Langer’s lines are areas of tension in the skin created by underlying collagen structures. Wounds created parallel to the lines tend to take the form of narrow slits, while perpendicular injuries will gape because they are pulled by tension. This can have important implications for surgery, particularly in cosmetic procedures where the goal may be to minimize the appearance of scarring. Forensic pathologists also have an interest in Langer’s lines because they can impact the appearance of injuries and may be important to consider when characterizing wounds.
Austrian anatomist Karl Langer noted these distinctive features while performing cadaver research in the 19th century. Other anatomists had taken note of underlying patterns of tension in the skin, but Langer conducted hands-on research to describe and map them. He used a distinctive circular instrument to punch the skin, creating a series of injuries so he could note how the skin reacted. In the course of his experiments, he made several important observations.
One was that far from being static, Langer’s lines could vary between individuals. He was able to create a general map of the lines on the body, but noted that different people might have slightly varying orientations. Additionally, they were dependent on position. Someone lying down had different patterns of tension than someone bending over, for example. His experiments, relying on cadavers, weren’t a perfect illustration of how skin tension behaved in the body because his subjects weren’t able to pose dynamically.
Despite some of the issues with Langer’s lines, they can be a useful tool. In surgery, incisions may be placed parallel to tension, if possible, to reduce the risk of creating gaping surgical wounds. The reduction in tension can also mean that the edges of the injury will pull less during healing. This can translate to reduced pain for the patient as well as smaller scars. For very small incisions, the surgeon may attempt to hide the cut in a fold of skin so the scar will be invisible after recovery.
Additionally, pathologists consider Langer’s lines when they evaluate bodies. The shape of an injury can depend on how a weapon enters the body and where, an important factor in evaluating victims of crimes. Positioning can also be important. From the nature of an injury, a pathologist may be able to determine how the victim was positioned at the time, based on the angle of entry and other wound characteristics.