A guide to Ankle Foot Orthoses (AFO's)
At the Buchanan clinic we have been making orthoses for over 50 years. Our Orthotists have extensive experience in the manufacture and design of AFOs which are made onsite in Helen Street, Glasgow
What is an AFO?
Ankle foot orthosis is the clinical name for devices which are sometimes called splints, braces or calipers. They are named based on the joints that they cover so as they cover the ankle and the foot we get the name AFO.
AFO is a general name and it will cover any device that covers these joints.
Who Wears AFOs?
There are many reasons someone will be required to wear an AFO. They can provide support where there is weakness, limit painful movements or prevent deformity where there is spasticity.
Some conditions that can require the use of the AFO are:
- spina bifida
- foot drop
- head injury
- nerve injury
There are however numerous other reasons that they are required
What are they made from?
Caliper or Below knee Irons are made from steel or Aluminium. They attach into sockets which have been added into the shoe. They will extend up to the calf band which is often covered in leather with velcro or buckle fastening.
Row of single BK Irons prior to manufacture
Shoe adapted with caliper fitted
Close up of Socket, backstop and BK Iron
This could be a number of different plastics which are selected based on their properties. The most commonly used are homopolymer polypropylene and copolymer polypropylene. A lesser used material is Ortholen which is best suited to PLS style devices due to the spring and high longevity of the plastic.
This is a composite material which is strong and light. Certain designs can also provide energy return based on the design
Stock Carbon Fibre AFO's
Custom Carbon Fibre AFO
These can be made from various fabrics but will generally include elastic to provide lift and support. We have written a separate blog on different fabric devices
Prim Airmed Textile AFO
How are they made
AFO’s fall into two main categories of Stock and Custom made. Stock devices are based off of either a shoe size or ankle measure. Custom braces can either be made to cast, measures or 3d Scan.
Thermoplastic AFO’s are either made to a cast or 3d scan with casting being the most common method. Casting involves wrapping the limb in plaster of Paris bandage.
Plaster Bandage preparation prior to casting
The orthotist will then position the foot and ankle as desired. After a minute or so the cast will be removed by cutting down the front often with scissors in a plastic panel.
Negative Plaster Cast
To make the AFO the plaster cast is filled with plaster. Once this is set the bandage is removed to leave a positive ‘cast’ of the leg. This cast will then require rectification to ensure the AFO will fit correctly. This often involves adding material to provide clearance at bony prominence such as the ankle bones.
Positive Plaster cast
Once the rectification has been completed the selected plastic is heated in an oven and then draped over the cast with vacuum being applied to ensure it is pulled tight to the cast. Once cooled the plastic is cut off so the edges can be smoothed, padding and straps added.
AFO's awaiting cutting off
Styles of AFO
There are a number of different styles of AFO which are mostly based on the trimlines selected by the clinician. The following styles are just a few of the possibilities.
Posterior leaf spring
The PLS style of AFO is a design to aid foot drop as it is only strong in one direction. It is characterised by a thin band of plastic up the back of the leg and is low profile in nature. It will not provide much support to the ankle.
Thermoplast PLS AFO
Carbon Fibre PLS with front shell
Ortholen PLS prior to trimming and finishing still on the cast
The Solid Ankle AFO is designed to be strong in all planes of movement. The plastic will pull round the ankle and enclose most of the foot. It will provide a large level of support and because of this it can cause problems with footwear. It is often used to restrict painful movement, increased tone is present of significant weakness below the knee.
Solid Thermoplastic AFO
Solid AFO with posterior cut out
A Hinged AFO is similar to a Solid Ankle AFO but has an ankle joint added. Depending on the joint selected this will allow movement in selected planes. The main disadvantage of a hinge can be the increased bulk.
Hinged Carbon Fibre AFO
Does the Buchanan Clinic Supply AFO’s
At the Buchanan Clinic we supply and produce most types of AFO’s. We believe that each device should enable the wearer to reach their maximal potential and will guide you to select the most appropriate device
We are also experts in activity / Sports specific devices. Our orthotists have designed custom AFO’s for use in cycling, powerlifting and boxing to name but a few. We love working with people to achieve a specific goal be it walking pain free to the shops or running a half marathon.
We have posts on other styles of AFO