The snap, crackle and pop of the knee could one day be used to help orthopaedic specialists assess damage after an injury and track the progress of recovery.
Research engineers at the Georgia Institute of Technology are developing a knee band with microphones and vibration sensors to listen to and measure the sounds inside the joint.
Omer Inan, assistant professor of electrical and computer engineering and a former discus thrower, pitched his idea for the device after the US Defense Advanced Research Projects Agency (DARPA) issued a call for research proposals on wearable technologies that could assist rehabilitation.
According to Georgia Tech, when he heard the first recordings of a knee joint´s crackly grinding in early experiments, Inan was delighted.
“It was a lot louder than expected and a lot clearer,” he said.
Wearers of the device can be somewhat alarmed when they hear the sound, however.
“It´s a little bit like some kind of Halloween stuff happening. You´re listening to your bones rubbing on each other, or maybe cartilage,” Inan explained.
The researchers have transcribed the knee sounds into moving graphs and found that the acoustic pattern produced by an injured knee is markedly different from that of an intact knee.
In the future, Inan hopes that medical research will build on the acoustic sensing technology his group is designing, and eventually decode the sound into useful patterns.
One day the research could lead to inexpensive, wearable monitors which could benefit athletes who have overburdened their knees, or elderly patients who have slipped and fallen. DARPA, meanwhile, wants to cut down on repeat knee injuries among soldiers and help them get back to duty safely.
Inan discusses his group´s work in a YouTube video at https://youtu.be/rCGCv17Spx4.
Details of their progress to date can be found in a paper published in the journal IEEE Transactions in Biomedical Engineering.