Today I shall be highlighting the importance and place that an AFO will have in someone’s life, the logic and science behind them, and sharing some practical tips.
What is an Ankle Foot Orthosis (AFO)?
An orthosis is an externally applied device suspended on the human body with an aim to correct or prevent deformity, realign or manipulate external forces that are acting upon the body or to assist in activities of daily living.
When you are assessed for an orthosis it is important to discuss with your orthotist any goals you want to achieve with your orthosis as this will influence the design, shape and materials selected for the job. For example; you may be referred to an orthotist by a doctor because you have trouble walking. The primary goal for your orthosis may be to assist in a safe and smooth gait (walking pattern), but if you are an avid gardener and want your orthosis to be garden friendly, your orthotist may consider lower trimlines on the calf to allow for a more comfortable kneeling position, they may opt for a different type of padding for your bones that don’t react to excess moisture, etc. At the end of the day, you are the person wearing the AFO and your ideas and goals are important. It is vital that you discuss your goals and any concerns you may have with your orthotist, so that they are able to help you the best way they can.
At the end of the day, you are the person wearing the AFO and your ideas and goals are important. It is vital that you discuss your goals and any concerns you may have with your orthotist, so that they are able to help you the best way they can.
Types of AFOs:
AFOs come in many styles and materials and can incorporate different features. Here is a short list of AFOs and their possible uses (please note that there are more AFO styles, “hybrid” styles, and a plethora of diagnoses that and AFOs can be used to treat)
- Solid AFOs: These are commonly made from polypropylene, co polymer, polyethylene, and carbon fibre. They can be used to control a person’s shank in walking, maintain foot clearance in swing (the part of the gait cycle where your leg moves from behind you to in front of you), and prevent contractures. They are used amongst cerebral palsy patients, stroke victims, spina bifida patients, spinal cord injury patients, and patients with a neuromuscular diagnosis just to name a few.
- Hinged AFOs: these can also be used to control shank alignment when walking and clearance in swing phase too. Hinged AFOs and are liked for their ability to allow movement at the ankle joints.
Ankle joints can come in all styles and shapes and sizes and your range of motion and strength are the biggest influences when selecting ankle joints.
A lot of people like the idea of a hinged AFO as it facilitates ankle motion however not everyone is suited to this prescription. If someone is a user of a hinged AFO but their range, strength, tone and bony alignment are not suitable for a hinged AFO, a number of issues can arise; from poor shank kinematics (movement in space) to excessive rubbing and poor bony alignment.
Hinged AFOs should only be used for those who are suitable.
- Supra- Malleolar AFOs (SMAFOs): These AFOs tend to be solid but have the potential to be hinged. These are suitable for those with mild calf weakness, mild spasticity or extreme ligament laxity of the ankles or feet. Most use the strength provided by the circumferential design to provide adequete stability. Compared to a regular AFO, SMAFOs start just above the malleoli (ankle bones) and therefore have less leverage power.
- CAM boot. CAM stands for controlled ankle motion and is also referred to as “moon boots”. These are used to treat lower limb fractures or ligamentous injuries. They can also be used for diabetic patients in conjunction with offloading foot orthoses.
- Posterior leaf spring (PLS). Although this AFO does not have hinges, because of its posterior trimlines (where the AFO finishes) it offers a small amount of energy return allowing a person to adequately clear their foot in swing. A PLS should not be used for complex patients with muscle weaknesses that extend to their calf musculature or quadriceps. It is commonly made from polypropylene and copolymer thermoplastics and carbon fibre.
- GRAFO (ground reaction ankle foot orthosis). This title is a little odd as it implies that this style of AFO is the only AFO that manipulates the ground reaction force. The ground reaction force is the equal and opposite force of your body weight going down through your body and into the ground. Every AFO modifies external forces, thus specifically naming only one of these as a ground reaction AFO is misleading.
Traditionally GRAFOs are set in some amount of plantarflexion (i.e.: the foot is pointing down) and then wedged (when material like EVA (ethyl vinyl acetate) is used to realign an orthosis) so that the shank is vertical or inclined. There is a section of the GRAFO where it swoops from behind and comes into contact with the leg just bellow the knee cap. This aims to get the knee into extension.
If you would like to know more about AFOs or have any questions relating to this post, please send me your questions using the contact form below.
The Supportive Orthotist