The Zweymüller prosthesis, developed at the end of the 1970s, was one of the first to be anchored in the bone without using bone cement to fix it in place. The prosthesis's special geometry and surface guarantee its stable anchoring and natural integration into the bone. Its hallmark feature is the roughened surface of the stem, which provides a place for the new bone tissue to grow onto.
In the past, the endoprosthesis has been made from ultra-lightweight titanium, has been implanted millions of times over, and has even been used in minimally invasive procedures with an incision in the skin measuring around ten centimetres. Nowadays, it is used in combination with a ball and socket made from ceramic, which produces less wear. In 67 per cent of the 200 test subjects investigated, the durability of the ball and socket, i.e. the second outcome of the study, which has now been published in the highly respected journal "The Journal of Bone and Joint Surgery", is still intact after 20 years.