12 exciting advances in bionic limbs for amputees
Amputees in the 21st century have come a long way from the image of the peg leg pirate and the dull, heavy prosthetic leg of even a few years ago. Increasingly, technological advances in prosthetic replacements for amputated arms, legs, feet and hands promise to exceed the Bionic Woman and Six Million Dollar Man TV fantasies a generation ago.My job as an Atlanta trial attorney handling serious injury cases in Georgia is to help clients with amputation injuries secure the funds to take advantage of these new advances.
Much of the funding for research and development has come from the Department of Defense in reaction to the large number of amputee survivors of the wars in Iraq and Afghanistan. However, as so often occurs, the technology spurred by wartime developments has broad civilian application.
One of the leaders in the field is Dr. Hugh Herr who at 17 lost both legs due to hypothermia in a mountain climbing incident. Driven forward by his rage at the prosthetic legs available at the time, he earned degrees from Harvard and MIT, won multiple patents for prosthetic innovations and became director of the Biomechatronics Research Group at the Massachusetts Institute of Technology Media Lab.
Among Dr. Herr’s projects now being pursued to improve prosthetic limbs are:
- Robotic ankle-foot prosthesis, one of Time magazine’s Top 10 Inventions of 2004, which mimics the action of a biological ankle and, for the first time, provides transfemoral amputees with a natural gait.
- Artificial gastrocnemius muscle, a large muscle in the calf which enables natural walking motion through plantar flexing of the foot at the ankle joint and flexing the leg at the knee joint.
- Biomimetic active prosthesis for above knee amputees. The goal is to design a new generation of robotic knee prostheses capable of generating significant energy during level-ground walking, that can be stored in a battery and used to power a robotic ankle prosthesis and such activities as stair climbing.
- Control of muscle actuated systems by electrical stimulation. The MIT team is investigating a variety of adaptive and robust control techniques to enable trajectory tracking, as well as mechanical power-output control under sustained oscillatory conditions. Got that?
- Integrate “smart” technology into lower-limb prostheses. To address the effect of powered ankles on shock absorption and pressure where the prosthesis is attached to the leg, the MIT team seeks to integrate sensors and actuators into prosthetic legs so as to alleviate the increased risk of further amputations, excessive stress on both limbs, and discomfort at the stump/socket interface.
- FitSocket. The FitSocket project aims to identify the correlation between leg tissue properties and the design of a comfortable socket. New 3D printers — of the sort my nephew in New York sells to industries around the country — will be useful for this.
- Human walking model to combine joint mechanics, electromyography and mechanical economy. The hypothesis is that series-elastic clutch units spanning the knee joint can capture the dominant mechanical behaviors of the knee in level-ground walking.
- Load bearing exoskeleton to augment running. A wearable exoskeleton designed place a stiff fiberglass spring in parallel with the complete leg during stance phase, then removes it so that the knee may bend during leg swing. The result is a bouncing gait with reduced reliance on the musculature of the knee and ankle.
- Neural control of advanced prosthetics. Researchers are working to develop means to allow amputees to control their powered prostheses by activating the peripheral nerves remaining in their residual limbs. This would be more natural than currently used myoelectric controls.
- Sensor-fusions for EMG controlled prosthestics. Researchers are working on improving the types of terrain a robotic ankle can successfully navigate by using command signals taken from the intact and residual limbs of an amputee combined with signals from sensors attached to the robotic ankle.
- Variable impedance prosthetic (VIPr) socket design. To relieve the universal pressure discomfort in prosthetic sockets, researchers are developing methods for 3D scanning of anatomical points of residual limbs in order to perfectly match them with prosthetic sockets.
- Volitional control of powered ankle-foot prosthesis. This projects seeks to give transtibial amputees volitional control over their prostheses by combining electromyographic (EMG) activity from the amputees’ residual limb muscles with intrinsic controllers on the prosthesis.
As a lawyer representing amputation injury survivors, when there is insurance coverage or assets sufficient to pay a judgment, I need to consider these advances in working with a life care planner to project economic aspects of damages.
Ken Shigley is past president of the State Bar of Georgia (2011-12), double board certified in Civil Trial Advocacy and Civil Pretrial Advocacy by the National Board of Legal Specialty Certification, and lead author of Georgia Law of Torts: Trial Preparation and Practice. His Atlanta-based civil trial practice is focused on representation of plaintiffs in cases of castastrophic personal injury and wrongful death.