The dominant clinical model for much of the last forty years described foot orthotics as alignment correction devices, or tools for repositioning a foot that had deviated from a neutral position.
Yet, the evidence does not support that explanation.
This blog post covers how foot orthotics work, what they cannot do, and what that means for how you prescribe them.
What are custom foot orthotics?
Custom foot orthotics are clinician-prescribed insoles manufactured to a specific clinical brief. Unlike off-the-shelf insoles, custom orthotics are built around an individual patient’s diagnosis, loading pattern, and the specific tissue that needs to be protected.
Orthotics are indicated where a tissue is being loaded beyond its tolerance and a modification to the mechanical environment would reduce that load enough to allow recovery. For example, you may have a patient with plantar heel pain, Achilles tendinopathy, tibialis posterior dysfunction, metatarsalgia, or patellofemoral pain who may benefit from a foot orthotic.
MM Podiatry manufactures bespoke 3D printed orthotics for lower-limb MSK clinicians, connected directly to digital rehabilitation and structured return to activity programmes.
How do foot orthotics work?
Custom foot orthotics alter the distribution of forces through the foot, ankle, and lower limb during movement, changing (1):
- where load is concentrated
- how much load a given structure experiences, and for how long.
The result of the foot orthotic is a reduction in mechanical demand on tissues that are irritated, injured, or at risk.
For example, a patient with plantar heel pain experiences high tensile load at the plantar fascia insertion during push-off — a specific structure, experiencing high load, at a specific point in the gait cycle. An orthotic that distributes pressure across a larger surface area and provides medial arch support reduces that tensile demand.
What foot orthotics cannot do
Foot orthotics cannot change alignment
Orthotics do not reliably change the position or alignment of the foot.
Research suggests that the kinematic effects of orthotics — that is, whether they change the position or movement pattern of the foot during gait, such as how much the foot pronates or where the rearfoot sits relative to the ankle — are modest and inconsistent.
However, consistently meaningful changes are seen in kinetic effects: changes in the forces acting on specific tissues.
For example:
- A 4-degree medial heel wedge produced only 0.25 degrees of rearfoot kinematic correction in controlled conditions (2).
- Wedging on orthotics produces very little kinematic change but has a more pronounced effect on kinetics (3).
- A large systematic review and meta-analyses of orthotic effects on lower limb biomechanics (conducted in runners) confirmed that the primary impact of orthoses was on kinetics, not kinematics (4).
The clinical model that fits these findings most clearly is tissue stress theory, first described formally by McPoil and Hunt in 1995 as an alternative to the alignment model (or Root theory) (5).
Rather than trying to correct foot position, this model asks: which tissues are being loaded beyond their tolerance, and what modification to the mechanical environment would reduce that load enough to allow healing and adaptation.
Foot orthotics cannot build tissue capacity
A custom foot orthotic can reduce the load on a plantar fascia to below the threshold that provokes symptoms, but it cannot make the tissue stronger or more resilient.
That is the purpose of progressive loading in rehabilitation (6,7)
A patient who recovers from plantar heel pain using orthotics alone, but does not build progressive capacity through a loading programme, will remain dependent on the device. When the orthotic is removed and they return to the activity that caused the problem, the mechanical conditions that created the injury will be recreated.
That is why MM Podiatry sees orthotics as one stage in a complete pathway to full recovery, rather than the destination:
- First, modify load, using a custom orthotic to reduce the mechanical demand on the injured tissue enough to allow symptoms to settle and recovery to begin
- At the same time, utilise progressive digital rehabilitation to build the tissue’s capacity to tolerate load independently, so the patient is not reliant on the device long-term
- Finally, consider structured return to activity, to bridge the gap between the end of treatment and full function, where re-injury commonly occurs.
Remember, orthotics can start your patient on the road to full recovery, but alone, they cannot complete that journey.
What does this mean for how you prescribe foot orthotics?
Given the mechanism is load modification rather than alignment correction, here’s what should change about how you prescribe foot orthotics:
- Identify the overloaded tissue. Find the structure that is being loaded beyond its tolerance, understand what is provoking it, and prescribe a device that changes that loading pattern. Foot shape matters insofar as it influences how load travels, but it is not the treatment target.
- Explain the device to patients in terms of load, rather than correction. Your patient should understand that their orthotic is reducing the demand on an irritated tissue while they build the strength to manage that load independently. That patient knows why they are doing rehabilitation alongside their orthotics and has a clear expectation of when they might not need it anymore.
- Treat the orthotic as one stage of a process, not a standalone solution. Orthotics create the conditions for recovery, but do not build tissue capacity or restore the functional demands of your patient’s activity. That is what rehabilitation and a structured return to activity are for.
Summary: How Custom Foot Orthotics Actually Work
Foot orthotics work by changing the distribution of forces through the foot and lower limb to reduce the mechanical demand on specific tissues. They do not reliably correct alignment and they do not build tissue capacity.
That means orthotics are most effective as part of a pathway: load modification first, progressive loading to build capacity second, structured return to activity third. Each stage depends on the one before it.
Understanding this fundamental truth about what foot orthotics actually do will change how you prescribe, how you explain foot orthotics to patients, and what a successful outcome looks like.
If you’d like to find out more about orthotic prescription at MM Podiatry, you can explore 3D Printed Orthotics here, including benefits, costs and more.
Custom Foot Orthotics FAQs
- What foot problems require orthotics? Common presentations include plantar heel pain, Achilles tendinopathy, tibialis posterior dysfunction, metatarsalgia, and patellofemoral pain, but the decision is always guided by the loading pattern and the tissue, not the diagnosis alone.
- Are orthotics actually good for your feet? When prescribed appropriately, yes, but they do not build tissue capacity on their own. Prescribed as part of a complete pathway, including progressive rehabilitation and structured return to activity, orthotics are an effective and well-evidenced clinical tool.
- Can orthotics fix overpronation? Not reliably. The research shows orthotics produce small and inconsistent changes in foot position, including pronation. What they do reliably change is the distribution of forces through the foot and lower limb. It is that kinetic effect, not postural correction, that drives clinical outcomes.
- How do MM Podiatry’s bespoke 3D printed orthotics differ from standard orthotic labs? Many labs manufacture the device and stop there. MM Podiatry connects bespoke 3D printed orthotic manufacture directly to digital rehabilitation and structured return to activity, so the orthotic is the first stage of a complete pathway, not the end of care.
- What is prescribe-by-pathology? A structured prescription route for clinicians who want to prescribe by presentation rather than specifying every device parameter. Select the diagnosis; receive an evidence-informed device recommendation and a linked rehabilitation programme suggestion.
References
- Kirby KA. Subtalar joint axis location and rotational equilibrium theory of foot function. J Am Podiatr Med Assoc. 2001 Oct;91(9):465-87
- Telfer S, Abbott M, Steultjens MP, Woodburn J. Dose-response effects of customised foot orthoses on lower limb kinematics and kinetics in pronated foot type. J Biomech. 2013 May 31;46(9):1489-95.
- Nester CJ, van der Linden ML, Bowker P. Effect of foot orthoses on the kinematics and kinetics of normal walking gait. Gait Posture. 2003 Apr;17(2):180-7
- Jor A. Effects of foot orthoses on lower extremity joint kinematics and kinetics in runners with asymptomatic feet: a systematic review and meta-analysis. Gait Posture. 2025; 121:281-94
- McPoil T and Hunt G. Evaluation and Management of Foot and Ankle Disorders: Present Problems and Future Directions. JOSPT. 1995; 21(6)
- Bohm S et al. Human tendon adaptation in response to mechanical loading: a systematic review and meta-analysis of exercise intervention studies on healthy adults. Sports Med Open. 2015 Dec;1(1):7
Lazarczuk S, et al. Mechanical, Material and Morphological Adaptations of Healthy Lower Limb Tendons to Mechanical Loading: A Systematic Review and Meta-Analysis. Sports Med. 2022 Oct;52(10):2405-2429.
