Economic issues are just as important as scientific advances in driving changes in medical techniques. Last year, in the USA alone there were 500,000 knee operations, which swallowed up a staggering 8.2 percent of the country’s Medicare budget. But as well as being expensive, these procedures are both painful and clinically unsatisfactory, as many operations have to be repeated when the implant breaks down. It would be so much better if the metal and plastic device could be replaced by something that continuously repairs itself and actually gets stronger in response to physical forces – in other words, something more like the original bone and cartilage.
One of the leading groups developing new tissue engineering treatments for osteoarthritis is based at Columbia University, New York. The team used magnetic resonance imaging to obtain precise measurements of the shape of a rabbit’s shoulder joint and, with computer-aided design technology, they created a replica implant made from a combination of synthetic and natural bone materials. This was then coated in the rabbit’s own stem cells grown and used to replace the original joint. The properties of the cartilage that formed on the surface of the implant were identical to the natural material and after about four weeks the treated rabbits showed no signs of a limp.
The group now wants to start trials of the technology in human patients but warns that, even if these are successful, it may take ten or more years before the operation is widely available. They first have to prove the safety of the method and then show that the artificial joints will stand up to several years of routine use.
