Sunday, March 26th, 2017

Motion Tracking and Medical Devices


July 11, 2013, Motion Tracking Developers' Conference, San Francisco—Herbie Kim and Josh Rabinowitz from Articulate described their efforts in integrating sensors into remote patient monitoring and assistance packages. They consider a combination of sensors and stimulators can provide benefits that exceed the contributions of either separately.

As the population ages, we are seeing two disparate trends; increasing active lifestyles that include sports and fitness, and rising levels of obesity. Both groups are striving to maintain productivity. While life spans are increasing, the costs of medical and health care are growing faster than inflation in the economy.

Medical providers are being squeezed by the payors and the need to increase caseloads. The increases in documents and recordkeeping are decreasing margins for all patients. The payers, mostly insurance companies, are focusing on cost effectiveness and efficacy data.

As a result, there is a push to decentralize healthcare delivery and to monitor patients at home and apply direct care only when necessary. In theory, these changes should improve the standards of care with targeted therapies, prevent unnecessary emergency room visits, provide early warning signals before significant events, and save time and money.

One of the best prognosticators for many physical aliments is physical condition. As a result, physical therapy is one of the most common and conservative first-line treatments. PT engenders proper rehabilitation, provides a training regimen that is specific to an injury and individual patient, and provides better outcomes. In-office PT has many drawbacks. It is costly, takes time, is limited to some small number of visits, and patients cannot comply with all the training on their own.

Prior attempts to crate assistive devices had challenges with comfort, weight, and battery capacity and weight. Therefore, combining a sensor array and assistive devices that is muscle activated allows the integration of neuromuscular electrical stimulation (NMES) and movement tracking. This combination helps to increase range of motion while re-educating the muscles. All movements retard disuse atrophy and the motions cause increased localized blood circulation.

The challenges are in data processing, better kinematics, improved batteries, and accurate motion tracking. The advances in motion tracking hardware and software can now be applied to a closed-loop sense and stimulate system to get specific motions through the desired ranges in a therapy session. The NMES can overcome the muscle inhibition that slows re-strengthening.

This combination of sensors and stimulus is now available in new products. One such device for knee work includes an interface to a smart phone or wireless remote to input personalized data like pain levels as the knee is put through its motions. The sensors can track range and direction of motion, enabling better at-home compliance to PT recommendations and directives. The equipment and associated data can be reviewed by the therapist without an office visit.

In a similar vein, prostheses for amputees can be smarter to provide active feedback to the user about positioning while the sensors help with overall stability. The NMES portion can stimulate and contract residual muscles as the user moves, allowing for a more comfortable and stable stump-prosthesis interface.

The ability to integrate high-accuracy sensors into a small package enables such diverse applications as joint kinematics analysis for performance improvements, sports medicine, and mHealth and quantified self apps. One example of this sensor integration and consumerization is the move from a $25,000 balance trainer at a PT office to a Nintendo Wii Fit with similar accuracy at a cost of under $500. Other types of injuries and conditions have similar responses and are amenable to the application of sensors and stimulators to that condition.

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