Foot Orthoses

Original Editor - Mariam Hashem

Top Contributors - Mariam Hashem, Kim Jackson, Jess Bell, Naomi O'Reilly, Admin, Tarina van der Stockt, Lucinda hampton and Matthew Chin

Definition and Mechanics

According to the Atlas of Orthoses and Assistive Devices, foot orthoses (FO) are like the tires on an automobile. They provide a critical, biomechanical contact point for the human body, and they can be helpful to correct problems in the foot, knee, hip, and spine''.

• An orthosis is a single device, a group of them are referred to as orthoses.
• We can use the term orthotic devices, but not orthotics as they refer to braces and splints.

Foot orthoses were historically believed to work by correcting mechanical abnormalities that are observed visually - e.g. correcting a perceived ‘over-pronated foot’. However, more current understanding leans towards the therapeutic benefit being achieved from internal kinetic changes.

Tissue stress principals can be used to explain how orthoses work: i.e. altering the internal demands on the overloaded tissue through the use of proper orthoses can explain pain reduction and improvement in function in foot conditions with orthoses.

There is also room for applying biopsychosocial modelling to foot orthoses.

• Understanding the patient's condition clearly and communicating effectively with them could have positive effects on the success of the orthoses.
• Asking questions on how the patient feels about orthoses. If they have positive feelings, then using the orthoses could promote a therapeutic benefit. If they do not feel positive, then having an effective conversation can help determine the best route of treatment.

Clinical Uses

The uses of orthoses vary from pain relief, comfort and enhancement of performance.

They are widely used in the treatment of different foot conditions:

Plantar Heel Pain

The use of foot orthoses for plantar heel pain is recommended by various research studies and reviews:

• A best practice guide from 2022 by Morrissey et al. found that core treatments for individuals with plantar heel pain should first include taping, stretching and individualised education. However, those who do not have sufficient improvements, "may be offered shockwave therapy, followed by custom orthoses."
• The Journal of Orthopedic Sports & Physical Therapy clinical practice guidelines encourage the use of "foot orthoses, either prefabricated or custom fabricated/fitted, to support the medial longitudinal arch and cushion the heel in individuals with heel pain/plantar fasciitis to reduce pain and improve function for short- (2 weeks) to long-term (1 year) periods, especially in those individuals who respond positively to antipronation taping techniques."
• Wittaker et al. reviewed 19 clinical trials and reported moderate-quality evidence supporting the use of foot orthoses as an effective intervention at reducing pain in the medium term in plantar heel pain.
• A study by Bishop et al. investigated the effect of wearing custom foot orthoses on: first-step pain; average 24-hour pain; and plantar fascia thickness in people with unilateral plantar fasciopathy over 12 weeks. The authors found improvement in first-step pain and reduced plantar fascia thickness over a period of 12 weeks compared to new shoes alone or a sham intervention.
• Rasenberg et al. reviewed twenty studies investigating the effects of eight different types of foot orthoses on pain, function and self-reported recovery with plantar heel pain compared with other conservative interventions. Their findings suggested there isn't enough evidence to support the use of foot orthoses for plantar heel pain.

Patellofemoral Pain Syndrome

A 2022 review and meta-analysis by Chen et al. found that foot orthoses can significantly improve knee, sport and recreation function in individuals with patellofemoral pain syndrome (PFPS). The 2019 guidelines in the Journal of Orthopaedic & Sports Physical Therapy recommend that "clinicians should prescribe prefabricated foot orthoses for patients with greater than normal pronation to reduce pain, but only in the short term (up to 6 weeks)." The use of foot orthoses should be combined with other interventions.

The single leg squat or double leg squat can be used to assess for provocation of patellofemoral pain:

• If this test reproduces pain in the patellofemoral area, then the clinician asks the patient to repeat the test wearing a foot orthosis.
• If this reduces the pain, it indicates that the patient might benefit from a foot orthosis.

Another test that was developed to identify patients with PFPS who are likely to benefit from foot orthoses:

• The width of the patient's foot is measured from a non-weight bearing position - this is then compared to standing mid-foot width.
• If there is a great increase in midfoot width, then foot orthoses might help. However, a study by Matthews et al. reported that the test is not reliable.

Tibialis Posterior Tendon Dysfunction

Tibialis posterior is a powerful foot inverter (see image). A 2021 systematic review found that using orthoses in the early stages of tibialis posterior tendon dysfunction may reduce pain. It has also been found that custom orthoses may be better than prefabricated foot orthoses for tibialis posterior tendon dysfunction.

• In case of dysfunction, an orthosis can be used to apply some external supinatory support and external inversion.
• Theoretically, this will decrease the load on the tibialis posterior muscle.

Peroneal Tendon Dysfunction

• Opposite to the use of orthoses in tibialis posterior tendon pain.
• It is possible to use an orthosis to provide an external eversion or pronatory force to the foot, which will hopefully have some therapeutic benefits.

Midfoot Osteoarthritis

A carbon fibre type shell orthosis can reduce the amount of bending stress through the midfoot.

Achilles Tendinopathy

• Wearing custom fit semirigid insoles for 4 weeks in combination with exercises has been found to reduce pain in Achilles tendinopathy patients.
• The use of higher heeled footwear and possibly orthoses can result in less load on the Achilles tendon compared to lower heeled and conventional footwear in runners.
• Theoretically, this could be applied to children with Sever's disease to assist in reducing the tensile pull around that growing calcaneum.

Metatarsophalangeal (MTP) Joint Pathologies

MTP joint pathologies such as sesamoid problems, arthritic joints, hyper-extension injuries that are common in rugby and American football players may benefit from orthoses.

• Depending on the pathology, foot orthoses can offload the area (e.g. in case of sesamoiditis) or offer support and reduce bending in case of capsular injuries.

Plantar Plate Injury, Metatarsalgia and Freiberg Disease

• A metatarsal dome can be used to shift the load away from the area of pain
• The plantar plate could be used to reduce the reverse windlass phase time. This will reduce the tensile pull on the plantar fascia

Prescribing Foot Orthoses

Time-frame

The fear of dependency and overuse is often associated with prescribing orthoses. In some conditions, foot orthoses are recommended for long-term use or for patient's lifetime, such as in tibialis posterior dysfunction. However, in other conditions, they should only be used in the short term. For example, the patellofemoral pain guidelines recommended the use of foot orthoses for six weeks only.

Prefabricated vs Customised

Prefabricated or off-the-shelf orthoses are often bought on the internet or at pharmacies. They come in various types and shapes such as full length, forefoot cut-outs and carbon polymer shells. There are various models and designs which allow the clinician and patient to choose freely depending on the desired therapeutic effect.

Prefabricated orthoses are recommended first before trying customised orthoses as you can always apply adaptations and test the results. A clinical adaptation to individualising orthoses is tuning the dosage up or down to meet the demands. It is also important to consider the patient's feedback and, for example, lower or increase the heel height.

Several randomised controlled trials have shown prefabricated orthoses to have similar efficacy to customised orthoses in the management of plantar fasciitis. A study by Pfeffer et al. found prefabricated orthoses better in comparison to customised orthoses in the treatment of plantar fasciitis pain. Another study found no difference between the two types of orthoses for the same condition.

The Patellofemoral Pain 2019 guidelines reported insufficient evidence to recommend customised over prefabricated foot orthoses.

Regardless of the type of orthoses, there are various considerations when choosing the type and design of the orthoses:

• Body weight
• Patient's beliefs
• Current footwear
• Activities

Also, good clinical reasoning, detailed history taking, shared decision and communication play an integral role in the success of foot orthoses. Depending on the condition, orthoses should be combined with other interventions with considerations to the time-frame to avoid dependency and overuse.

Why Do Some Clinicians Hesitate to Prescribe Foot Orthoses?

Some health professionals might be against the use of orthoses for the treatment of foot conditions. This might be due to to the fact that orthoses have been overused over time and the common belief that orthoses contribute to weakening the muscles. However, if they are prescribed properly and are tailored to the individual's needs and their condition, they can be a useful tool when combined with other interventions.

An important point to consider is the difference between the use of orthoses in research and clinical practice. In some mechanical studies, customised orthoses are standardised and fabricated using scanning or casting method. Unlike in clinical practice, prescribing orthoses depends on the applied assessment of foot mechanics in the clinic, linking those findings to the presentation and applying corrections then testing their efficacy.

In regards to muscle weakness, Jung et al. reported an increase in cross-sectional area of abductor hallucis and flexor hallucis muscles in subjects with pes planus with a combined foot orthosis and short-foot exercises for 8 weeks. Contrary to this, a 2017 study by Protopapas investigated the effect of a 12-week custom-made foot orthotic intervention on the intrinsic muscles of the foot and dynamic stability. The author found a significant reduction in the cross-sectional area of flexor digitorum brevis, abductor digiti minimi and abductor hallucis. The changes in the muscle size didn't affect the gait parameters and the dynamic stability which might indicate adaptations of these structures when off-loaded.