New microprocessor technology could improve gait in prosthesis users

ATLANTIC CITY, N.J. — A speaker here at the New Jersey Chapter of the American Academy of Orthotists and Prosthetists Annual Meeting presented a novel prosthesis that could increase balance and stability, while normalizing gait characteristics for transtibital and transfemoral users.

Stephanie Porter, MS, CPO, regional clinical director at BionX, who spoke on behalf of Brian Frasure, CP, said there are challenges that minimize function in current prosthesis wearers.

Stephanie Porter


Conventional prostheses require significant amounts of metabolic energy, which could lead to fatigue, muscle pain, slower gait speed, reduced endurance, and risk of obesity and vascular issues. Also, conventional prostheses have little shock absorption and do not adapt well to terrain, causing wearers to feel less stable and have an increased risk of falls, Porter said.

She added that conventional prostheses are passive, and without muscle-powered plantar flexion, users are challenged by stairs, ramps and hills. Adapting to natural gait puts stress on the kinetic chain, so users also frequently experience excessive forces in the socket, diminished quality of ambulation, and chronic hip, knee and back pain. Porter said many of these problems are addressed through the BiOM prosthetic system.

“There were several studies done at [the] Spalding Rehabilitation [Network] in conjunction with the Providence [Department of Veterans Affairs] VA,” Porter said. “When [the researchers] looked at the BiOM and compared [it] to non-amputees and amputees wearing their passive device, [they] found that it was able to reduce the energy requirements.”

Clinical studies showed the BiOM system could normalize gait characteristics and reduce metabolic energy requirements to that of an able-bodied individual. Studies also showed increased self-selected walking speed in users at an average of 23% and a potential to reduce the risk of premature osteoarthritis. Additional user trials have shown a reduction of pain, and quicker return to work and activities of daily living.

The BiOM prosthesis is equipped with sensing technology that includes an accelerometer, gyroscope, torque angle sensor and a high resolution encoder. It has a ball screw actuator, elastic series spring and a carbon foot blade.

“Functionally, the main differences between the BiOM and any other microprocessor ankle out there is power,” Porter said, “Power is where we emulate the loss muscle function and allow users to return to a metabolic neutral as compared to non-amputees.”

According to presented data, the BiOM is the only prosthesis that offers powered propulsion, minimizes ankle plantarflexion, decreases transition work collision forces and uses dynamic resistance to controls movement from heel strike to push off.

The Personal Bionics System, paired with the BiOM, verifies settings against normalized gait data, documents patients step count and ability to ambulate at variable cadence.

“It is a nice way, in real-time, to see if what you are aiming for is really being achieved,” Porter said. “Ultimately, providing technology that allows users to do those day-to-day activities that they could not do with a passive device, [that] is the goal.” – by Shawn M. Carter


Porter S. BiOM: Personal Bionics. Presented at: New Jersey Chapter of the American Academy of Orthotists and Prosthetists Annual Meeting; Nov. 4-6, 2015; Atlantic City.

Disclosure: Porter reports she is employed by BionX.

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