Hypertrophic scars. (With permission from Mulholland MW, Lillemoe KD, Doherty GM, Maier RV, Upchurch GR, eds. Greenfield’s Surgery. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.)

Keloids. (With permission from Mulholland MW, Lillemoe KD, Doherty GM, Maier RV, Upchurch GR, eds. Greenfield’s Surgery. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.)

Keloid

•Can occur anywhere

•Scar extends beyond the borders of the original scar tissue due to collagen deposition in adjacent tissue

•Fibroblast collagen synthesis is 20 times normal

•Can be improved with topical or injectable glucocorticoid use

•Typically recur following surgical excision

•Can use radiation therapy in refractory cases

•Has a genetic disposition

Excessive scar tissue that forms hypertrophic scars or keloids usually develops within 6 to 8 weeks after the original injury.

A 45-year-old female presents with a hypertrophic scar on her left hand after sustaining a thermal injury approximately 1 year ago. What is the predominant collagen in scar tissue?

Type I is the predominant collagen type in a wound scar by day 3 or 4. The initial collagen in wounds is type III.

Collagen

•A protein polymer that acts as scaffolding for our bodies

•Has proline as every third amino acid

•Also has an abundant amount of lysine

•Type III collagen is the initial collagen in wound healing and is then replaced by type I collagen

•α-Ketoglutarate, vitamin C, oxygen, and iron are needed for hydroxylation of proline and subsequent cross-linking of proline residues

•Scurvy is vitamin C deficiency

•D-Penicillamine prevents collagen cross linking

•Maximum collagen accumulation at 2 to 3 weeks

•Afterwards, the amount of collagen remains the same but continued cross-linking improves collagen strength

Mutations in type I collagen produce osteogenesis imperfecta, which is characterized by deformed bones, short stature, and abnormalities of teeth.

A 64-year-old male had a ventral hernia repair performed 2 days ago. When will the wound achieve the greatest tensile strength?

Eight weeks. Wounds gradually increase their tensile strength as collagen deposition continues and scar remodeling takes place.

Tensile Strength

•After 3 weeks, tensile strength is only 15% to 30% of original strength

•After 6 weeks, tensile strength is 80% of original strength

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