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Compas™ Selected by R&D Magazine as 2009 R&D 100 Award Winner

The reality of accidents, warfare, and genetics means that in the U.S., there are about a million people in need of prosthetics. About 100,000 new prosthetics are made each year, each of them modified slightly to accommodate each patient. But despite the use of lightweight plastics and titanium, the ultimate fit of the prosthetic is a trial and error process.

David Boone, a Seattle, Wash.-based physician and prosthetics expert, says the need for a new approach to prosthetics was well illustrated at a world congress for prosthetics technology two years ago. His peers felt that sub-optimal alignment for using of prosthetic limbs, especially leg prosthetics, is a persistent problem.

“It’s not because people aren’t trying,” Boone says, “it’s just that manual methods we have are trial and error, insensitive, and observationally based.”

The solution was not in advanced materials—which physicians already had—nor was it in more time spent with trainers—which certainly is of help. The better way, theorized Boone, chief technology officer at Orthocare Innovations, which won a 2009 R&D 100 Award for its Compas™ alignment system (page 18), was in changing the language. Instead of repositioning a lower-limb prosthesis after blisters, skin breakdown, discomfort, and pain had already set in, he believed a computationally-based system would find the optimal alignment for prosthesis without the need for trial-and-error.

Toward that end, Orthocare Innovations, supported by funding through the Dept. of Veterans Affairs and the National Institutes of Health, began answering questions about how to quantify the process of alignment to make a better prosthetic ankle and apply it to a clinical setting. In development, they realized they could gather lots of dynamic data that had never been collected before. Their ultimate innovation, Compas™, was extended to a larger system—the lower-leg and knee—and depends on the intersection of a number of disciplines: medicine, engineering, computing, and visualization.

“The purpose of Compas™ is to identify functionality that has eluded people before. People can feel comfortable in a prostheses, but neither the people using it nor the people designing it knew exactly how a comfortable fit was achieved. No one had any tool to measure what the prosthesis was doing,” says Boone.

The hardware of Compas™ measures live dynamic torques and forces generated during walking. Developers at Orthocare Innovations were able to measure these forces by developing a gyroscopic device contained within the prosthesis. Packaged in titanium, this Compas™ Sensor is able to collect values of movement and force in 3-D space. During evaluations in the clinic, a pyramid-shaped Master Module is mated to the sensor, which is a permanent part of the prosthesis, providing power, Bluetooth connection, gyroscope and laser.

“The real breakthrough was to understand the orientation of the sensor in space,” says Boone, and it is achieved through this module-sensor combination. Clinicians interact with the prosthesis through software designed to process and visualize the data collected by the Compas™ Sensor.

A series of proprietary fuzzy logic algorithms were developed that can interpret complex gait variables and other force dynamics in three dimensions down to the micrometer. The output is displayed numerically and graphically, and the data can optimize both static standing balance and dynamic walking alignment.

Alignment System Reduces Prosthesis Pain

Misalignment of a lower-extremity prosthesis can lead to instability, tissue breakdown, and discomfort
for the patient. The Compas™, Computerized Prosthesis Alignment System from Orthocare Innovations, LLC, Washington, D.C., provides the prosthetist with information about what is happening bio-mechanically, removing guesswork and assumptions about making adjustments. The Compas™ includes a titanium sensor that measures the socket reactions (torques) in the anterior/posterior plane and the right/left planes dynamically. The system also determines the weight, balance, and gait timing of the prosthesis. During evaluations in the clinic, a master module is mated to the sensor; this permanent part of the prosthesis provides power, Bluetooth connection, a gyroscope, and a laser. Compas™

communicates with a host computer running software system that automatically interprets the Compas™ data with proprietary fuzzy logic algorithms, and displays and records the output numerically and graphically.