Pracrise Listening 33 - 3D Printing Inside the body shop - Thấm Tâm Vy

Thẩm Tâm Vy, May 18, 2019 PRACTISE LISTENING 32

3D Printing

INSIDE THE BODY SHOP

CARRIGTWOHILL Using 3d printers to make implants should improve orthopaedic surgery

A robotic lawnmower keeping the grass neat and tidy outside a modern industrial building in Carrigtwohill, near Cork in Ireland, is a good indication that something whizzy may be going on inside. And so it proves. The airy production hall contains row after row of 3D printers, each the size of a large fridge-freezer. The machines are humming away as they steadily make orthopaedic implants, such as replacement hip and knee joints. Even though several hundred employees’ cars are parked outside, the hall is almost deserted.

Every so often a team appears, a bit like a Formula One pit crew, to unload a machine, service it and set it running again to make another batch of implants. It is not unusual in modern, highly automated plants to find the workforce distributed like this, with most of them in the surrounding offices engaged in engineering tasks, logistics, sales and so on, rather than on the factory floor. But this two-year-old factory, owned by Stryker, an American medical-technology company, differs from conventional manufacturing in another way as well. It is an example of how 3D printing, which a decade ago was seen by manufacturers as suitable only for making one-off prototypes, is quickly entering the world of mass production. For commercial reasons, Stryker keeps some of the details secret. But the factory, the largest 3D-printing centre of its type in the world, works around the clock and is said to be capable of producing “hundreds of thousands” of implants a year. Those made at Carrigtwohill have a feature that is impossible to create with conventional techniques such as casting and machining. Because 3D printing lays down an object layer by layer, complex shapes with intricate internal structures can be built. Stryker uses this facility to print a special porous surface onto the implants. That surface encourages bone to grow into the implant, which secures it more firmly in place. When combined with the precision of robotic surgical processes the firm has developed, this makes replacements more successful, says Robert Cohen, the company’s technology chief. Replacing worn and damaged body joints with implants is an old idea. The first hip-replacement operation was performed in 1891, in Germany, by Themistocles Glück, using a ball and socket carved from ivory. And Phillip Wiles, a surgeon based in London, carried out the first successful totalhip replacement in 1938, screwing a stainless-steel joint into the patient’s bone. Since then, things have moved on. Cobalt and chromium alloys, along with titanium, are now more commonly employed for implants than steel is. And operating procedures and devices have improved greatly, including the use of hard-wearing ceramic surfaces as bearings. Nevertheless, complications still arise. One of the commonest is dislocation—with, for instance, the hip ball coming out of the socket because soft tissue has not healed properly. A loosening of the implant over time is also a frequent problem, causing pain and a need for remedial surgery. That, though, should be helped by the implant’s porous surface encouraging bone and implant to meld, making such loosening far rarer than it was.

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