Types of Ankle Foot Orthoses (AFOs)

Types of Ankle Foot Orthoses (AFOs)

An ankle foot orthosis (AFO) is a brace that supports the ankle, foot, and lower leg, helping to improve walking patterns. They accomplish this by limiting or preventing movements in the lower leg and foot while supporting weak muscles. AFOs may also be used to accommodate deformities, maintain joint alignments, and reduce spasticity.

An AFO is not a replacement for the lower limb but instead a supportive, external device. Users of AFOs find that they help decrease the risk of falling, improve balance, and help with weak lower leg muscles. All these benefits combine to allow for greater mobility or a return to the previous activity.

Girl wearing custom ankle foot orthoses

Gait and joint positioning abnormalities can result from a range of causes, such as:

– stroke
– cerebral palsy (CP)
– multiple sclerosis (MS)
– ALS
– idiopathic toe walking
– trauma
– spinal cord injury
– nerve damage
– partial foot amputation
– muscular dystrophy

AFOs can help treat many different conditions, with different types best serving certain conditions.

Some of the conditions AFOs can treat include:

Foot Drop

Those with foot drops are unable to raise their foot when walking, which causes their toes to drag on the ground. This condition often results from weakness or paralysis on one side of the body, typically due to a nerve or brain condition.

Heel/Foot Eversion or Inversion

With heel/foot eversion, the heel or foot collapses inward, and as it worsens, the sole faces further away from the opposite foot.

With heel/foot inversion, the opposite occurs, with the sole turning towards the other foot.

Excessive Pronation

Excessive pronation, also known as overpronation, occurs when the arches of the feet flatten more than they should, putting a strain on the muscles, ligaments, and tendons supporting the arches. It results from an abnormal gait where the foot rolls inward while walking.

Gait Instability

Gait instability occurs when someone cannot walk normally, whether because of underlying conditions, injuries, or issues with the feet or legs. It can result from various conditions, such as arthritis, neurological disorders, or even ill-fitting footwear.

Some gait disturbances can include:

– faster and shorter steps
– knees and thighs hitting when walking
– one leg stiff and dragging in a semicircular motion

Forefoot Adduction or Abduction

Forefoot adduction occurs when the front part of the foot, where the toes are, is turned inward toward the other foot. This condition appears at birth but might not present until the child begins walking, leading in with in-toeing. In around 90% of cases, this condition resolves on its own by the time a child turns 4. However, forefoot adduction remains in 10% of cases, requiring a brace to correct foot positioning.

While forefoot adduction results when the forefoot turns inward, with forefoot abduction, the forefoot turns outward or away from the opposite foot. This condition is common in those with flat feet.

Knee Hyperextension

Knee hyperextension occurs when the knee joint bends back or straightens too far, which places excessive stress on the knee. While an AFO is intended to brace the ankle, foot, and lower leg, its ability to influence the movement of these body parts can indirectly reduce knee hyperextension.

Types of AFOs

Overall, AFOs are used in cases where the ankle joint, foot, and lower leg do not remain in proper alignment, potentially due to muscle weakness or partial paralysis. AFOs help to hold the ankle joint and foot in the correct position, correcting gait patterns in the process and remedying the symptoms that result from improper alignment.

With this goal in mind, many different types of AFOs accomplish this primary goal with variations in other benefits.

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Custom vs. Off the Shelf AFOs

Only some AFOs are custom, and a custom model is not always needed. For those with temporary gait issues, an off-the-shelf AFO may be all that is required.

However, there are many instances when a custom-molded AFO will offer more significant support and comfort. Examples of a custom molded AFO are when a patient has a condition that will last more than six months; there is a need for triplanar control, or if the patient has an anatomical presentation that can not be accommodated by using an off-the-shelf AFO. The types of AFOs outlined below are all custom AFOs.

Metal Vs. Plastic Design

One of the first differences regarding AFO types is the material. AFOs can have either a primarily metal or plastic design. Depending on each patient’s needs, their physician or orthotist will determine which style to utilize.

Plastic AFOs are total contact, providing a lower profile design with a great ability to control the foot and ankle alignment. The plastic design is custom molded through a plaster impression. There are cases where the patient has an allergic reaction to plastic. In such a case, we will refer them to a metal design. Finally, another advantage of plastic braces is that they fit inside a patient’s shoe.

As for the metal design, these AFOs are ideal for patients with sensations, skin issues, or swelling because the brace allows for fluctuations in swelling. These braces attach to a patient’s shoe, which is typically a diabetic shoe. It does not touch a patient’s skin, so there is no risk of breakdown. The disadvantage of the metal AFO is they are heavier and cosmetically less appealing. However, like plastic AFOs they provide excellent support and accommodate for weaknesses, helping patients ambulate safely.

Solid AFO

The solid AFO provides maximum ankle stability and can be used to treat:

– Drop Foot
– Heel eversion or inversion
– Excessive pronation
– Forefoot abduction or adduction
– Knee instability

Sometimes, the solid AFO will be fabricated with a molded inner bootie, reducing shear forces and improving foot alignment through triplanar control.

One problem with solid AFOs is that they can be restrictive because it does not allow for any ankle motion. Still, some individuals need this extra support to stabilize the ankle, foot, and even knee when walking.

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Articulated AFO

The articulated AFO treats many of the same conditions as a solid ankle AFO, such as:

– Drop Foot
– Heel eversion or inversion
– Excessive pronation
– Forefoot abduction or adduction
– Foot dop
– Genu recurvatum

However, the articulating AFO will allow natural tibial progression during gait, allowing for a more natural gait through this added range of motion. The articulated AFO will prevent plantarflexion, which will prevent foot drop and help to limit genu recurvatum.

Articulated AFOs can also be created with the molded inner bootie, similar to the solid AFO. Unlike the solid AFO, though, the articulated model allows for some ankle flexion, while the solid AFO does not.

Posterior Leaf Spring AFO

The posterior leaf spring (PLS) AFO is used to treat conditions that include:

– Foot Drop

It is a lower-profile design. But the footplate trimilines can be molded and customized to accommodate and control various foot deformities or alignment issues.

The thin plastic design allows ankle flexibility and passive ankle dorsiflexion when in the stance phase. This increase in flexibility offers smoother knee-ankle motion when walking.

Neuroswing Carbon Ankle Foot Orthotics

Carbon Fiber AFO

Carbon fiber AFOs have an open-heel design that is lightweight and semi-flexible design, similar to the PLS AFO. The carbon fiber AFO has an energy-storing component that is released during late stance.

This type of AFO possesses little or no medial and lateral support to control ankle pronation and eversion. This AFO is ideal for a patient seeking a lightweight brace to address their drop foot.

Wearing Your AFO Correctly

After choosing the best type of AFO for your needs, it is crucial to ensure that it is worn correctly to see the greatest assistance and comfort.

When wearing an AFO, wear a smooth, long sock underneath to prevent the AFO from rubbing against your skin and causing irritation and pain. Additionally, the sock ensures that the AFO does not stick to the skin, which can be painful when attempting to move.

If you wear an AFO that does not fit properly, it can rub against your foot and ankle, causing redness and potentially bleeding. If you notice this while wearing your AFO, discontinue using it and see your orthotist to have the AFO adjusted.

For children using an AFO, it is also essential that they receive a new or adjusted model when they have outgrown their current one. This ensures that the AFO still fits correctly and provides the intended benefits.

Choosing the AFO For You

At Lawall Prosthetics & Orthotics, we understand the many choices in AFOs, which is why we are here to help. Whether you are unsure about a plastic or metal AFO or are debating if a PLS or solid AFO would best fit your needs, our experienced care team can help you consider your options to choose the AFO that is a perfect match.

To assist you in this decision, our team members will evaluate your needs to determine if an AFO is needed and what type will be best. Reach out to Lawall Prosthetics & Orthotics today to schedule an appointment.