Key Insights On Digital Casting Techniques

Bruce Williams, DPM, FACFAS

Digital casting reportedly facilitates more control of the orthotic impression, better efficiency and greater cost savings than plaster casting techniques. This author assesses the literature, shares biomechanical insights and offers pertinent tips on casting technique.

   Digital scanners are affordable, save time for the practitioner and staff, and provide comparable outcomes to traditional plaster casting techniques. Techniques for digital casting range from traditional non-weightbearing subtalar neutral position casting to partial weightbearing casting. Regardless of the preferred technique, one can achieve the same outcome in the custom foot orthotic. The digital age has arrived and we can no longer ignore it.

   The plantar foot impression is one of the key components in the creation of a custom foot orthotic. Traditional techniques for the creation of a negative cast of a patient’s foot have utilized plaster almost exclusively. Plaster, of course, can be a messy procedure for both the patient, the practitioner and office assistants. Plaster casting takes time as well, reportedly taking an average of 11 minutes according to a cost benefit analysis study.1

   While there are many other options for impression casting besides plaster, with the advent of digital technology in the custom foot orthotic manufacturing industry, more and more foot healthcare practitioners are turning toward digital scanning or casting of patients’ feet.

   According to a cost benefit analysis study which compares plaster impression casting versus digital impression scanning, plaster casting costs anywhere from $28 to 50 per casting event versus $3 to 11 per digital optical scanning event.1 While plaster casting averages 11 minutes, digital optical scanning only takes two minutes on average. This shows a consistent potential time savings for busy practitioners and the ability to quickly make up the initial investment in the acquisition of a digital scanner.

   There can be a large cost savings as well due to the elimination of shipping plaster casts to the lab for manufacturing and the potential risks of damage occurring to the plaster casts during shipment. Obviously, the initial investment in the acquisition of a digital scanner can be large but the study seems to support a significant return on investment through savings in both time and the materials that are used in the plaster casting technique.

   Traditional plaster casting positioning usually consists of having the patient in a sitting, supine or prone position during the plantar foot impression. For most practitioners who are considering the use of a digital scanner, the first question they usually ask is: How exactly does one take the cast impression utilizing the scanner?

   Knowing whether one can position the scanner in such a way so as to match a practitioner’s usual impression casting style is very important. Most systems come with stands that allow for a variety of positioning for the scanner and the practitioner using it. It is also important to know there are other reliable and repeatable ways to capture a digital impression image.

   Digital foot impression casting consists of: utilizing a digital scanner of some type such as a contact or non-contact optical laser scanner; a pressure pin digitizer; 3D image capture through digital photography or video, or a pressure mat system.

Debating Partial Weightbearing Versus Non-Weightbearing Casting

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