A scar is a mark left on the skin after an injury like a cut, burn, or surgery has healed. It is the result of the body’s natural repair process, which involves creating new tissue to close the wound. This new tissue, however, often has a different texture and quality than the surrounding skin, creating a visible mark.
The Biological Process of Scarring
When the skin is injured, the body initiates a repair process. The first response is hemostasis, where blood vessels constrict and a clot forms to stop the bleeding. This is followed by the inflammatory phase, where white blood cells clear away bacteria and damaged tissue, causing redness and swelling.
Following inflammation, the proliferative phase begins. During this stage, which can last for several weeks, cells called fibroblasts migrate to the wound and produce collagen. This collagen forms new connective tissue, and new blood vessels develop to supply nutrients. This process fills and closes the wound, building the foundation of the scar.
The final stage is the maturation or remodeling phase, which can last for months or years. During this phase, the rapidly deposited collagen is reorganized and strengthened. Haphazardly arranged collagen fibers are broken down and replaced with more organized ones, increasing the tissue’s strength. However, this new structure is never identical to the original skin, which results in the visible texture of a scar.
Common Types of Scars
Scars present in various forms, depending on the injury and the body’s healing response. Atrophic scars, for example, appear as sunken or pitted indentations. These result from a loss of underlying tissue, like fat or muscle, and are often associated with acne or chickenpox. The depressed appearance is caused by insufficient collagen production during healing.
In contrast, hypertrophic scars are raised and red, developing directly at the site of an injury. They form due to an overproduction of collagen but remain within the original boundaries of the wound. These scars often appear within weeks of the injury and may gradually improve in appearance over a year or two.
Keloid scars are another type of raised scar. Unlike hypertrophic scars, keloids grow beyond the original wound site and invade the surrounding healthy skin. They can become large, itchy, or painful. Keloids are more common in individuals with darker skin tones and can appear long after the initial injury.
Contracture scars result from burns or other injuries causing a large area of skin loss. As the wound heals, the new skin and underlying tissue pull together, or contract. This tightening can restrict movement, especially if the scar is located over a joint. The severity of the contracture depends on the depth and size of the injury.
Factors That Influence Scarring
Several factors influence a scar’s final appearance, including age and genetics. Younger skin has a more robust healing response and higher collagen turnover, which can lead to more prominent scars. Genetics also have a substantial impact, as a family history of keloids can indicate a predisposition to forming them.
Wound location is another factor. Skin over joints like the knees or elbows is under constant tension, which can lead to larger scars. Similarly, the tighter skin on the chest, back, and shoulders makes these areas more prone to hypertrophic and keloid scarring.
The nature of the initial injury is a primary factor. Deeper wounds that damage the lower skin layers, or dermis, are more likely to result in significant scarring. The duration of the healing process also matters, as wounds that take longer to close due to infection or other complications often produce more substantial scars.
Methods for Scar Management
Managing the appearance of scars often begins with at-home care. Sun protection is important, as exposing a new scar to ultraviolet (UV) radiation can cause it to darken and become more noticeable. Applying a broad-spectrum sunscreen with a high SPF helps prevent this post-inflammatory hyperpigmentation.
Silicone products, available as gels or sheets, are a common at-home option. They work by hydrating the scar tissue and regulating fibroblast production, which can help soften the scar and reduce its height and redness. Gentle massage can also be beneficial, as it helps break down dense collagen bundles and improve flexibility, particularly for contracture scars.
For scars that do not respond to at-home care, professional treatments are available. Laser therapy uses focused light to resurface the skin, reduce redness, and improve texture. Different lasers can target blood vessels to diminish discoloration or remove the outer skin layer to stimulate new collagen growth.
Other professional options include microneedling, which creates tiny punctures in the skin to encourage new collagen formation. Steroid injections can be administered into raised scars, like keloids and hypertrophic scars, to reduce inflammation and shrink them. Surgical scar revision may also be performed to remove the old scar and re-close the wound for less noticeable healing.