Hip hooray

University of Alberta engineers have created a self-powered wireless microsensor that can monitor the bone healing process in people recovering from hip replacement surgery.



‘This microsensor not only reduces post-operation recovery time, it will also help reduce the wait time for patients needing artificial joint implants,’ said Dr Walied Moussa, a professor in the Department of Mechanical Engineering.



During the healing process that follows joint replacement, bone grows and attaches to the pores on the surface of the implant creating greater fixation and stability of the joint. This process is known as osseointegration.



Using nanotechnology, the researchers built a device that measures and compares the relative osseointegration of a hip implant over time. The microsensor will be able to monitor the progression of the biological fixation between bone tissue and the implant.



The sensor is permanently implanted with the joint and is powered kinetically, using the natural movement of the patient’s body as its power source. When it isn’t being used, it stays dormant until a doctor asks it to start transmitting data.



Careful monitoring of how the patient is healing will help patients recover as quickly as possible and resume normal activities with less chance of over stressing the fracture during recovery and rehabilitation. It also allows the surgeon to more accurately decide when it is safe to send patients home from the hospital with their new implants.



‘The ability to monitor and quantify this healing process is critical to orthopaedic surgeons in determining a patient’s rehabilitation progress,’ said Moussa, who has a lab in the National Research Council’s National Institute for Nanotechnology. ‘Until now, there has been no quantitative method for assessing osseointegration.’



The device will also cut down the need for X-rays to monitor bone functionality, reducing costs and exposure to radiation. The sensor can also detect and identify bone before it is even visible on a radiograph.