There are three phases to scar healing INFLAMMATORY, FIBROBLASTIC, & REMODELING.
Our body structures can be divided into at least 14 different types of collagen. Mature scar is formed from type-I collagen; yet it is the greatest chameleon in its ability to imitate the structure of other collagen types. Somehow, the scar formed in dense tissue "senses" the need for strength and attempts to mimic the surrounding tissue in structure. Likewise, scar, filling a defect in loose, flexible tissue, will change in its last phase of healing to reproduce, as much as possible, these physical characteristics. Thus, in response to certain internal and external influences, scar does differentiate to become quasi-tissue specific. Experience tells us that often this attempt by scar to blend in cosmetically and functionally is not successful. Enhancing the potential of scar to duplicate the desired outcome is the basis for surgical, pharmacological, and therapeutic management protocols.
Chemical mediators of inflammation are the first and most integral step in the healing process. The majority of specialized cells that will operate and control this phase of healing come from the blood. The vessels that have been severed pour blood into the area, which coagulate and work to seal off the injured vessels and begin to seal the wound.
At the same time neighboring blood vessels open wider to accommodate flow to the area. This is a necessary step, however, this leads to a red, hot, swollen, and often painful environment.
The next stages of this phase are clean up and neovascularization. Specialized cells will work to contain bacteria and clean the wound. This process continuously signals and recruits specialized cells to continuously clean the wound and prevent infection. This process is all modulated by the ability to supply oxygen and nourishment to the injured tissue. This is where the body's ability to establish new vessels is critical.
Reviewing the complex, interrelated dynamics that have occurred in this first phase would lead one to believe that weeks must be necessary for completion. In normal conditions, all these events happen within the first four days after injury. Complications, major injuries, and secondary trauma elsewhere in the body can prolong the inflammatory period. Our main directive is to minimize all factors that can prevent or prolong inflammation. Treatment is directed toward assisting the role of the macrophage through the use of antibiotics, debridement, wound cleaning, RICE regimen, and proper positioning.
With the inflammatory phase completed, rebuilding can commence. This phase is named for the primary cell of scar production - the fibroblast. Although many different cells are involved in the inflammatory phase, fewer types of cells operate in the fibroplastic phase; their work will last about three weeks. The purpose of this phase is to resurface and impart strength to the wound.
Clean approximated wounds will show signs of clinical resurfacing within 48 hours, however larger more open wounds can take several weeks for this thin covering to become multi layered and to differentiate into the different normal layers of the skin. Skin healed in this manner, however, never truly develops a full basal layer of cells and will always be thinner in appearance.
Unlike the production of the new cells that is blanketing the wound closed, contraction is a process where the entire wound is pulled closer together. This, in effect, makes the entire wound smaller, minimizing the area that needs to be healed.
This is the climax of the wound healing. Collagen is laid down in a loose disorganized pattern. It is not the amount of collagen that is deposited that governs the strength. It is the cross linked bonds that form between them. The more intermolecular bonds the stronger the filament.
Successful wound healing requires more than closing the wound with sufficient tensile strength. The ultimate goal is the return of function. Remodeling requires the scar to change to fit the tissue. This differentiation is critical. The process of scar remodeling, which is not fully understood, is responsible for the final aggregation, orientation, and arrangement of collagen fibers.