LOWER EXTREMITY ORTHOTICS

An orthotic can be defined as a device placed externally on the body to modify the structure and/or function of the muscular, skeletal, or neurological system.   Some people call them splints.

One important use of orthotics after a stroke is to prevent contracture (stiffening of a joint due to shortened muscles).  At least 50% of stroke survivors develop some type of contracture. (1)

Orthotics can also be used to improve function, such as an Ankle-Foot Orthotic (AFO) improving a person’s walking ability by preventing the foot from dragging when they don’t have the strength to lift their foot and toes on their own (that’s called drop-foot).

Sometimes you have to find the line between using an orthotic too soon (or too much) and not using an orthotic soon enough.  Using an orthotic too soon or often could lead to a decreased need to regain muscle control over that body part, and thereby hinder the process of re-wiring the brain to control that foot or leg.  However, not using an orthotic soon or often enough could lead to contractures and deformities that would hinder function down the road.

Here are a few types of orthotics for the lower extremity:

a night splint available at www.orthoticsandbeyond.com

Night Splint

A common contracture after a stroke is when the foot is pulled into a downward position with the toes curled.  Wearing a splint at night, simply for prevention of this type of contracture, is one type of lower extremity orthotic use.

A design that covers a large surface area of the foot and lower leg might be a good idea, to decrease focal areas of too much pressure (bed sores).  Also, a design that controls the position of the toes might be helpful.

Another use of a lower extremity orthotic is to improve walking.  Either an AFO (ankle-foot orthotic) or a KAFO (Knee-ankle-foot orthotic) can improve walking safety (prevent falls), efficiency (decreasing the amount of energy and effort required for walking), speed, and prevent unwanted compensatory movements. There are many variations of AFOs and KAFOS,  so have a physical therapist help you select the best one for you.

Non-articulated AFOs

– these do not have a hinge or separation at the ankle joint.   Some mistakenly assume that a non-articulated AFO will not allow any motion at the ankle, but this is not true.  They range in their stiffness, or resistance to movement, depending on the material and the design of the splint.

More rigid AFOs are generally good for those who have significant weakness of ankle dorsiflexion (pulling your foot and toes upward toward your shin) as well as weakness of ankle plantarflexion (pushing your foot and toes downward away from your shin).  If you don’t have adequate dorsiflexion strength, you will drag your foot on the ground when you swing your leg forward to step (called drop foot), and this can cause falling.  And if you lack plantarflexion strength, you will not be able to push the front of your foot into the ground to prevent your knee from buckling and your shin from falling toward your foot….again, risking a fall.

As you will read later, there are options for controlling just one of these motions with an articulated AFO (hinged).

an example of a rigid AFO, available at www.cascadeorthotics.com

This is an example of a rigid AFO.  (sometimes called a “solid” AFO)  The material of the splint (polyethylene plastic) is very stiff, and it wraps around the sides of the ankle enough to provide a great deal of stability.

example of a semi-rigid AFO, available at www.activeforever.com

This is a semi-rigid AFO (sometimes called a “semi-solid” AFO), which would allow a small amount of motion.  Most likely, when you roll over the front part of your foot when walking, it would allow your shin bone to move toward your toes slightly (dorsiflexion), which is a much more normal walking pattern, if you have adequate strength to prevent your knee from buckling.

Here are a few examples of posterior leaf spring (PLS) AFOs, which are generally much more discrete.  They do not provide enough support if you have significant spasticity or tone that causes your foot to point downward and your toes to curl.  But if you simply lack the ability to lift your toes and foot (dorsiflex your ankle), these might be a good option.

example of a posterior leaf spring type AFO – “The Noodle” available at www.kineticr.com

another example of a posterior leaf spring AFO, available at www.ottobock.com

example of PLS AFO. This, and other AFOs available at www.langerbiomechanics.com

Here is an example of a posterior leaf spring AFO that does not extend under the toes.  If you have a problem with spasticity or contracture of your foot that causes your toes to curl under, a posterior leaf spring AFO probably wouldn’t be appropriate for you anyway (you need something more rigid).  But the presence or absence of toe control is something to consider in a splint.

Articulated AFOs

these have hinges to allow motion in certain planes.  They can be designed with plantarflexion stops (prevent the foot and toes from pointing downward), plantarflexion assists (springs that help the foot point downward), dorsiflexion stops (prevent the shin from collapsing too far toward the foot when bearing weight on the foot), and dorsiflexion assists (springs that help pull the foot up to clear the ground when taking a step).

articulated AFO available at www.cascadeorthotics.com

Ground Reaction AFO –

this title usually refers to a rigid, non-articulated AFO designed to assist the wearer in stabilizing his/her knee, when there is quadriceps weakness.  This AFO is built to keep the foot pointed downward slightly, which forces the knee into a more straightened position for a longer part of the gait cycle, and therefore helps to prevent the knee from buckling due to weakness of certain leg muscles (the quadriceps).

Knee-Ankle-Foot Orthosis   (KAFO)

– when control of the knee joint is needed, as well as the ankle joint.  Many devices are available that keep the knee straight when you are standing on your affected leg (stance control), but allow the knee to bend when you swing your leg forward for another step.

KAFO available at www.orthoamerica.com