Jerry Ward needed a new knee, and while he was at it he figured he might as well become part of medical history, too.
Ward now sports the world's first wireless electronic knee prosthesis. His new knee will transmit information about its inner workings to scientists in real time as Ward walks, climbs stairs, exercises and performs other basic activities.
The information gleaned from Ward's e-knee will be used to design improved, longer-wearing knee-replacement prostheses, as well as better knee braces and even knee-sparing sports equipment and shoes.
A retired aerospace engineer, Ward understands the benefits of access to data and artificial joints – he previously received a total hip replacement and total knee replacement on his other knee – and said he was happy to participate in the experiment.
"The last eight years of my life would have been vastly different if not for artificial joints. It's a lot more fun to go shopping for golf clubs than for a rocking chair," said Ward, who believes he would have been dependent on a walker if medical science hadn't been able to provide him with replacement parts.
Clifford W. Colwell, a surgeon from the orthopedic surgery division of the Scripps Clinic, implanted the e-knee early in March.
"Implanting the prosthesis was like the Mars landing," Colwell said. "It was exciting but what we're really looking forward to is the knowledge we'll gain from the data."
The e-knee, which was manufactured by DePuy Orthopaedics, a Johnson & Johnson company, is similar to a standard knee-replacement implant on its top half. But the lower metallic component, made from titanium, is customized with tiny sensors that will measure strains on the device that are produced as Ward moves about.
The sensors are wired to a transmitter that is connected to an antenna, all housed on an electronics board – measuring 12 mm long by 8 mm wide by 1 mm thick – tucked inside the e-knee.
The antenna will transmit data in a computer-readable format to a receiver outside of Ward's body. Power for the e-knee is also external. A removable inductive coil fits around the knee and powers it up, after which the knee will begin to wirelessly transmit data to the receiver, which will then be sent to a computer system.
Since the e-knee is a research device, no FDA review was required before implanting it.
But the procedure had to pass stringent reviews by a human experimentation ethics committee, a group of medical professionals that is formed before any experimental procedure that involves living patients. Committee members discuss procedures to ensure the potential benefits outweigh any possible problems.
"The ethics committee found that the e-knee had the potential to contribute greatly to medical knowledge, while not causing Jerry Ward any harm," said Steve Arms, president of MicroStrain, the company that developed the wireless microsensors that are used in the e-knee.
Ward is recovering well, although he's still unable to take more than a few steps. Scientists plan to start collecting data from the knee in about two weeks, as Ward regains mobility. But they have already confirmed that the implant is working, and is capable of transmitting information.
"It wasn't a huge surprise when we got confirmation that it was working – we tested the e-knee like crazy before it was implanted," said Arms. "The knee and its components were developed and tested over a decade, and the completed devices went through really stringent tests, 10 million cycles in a very harsh knee motion simulator.
"We knew we had only one shot to get it absolutely right," added Arms. "It had to be perfect. After all, it's not just an important medical experiment; it's also a guy's knee."
