Subcision is a dermatological technique used to treat depressed scars, such as those left by severe acne, by physically releasing the skin from underlying fibrous tissue. The procedure involves inserting a specialized hypodermic or cannula-like needle beneath the skin to mechanically break the bands that pull the scar downward, allowing the skin to elevate. A common concern is the possibility of this controlled trauma leading to a worse final appearance than the original scar. Understanding the risks requires differentiating between permanent structural complications and temporary side effects.
The Subcision Procedure Defined
Subcision, also known as subcutaneous incisionless surgery, is designed to treat atrophic scars tethered to deeper dermal structures. The procedure uses a specialized instrument to sweep beneath the scar, separating the skin from the subcutaneous layer. This action severs the rigid collagen strands that anchor the scar, sometimes producing a soft “snapping” sound. Severing these tethers allows the depressed skin to rise and initiates a controlled injury to stimulate the body’s natural wound-healing cascade. The resulting pocket fills with blood, forming a clot that prevents immediate reattachment and encourages the production of new collagen and elastin fibers.
Structural Complications That Permanently Worsen Scars
The most concerning outcome is the development of a structural change that leaves the treated area objectively worse than the original scar. This occurs when the healing process becomes dysregulated and produces an excessive amount of new tissue. Hypertrophic scarring and, less commonly, keloid formation are examples of this overcorrection, where new collagen deposition extends beyond the original wound. These raised, firm scars are most likely to develop in areas of high skin tension, such as the upper lip, glabella, and periorbital skin.
The risk of developing a raised scar is higher in patients with a history of abnormal wound healing. Structural complications can also arise from issues with the procedure itself. Improper technique can fail to release all tethers, or conversely, cause excessive tissue trauma that results in new, deeper indentations in surrounding, previously unaffected areas.
Another structural issue is the formation of a subdermal hematoma, a collection of blood under the skin that does not properly resolve. If this clot is not managed correctly, it can lead to organized fibrosis, resulting in a firm, palpable lump or nodule beneath the skin surface. A persistent nodule represents a permanent contour irregularity that makes the scar appear worsened or distorted.
Transient Side Effects That Mimic Worsening
Many side effects following subcision cause temporary alarm because they make the treated area look worse, even though they are expected to resolve naturally. Bruising (ecchymosis) is nearly universal, particularly when sharp needles are used, and can be extensive, lasting for one to two weeks. This temporary discoloration and associated swelling can make the original scar appear significantly deeper or more prominent until the blood is reabsorbed.
Post-inflammatory hyperpigmentation (PIH) is another common transient effect that causes the treated area to appear darkened or discolored. PIH results from the inflammatory process stimulating melanocytes, the pigment-producing cells in the skin. This side effect is especially common in individuals with darker skin tones (Fitzpatrick skin types III through VI).
While PIH can persist for several weeks to many months, it represents a change in color, not a change in the scar’s underlying texture or structure. Severe swelling and inflammation can also create temporary lumpiness or asymmetry, masking the procedure’s positive effects. These effects are part of the normal healing response and do not indicate a permanent negative outcome.
Patient and Practitioner Factors That Determine Risk
The risk of a negative outcome is influenced by the patient’s individual biology and the skill of the practitioner performing the subcision. Patients with a known predisposition to forming keloids or hypertrophic scars are at a higher inherent risk for developing an overgrowth of new, raised scar tissue. Patients with active skin infections or those taking medications that impede blood clotting are also at greater risk of complications like infection or excessive hematoma formation.
Practitioner expertise and technical choices play a significant role in minimizing complications. Using an improper angle, depth, or tool can lead to unnecessary trauma to the surrounding tissue, increasing the chances of permanent scarring or nerve injury. Studies suggest that using blunt-tipped instruments, like cannulas, may reduce the risk of intraoperative bleeding, bruising, and PIH compared to traditional sharp needles. Selecting the correct tool and technique based on the scar type and location is essential for a successful outcome.