#7 Active Bionic Prosthesis: Wearable Robotic Devices


Yesterday, all below-the-knee prostheses functioned more or less as a passive carbon-fiber cane or crutch, simply filling in where a limb used to be. Today, however, thanks to a quantum leap in prosthetics technology, amputees are now able to easily walk without stress, engage in rigorous physical activity and stay in step with their remaining biological limb—the way that nature had intended.

Estimates of the amputee population in the United States vary widely, from fewer than 400,000 to more than 1 million. The projected number of American amputees is expected to rise to almost four million by 2050. This unheralded increase is expected to continue to be impacted by military casualties and a growing new enemy—diabetes—with its devastating side effect of limb loss.

About 9 out of 10 amputations involve the leg, from the foot to above the knee. For centuries, wood and metal were the basic materials used for prostheses, and they were held to the body with leather attachments. Thanks to remarkable advances in prosthetics research, space age plastics and carbon fiber composites, which are much stronger and lighter and more durable, have been engineered to become enhanced limbs.

Now comes the computerized bionic leg with its microprocessors and computer chips that can rival the functionality provided by biological limbs. Getting through the day with the new bionic leg entails less work on the body for lower leg amputees. The world’s first high-tech bionic prosthesis employs precision robotic engineering to propel the user from one step to the next, automatically adjusting to changes in speed and uneven terrain through a series of sensors.

Thanks to this technologically advanced leg, users can now live more active and fulfilling lives. Durable and weighing a little more than four pounds, the bionic prosthesis emulates and even enhances movement through electromechanics, so users can walk effortlessly where they want and do what they want. This includes walking up and down stairs, walking backwards, and even taking part in high-level competitive sports.

Making use of microprocessors, sensors, a motor, and a carbon-fiber spring to replicate the action of a person’s Achilles tendon, ankle, and calf muscle, the active prosthesis mimics natural human body motion. A battery-powered motor to replace the function of the missing muscles and Bluetooth links allow a person to adjust settings easily with a smartphone to ensure a consistent, efficient gait.

A recent clinical study in Proceedings B reported that lower-limb amputees who wore the active prosthesis bionic lower leg system were able to walk at the same speed and with the same metabolic energy as their peers with intact biological limbs. By contrast, traditional carbon fiber lower limb prostheses have proven incapable of adapting to various terrains and walking velocities while requiring the amputee to expend significantly more energy—from 10 to 30 percent—than non-amputees.

Previously available only to military personnel, the active bionic lower leg system is now available through a network of select prosthetics providers around the country. The challenge to all Americans may be to ensure, through lobbying efforts and fundraising, that this advanced technology be available to all those who need it.


Where Are They Now

Technology in newer prosthetics is advancing rapidly. Users of a new 4.5-pound lower limb prosthetic report less pain, more energy, an increase in daily activities, fewer pressures inside of the socket and more stability on uneven terrain. Increasing scientific data now supports these many advantages. In addition, patients with more severe mobility-inhibiting injuries now have a commercially-produced prosthetic exoskeleton to use instead of wheelchairs. Delivery of the first $130,000 lower body exoskeleton was made in February or 2015, after its FDA approval. Since then, the price of the device has lowered slightly and it has become available to more paraplegic patients, stroke victims included. This high-tech medical device supports the body while moving the user's legs for them—it lets paraplegics walk again. 

Recent design advances have allowed lower leg amputee victims to rock climb and dance again with the use of active bionic prosthesis. The next frontier is to create active bionic prosthesis for more detailed and delicate movements performed by the upper limbs and hands.

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