Alignment Systems Step Forward

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Jay Martin, CP, uses the Compas system to calibrate Jim Bob Bizzell's alignment. Photograph courtesy of Orthocare Innovations.

Any prosthetist will tell you that a successfully fitted prosthesis depends, in part, on achieving the proper alignment. And yet learning to make alignment adjustments through observational gait analysis—not to mention becoming comfortably proficient at it—is no easy task. Not only does it involve classroom training and perhaps years of on-the-job experience, it also relies on keen observation and communication skills. Even the most proficient prosthetists will admit that achieving "perfect" alignment is out of their reach.

"Prior to the 1960s, the worldwide standard for alignment was 'not bad,'" says John Michael, MEd, CPO, FISPO, FAAOP. In the era where re-alignment meant literally cutting the prosthesis in half and re-gluing it after each and every change, once there were no grossly visible abnormalities, the process was done. If the patient's gait changed over time, there was no practical way to angulate or rotate the socket due to costs of cutting it in half and re-laminating. If the alignment wasn't 'too bad,' amputees just lived with it, despite the discomfort and gait inefficiencies.

"The real meaningful change occurred when Otto Bock introduced the 'inverted pyramid' endoskeletal design...because for the first time, the alignment of the prosthesis could be incrementally adjusted—in all planes and at all levels—for the lifetime of the prosthesis. Adjustable endoskeletal components proved to have such a clinical advantage that they are now the standard for practice worldwide." But even with this advance, Michael continues, "the standard of care went from 'not bad' to 'acceptable.'

"The fundamental limitation of current alignment is the difficulty in optimizing characteristics that cannot be seen with the eye, such as torques," he says. Not only must a clinician rely on his or her educated interpretation of a split-second observation, "clinicians rely on patient feedback about how the prosthesis feels as an indirect indicator of when the torques on the residual limb are too high, too abrupt, or too inconsistent." This introduces variations in how accurately the patient communicates what he or she is feeling and how accurately the prosthetist interprets that feedback. "Good prosthetists working with experienced amputees consistently achieve acceptable alignment results," Michael says, "but there is good scientific evidence that a range of alignment styles are acceptable. Optimal alignment remains the holy grail."

Prosthetists and their patients are now one step closer to that ultimate prize, thanks to two companies that are bringing new prosthetic alignment systems to market.

Compas Prosthetic Alignment System

A glimpse inside the Smart Pyramid.

Orthocare Innovations, Oklahoma City, Oklahoma, released its Computerized Prosthetic Alignment System (Compas) on a limited basis earlier this year. The Compas system consists of hardware and software that allows a prosthetist to analyze the dynamic functions of a prosthesis, and a modular, endoskeletal, multiaxial force sensor called the Smart Pyramid. This component "will take the standard lower-limb prosthesis and make it an intelligent, active, part of the care process," says David Boone, CP, MPH, PhD, chief technology officer at Orthocare. According to the Orthocare website, the Smart Pyramid's design is based on the industry-standard inverted pyramid and is easily integrated into any new or existing endoskeletal lower-limb prosthesis.

The Compas system "provides the kinetic information that one might seek in a gait laboratory, but the measurements can be made without specialized laboratories or technicians, and the information is relayed [via Bluetooth technology] instantaneously and directly to the prosthetist," Boone wrote in the article "The Next Challenge in Prosthetics," Rehab Management, July 2009. The software then provides recommendations to the prosthetist "for adjusting the pyramid screws to optimize sagittal and coronal plane alignment," according to Orthocare's website.

In other words, the Compas system helps the prosthetist see more than he or she can observe.

David Boone adjusts Bizzell's alignment.

"Fifty years ago, cardiologists would use a stethoscope to listen to your heart, and they could tell a lot about the function of your heart and blood pressure from that," Boone told The O&P EDGE, "but having the electrocardiogram and the ultrasound of your heart gives them so much more information to properly diagnose what's going on. That's the level of information that we're getting to the prosthetist now.

"What we want to do," Boone continues, "is to make prostheses that adapt to the environment and to the needs of the user rather than having the user adapt to the prosthesis." The Compas Smart Pyramid creates a prosthesis that has the ability to "inform the user or the prosthetist how it's working. It's a fundamental change to practice and service delivery for amputee care all the way around."

Michael, who had some involvement in the development of the Compas system, says he has been impressed by the system from the start. "I was stunned by how closely the Compas feedback coincided with my own clinical judgment," he says. "Even more remarkably, the Compas data coincided 100 percent with the patient's feedback about when alignment was 'better than before.' [This is] the first meaningful change in prosthetic alignment since the transition from fixed exoskeletal or endoskeletal systems to adjustable ones," he adds.

According to Carol Sorrels, Orthocare's director of marketing and communications, the Compas system is scheduled for wide market release as this issue of The O&P EDGE goes to press.

iPecs (Intelligent Prosthetic Endoskeletal Component System)

iPecs prosthetic component. Photograph courtesy of College Park Industries.

College Park Industries, Fraser, Michigan, is billing its Intelligent Prosthetic Endoskeletal Component System (iPecs™) as a "wireless prosthetic gait lab." The iPecs device "is incorporated into the prosthetic system, where it measures the force being transmitted from the ground into the person's leg," according to a College Park press release. "The device can monitor the position of the foot throughout the phases of gait. It can measure twisting, the magnitude and direction of force, and other parameters that will help researchers and clinicians refine the way a prosthetic limb fits and performs," according to Mike Leydet, senior research and engineering officer at College Park.

The iPecs is designed for universal application and integrates into a finished endoskeletal prosthesis with the use of standard four-hole adapter options, says Karen Bieniek, College Park marketing and communications manager. The device is currently being tested in university gait labs at Northwestern University, Chicago, Illinois; and the Georgia Institute of Technology, Atlanta, she adds.

A key attribute of the product, says Leydet, is "the ability to use the iPecs in conjunction with current gait-lab devices for more accurate measurement of amputee gait. "This precision data is collected and transmitted wirelessly to a PC or to a removable, onboard memory micro SD chip," he says.

The research-grade data gained from the iPecs will be used to develop clinical algorithms that show how prosthetic component selection and alignments can be facilitated and possibly improved. "Traditional laboratory-based gait-analysis systems (i.e. force plates and video capture) do not provide quantifiable information during real-world use," Leydet says. "The wireless iPecs can be used both in and outside of laboratories, making it possible to capture previously unavailable objective measures pertaining to daily use. It also includes a built-in three-axis inclinometer to measure the angular orientation of the iPecs wherever it is located in the prosthetic appliance."

Disclaimer: This project was supported by Award Number R43HD059285 from the Eunice Kennedy Shriver National Institute of Child Health & Human Development. The content does not necessarily represent the official views of the Eunice Kennedy Shriver National Institute of Child Health & Human Development or the National Institutes of Health.

Broad Implications

Both Orthocare and College Park are quick to point out that their systems are not meant to replace gait training or the function of the gait laboratory, but rather augment them. "We're really not...trying to get any new result," Boone says. "We're just providing more information that good prosthetists are going to use."

The larger benefit to using one of these systems is the ability to record and document objective outcomes data, which can then be sent to third-party payers or insurers.

"A part of prosthetic care that is very difficult for the prosthetist is trying to document function," Boone says. "We can document whether or not we made something, whether or not the patient received it, and maybe whether or not they like it, but we haven't had the means to document how well it is working, and that's exactly what Compas does. It provides a printable electronic record that documents how well someone is able to use a prosthesis.

"The basic function or task of a prosthetist is not to make a thing, it's to return function to a person who has lost a limb, and that's what we need to do," Boone continues. "People talk about evidence-based practice, and Compas is an entirely evidence-based method for assuring function of a prosthesis."

Leydet expresses a similar sentiment. "The prosthesis user experiences forces and moments similar to those of an able-bodied individual during walking but has fewer anatomical joints with which to accommodate or mediate their influences," he says. "Prosthetic devices are designed to address these anatomical deficiencies by mechanically absorbing and redistributing the resultant forces and moments. Various prosthetic components and alignments redistribute the moments and forces differently to the residual limb based on their design and application. Fundamental research has been lacking in this area due to the absence of adequate tools that objectively and accurately measure forces and moments in the prosthesis during normal daily activities. The iPecs product specifically addresses the stated orthotics-and-prosthetics-industry need for measurement tools."

As lower-limb prosthetic devices continue to become more technologically advanced—and by extension more difficult to be reimbursed for—these new products may hold one of the keys to moving those devices that are currently in the "experimental" category into the "medically necessary" one. "As we move toward more and more advanced prostheses, it's important that we keep the level of care up to the same standard as the technologies that are going into them," Boone says. It looks like the iPecs device and Compas system may do just that.

Karen Henry can be reached at

Editor's note: The O&P EDGE does not endorse any particular product or service. The information provided in this article is for reader information only.