The Manufacturing Podiatrist

Does New Technology = New Casting Techniques…?

We currently find ourselves in a brave new world of orthoses manufacture. New techniques, materials and software programs are rapidly becoming available to the practising clinician.

A tale of caution about these times needs to be told:

    • Are the materials doing what we think they’re doing?
    • Do the algorithms embedded in the design software do what we think they do?
    • Does the process the manufacturers follow, create the devices we think they are creating?

We practice in times akin to a time when cigarettes has no warnings, or the motor car being manufactured without seat belts. At that point in history, every participant was happy to drive around, at never seen before speeds, shortening times between A to B, allowing us to get more done in the same time. Great times… until someone realised that there was a strong correlation between injuries associated with motor vehicle accidents and the lack of a restraint. History shows us that regulations rapidly followed, across the globe.

We live in similar frontier times with the technology available to us as practitioners scanning and digitally manufacturing custom orthoses. Do we know the innate differences between the well understood process of direct from cast (“Plaster of Paris” orthotic manufacture) to that of capturing the foot in space electronically and machining out a shape? and the process of submitting this data into programs that innately “smooth” the shapes to the line of best fit easiest to program into a computer?

In other words; its far easier to manufacture from five reference points and extrapolate the foots position in space. The five point technique requires far less processing time and power than it is to use the approximately 2.8 million data points a modern scanner can capture. Those with appropriate laser range finders can even capture foot datum points that reference colour and position. Unfortunately the latter are not overly promoted or widely used at this point in time.

What about our techniques for capturing a foot in space? Nothing has changed with regard to the clinical thinking… why does waving a scanner around the foot left to it’s “unloaded” self in space?

Where did foam boxes come from?? Using this method, how to we follow our training and assess what position we have captured the foot in? and report this to the manufacturing technician to make the exacting custom device we invariably charge significant design time for?

One truth about making the “correct” cast and prescription: It takes time.

Labs don’t want to spend too much time doing it, and as evidenced by the number of poor prescribing and foot casting practices, nor do we as practitioners. Unfortunately we don’t have a choice; Paying attention to the capture, design and manufacture process is something we are mandated to do as medical professionals.

It is our role, as the registered professional in a manufacture process, we need to make ourselves aware of the limitations and assumptions innate in evaluating, capturing, submitting and communicating our custom prescriptions in an electronic way. It is legally and morally essential for us to be aware of all the factors that go to manufacturing a medical device that presents itself as a fully customised product.

The following sections are designed to generate thought and discussion on the modern manufacture of the customised orthoses. This highly important tool and adjunct to the therapies we follow needs urgent review and attention for it to remain relevant into the future on a global scale.

Concepts in the Modern Manufacture of Customised Orthoses

The following concepts of manufacture and orthoses therapy have been developed over may years embedded in the manufacture of sports and medical devices, particularly footwear and functional foot orthoses. Some have been developed with fellow practitioners and others are completely unique. Please feel free to apply these concepts and principles to your designs, however always appropriately reference “Roeszler (2019)” at this site &/or the product / design name when doing so.

Please feel free to contact the authors to clarify the application and use or hybridisation of these concepts ;).

A Summary of Concepts Sofar…


      The Power of Ultimate Variation

    Have you ever played the game where you double each number from 1? One and one make two. Two and two make four. Four and four make eight… you get the idea. Fun to play with kids in the car, ever more so if you want them to fall asleep.

    By its nature, the ultimate variety of plastic / composites available in the manufacture of a customised orthoses, applied to a specific function, can lend itself to these same numerical exponents. Each decision point that we make, may have three, four variables for that presenting situation. Consider how many other alternatives may achieve the same or similar therapeutic results… virtually limitless with the materials and precessing techniques available and yet to be available to the garden variety podiatric professional.

    Acknowledging that there may be more than one way to achieve the same goal can bring some comfort when prescribing customised orthoses. There is no “one way”, and many options may or may not work as well as another. This is both the innate strength and possible weakness of customised orthoses.

    The initial concept of this principle was developed in discussions with clinical practitioners Dr Kevin Kirby and Heidi Meckler at the Biomechanics Summer School, United Kingdom, September 2019.


      The Chain of Orthoses Manufacture

    The manufacture of a customised orthoses is often complicated. At times, the process can be troublesome for both clinician and manufacturer alike. The many variables involved in producing the ideal device for that situation can be as vast as they are varied.

    Now consider the manufacturing process akin to the chain of a bicycle. Each link of the chain is dependent on the integrity of each preceding link for the entire chain to work. In the case of orthoses manufacture, this chain of events starts at patient referral into our clinic, extends through our clinical assessment, prescription, design and manufacture. It winds up at our fourth or fifth review where we can objectively measure and record the success (or otherwise) of our planned treatment. Any weakness along the chain of manufacturing events will have ultimate effect on the solution we as practitioner’s are providing.

    Poor results can creep in where one weak link can affect the entire sequence of events and the product may be different to that to which was intended. As practitioner’s, it is important to consider which portion of the manufacturing pathway is controlled by you, the clinician, and which portion is determined by the manufacturer.
    Any delay or miss-communication in these critical tasks, invariably affects the completion time, due to the need to review, back-track and fix the errors that stem.

    Understanding of the entire path of our individual ‘orthoses projects’ is key. By identifying and prioritising those tasks that are critical to the success of the intended therapy, device accuracy, efficiency, repeatability, efficacy and/or production time can all be managed. In this way all parties can do their roles to complete a successful project, every time.

    Classification of issues that may arise:

    When considering the issues that may arise in the manufacture of a customised device; errors may be classified into three primary areas;

        • Those based with the clinician (thinking errors)
        • Those based with the manufacturer (process errors)
        • Those based in the interpretation process between two parties (Interpretation errors)
  • Historically, the whole concept of internationally recognised medical terminology and education is designed to allow communication of this nature to flow. As busy technicians and practitioners, we often miss, abbreviate and / or misunderstand the information that is being delivered. Pressures on our attention often allow errors of interpretation and thinking to occur.

  • One of the benefits of current modern technology is that we can potentially record, store and repeat everything once a successful outcome has been achieved. We as practitioners need to consider the challenges presented in understanding what it is we think we are recording and storing. As manufacturers, we need to consider how we currently understand what is presented and how we reproduce it.


      The Orthoses Therapy Zone

    Ok, with the power of ultimate variation available to us and acknowledging there may be more or less than say ‘2 million’ plausible orthotic therapy alternatives to the condition, patient, materials and/or clinical situation that presents in front of us… How on earth do we manage the decision of what best to do?

    Consider the simple thought process described below to put you in the ‘correct ball park’ and then lean on your own professional judgement and consider two states of play:

    A: What is the MAXIMUM orthotic profile I could do for this patient and clinical presentation?

    AND / OR

  • B: What is the MINIMUM orthotic profile I could do for this patient and clinical presentation?
  • Now consider the ideal answer will lie somewhere in between these two. You have whittled down a few of your potential treatment options. However you’re not all the way to superstar status orthotic therapy just yet.

    Now think: What is the ideal option with current tools and information I have? Work your clinical process between these boundaries’ and the most appropriate solution for you and your client will present itself.

    Remember; The solution that is most comfortable to you, how you work, and how you support it, will be the best solution for that patient, on that day. This is the essence of fully customised (and customisable) orthoses therapy.

    The initial concept of this principle was developed in discussions with clinical practitioners Dr Kevin Kirby and Heidi Meckler at the Biomechanics Summer School, United Kingdom, September 2019.


      Fundamentals of Communication

    Please check back to this section soon. I am currently reviewing the current best practice with professionals in pedagogy, human psychology and modern forms of human communications.

    I hope to present a clinical shortlist to reference for tools and techniques we as clinicians can use as a tool to engage patients and help them reach their ultimate health goals.

    Exciting stuff 😉


      The MLA Support ®

    This is a registered design and manufacture technique that relates an intrinsic addition / modification to orthoses shells enabled by advances in orthoses design and modern manufacturing technologies.

    It relates the practitioner to quantify and reference the subtalar joint (STJ) rotational equilibrium positions described by Kevin Kirby (2001) and in his subsequent 3D STJ axis position technique of visualisation.

    The technique also relates the practitioner to quantify the application of concepts presented by Harradine et al (2008) and (2011) to consider the alignment of the application of the orthoses reaction force to be at more of an optimal parallel angle to the STJ axis as it moves (translates and rotates) through weight-bearing activity.

    The MLA support technique uses information gathered directly from prescribing practitioner orienting the positions of the STJ to subsequently create a support structure on the plantar surface of a shank independent orthotic shell that is entirely bespoke to that patient.

    Further information on the prescription communication specifics and design and manufacture technique to follow on this site in the very near future.

    Stuart Roeszler (B.Pod, B.Bus) 2019

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