Prostheses Should Look Natural
Grützmann uses fine spatulas and knives to work out indentations, raised tendons and wrinkles. To make the hand look less artificial and more lifelike, the silicone is not uniformly colored. Instead, viscose flocks, chopped threads and some other tricks are incorporated to provide a degree of three-dimensionality. “Uniformly colored plastic dolls are not translucent, which is why they do not look alive,” says Andreas Leiniger, head of the Silicone department at Ottobock. “We use the material’s translucency to mimic the skin’s light permeability, which allows the different colors of adjacent tissue, veins and bones to influence each other.”
With the aid of photos and the cast of the remaining extremity, the employees at Ottobock – who truly are craftsmen – try to replicate the original as accurately as possible. This sometimes takes so long that the silicone compound begins to cure and can become too hard to work on. When that happens, the craftsmen in Leiniger’s department don pullovers and scarves and repair to the cold store, where the temperature of 17 °C prolongs the time available to work the material into a hand or foot. Once all the subtle details – from original hairs on the lower leg, age and liver spots, through to paintable acrylic fingernails – have been copied, the prosthesis is cured at 130 to 180 °C.
Even after 17 years – Leiniger, a qualified orthopedic technician who has been at Ottobock since 1997 and has expanded the Silicone department from two to 14 employees – never fails to be impressed by the natural appearance that silicone can produce. “A patient once got a fright when she saw her lower leg prosthesis for the first time,” he says with a smile. “The prosthesis looked so lifelike that at first she refused to put it on.” It took her a while to get used to it, but after that she was delighted with it, he adds.