Understanding the Risk Factors for Burn Hypertrophic Scar Development

Yu-Chieh TSENG, Occupational Therapist, Rehabilitation Supervisor

Sunshine Social Welfare Foundation

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Hypertrophic scars are a common challenge for burn patients and burn rehabilitation therapists. Burn hypertrophic scars typically start forming 6 weeks to 3 months after wound closure and can take years to mature. While scar formation is a natural part of the healing process, understanding the risk factors for hypertrophic scar development can help therapists predict and manage their occurrence more effectively.

In this post, we’ll explore the key factors that influence hypertrophic scar development, focusing on those related to the burn injury, treatment approaches, individual characteristics of the patient, and the broader social determinants that can affect scar outcomes.

Burn Injury and Treatment-Related Risk Factors for Burn Hypertrophic Scar Development

Several aspects of the burn injury and its treatment significantly impact scar development:

1. Wound Closure Time: Burns that take longer than 14 days to heal have a higher likelihood of developing into hypertrophic scars. Prolonged healing time increases the inflammatory response, which is a critical driver of excessive scar tissue formation. You can read more about how the "time factor" affects scar development here.

2. Burn Depth: Burns that extend into the dermis, such as deep partial-thickness and full-thickness burns, are more likely to result in hypertrophic scars. At these depths, the repaired tissues become scars.

3. Burn Location: Certain areas of the body are more prone to hypertrophic scars, especially those subject to high tension or movement. For example, burns involving joints, the neck, axilla, forearms, hands, trunk, knees, ankles, or feet demand careful monitoring. Scars crossing joints or skin creases face constant tension forces, increasing the risk of hypertrophy.

4. Skin Grafting: The type of skin graft surgery used will also influence scar development.

   • Split Thickness Skin Grafts (STSGs): These grafts can develop hypertrophic scars at the recipient site. Because deep dermal structures are not harvested, the STSG is aesthetically and functionally different from normal skin. Additionally, some common methods to expand STSG (like mesh skin graft, postage stamp skin graft) can subsequently form hypertrophic scars. In addition, the donor sites that are repeatedly harvested for STSGs can also be prone to scarring due to the cumulative trauma of multiple harvests.

   • Full Thickness Skin Grafts (FTSGs): Although a FTSG includes the entire epidermis and dermis layers and it will not be subject to scarring in itself, hypertrophic scarring is commonly observed at the suture line of FTSGs.

Individual Risk Factors

Patient-specific factors also play a crucial role in scar development:

1. Age: Younger patients, particularly children, are more likely to develop hypertrophic scars than older adults. This heightened risk is attributed to their robust skin regeneration: younger patients will produce collagen at a faster rate than elderly patients, so scar growth will be more rapid.

2. Genetics and Skin Type: Genetic predisposition is a significant determinant. [1] Individuals with darker skin tones are at a higher risk of hypertrophic scars and keloids.

Social Determinants and their Impact on Scar Outcomes

Scar hypertrophy is an inevitable physiological response to deep tissue injury, with the risk largely determined by factors such as burn severity, wound healing time, and individual patient characteristics. However, it’s important to acknowledge that scar hypertrophy development and its management can be significantly influenced by social determinants that will shape the overall outcome of rehabilitation.

As highlighted in Fanstone and Price's research on burn contracture risk factors in low-middle income countries (LMICs) [2], social determinants such as limited access to healthcare, poverty, and inadequate rehabilitation resources exacerbate the risk of poor outcomes. Her findings emphasize that these systemic barriers often compound the challenges of effective scar management.

Because social determinants impact access to timely treatment, adherence to scar management protocols, and the resources available for optimal healing, they should not be overlooked.

1. Access to Healthcare: Limited access to burn centers or specialized care in the early stage can delay wound closure, increasing the risk of hypertrophic scar development in the future. Lack of essential scar management tools, such as pressure garments or silicone sheets, complicates the scar management process later on.

2. Socioeconomic Status: Financial constraints can limit access to necessary interventions like pressure therapy or follow-up care. Malnutrition, often linked to food insecurity, can affect wound healing and by extension, scar formation. The living environment also has an impact. For example, living in a stuffy apartment without air conditioning can affect compliance with the pressure garment wear schedule.

3. Education and Awareness: Patients and family members with lower literacy may struggle to understand, remember and follow treatment plans, impacting their ability to manage scars effectively. Sometimes, cultural beliefs or misconceptions about scars and treatments may lead to inconsistent or inappropriate care.

4. Psychosocial Factors: Stress, anxiety, or depression, as well as a lack of family or community support may hinder adherence to scar management protocols.

Implications for Burn Rehabilitation Therapists

By understanding the risk factors for hypertrophic scar development, including social determinants, burn rehabilitation therapists can anticipate challenges and develop holistic care strategies. This approach might include:

• Early identification of high-risk patients for timely intervention.

• Tailored education programs to improve treatment adherence.

• Collaborations with social workers or community health programs to address barriers such as access and affordability.

Hypertrophic scars are more than just a medical concern—they are influenced by a complex interplay of biological, environmental, and social factors. Therapists who adopt a comprehensive approach to scar management can significantly enhance outcomes for burn survivors.

References:

[1] Thompson, C. M., Hocking, A. M., Honari, S., Muffley, L. A., Ga, M., & Gibran, N. S. (2013). Genetic risk factors for hypertrophic scar development. Journal of burn care & research : official publication of the American Burn Association, 34(5), 477–482.

[2] Fanstone, R., Price, P. (2024). Burn contracture risk factors and measurement in low-middle income countries: A clinical perspective, Burns, Volume 50, Issue 2, Pages 466-473

To learn more about the development of burn scars and other burn rehabilitation basic concepts, check out our online course Burn Rehabilitation: Introduction to Basic Concepts.