Fracture Healing

From the moment your bone is broken your body begins a process to heal the fracture. This is a very complex process that involves multiple cell types from the bone and bloodstream, and a complex mixture and interaction of chemicals, proteins and growth factors. Ultimately, the bleeding from the fracture is converted into new bone.

Inflammatory Phase
The initial part of fracture healing is called the Inflammatory Phase. This lasts for several weeks. Different inflammatory cells are involved with this process. Unfortunately, they also are responsible for mediating the pain that is associated with fractures. In essence, the pain is a necessary part of the beginning of fracture healing. During this phase osteoblast cells from the bone make an extracellular matrix of collagen and proteoglycans that acts as a scaffolding for the new bone.

Reparative Phase
The inflammatory phase evolves into the Reparative Phase. At this point mineral is being incorporated into the bone. We call this new bone "callus". The mineral is called Crystalline Hydroxyapatite and has a chemical structure Ca10(PO4)6(OH)2. The initial callus that is formed can be seen on an x-ray. It is relatively weak, because the matrix it is built upon has a disorganized structure. This phase generally lasts for a few months.

Remodeling Phase
The final phase of bone healing is called the Remodeling Phase. This phase lasts for many months or even years. During this phase the callus is slowly remodeled, a process that involves different cell types and causes the shape of the bone to return to an appearance similar to before injury. The bone remodels in response to stress put upon it. We allow weight-bearing during this phase because the stress on the bone stimulates the bone to regain its normal strength and shape.