The use of orthoses can be traced back to ancient civilisations. There was little development until the 20th century when we began to apply mechanical principles to orthotic design. However, it took until the 21st century when modern material science enabled us to produce highly precise, bespoke orthoses underpinned by an improved understanding of biomechanics.

Unfortunately, the exact mechanism of action through which orthoses produce a therapeutic outcome is still being debated and developed. This uncertainty surrounding orthoses therapeutic efficacy has left the door open for abuse in marketing claims by unscrupulous suppliers, the proliferation of logical fallacies and huge variability in the quality and effectiveness of the orthoses on the market.

There are several reasons for this poor understanding of orthoses’ cause and effect. Not least, because of the multifactorial nature of injury and the variety of orthoses making it difficult to show one intervention having a consistent effect in a diverse population. Hampering things further has been initial foot and ankle paradigms developed in the late 1950s and taught for decades not being as robust and ironclad as first thought.

However, what the research does consistently show is that orthoses do elicit a therapeutic response. The fact that orthoses can elicit a therapeutic effect could be a sign that they are working and do not need to investigate further. However, if we are unable to consistently do this, or understand the reason why this is happening, we are just getting lucky.

Historically, we viewed orthotics through a kinematic lens and worked around the idea that foot orthoses held the foot in a certain position or changed alignment. Often with the intention of working towards a subtalar joint neutral position. However, the idea of the foot functioning around this neutral position is not supported in any population in any study.

Furthermore, we have plenty of studies which show orthoses do not consistently change rearfoot position, or do not change rearfoot position to the degree we imagined, in a diverse population.

Understanding the cause and effect of orthoses is crucial if we are going to generate consistency in our prescribing and successful achieve our outcome measures.

Moving away from attempting to understand orthoses through kinematics and looking at what orthoses do in all people all the time – they alter kinetics. Even when there is no visible change in position orthoses can significantly alter kinetics.

Interesting, but how does this help you treat pathology?

In respect to musculoskeletal injuries and as a generalisation, injury occurs due to loading a tissue beyond its capacity. Either through a single major event or repetitive submaximal loads. Tissue damage will occur when a health tissue is loaded in an abnormal way, an unhealthy tissue is loaded in a normal way or the worst of both worlds and an unhealth tissue is loaded in an abnormal way.

Here we can use Sir Isaac Newton’s irrefutable Laws of Motion to manipulate the ground reaction forces in a considered and repeatable way through the geometry and material properties of our orthoses. Simply put, this will change how high the forces are, the direction they push in and the amount of time a patient is exposed to a force.

Knowing this, we can manipulate forces to change joint moments and loading in selected tissues. An orthotic should aim to load specific tissues within their optimal capacity range.

Orthoses are a mechanical device and should be considered as part of a holistic patient centred approach to injury with wider consideration given to biopsychosocial factors. Understanding the function of orthoses will make them a key part of your treatment plan and a powerful tool when considering load management and rehabilitation.

At 3D Printed Orthotics we will continue to use the most up-to-date evidence-informed research to ensure the orthoses your supply will successfully treat your patients and we will continue to go where the evidence takes us.