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The Medical All-Rounder Called Light (Part 1)

The Medical All-Rounder Called Light (Part 1)

He has never heard of Darth Vader from the science fiction film Star Wars, but the idea of a laser sword is a totally realistic one for Peter Hering. The professor knows all about the cutting potential of light. He is chairman of the Institute for Laser Medicine at the University of Düsseldorf in Germany and works on a device that cuts easily through bone. A task that requires a lot of sensitivity because on one hand bone is an incredibly strong material - twice as strong as granite and with a melting point of 1300 degrees Celsius - and on the other hand it is a very delicate living tissue that cannot withstand temperatures above 42 degrees. Heat kills the cells.

Due to these particular properties the bone saw used in surgery is not the best choice when it comes down to cutting bone: It destroys bone cells mechanically, but also through a side effect: The hard work required for cutting through bone makes the sweat ooze out of the surgeon's pores and also causes frictional heat in the surgical margins - a death sentence of adjacent bone cells. According to Hering the new laser system prevents such disadvantages by using another particular bone feature: Nearly a quarter of it is made up of water.

Microexplosions divulse bone


Photo: Laser cuts through an animal bone

Hering and colleagues therefore produced a laser with a particular wave length that heats up water in not time. „This happens so fast that the water virtually explodes which in turn happens so quickly that the bone margins cannot heat up.“ The laser pulse lasts a few nanoseconds and penetrates the bone for 20 micrometers where the tiny water bubbles rip off nearby bone tissue. Point by point the laser works through the hard living material resulting in a very thin cut of 150 micrometers which is a few dozen times smaller than the cut caused with a modern saw. „Just enough space for one of my beard hairs“, says Hering.

This procedure allows to work without touching tissue and a surgeon is now able to produce curved cuts which may improve heart sugery: Up to now the thorax is opened with a straight cut and closed rigidly with wires after surgery. The new laser enables the surgeon to make a sinusoidal cut. „Around 40 per cent of the patients having undergone conventional surgery suffer from pain during breathing. They are scared because they do not know whether the pain is due to problems with the heart or recovery“, Hering states. The curved cut could theoretically support the healing process since the bones seem to get a grip on each other and that way are able to slightly move back and forward during breathing. „We expect that this procedure works better“, Hering says.

- Part 1: The Medical All-Rounder Called Light
- Part 2: The Pathologist and the Tip of the Endoscope


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