Like many other materials, human skin has a "grain" to it. What's more, cutting across that grain leads to more visible scars than cutting along it. A new device, currently in prototype form, could help surgeons ensure that they're doing the latter.
The skin's dermis layer is made up of collagen and elastin fibers, which are aligned in a certain orientation. This causes the skin to exhibit greater stiffness when stretched in a given direction – the result is "tension lines," which it's possible to see on the skin's surface. Surgeons will ascertain the direction of those lines, then make their incisions in that same direction. This reduces the likelihood of raised keloid scar formation.
Typically, surgeons either use body maps, that show what the tension-line direction tends to be in different parts of the body, or they manually manipulate the skin in order to see the lines for themselves. Because everyone's body is different, though, the maps can only serve as approximations – plus not all maps are in agreement with one another. Manual manipulation can also be inaccurate.
That's where the new device comes in.
Developed by a team at New York's Binghamton University, it uses a vacuum pump to painlessly apply radial stress to a circular area of the patient's skin. A computer-connected dermal camera then analyzes the resulting deformations of the skin, determining the direction of greatest skin stiffness – and thus the true direction of the tension lines. The whole single-test process takes only a few seconds.
Although there are other devices that serve the same basic purpose, Assoc. Prof. Guy German states that his team's technology is superior.
"Many devices require more than one measurement to establish the direction, and the devices that use a single test can currently only measure the skin tension direction to an accuracy of 45 degrees," he says. "Rather than using guidelines, our device directly measures the skin tension direction, avoiding the need to use maps or guidelines. We believe our device is more reliable and accurate than existing methods."
A paper on the research was recently published in the journal Acta Biomaterialia.
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