A new research project underway at Scripps Health will attempt to design and test a smart shoulder, one that could record and relay the actual forces that occur inside an implant after surgery.
Scripps Health recently received a $317,000 grant from the National Institutes of Health to make and test such a device, allowing Dr. Darryl D’Lima and Dr. Heinz Hoenecke, the director of orthopedic research and an orthopedic surgeon respectively, to build a prototype that leverages recent advances in solid-state miniaturized sensors and microprocessors whose development has continuously accelerated with the advent of smartphones and other smart devices.
The idea, D’Lima explained, is to pack all of the smart stuff inside a standard replacement shoulder joint such that there would be no external difference between the current standard of care and a much more wired version.
“Once it’s sealed, it should look and feel and behave like an off-the-shelf implant,” D’Lima said.
But inside, digital sensors capable of measuring physical properties such as strain and inertial motion would make and record real-time data, relaying it outside the body wirelessly and even recharging internal batteries without wires.
“We could do what we call sensor fusion, taking data from multiple sensors that can boost the overall accuracy compared to any single sensor alone,” D’Lima said.
Potential patients might wonder why such a device is necessary, given that replacement joints have become steadily more reliable decade after decade.
The researcher said that knee replacement has already shown that there is just so much more to learn from internal rather than external measurement.
Tasks measured in the lab such as having patients walk along lines drawn on the floor over carefully calibrated pressure plates in the floor and past high-speed cameras watching how joints moved could not compare to the information gleaned from recording the forces that occurred inside a smart knee when a person got out and about. Walking on grass, muddy or sandy ground, uphill or downhill, all broadened the understanding of the forces that such devices undergo in the real world.
“Once one of the patients accidentally tripped on a root and we recorded the maximum force we’ve ever measured in an electronic knee implant,” D’Lima said. “The shoulder is even more complex.”
Information cannot only be used to design better implants but also during rehabilitation, helping to bolster confidence during physical therapy by allowing patients to understand whether they are pushing their new joint too hard or not hard enough. And, there could be opportunities to detect when a joint, or the bone around it, could be headed toward failure, allowing action to be taken earlier than would otherwise be possible.
Ultimately, the idea is that better data will help push the overall quality of shoulder replacements closer to restoring the function that recipients had before deterioration occurred.
“Our holy grail is not just removing pain and disability, but restoring them to a more normal quality of life,” D’Lima said.
The NIH grant will pay for the creation and testing of a prototype shoulder joint, first in a lab and then in a human cadaver, to verify that the device operates consistently and safely. If the U.S. Food and Drug Administration finds results persuasive, further approval, still anticipated to be several years away, could result in human trials.
