# Topology, geometry and mechanics of surgical Z-plasty

## TL;DR

This paper analyzes the geometry and mechanics of Z-plasty, a surgical technique that reorients tissue stress to minimize scarring, using theory, simulations, and physical experiments to inform surgical decisions.

## Contribution

It provides a quantitative analysis of Z-plasty geometry and mechanics, enhancing understanding of stress reorientation and forces involved in the procedure.

## Key findings

- Quantifies stress rotation achieved by Z-plasty.
- Corroborates theoretical predictions with physical foam experiments.
- Provides insights into optimal surgical angles for Z-plasty.

## Abstract

Reconstructive surgeries often use topological manipulation of tissue to minimize post-operative scarring. The most common version of this, Z-plasty, involves modifying a straight line cut into a Z-shape, followed by a rotational transposition of the resulting triangular pedicle flaps, and a final restitching the wound. This locally reorients the anisotropic stress field and reduces the potential for scarring. We analyze the planar geometry and mechanics of the Z-plasty to quantify the rotation of the overall stress field and the local forces on the restitched cut using theory, simulations and simple physical Z-plasty experiments with foam sheets that corroborate each other. Our study rationalizes the most typical surgical choice of this angle, and opens the way for a range of surgical decisions by characterizing the stresses along the cut.