Post-surgical healing is a complex, highly coordinated biological process. Whether following knee replacement, MCL repair, C-section, or other orthopedic/abdominal surgeries, tissue repair occurs in predictable phases but may result in different types of scar formation depending on local and systemic factors. Chronic scar tissue is characterized by tightly packed collagen type I fibers, reduced vascularity, persistent fibroblast activation, and often elevated TGF-β1 signaling. This dense and metabolically inactive matrix can restrict mobility, impair tissue glide, and contribute to chronic discomfort.
Phases of post-surgical wound healing includes the hemostasis phase, the inflammatory phase, the proliferative phase, and the maturation/remodeling phase. The hemostasis phase occurs just hours after the incision is closed. Platelet aggregation and clot formation occurs as well as the release of growth factors. The inflammatory phase occurs 1-5 days following the incision. Neutrophils and macrophages clear debris and cytokine signaling initiates tissue repair. Excess or prolonged inflammation during this phase can lead to fibrotic scarring. The proliferative phase occurs days 5-21 following the incision. Fibroblasts proliferate, collagen deposition appears, and the formation of granulation tissue and epithelial resurfacing occurs.
The maturation and remodeling phase is the final, longest stage of wound healing, beginning around 3 weeks after the incision and lasting up to 2 years. During the proliferative and early remodeling phases, type III collagen is rapidly deposited and later replaced by stronger type I collagen to increase tensile strength during the remodeling phase. Eventually, the scar becomes flatter, softer, and less vascular, achieving 70-80% of original skin strength.
Prolonged inflammation during the inflammatory phase of wound healing is one of the primary drivers of excessive scar formation. When inflammation does not properly resolve, the body remains in a “repair alarm state,” which overstimulates fibroblasts and promotes fibrotic tissue deposition instead of organized regeneration. If the tissue continues to experience excess motion at the incision site, high mechanical tension, or micro-tearing from premature activity the body continues to interpret the area as injured and inflammatory signaling continues.
During the proliferative and early remodeling phases when type III collagen is rapidly deposited, if there isn’t adequate oxygenation, vascular support, and metabolic activity, this collagen matrix can become randomly aligned and rigid, and they can’t be replaced by type I collagen leading to failed collagen maturation. The random, dense, and inflexible collagen bundles increase the scar's rigidity and thickness, often resulting in raised hypertrophic scars.
Scar tissue only reaches 70-80% of original tensile strength and is biologically different from native tissue. The primary components of scar tissue include type I and III collagen fibers, fibroblasts, disorganized extracellular matrix, reduced vascular density, and altered nerve fiber distribution. This causes the area to be dense and stiff. It also leads to limited vascularity and irregular nerve regrowth. Symptoms of incision scarring include reduced mobility, tightness, adhesions, altered sensation, and biomechanical dysfunction.
Types of Post-Surgical Scarring
Hypertrophic scar tissue is typically raised, red or pink, and itchy/painful. This type of scarring is associated with prolonged inflammation and is common after joint surgeries where tensions across the incision is high (e.g. knee replacement).
Keloid scarring extends beyond original incision and is thick, rubbery and nodular in appearance. This type of scar tissue can continue growing. Genetic predisposition plays a role in keloid scarring formation.
Atrophic scar tissue is sunken or depressed and has a thinned dermis and reduced collagen deposition. This type of scar tissue is seen in cases or poor collagen synthesis or infection.
Adhesions (deep scar fibrosis) contain characteristics of internal fibrotic bands and restrict mobility. This causes a pulling sensation and chronic pain. This type of scarring may not be visible externally but significantly impact biomechanics. It is most common after knee replacements, MCL reconstruction, C-section, or abdominal/pelvic surgery.
Cesarean Section Scarring
Cesarean section surgery involves multiple tissue layers, including skin, subcutaneous tissue, fascia, abdominal musculature, and the uterus. While the surface incision may appear healed within weeks, deeper fascial and uterine tissues undergo a much longer remodeling process that can extend for months.
In some patients, prolonged inflammation, mechanical tension, hypoxia, or dysregulated TGF-β1 signaling leads to excessive extracellular matrix (ECM) deposition and dense collagen bundle formation. This can result in hypertrophic scarring, internal adhesions, fascial restriction, and altered pelvic biomechanics. Because the uterus and surrounding pelvic organs rely on mobility and adequate vascular exchange, fibrotic changes following C-section can contribute to symptoms such as pelvic tightness, low back discomfort, painful menstruation, bladder pressure, or reduced core engagement.
Stretch Marks
Stretch marks are a form of scarring that appear after the skin quickly stretches or shrinks. They often happen due to pregnancy, weight gain, weight loss, and body building. Stretch marks (striae) are discolored, slightly sunken (depressed), scar-like lines in the skin. Stretch mark symptoms may include sunken lines in the skin, discoloration, glossy skin, itchiness, and irritation. Scar tissue in stretch marks are caused by the tearing of the dermis. When the skin stretches or shrinks too quickly, it disrupts collagen and tears elastin. This triggers the body to produce new collagen fibers to repair the fast changes, resulting in discolored stretch marks.
