Granulation is the phase of wound healing in which the wound is firmly closed and new tissue is replicated. During granulation, (problematic) scarring may also occur.
What is granulation?
Granulation is the phase of wound healing during which the wound is tightly closed and new tissue is replicated. A bleeding wound is initially provisionally closed by the body with the help of platelets and fibrin. These are components that are present in the blood of healthy people at all times, so that they are immediately available if needed. In the first step, the sticky fibrin forms a net in which the large platelets are caught to form a tight wound closure as soon as the structure dries. Granulation begins about 24 hours after this preliminary wound closure. Within 72 hours of injury and formation of a wound, granulation is finally at its peak. During this phase of wound healing, the body has taken enough preliminary measures to shield the wound from the outside, so that vessel-forming cells (endothelial cells) now accumulate in the wound area, especially at the wound edges. From there, injured vessels are reconnected, and new vessels and vessel segments are formed. Any invading bacteria are rendered harmless by macrophages, so that no wound infection can develop. This is also why the wound feels warm during granulation, may swell, and the skin around it may appear reddened. This is a normal and healthy immune response and is not a cause for concern unless these signs are too obvious or associated with feeling ill. Fibroblasts provide further new tissue formation beneath the wound crust. In doing so, they feed on the breakdown of the accumulated platelets, causing the wound crust to fall off on its own when sufficient new tissue is formed. Therefore, there is no need to remove the formed crust of a wound by itself. This tends to disrupt and delay the delicate granulation.
Function and task
Granulation is a crucial phase of wound healing, but one during which wound healing disorders can occur. First, the body works to temporarily close a wound as best it can. This is done by a sticky fibrin net that forms over the wound to trap platelets, which form a tight seal on the outside. Underneath, new skin and new tissue structures can be recreated in the shot, which would not be possible if the wound were still open. In granulation, therefore, the body recreates the tissue it lost in the injury. The replication of skin, vessels and connective tissue is not a problem; even small parts of organ structures can be replicated in this way. Without this important step in granulation, the injury would last a lifetime, but a temporary wound closure made of platelets cannot last that long. It is brittle and softens in fluids. In children, the rebuilding of tissue in the granulation often still works very well – often the healed wound is no longer visible afterwards. In adults, on the other hand, wound healing also still takes place efficiently, but they are more likely to be left with a visible scar after granulation. This is due to the fact that the new tissue regenerates more slowly at an older age and is somewhat more unstable.
Diseases and complaints
Granulation is a crucial phase of wound healing; however, wound healing disorders can occur during this phase. Initially, coagulation disorders may occur, for example, due to hemophilia or as a side effect of medication, but also in large and severe wounds. If coagulation cannot occur, granulation cannot occur either, since stable wound closure must be present for this to occur. During granulation itself, there is the greatest risk of problematic scar formation. During the granulation phase, large amounts of collagen are regenerated as connective tissue. The newly regenerated tissue therefore no longer corresponds to the previous structure anyway. In small wounds and when young, a scar is often indistinguishable from the surrounding skin. With increasing age, however, and also with large or unfavorably developed wounds, granulatio is more difficult for the body.Another possible complication of granulation is fibrin persistence. The fibrin that accumulates on the wound is normally degraded as new collagen is incorporated during wound healing. However, if this does not occur, as may be the case in chronic wounds, the remaining fibrin is deposited on the wound surface. In addition to these complications, scar fractures can still occur at the scar after granulation, which is due to the fact that the replication of tissue during granulation has not occurred in a sufficiently stable quality. This is more likely to happen with age, but can also be the case with difficult wound edges, too late or incorrect wound care. Wound infections also severely disturb granulation. In some cases, these are even self-inflicted. It is essential to leave a closed wound alone, as granulation can occur as early as 24 hours after the injury. If the wound is scratched open during this time, wound closure must occur again, and the new tissue that has already formed could be destroyed.
