I think someone said "easy..." ?
Casting, scanning, assessing and submitting foot modelling data is easy right? Press a button, lights flash, the magic processing wheel turns, a 3D foot appears on our screen. Press another button and the lab has all they need!
Foot printing clinician Ian Drakard takes us through the processes of casting and/or scanning in preparation for sending information to a manufacturing lab…
" Modern technology correctly applied "
How to cast and scan...?
Now I’ve seen some pretty fierce arguments about the way casts and scans should be done, so I’m not expecting you to agree with everything, but hear me out ok?
I’ll also use cast and scan somewhat interchangeably at times, because I just mean the method of volumetric capture.
So, what are we trying to achieve with the scan? As someone who has spent years designing orthoses around scans, not only for other clinicians but also my own patients, I can’t repeat this point enough; the closer the scan to the final shape of the device you want to achieve, the easier the process and the greater the chance of a successful outcome.
Footprint Hubs Stuart Roeszler has done an excellent blog on communication here, and the scan is a huge part of communicating the shape we want to end up with. I’m confident I could get a similar looking cast from 2 sets of feet with very different mechanics. So when I’m teaching people to cast or scan, I show them the basics, but the point always comes back to not just does it reflect the foot, but does it reflect the device geometry you are thinking of? Where the device is higher or lower will influence the magnitude and vector of the orthotic reaction force applied to the foot.
The prescription forms we see have not changed from the days of plaster. Most labs don’t use a separate form for digital scans or plaster casts or foam boxes. But the form options are the same. Expansions, arch fills etc all have the same check boxes.
So, suppose I take a traditional suspension plaster cast, loading the lateral column, and a digital scan with the foot left hanging. I’m not going to tell you which one is better, because that’s not the point. Suppose I fill in the same boxes on the prescription form. I should end up with 2 different shaped devices right?
Either that or the person doing the designing has made a load of assumptions I didn’t ask them to make to get to a different shape – in which case what’s the point of the prescription?
The simple answer to the above is YES. For a lot of the things we do (and say we do)… as an industry, current technology has a de-skilling effect. It is much quicker and easier in exchange for a bit of “loosening” of our protocols and effects the customised nature of the product(s) we produce.