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  • MrD.Smith MSc Biomechanic

Ankle Foot Orthotic for 1. Lateral ankle instability, 2. Weak foot/ankle/leg muscles 3. Foot drop.

Updated: Dec 13, 2019

Ankle Foot Orthotics (AFO)

AFO’s - What are they, how do they work and why do we need to use them?

Humans are a highly versatile and adaptable in terms of movement, activity and locomotion. We walk, run, swim, dance, jump, climb, tumble and fight.

In all activities we make unconscious and conscious considerations and decisions about how we accomplish the objective of the activity.

Speed, direction, efficiency, injury and avoidance, pain protection, balance, aesthetics. Maintaining the balance and coordination between all those things during all the many and various activities we may want to do seems effortless and taken for granted when everything works well. However, when we have foot pain and joint instability just getting to the car becomes a task and sports or walking holidays are out of the question.

This is when we might seek the help of a specialist Musclio-Skeletal Biomechanics Podiatrist who may recommend some type of Orthotic or Ankle-Foot-Orthotic (AFO) in the treatment and rehabilitation plan.

Orthotics cover a wide range of appliances that assist the function of a limb or joint. Orthotics can be used to support an injured wrist, stabilise an arthritic knee or offload sore toes for instance.

They differ to prosthetics because prosthetics replace a limb or joint and we’ve all seen how effective replacement limbs are for athletes and soldiers. Prosthetic knee and hip joints are common place interventions for relieving the pain and debilitating effect of arthritis in those major joints but surgeons can also replace small joints like in the big toe and ankle resulting in improved mobility and quality of life.

Orthotics, when designed, fitted and used correctly, also reduce pain, increase mobility and enable daily and exceptional activities, from walking round the shops to playing professional football.

Orthotics work by changing forces applied to the limb so that either, there is a desirable change in limb position and stability - or - the forces within damaged and painful internal tissues, such as tendon, cartilage and muscle, are reduced to allow healing and strengthening.

Orthotics can work indirectly or directly. So, for instance, a foot orthotic in the shoe works directly on the foot but may also have an indirect effect on the knee, whereas a knee brace works directly on the knee. When fitting orthotics we must consider both to ensure good desired outcomes and avoid secondary undesirable effect, this is why a thorough assessment by a skilled and qualified practitioner should always be carried out.

The Ankle-Foot-Orthotic, as the name suggests, works directly on the foot and ankle, and in some designs the knee as well. They can hold the ankle rigidly or allow joint motion in a desired direction. They can be ready made or bespoke/custom made.

Semi Rigid AFO - Hinged AFO - Rigid AFO

There are different categories of Ankle Foot Orthotics such as Ground reaction AFO, dynamic AFO, Silicon AFO. The Ground Reaction AFO is used to control knee flexion in walking, the Dynamic AFO allows control with agility and is especially useful in children.

Dynamic AFO - Ground Reaction AFO - Silicone AFO

These AFOs more commonly used in Podiatric Biomechanics have many designs, purposes and reasons in the treatment of foot and ankle pain, instability and disability.

Typically someone coming to a Podiatry clinic and requiring an AFO would have foot pain caused by;

1. Lateral ankle instability,

2. Weak foot/ankle/leg muscles

3. Foot drop.

After a full biomechanical assessment they may be fitted with a ready-made AFO or a bespoke customised device.

The advantage of an off the shelf ready made product is that they are less expensive and are immediately available. The bespoke custom made AFO requires casting or 3D scanning of the foot, ankle and lower leg so it has the exact contours to fit perfectly and so are more comfortable, less likely to cause rubbing or local pressure trauma and tend to be more exact and effective for the intended action and outcome.

The exact type and design of the Ankle Foot Orthotic for the individual person must be well thought out and bespoke is not always better than a Ready made device. There are a wide choice of ready made off the shelf devices and, especially for foot drop, are well designed, relatively low cost and work well for most people.

The Seabostep is one example of a ready made devise that we use, and you can find out more here

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