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The time factor: Understanding the temporal influence on hypertrophic burn scar development

Vita Yu-Hsien TU, Occupational Therapist and Project Manager,

Sunshine Social Welfare Foundation

 
hypertrophic burn scar development

The development of scars after a burn is almost inevitable, and scar hypertrophy is one of the processes of wound healing in the human body. Did you know that there is an intricate relationship between “time” and scar hypertrophy, and that the timing or the length of time of many events or factors has an impact on scar hypertrophy? In this article, we’ll discuss the temporal influence on hypertrophic burn scar development, as well as key precautions to prevent hypertrophic scars.


5 ways in which time influences hypertrophic burn scar development

  1. Wound healing time

  2. Length of wound inflammatory response

  3. Timing of wound debridement

  4. Time in life when the burn injury occured

  5. Time of collagen synthesis


How does “time” influences hypertrophic burn scar development?


Wound healing time

The longer it takes for a wound to heal, the higher the chances of developing hypertrophic scars. Usually, wounds that take more than 14 days to heal are likely to become hypertrophic scars, and wounds that take more than 21 days to heal have an even higher chance of developing into hypertrophic scars.


Length of wound inflammatory response

The longer wound inflammation lasts, the easier it is for the wound to develop hypertrophic scars. When the wound is in a state of continuous stimulation from an inflammatory response, it delays wound healing and promotes the development of hypertrophic scars.


Timing of wound debridement

In a study examining the timing of debridement using a porcine model [1], meaning wounds on pigs’ skin, early debridement at two days post-injury reduced scar thickness to a greater extent than late debridement at 14 days post-injury.


Time in life when the burn injury occurred

By this we mean the effect of age at time of injury. People have different metabolic rates at different age, and this will affect scar hypertrophy. Collagen proliferation in young people is more active and rapid, meaning that a child who sustained burns will produce more collagen at a faster rate, and is thus more likely to develop hypertrophic scars. Scars of teenagers who are still in their developmental period are also more prone to thickening. On the other hand, wounds of elderly people heal slowly and rarely produce hypertrophic scars, because at their age, they produce less collagen at a slower rate.


Length of collagen synthesis process

There are many mechanisms that interact with one another during the wound healing process. The main mechanisms that affect scar hypertrophy are myofibroblasts that act to contract the wound, and the synthesis of collagen, which usually reaches a peak 2 to 3 months after the injury, and then progressively starts to slow down. The issue with collagen synthesis is that it reaches its peak very rapidly within 2 to 3 months, but the decline is very slow and progressive, taking one or even two years. [2]


What are precautions or considerations to prevent or reduce hypertrophic burn scar development?


Knowing that the timing or length of time of many events is related to hypertrophic scar development, what are special considerations or precautions that we should be aware of in our clinical practice? Although we cannot stop time nor can we turn back time, there are key points to remember.


Incorrect or improper wound care will increase the risk of hypertrophic scar development

Anything that delays wound closure, makes the wound more severe or prolongs the inflammatory phase will only increase the chance of hypertrophic scar development. In the immediate early stage of the injury, incorrect first aid (like using toothpaste or soy sauce on the burn wound), not only risks causing infection and prolonging the inflammatory phase, but it also fails to cool down the wound, with the heat reaching deeper within the dermal layers and causing more damage. The deeper the burn wound, the higher the risk of hypertrophic scar development. In addition, poor wound care in later stages of wound healing may delay wound closure or result in wound infection. It is recommended to follow the advice of medical personnel and perform wound care correctly.


Just because there is no hypertrophic scar at the time of hospital discharge, doesn’t mean that there will not be any later.

Some patients do not have hypertrophic scars when they are discharged from the hospital and will easily think that there won’t be any in the future, therefore they may think that rehabilitation or follow-up is unnecessary. The fact is that collagen synthesis may have just begun to increase and will soon enter the most active stage, therefore scar development needs to be carefully monitored. Understanding at which stage of wound healing is the patient (How long since the injury? How much time was necessary for wound closure?), as well as other individual factors that may affect scar development (like age, race, etc.) can help determine the risk of scar hypertrophy. That is why it is still recommended to continue follow-up for several months.


Scars can rapidly reach their development peak in a short period of time

As mentioned above, some patients do not have hypertrophic scars when they are discharged from the hospital. However, collagen synthesis can rapidly gear up and the rate can reach its peak in a short period of time. Therefore, hypertrophic scars can start to develop rapidly. Maybe the scar looked flat last week, but it will become raised two weeks later. Therefore, it is recommended that pressure therapy interventions be provided preventively, so as not to be caught off guard the next time the patient returns for a follow-up consultation. If at first you are not sure how scars will evolve and whether it will be necessary to make pressure garments, elastic bandages and self-adhesive elastic bandages like Coban can be used as temporary scar control measures (mostly for upper and lower extremities), which is also a good preventive pressure therapy intervention.


Overall, time is an important factor affecting scars. Wounds need to be treated immediately and accurately, and preventive treatments for scars need to be provided in a timely manner to effectively prevent the occurrence of hypertrophic scars.


References:

1. Singer AJ, Toussaint J, Chung WT, McClain SA, Raut V, Rosenberg L. Early versus Delayed Excision and Grafting of Full-Thickness Burns in a Porcine Model: A Randomized Study. Plast Reconstr Surg 2016;137:972e–e979.

2. Gauglitz, G.G., Korting, H.C., Pavicic, T. et al. Hypertrophic Scarring and Keloids: Pathomechanisms and Current and Emerging Treatment Strategies. Mol Med 17, 113–125 (2011).


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