IDS ::: Orthotics ::: Ankle and foot

Ankle braces

These are available in a wide range of designs, sizes etc., off the shelf. They are generally intended to provide support and protection to unstable or vulnerable ankles. They are often provided by persons other than orthotists and are even sold in non-specialist shops. They can be very beneficial in acute situations such as ligament strains as well as in chronic conditions such as arthritis. In principle these are actually a type of AFO but are not generally regarded as such.

Ankle foot orthoses (AFO's)
These are available off the shelf or custom made depending on the required specification. While encompassing the foot and ankle joint, an AFO may also influence more distal and proximal joints. For simplicity they can be considered in three categories: Rigid, Flexible and Hinged.

Rigid
Rigid AFO's – where the intention is to block ankle movement in every plane. These may be used in neuropathic conditions to prevent deformity or provide a rigid support to assist stance. They may also be used to prevent pain by blocking painful movement.

It is a basic principle of orthotic management that, where possible, a useful range of ROM at a joint should be maintained. In a situation where there is no useful ROM, a rigid AFO may be required to hold the foot/ankle in an improved position or provide a biomechanical function. There may be situations where there is passive ROM which is not useful because of lack of power, lack of control, or high tone.

There may also be a situation where there is very limited ROM and even this residual movement is painful. This is often the case with severe RA and can occur with unsuccessful surgical fusion.

Some conditions result in flaccid ankles. Examples of these include spina bifida, spinal cord injury,brain injury or neurological conditions such as cerebral palsy and multiple sclerosis. A rigid AFO in gait will produce floor reaction which may assist weak quads.

Foot stiffly positioned in equinovarus and adductus due to C.P.

The same foot in a rigid AFO

Flexible AFO's– where the intention is to assist the movement of the foot and ankle in one plane while restricting it in another.

These AFO's are designed to flex in use. A very common example is the drop foot splint where the orthosis is designed to aid dorsiflexion to avoid ‘foot drop’. There is a wide variety of designs, both "off the shelf" and custom made. There are contraindications for the use of most designs, which is one reason why so many exist. Flaccid situations are relatively easy to control but high tone or fixed abnormalities are definite complications.

An Otto Bock "Walk on" carbon fibre AFO for drop foot.

Hinged AFO's

These are designed to permit a limited ROM on a single plane, i.e. they permit plantarflexion or dorsiflexion within limits fixed by the hinges, while blocking or attempting to block inversion and eversion. These are used, for example, in situations where there is varus or valgus instability but where it would not be advisable to completely block dorsiflexion or plantar flexion. The primary intention may be to simply block the ROM at a specific point Hinged AFO's may also be spring assisted, generally to assist dorsiflexion. A wide range of joints is available. NB These can only be effective when the patient has useful range of movement.

A small child's hinged AFO which is designed to permit dorsiflexion from plantagrade, but not plantarflexion

"Special" AFO's

There are also several types of special AFO which are designed for very specific purposes. It would be difficult to make a comprehensive list. The following are some examples:

Ground Reaction AFO's
These are very rigid AFO's where the trim lines encompass the anterior proximal shin to provide effective support and resistance to ankle dorsiflexion in stance. This has the biomechanical effect of assisting the quadriceps and hip extensors. Any rigid AFO will provide some ground reaction, but these are designed to provide it more effectively and comfortably in a situation where it is intended to be a main function of the orthosis.

A ground reaction AFO which is designed to prevent unwanted knee flexion in stance by effectively blocking ankle dorsi flexion .

Torsion Cable/Strut AFO's
These are really an addition to AFO's which are designed to control abnormal flaccid rotation of the hip joints. The AFO's are connected to a pelvic section by hinged struts or flexible cables. They cannot be used to overcome tight hip rotational problems because there is a risk of damaging the knee joints

Bilateral AFOs with torsion cables. These are used to control excessive flaccid rotation at the hips. They are not suitable in cases of tight rotation as knees could be damaged.

IDS_Ireland_prosthetics_orthotics_IDS Ireland offer this free resource for Healthcare Professionals who are encountering prostheses and or orthoses for the first time, or are only occasionally in contact with them.

A diagnostic AFO showing tissue blanching due to excessive pressure.

Fitting a silicone AFO

Pateller bearing AFO

AFO's large and small.

Fracture Braces

Some specially designed AFO's are used as fracture braces. These are covered under the Fracture Brace section. Click here to return to Orthotic Categories.