Researchers funded by the Swiss federal Nano-Tera programme have developed a smart knee prosthesis which is able to feed information back on how it is performing. The system will provide a more objective diagnosis of the state of the implant than the patient’s own feelings.
In the coming years, with an ageing population on the one hand and more and more people engaging in recreational sports on the other, we are likely to see an increasing number of surgical operations to replace defective joints. Around one million people in Europe and the United States currently undergo prosthetic surgery to the hip or knee every year. Now a Swiss research team is looking at fitting smart sensors inside knee prostheses. “With the extra information about the prosthesis, we could take preventative measures and explore other avenues of gait rehabilitation without necessarily having to resort to fresh surgery,” explains Dr Brigitte Jolles-Haeberli, head of prosthetic knee surgery at the University Hospital of Lausanne, who has been working with researchers from the Center of Translational Biomechanics at the Swiss Federal Institute of Technology in Lausanne (EPFL). The objective is to detect potential problems early on.
Five laboratories at EPFL in Lausanne began working together in 2009 to develop the Smart Implants for Orthopaedics Surgery (SimOS) sensors. The sensors are designed to fit into the polyethylene insert – the middle part of the knee prosthesis which is common to all such joint replacements, regardless of manufacturer. The system uses an external knee support incorporating wireless communication with the sensors in order to measure a range of biomechanical parameters, including external constraints, temperature due to rubbing, 3D orientation, micro-movements and (with the aid of accelerometers) impacts. These sensors will be particularly useful for detecting cases where the prosthesis is misaligned or if it comes unsealed, which in fact occurs in about 20% of cases.
One more step towards the bionic man?
Most of the progress to date in the field of prosthetics has been in modifying the surface of the biomedical metals which come into contact with body tissue, in order to ensure that the body accepts the prosthesis and to control cell growth around the implant. The development of the SimOS sensors marks a new step in prosthetics research as in the long term they could be used in other joints than the knee. L’Atelier recently interviewed Rich Walker on the subject of creating a human body made up entirely of prostheses. This ‘Bionic Man’ project was mainly intended to support and encourage scientific communication. “You have to see this project as a snapshot of today’s scientific research at a given moment in time,” explained Rich Walker. He believes that we are now witnessing an interesting technological transition which is bringing us closer to a time when robotics will be part of our everyday lives. With such initiatives as the SimOS project, progress in this field is clearly ongoing and may even be speeding up.