The relationship between keloid growth pattern and stretching tension: visual analysis using the finite element method.

BACKGROUND Keloids grow and spread horizontally, like malignant tumors, for reasons that remain unknown. Yet, stretching tension is clearly associated with keloid generation, as keloids tend to occur on high tension sites such as the anterior chest and scapular region. Thus, we analyzed the relationship between keloid growth patterns and stretching tension using a visualized finite element study. MATERIALS AND METHODS Keloids, normal skin, and fat structures were reproduced using DISCUS software. The contours were transferred to ADINA analytical software to rebuild and mesh volumes. RESULTS (1) High tension was observed at the edges, and not in the entire region, of stretched keloids. (2) Keloid centers were regions of low tension, which helps to explain the healing that generally occurs in the central regions of keloids. (3) Expansion of a keloid occurred in the direction in which it was pulled. (4) The "crab's claw"-shaped invasion occurred in response to increased stretching tension. (5) Skin stiffness in the circumference of a keloid was associated with greatly increased tension. (6) Fat hardness and thickness did not influence the amount of tension. (7) Adhesion with subcutaneous hard tissue greatly increased the tension in the keloid. CONCLUSION These stretching results have advanced understanding of keloid formation under various conditions. Our results suggest that stretching tension is an important condition associated with keloid growth.