Knee replacements are more common now due to exercise and old age. How do doctors know if the replacement knees they place in people are really helping them, or even if they’ll last? Here’s how, sensors, self powered wireless sensors!
Sure it sounds like science fiction; some septuagenarian walks by and throws off your local FM radio to the tunes of “This is an old man walking”. Well ok, that’s not quite how it happens, but sort of.
A Vermont company called Microstrain has developed a sensor suite that is placed inside replacement knee prosthetics.
It couples a perfectly sealed (just like they seal and test pacemakers) unit placed inside Titanium replacement knees (it’s not just for F-22’s and mountain bikes!). With a piezoelectric power generator, (that uses the motion of the walker to power the tiny device) the tiny sensors can deduce bending, twisting, compressive and shearing loads in real time. Then the wireless transmitter inside transmits the data outside of the body wirelessly and to a waiting data logger. The information is received and digested by the researchers in their computer to analyze changes in gait, forces generated, status of rehabilitation, and general wear characteristics over time for the prosthesis.
This system works much like the “Heads up display” telemetry shown in auto racing footage, where throttle, brake, speed, G’s and R.P.M.s are displayed. In the future both external sensing (in the form of a knee brace), and internal sensing inside prosthesis will be able to detect body motions in real time and display it. This can be transmitted to the wearer of course, but many other options open up as well.
Imagine the coach being able to tell the speeds at which their players are performing in real time. View the football player’s newly operated upon knee in real time to see if they are putting the proper amount of force in, or if they are favoring it as they run. As sports and sports injuries continue to change, and more dollars are associated, rehabilitation technologies like these will trickle down to sporting and other medical specific uses to benefit us all in new and interesting ways.