The Pros and Cons of Computerized Foot Orthotic Technology

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We tend to take our feet for granted--until problems develop!

Although many people believe that each foot only takes half your body weight during walking, actually walking creates forces through the feet of about one to two times body weight. And in an average day, people may take as many as 10,000 steps or more. During running, it is estimated that these forces can increase to an amazing nine times body weight. Thus, any inefficiency in foot function is multiplied many times over--causing many foot and lower limb problems, points out the podiatric practice of Dunning and Trinder in the United Kingdom.

Sometimes an orthosis is all that is needed for successful treatment, but often the orthosis is prescribed along with other therapies, such as stretching or strengthening exercise, oral or injectable medications, and specific types of shoes to provide the fastest healing, explains Kevin A. Kirby, DPM, MS, editor of the website PodiatryNetwork.com. Kirby lists the advantages of custom prescription foot orthoses, which include 1) since they fit so exactly to the foot, they can be made with relatively rigid, durable materials with a minimal chance of discomfort or irritation; and 2) they have a much greater potential to effectively and permanently treat painful conditions, all the way from the toes to the lower back, since they are designed specifically for an individual's biomechanical nature. (Note: the terms "foot orthoses" and "foot orthotics" are used interchangeably in this article, since the orthotic and pedorthic professionals quoted used both terms.)

The only disadvantage Kirby sees is cost as compared to over-the-counter foot inserts. However, he points out a disadvantage of the OTC orthotics. "Even though the OTC inserts do help some people with symptoms, they do not have the potential to correct the wide range of symptoms that prescription foot orthoses can, since they are made to fit a person with an average' foot shape." He compares them to prescription eyeglasses: OTC glasses may work for some people, since they are made to correct the average' eye; however, they will never work as well as prescription glasses. "Prescription foot orthoses, since they are custom-made to each foot of a patient, are almost always more corrective and comfortable than OTC foot inserts, even though OTC inserts do work for some people."

Despite their value to patients, providing custom foot orthotics is not one of the higher generators of revenue. So the question arises, how to make them more efficiently and cost-effectively?

One partial answer at least has proved to be automated foot orthotic technology. Orthotists, pedorthists, and other healthcare professionals have found that the technology provides accurate measurements for fabrication at a big savings in time and labor. However, even some of the happiest users of the technology still use other measuring and casting methods for certain patients' needs.

Versatility, Digital Record, Cost Savings

For instance, Jim Rogers, CPO, FAAOP, Orthotic & Prosthetic Associates Inc., Chattanooga, Tennessee, is an enthusiastic proponent of the Amfit system, produced by Amfit Inc., Vancouver, Washington. Rogers was introduced to the Amfit system about ten years ago. "The system did a couple of great things," says Rogers. "It was repeatable--and at that time about the only repeatable system out there was E-Med. It was very expensive and primarily diagnostic--not really designed for fabricating an orthosis."

Courtesy of Amfit
Courtesy of Amfit

Being repeatable means that the system provides an exact digital record, so a cast doesn't have to be saved in case the patient later wants another orthotic. "You can push a button, remake another orthotic at a fraction of the cost of the first one, and pass that savings on to the patient, which we do," says Rogers. With repeatable measurements and a digital record, a scan can be compared with an earlier one, which is helpful for assessing changes in the foot, especially with progressive conditions such as diabetes, multiple sclerosis, or arthritis, he adds.

Rogers especially likes the option of being able to print out the scan: "It's a great marketing and educational tool." The practitioner also has the option of scanning with weight bearing, semi weight bearing, or non weight bearing, he noted.

The Amfit program evolved over the years, Rogers said. "What I really like is the ability to manipulate the image--to modify the positive mold digitally and send it to a remote carver."

One challenge for practitioners is transferring their mindsets and skills from being tactile to being able to quantify. "What we do in orthotics and prosthetics is so tactile," Rogers says. "If you ask someone how much build-up is needed, they'll show you with their fingers: about this much,' but if you ask them to quantify it, they often have trouble doing it." However, once users make this transition, the orthosis can be modified right on the screen and carved in eight minutes, Rogers says, adding that users have five choices of density: soft, medium, two versions of dual density, which is a combination of soft and rigid, "so you can impart structural control where you need it," and totally rigid.

Recent developments in the Amfit machine provide more versatility, according to Rogers. "Traditionally, you were carving out the orthotic from the negative with a single material, EVA, but now you can carve it from EVA or cork. Also, instead of the orthotic, you can insert an EVA block, a cork block, or a foam block for a positive mold from which you can fabricate a device with any material, not just EVA. It can be carbon fiber, polypropylene, TPE--any number of materials."

Rogers continues, "So what started out as a way to fabricate a relatively soft EVA orthosis has evolved into a system to get an excellent scan of the foot, modify it very conveniently, then decide what material you want for the orthosis and fabricate it." He also praises Amfit's training: "Amfit really tries to educate the practitioner on how to use the machine and get the most out of it."

However, Rogers points out that he doesn't use the machine 100 percent of the time. Orthoses that need to go beyond the margins of the plantar or dorsal surfaces need to be cast; plus sometimes the patient's condition makes traditional casting and fabricating the methods of choice. And, "sometimes it's even appropriate for me to use an off-the-shelf orthosis," he adds.

Chuck Greene, CPed, University of Michigan Orthotics and Prosthetics Center, Ann Arbor, also comments that, among other methods, the center has two Amfit systems that are used a great deal.

System Garners Pedorthist's Kudos

Versatile technology has many uses. Courtesy of Tekscan
Versatile technology has many uses. Courtesy of Tekscan

Rick Sevier, CPed, RPOA, RFO, National Foot Specialties, Tulsa, Oklahoma, happily uses the 3DO system manufactured by the Quasar Group, Digital Orthotics, Tustin Ranch, California. The totally portable system includes a laptop computer, preloaded with the Digital Orthotic software, and a digital sensor pad, explains Sevier. "The software has some nifty features and seems very intuitive," he adds. "Just we as practitioners gather personal data, do an assessment, and then decide which orthotic design best fits the needs, this software does the same."

Data such as name, age, height, weight, and physical measurement of the feet is gathered, he explains. Next, a static scan is taken, which can be viewed in either 2-D or 3-D. Then, a dynamic scan is taken, in which the patient walks across the pad left foot first, then right. Sevier notes, "I have found that building a pad from gym foam' squares (available from any home improvement store) that brings the ground elevation up to that of the pad gives me much more reliable results during the dynamic scan and gait analysis phase. This seems to eliminate the step up' to the pad surface and provide much more accurate data." The dynamic scan can be viewed in either 2-D or 3-D. "The unique part," says Sevier, "is that the step can be viewed frame by frame forward, backward, from any angle and at any speed. An analysis is available for printout that compares the patient gait with that of accepted norms."

Then, an order can be placed for orthotics with an unlimited number of modifications through a menu that creates production notes via a system of shoe type selection clicks or a modifications screen for fine-tuning the order, Sevier explains. There is also a place to enter specific notes for the central lab. At the end of the day, the laptop is plugged into a standard phone jack and the data is downloaded to the users' choice of more than seven different fabrication labs across the country. Says Sevier, "In seven to ten days, you get your orthotics back priority mail. Cool stuff!"

An option on the 3DO system is "Request Biomechanical Analysis," Sevier notes, although he mentions he has not used it. "A typical report may include whether the patient pronates or supinates, time spent in specific phases of the gait cycle, metatarsal flexion / extension problems, or other gait abnormalities.†This is a 'for a fee' item with the data is currently analyzed by Dr. Craig Lowe of the Quasar group, an expert in digital biomechanical analysis. The software that he uses provides a playback of the patient exam. This differs from other systems, where the system itself compares the dataset against known points of norm and provides a 'canned' analysis. These reports are very useful†as third-party verification for insurance."

Greg Storz, CO, CPed, president, Orthocare Orthopedic Services Inc., Lincoln, Nebraska, also reports that he has used the Quasar Group 3DO scanning system for several months, with good results. He also utilizes foam impression boxes when he feels a conventional method is needed.

Losing the Touch

Courtesy of Tekscan
Courtesy of Tekscan

However, some practitioners who have tried automated foot technology systems are less than happy with computerization. Brian Moore, CPO, Arnold Orthotics & Prosthetics, Shreveport, Louisiana, says, "I have found that when the practitioner's hands are taken away from his craft by computers and scanning devices, both the patient and the practitioner lose something." Moore feels that the personal casting and hand manipulation of the underlying tissues in order to fabricate a custom device is becoming a lost art. However, Moore has tried some types of automated systems. "I have found that you get the same results from an OTS insert with some slight modifications," he says. "I trust my hand casting†over any computer-generated model any day. I believe that†only†competency can provide a well-fitting device of any type; whether one relies on a computer to do it for you is up to the individual."†

'Work Still Needs To Be Done'

Many automated foot technology systems seem to fall into two basic categories, believes Sťamus Kennedy, CPed, co-owner of Hersco Orthotic Labs, Long Island City, New York.

"The first type uses pressure plates or plantar foot scans that capture the bottom surface of the foot. Some of these systems will also show areas of pressure when the foot is weight bearing. These are two-dimensional methods that will accurately measure the size of the foot i.e. plantar length, width at the metatarsals, and possibly arch location. However, in my opinion, they do not fully and accurately translate into the 3-D topography necessary to make a custom foot orthotic," he says.

The second type of system uses laser or light scanning technology to capture the full shape of the foot. "These systems seem to have sufficient resolution to generate good images of the foot," Kennedy continues. "However, the difficulty arises in trying to translate the scanned data into a final orthotic. It is the machining tolerances of the milling system, whether making the positive cast or the final orthotic, that determine the quality of the final product. We had one CAD/CAM system that digitized the negative cast. The foot could then be modified on the screen, and an orthotic milled out from a sheet of polypropylene. In concept and theory the system was very advanced, but in reality the milling process was not as accurate as we required."

Kennedy comments that although some of the systems currently available do an adequate job, he does not see any as the clear leader. However, he sees continuing improvement in both cost and capability, with many innovations coming directly from the O&P industry. "I think in time we will see the transition of foot orthotic manufacture from the traditional methods to integrated scanner CAD/CAM systems, but some work still needs to be done to ensure quality and cost."

Recognizing Wrong Information

With automated foot technology, the user must be able to quickly recognize when the computer is giving the wrong information and be able to quickly override it, warns Jim Pattison, BSc, CPed (c), P.A. Euroclogs, Prince Albert, Saskatchewan, Canada.

Pattison has looked at several systems, although he is not at present using automated scanners. However, he says he has strong opinions about how some things they predict line up with conventional models and methods. For instance, he describes, "people coming through the door who have been to a podiatrist and say that the orthotics aren't helping their metatarsalgia. What has happened is their feet were scanned, and the scan called for the met pad to be put right under the MT heads instead of about 1/4" proximal to the heads so that it could lift the pressure off the met heads and simulate the transverse metatarsal arch. When people tell me that the computer is more accurate, I agree that it might be in some instances. But you have to know when the information is wrong and be able to override it. Arch height can be different, but it is not as variable as the MT pads!"

For casting, Pattison prefers casting foam for most clients, but uses slipper casting as well for a number of problem feet, such as hyperpronated feet where he needs to make a deeper cut orthotic of PCFO that he can't get with casting foam. He also uses slipper casting for some clients with feet too large to fit in the casting foam. Slipper casting is his method of choice for mid-tarsal and mid-foot amputation, where he needs to see the shape of the residual limb to obtain a good fit with the shoe filler. However, Pattison says, "Casting foam is a lot quicker to do and provides work with a lot less mess than slipper casting!"

Technology Can Help

To sum up: Although at this point automated scanning and fabrication does not replace traditional methods of measuring, casting, and fabricating, the technology can be a useful and cost-effective tool to meet a substantial segment of patient needs, providing good outcomes with significant savings in time and cost.

For more information on automated foot systems included in this article, visit†www.amfit.comand†www.digitalorthotics.com. Along with the systems discussed in this article, other systems mentioned by orthotists and pedorthists were Tekscan, Foot Maxx, Canfit-PlusTM, and Sculptaped. For more information, visit†www.tekscan.com;†www.footmaxx.com; for Canfit-Plus, Vorum Research Corporation,†www.vorum.com; and†www.sculptaped.com. Note: This is not a complete list of companies providing automated foot scanning and fabricating technology.

The O&P EDGE does not endorse any products. Products discussed in this article are included for informational purposes only.

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