartilaginous callus, which turns into a bony callus that is later remodeled into mature bone tissue.
Step-by-step explanation:
The healing of a bone when the gap is greater than 10 micrometers (uM) during the inflammatory stage involves several critical steps. Initially, blood vessels that have been torn during the fracture create a fracture hematoma, a localized collection of blood outside the blood vessels. This stage occurs within six to eight hours after the injury.
Within days, new capillaries grow into the hematoma, and phagocytic cells start to remove dead tissue. Fibroblasts and osteoblasts migrate to the fracture and commence the repair process. Fibroblasts produce collagen fibers to connect the broken bone ends, while osteoblasts begin the creation of spongy bone, which progresses to form the fibrocartilaginous callus, a mix of hyaline and fibrocartilage. Subsequently, this callus is transformed into a bony callus of spongy bone, and this phase takes approximately two months to unite the broken ends firmly.
Lastly, bone remodeling plays a crucial role in healing, as the bony callus is refined and reshaped by the activity of osteoclasts and osteoblasts. Excess material is removed, and compact bone replaces the spongy bone, leading to a structure similar to the original, unbroken bone. This remodeling can extend over many months and even years.