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From plaster casting to digital model: how technology changes the work process in the workshop
For many years, plaster casting has been the standard method when an orthotist needed to take measurements of a body before making an aid. Today that method is supplemented and in many places replaced by 3D scanning, which quickly provides an editable digital model of the body part and thus changes large parts of the work process in the workshop.
Where a plaster cast requires the user to remain still while the plaster sets and leaves a physical positive that must be stored, a 3D scan typically only takes about a minute. The result is a digital 3D model that can be saved, forwarded and edited in CAD software, without the user needing to show up again each time adjustments need to be made to the form.
3D printing is increasingly a permanent part of many orthopaedic companies' production. The Danish company Bandagist Jan Nielsen has told Danish AM Hub that they have around 35 3D printers and now print around 70 percent of their prostheses, from leg prostheses to corsets used to correct the spine. This is an example of how much of the production can be moved from hand-forming to digital manufacturing.
| Step | Traditional (gypsum) | Digital (scan/print) |
|---|---|---|
| Impression | Hand-made plaster cast with drying time | 3D scanning in around one minute |
| Adjustment | New casting is often necessary | The model is edited digitally |
| Production | Hand forming over a physical positive | CNC milling or 3D printing |
| Archiving | Physical storage of positives | Digital file easy to reproduce |
Digitalization changes the tool but it does not remove the need for professional judgment. It still requires thorough understanding of anatomy and biomechanics to assess whether a scan is accurate and to translate it into a model that actually works on a living body. Therefore the orthopedic technician uses the new technology as a tool that frees time for what still requires craft: the final adjustment finish and control when the user tests the aid.
“The scanner takes the measurement in one minute — but it still takes a qualified orthotist to translate it into something that works.”
— The point of digitalization