The Geometry of Skin Grafting: Boundary, Seams, and Epithelialization.

Split-thickness skin grafting remains central to definitive wound closure in burn surgery. Although the biology of successful engraftment is well established, less attention has been paid to the geometric and mechanical determinants of graft behaviour. Broader grafts often appear more stable and require fewer peripheral fixation points per unit area than surfaces reconstructed from multiple narrow pieces. We propose a clinically grounded framework in which graft geometry defines boundary, interior, seams, and epithelialization gaps. Larger grafts have a lower perimeter-to-area ratio and proportionally more interior, whereas multiple graft pieces create internal seams and additional interface length. These principles apply to unmeshed sheet and meshed grafts. Geometry is not an isolated determinant: central fixation, fibrin adhesion, bolsters, wraps, splints, and negative-pressure wound therapy improve coupling and reduce displacement, but do not remove physical edges, seams, or gap geometry. Seam orientation is clinically consequential. Straight seams should be avoided across flexion creases, joints, and concavities when an alternative is available; unavoidable seams should be reoriented, staggered, interrupted, or constructed nonlinearly. In donor-limited grafting, the objective changes. At comparable high expansion ratios of 3:1 or greater, widely meshed grafts and Meek micrografts distribute epithelial fronts and migration distances differently. This conditional framework translates common operative observations into a vocabulary for planning, teaching, and research. It identifies practical decisions under the surgeon's control and generates testable hypotheses regarding interface length, stabilization, seam orientation, and epithelialization distance.