The body’s natural response to skin injury is to form a scar, a process that closes the wound by laying down new collagen fibers. While most scars mature into stable, flat, and largely unnoticeable tissue, a small percentage fail to follow this typical trajectory. An unstable scar never fully stabilizes, remaining fragile, dysfunctional, and prone to chronic problems. This persistent vulnerability requires specialized attention to prevent long-term functional and health consequences.
Identifying the Characteristics of an Unstable Scar
An unstable scar is a fragile repair site incapable of withstanding normal mechanical stress, leading to chronic breakdown or discomfort. Unlike a mature scar, an unstable scar continues to exhibit persistent irritation and structural weakness. Clinically, it is defined as a scar with a “frequent loss of covering of skin,” meaning it regularly breaks open, ulcerates, or fails to maintain an intact surface layer.
Patients often report chronic tenderness or neuropathic pain, which can feel like burning, shooting, or electric sensations. Persistent itching, known as pruritus, is also a common sensory complaint. The texture of the scar tends to be abnormal, often appearing thin, shiny, and atrophic, or conversely, thick and rigid.
Frequent minor trauma causes the surface to separate, resulting in recurring wounds that resist complete healing. Scars that are constantly raised, red, or that spread beyond the original wound boundaries, such as keloids or hypertrophic scars, are also considered unstable due to their ongoing biological activity and abnormal structure.
Underlying Causes of Scar Instability
Instability arises when the biological and mechanical forces involved in wound healing are compromised. One major contributing factor is high mechanical tension across the wound site, such as scars located over joints or areas of constant movement. The constant pulling motion prevents the newly formed collagen matrix from organizing into a strong, stable structure.
Poor blood supply, or ischemia, is another significant cause of instability. Tissues damaged by severe trauma, radiation therapy, or underlying conditions like diabetes may lack the necessary oxygen and nutrients to complete the maturation process. When the tissue is poorly vascularized, the scar remains weak and susceptible to breakdown.
Chronic, low-grade infection or inflammation during the initial healing phase can also disrupt the orderly process of scar formation. This prolonged inflammatory state leads to a disorganized deposition of collagen and failure to establish a durable epidermal layer. Scars located on the lower extremities face increased risk due to gravity and pressure, which can impair circulation and increase the likelihood of recurring ulceration.
Serious Complications of Chronic Scar Breakdown
The long-term failure of an unstable scar to stabilize can lead to severe structural and medical complications. One debilitating consequence is the development of severe contractures, where the scar tissue tightens and shortens, restricting the movement of adjacent joints, muscles, or tendons. This functional loss is particularly problematic when the scar crosses a joint, significantly limiting physical ability.
Chronic non-healing ulceration is a direct result of the tissue’s fragility, where the skin surface repeatedly breaks down and fails to close for extended periods. This persistent open wound introduces a risk of chronic infection and significant pain. For scars that have been unstable for many years, there is a rare but serious risk of malignant transformation into a form of skin cancer known as Marjolin’s ulcer.
Marjolin’s ulcer is most often a highly aggressive squamous cell carcinoma that develops within the long-standing, non-healing scar tissue or chronic ulcer bed. The chronic cycle of inflammation, tissue damage, and incomplete repair creates an environment conducive to this malignant change. Any unhealed ulcer in a scar that persists for three months or more, especially if it develops new pain, bleeding, or foul odor, warrants immediate biopsy.
Options for Stabilization and Repair
Treatment for unstable scars aims to remove the problematic tissue and replace it with healthy, well-vascularized skin that can withstand normal tension. Conservative management is the first approach, involving specialized topical treatments like silicone sheets or gels to regulate collagen production and hydration. Pressure garments and specialized dressings are also used to manage chronic breakdown and reduce mechanical stress on the fragile area.
Corticosteroid injections are frequently used to treat instability symptoms, helping to reduce thickness, inflammation, and associated pain or itching. These injections target the overproduction of collagen and local inflammatory processes that contribute to the scar’s abnormal structure. This non-surgical approach can stabilize many hypertrophic or keloid components.
When conservative methods fail, surgical intervention becomes necessary to achieve stable coverage. The procedure involves complete excision of the unstable scar tissue, followed by reconstruction using techniques designed to release tension. This reconstruction may involve a skin graft, where healthy skin is transplanted, or a local flap, which uses adjacent, healthy tissue with its own blood supply to cover the defect. The goal of surgery is to introduce durable, pliable tissue that will mature into a stable and functional surface.