To find out more on the current state of microprocessor-enhanced prosthetic knees and how they can be most effective, you could look at a case study, you could hear from a prosthetist who understands the ins and the outs of the technology—or you could listen to someone who is a bilateral above-knee amputee living with these devices and is willing to talk openly and honestly about his struggles, triumphs, and relationship with his physical therapist (PT).
Attendees to a June 14 presentation at NEXT got all 3. And how.
"Rehabilitation Care in the Community for Individuals With Above-Knee Amputations and Technology-Enhanced Knees" explored the advancements in that include artificial limbs filled with magnetically responsive fluids, high torque motors, and computers installed at both the knee and ankle joints.
Presenter Stephanie Rehm, PT, DPT, GCS, told attendees that prosthetic technology has advanced rapidly in recent years, in large part due to the numbers of soldiers returning from the conflicts in Iraq and Afghanistan with amputations. These procedures occur at more than twice the rate than in previous wars, she said, with about a third of soldiers undergoing multiple amputations. The sheer volume sparked the development of new ways to respond, and those new technologies have now entered civilian settings.
The differences between mechanical knees and microprocessor-enhanced knees are at once simple and highly complex. Mechanical knees still depend largely on basic physics, by using inertia, momentum, and friction to make it possible to control swing and stance phases—to a degree. Microprocessor-enhanced knees, on the other hand, employ computers to monitor and adapt to use, and to trigger resistance and other elements in response to position and velocity. It's really a "thinking technology," she said, with "a little library" stored inside each joint that has recorded past movements in order to reduce the likelihood of stumbles and falls.
Rehm walked attendees through a case study of "Mr C," a 71 year-old civilian male with above-knee bilateral amputation due to Type 2 diabetes. A cancer survivor, Mr C also suffers from hyperthyroidism, arthritis, and chronic anemia.
Rehm's presentation focused on not only the mechanics behind the new knees, but the PT-guided work that patients need to do to successfully rehabilitate. She provided multiple videos of Mr C engaging in the exercises that would help him make the most of the knees, and provided information on the evidence-based research that supported each of the interventions used.
The latest news for Mr C, according to Rehm, is that he has been determined to be eligible for an even more recent advancement—a "power knee," a microprocessor-enhanced joint that includes an electric motor that can help wearers stand. He could be using the new device as early as fall of 2014, she said.
Paul Morton, a certified prosthetist, told attendees that while the technological advances are remarkable, the effectiveness of the device depends heavily on the fit of the socket that accommodates the user's leg. Prosthetists have to work carefully and artfully to create something that will not just serve as a receptacle, but actually work with the user's bone and musculature to ensure optimal use of the device.
The rapid increase in technological possibilities means that it's important for PTs to develop solid relationships with prosthetists, Morton said, advising attendees to seek out professionals who were certified in the field.
Perhaps the most memorable part of the presentation came when Jessie Fletcher, an ex-marine who lost both legs and several fingers to an IED in Afghanistan, talked about his experiences and demonstrated how the prostheses work.
Fletcher walked with up and down the aisle of the conference room, and delivered his remarks while shifting naturally from foot to foot, turning with seeming ease to talk directly to audience members asking questions. He emphasized that his outcomes were not typical, citing a high level of motivation and a great relationship with his rehabilitation professionals.
The key to his success, Fletcher said, was the way in which his PT responded to his own motivational needs. Early on, Fletcher realized that he was the kind of person who responded best to a no-nonsense, high-discipline, rigid approach that pushed him to his limits. "I said, 'I don't want to be a baby. I'm a tough, rugged Marine. Treat me like one.'"
Besides the importance of understanding a patient's needs, Fletcher said that communication and teamwork were crucial. He described his work with his PT and prosthetist by saying that "half the time when they were walking with me, they were videoing me, and text messaging each other." He told attendees that his rapid advancement with the prostheses was possible "only because I was able to get everyone in 1 room—or at least on the same bandwidth."
Fletcher said that, in the end, sheer commitment to the device may be the key. He said that he wears his prostheses anywhere from 8 to 12 hours a day, and often as many as 18 hours a day when he's traveling. And all that use—fueled by his remarkable commitment and determination—are making some significant changes in this life.
"The prostheses are a part of my being now," he said. "It's a part of my identity as well."