'Grow your own' hip replacements in a decade When the stem cells attached themselves to the material, they took this as the signal to turn themselves into bone cells rather than blood cells, he added. He said the idea behind the seven-year project was to create a type of artificial bone which could help heal shattered or worn out limbs. Those with osteoporosis could benefit, he said, before adding: "Certain things wear out before others - hips for example." He continue: "The idea is that you would shape a replacement hip to what was wanted, put it in position, and wait. Over time the cells would recruit on to the scaffold, which would itself start to degrade. The good bone formed would take its place. He and Richard Oreffo, professor of musculoskeletal science at Southampton University, have started testing the material in animals. They have also proved the principle with human tissue in lab tests. Their study, published in the journal Advanced Functional Materials, was funded by the Biotechnology and Biological Sciences Research Council. Prof Bradley said: "We would like to start human trials, but we have to get regulatory approval, which takes time and is expensive. It will probably be five years until we start them. He emphasised that, if these trials were successful, it would be longer still before 'plastic hips' were widely available to patients. Prof Oreffo said before whole hips were created, it could be used to help surgeons add bone material when carrying out second hip replacements using conventional implants. "If you have a hip replacement, and you have to have it revised after 10 or 15 years, you need bone stock to keep it from rattling around," he said. This is because when surgeons take out an implant and replace it, they need to take a little more natural bone off to create a fresh surface. He explained that the material was "osteo-conductive" for stem cells: "They realise this is a nice structure to colonise" He said they had already tested the technique in mice and would next be trying it in sheep. Part of the purpose of the trial is to rule out any toxicity issues. Bone fragility is a huge health issue in Britain, one which will increase as the number of older people rises. According to the National Osteoporosis Society, there are about 300,000 fragility fractures in the UK every year, while some 14,000 die due to hip fractures. Neither are hip replacements confined to those with osteoporosis. Significant numbers have hips replaced at a relatively young age. They then need second replacements as they original prosthetics wear out. Problems have also arisen recently with some types of "metal-on-metal" implants, which are meant to last longer, but have been found to have high failure rates and potantially cause blood poisoning.