Formation of hypertrophic scars: evolution and susceptibility.

Formation of hypertrophic scars is a common complication of wound healing, and at present little is known about the incidence and risk factors. Our aim was to analyse the incidence, progression, and regression of postoperative hypertrophic scars over time and to identify risk factors of hypertrophic scars. Patients who had had bilateral reduction mammoplasty or median sternotomy incision were included in the study. All patients were examined at 3 and 12 months postoperatively. We recorded: height, weight, allergy status, smoking status, skin type, tanning, and shape of the scar 3 and 12 months postoperatively. Of the 204 patients who were included, 122 (60%) developed a hypertrophic scar within 12 months of operation. Of these patients, 117 (96%) developed a hypertrophic scar within 3 months of operation. Twelve months postoperatively, 66/204 patients (32%) had a hypertrophic scar. In 31 of the 66 of the patients with a hypertrophic scar 3 months postoperatively (47%), the hypertrophic scar(s) regressed after 3 and 12 months. Smoking and age were associated with formation of hypertrophic scars. In conclusion, 60% of patients developed hypertrophic scars postoperatively, typically during the first three months. Most hypertrophic scars that are present after three months are still hypertrophic after 12 months. Young, non-smoking patients are more susceptible to formation of hypertrophic scars.