I love technology, don’t you? I would much rather compute something with a device for speed, accuracy and data storage than to do it by hand. Nowadays, we do it with our communication, socializing, entertainment and pretty much every other modern function of life. Using technology for foot scanning is becoming more mainstream and will continue to grow. Keep reading and I will tell you what you need to know about three ways of scanning feet for orthotics.

Pressure Mapping

To start, there is the pressure mat method. This captures a two dimensional image by having the patient stand on or walk across the plate. Plantar pressure information is then captured in the computer.

Dr. Scholls Kiosk

Nowadays, you can walk into a retail store and stand on a kiosk with a pressure plate under your feet. During a single legged stance for each foot, it will read your pressure information and tell you which over the counter insoles will work best for you. Keep in mind that the neutral position of the foot is not part of their assessment. On the other hand, in a clinical setting, they will have you stand still on both feet for one reading and then take another reading as you walk across the mat.

Tekscan Pressure Mat

Be Aware of This…

Keep in mind that the arch height is not truly captured using the pressure reading. Instead, there is and “arch type” assessment made or the computer can be used to alter the image to create the desired arch height. In some software programs, there is an example of a generic “normal” pressure reading next to the patient’s reading to help the practitioner assess the patient’s scan. This is a bit unnerving to me. Where did this “normal” reading come from? How is normal foot pressure defined? Hmmm, maybe fodder for a future article! I think that the pressure information is helpful and some decent arch supports can be made with these systems. However, these should not be considered “custom” devices.

Contact Digitizing

The second way is using contact sensors. This involves a contact digitizer with sensory pegs coming up to the foot and surrounding the foot. This captures a three dimensional image.

Amfit Contact Digitizer

The pegs are usually about 30 mm high. Usually they are set up so that you can do a semi or fully weight bearing reading. You should be aware of the stance of your patient when using these systems. Some of them advocate the fully weight bearing scan without regard for the neutral position of the foot. Also, some actually have the contralateral foot elevated in relation to the foot being scanned.

I Found This Out…

Using sensor pegs at 30mm high presents a limitation that you should be aware of. If your arch height is higher than that…it won’t capture your arch at the highest point. Most of the time this is ok, but if you are designing a total contact device, this may present a problem. Additionally, if you want to do something like a high medial flange, you might run into an occasional height limit. In those cases, the Pedorthist or manufacturer will need to build up the cast manually to add more height for the flange. Also, it is difficult to know if the ff varus in a foot is captured in the scanning process. The computer can alter the ff position on the image to correct it if necessary.

Laser Scanning

The third way is laser scanning. This type of scan can be done in a semi weight-bearing or non weight-bearing position. This can capture a three dimensional image of the foot without any limitations. The images can be altered to obtain the desired modifications needed to produce the orthotics.

Canadian Orthotics Laser Scanning

Thumb Placement is Critical

When using this method in a non-weight-bearing position you may have to alter your thumb position as you hold the foot in neutral. If you load the foot using your thumb under the fourth and fifth met heads as you would with plaster casting, your hand and wrist will be in between the scanner and the foot as it rests on the scan surface. As a result, the forefoot is lifted off of the scan surface by your thumb and hand. This will block the laser from capturing a scan of that area.

Two Scans Might Be Necessary

Also, if there are any landmarks on the forefoot that you have marked for reference, it will not be captured in the image. For example, you may have a callous under the met heads that you want to mark so that you can accurately offload that area on the orthotic. What you need to do in this case is to take a second scan of the foot without loading with your thumb. This allows the forefoot to fully rest on the scan surface and capture the exact location of the marked callous area. There are two ways that scan operators get around this. First, they will resort to more of a semi weight bearing scan. They will not attempt to load the foot at all and just position the foot in neutral, letting it fully rest on the scanner. The other way is to slide your hand distally to grasp the fourth and fifth digits. This allows the forefoot to rest on the scan surface without your thumb and hand in between. The marked callous area will be captured this way. Be aware that in this method you have to dorsiflex the fourth and fifth digits to load the foot properly. When the digits are dorsiflexed, the met heads will plantarflex. It is helpful to be aware of this when assessing the image in the computer and making modifications.

Should You Use One Of These Methods?

All three of these methods can be useful. Laser scanning in particular is very accurate and is the best way to achieve consistent accuracy. In all three of these methods, a digital image is stored in the computer indefinitely which makes it easy to make additional pairs in the future.

What if it Costs Too Much?

Initially, most practitioners shy away from using some of these methods due to the upfront costs associated with purchasing a scanner for your office. If that is the case, manufacturing labs have the capability do the scanning for you. Most companies that sell these different scanning systems have the capability to scan your plaster casts or your foam impressions for you if you send them in. This saves you the upfront cost of purchasing a system yourself. Here’s how it works… you simply cast the foot as you normally would and send it to the lab. They will insert the cast into a laser scanner that will capture the interior surface on a negative cast. Or they will use a digitizer wand to scan the cast by hand. This is a digital hand held tool that glides over the interior surface that marks hundreds of reference points that are used to create the image.

So Now What?

Laser scanning is the way that things are going in terms of fast production and consistent accuracy. No doubt that the use of these systems have their benefits. We should also keep in mind that if we choose to use these systems, there is still a learning curve. It is not quite as simple as it is made to appear in the usual demonstrations that you would see online.

Count The Cost

1. A simple rule I use is this: It will take at least twice as long as you think it will to learn to use a scanning system. It will cost you twice as much as the salesman tells you. You will have the cost of the equipment, any needed accessories and the cost of your time as you take the time to learn it.
2. Also, whether you scan in your office or have the lab scan your casts for you, human error is still a factor. Laser scanning is very accurate if the person using the scanner or digitizer is accurate and the person modifying the image in the computer is accurate. What happens when someone is on vacation or leaves the company? Someone else steps in with a different skill level, or without much daily practice.
3. In my opinion, it is worth the investment to scan at your facility if you plan on doing at least 20 pairs per month for your patients. This way you will have almost daily use of the system and it will be worthwhile to have others trained up to use it with the opportunity to keep their skills honed.

So if you are not ready to try this out just yet, keep an eye on it. I believe these systems will continue to be improved upon and we will be seeing more of them in the future. In particular, check out 3-D printing. It may be the next major advancement in the fabrication of orthotic devices. As a reminder: Be sure to subscribe for free to receive future articles in your email inbox. Question: Do you feel comfortable with the use scanning technology for your orthotics? You can answer in the comments section below…