The AFO: Ankle-Foot Orthosis Made Simple

You might have come across the term AFO, short for Ankle-Foot Orthosis.  This may sound greek to you but for those who have special needs with their ankle and foot, AFO has become a by-word.  For the benefit of those who do not know about it, AFO are braces usually made of lightweight polypropylene-based plastic in an L-shaped, covering the ankle joint and part of the foot.

Ankle-Foot Orthoses are applied to control the position and movement of the ankle, correct any deformities and aid in weakness of ankle and foot and control the ankle and knee joints in direct manner.  These braces are being used to treat muscle dysfunction caused by stroke, injury in the spinal cord, muscular dystrophy, cerebral plasy, polio, multiple sclerosis and peripheral neuropathy.  Orthoses can give support to weak or unusable limbs and eventually reform them in their normal position.  And in the United States, AFOs are the commonly used orthoses.

We have identified major types of AFOs.  First, we have flexible AFOs that gives dorsiflexion assistance, however cannot stabilize the subtalar joint.  Next, we have the Anti-Talus AFOs that block dorsiflexion of ankle but cannot give proper stabilization for the subtalar joint.   We also have Rigid AFOs that block ankle movements and stabilize the subtalar joint and helps to control adduction and abduction of the forefoot.

Long ago, looking for a brace for Ankle Foot Orthosis has never been easier because you need to go to a specialist.  But now you can order right in the comfort of your home.  There are different stores online that offers different kinds of AFOs. You may visit our website: www.bracemasters.com and you can choose from wide array of AFOs right for your needs. Buy now and see the difference.

See your health care provider to see if an Arizona AFO as an appropriate approach for you to gain mobility, avoid pain and avoid surgery.

The SOLID AFO: Well shaped to the foot, flexible fit with full contact padding at key pressure points. Ball of foot toe-plate area is flexible and not bounded by sides that would impede toe roll over. The vertical10 degree forward pitch is perfect, especially for sneaker wearing. There is sufficient strapping and forward ankle envelopment to keep the foot shaped and positioned where intended. Remember, there are two main objectives. 1) Walking and 2) Shaping the foot against deformity. If the latter is important, then the enveloping fit, as seen here, is ideal.

The main problem with this orthosis, is that there are certain kids with postures that  simply cannot attain this ideal configuration. They need totally custom fit orthoses that, by application of filler material (applied outside the brace), the brace attains an outer contour that looks like this even though the ankle and foot, inside, do not. Thus we satisfy an inner anatomy shaping-holding need as well as the outer walking geometry.  We marry the concepts of orthosis making with prosthesis making.

The HINGED AFO:

Some children have mostly foot shaping needs. Hinges are fine, in that case. However, some have control only so far and not with every step. Rather than allow any degree of free forward movement, a back strap is used (see image) which lets the brace go so far and no further. This is a “control arc” concept. Allow some range which has demonstrated control (strength equal to the task and reaction speed), but no more.

The SPIRAL AFO:

Another way to allow “control arc” (limited arc) motion in ALL directions (not just forward) and even nudge in one particular direction, is the spiral AFO. Certain children almost demand these. Regardless of the medical biomechanical logic or physical needs, the athetoid patients, ataxic patients, and some dystonic patients fall apart when held stiffly. In these sensory dependent conditions, DAMPENING motion beyond an allowed minimum is better than complete limitation. The spiral fit allows flexibility, the carbon component, limits or encourages motion in one direction over another. Because these cases are so sensory needy, leaving the ball of the foot and toes uncovered is best (tactile reasons, not brace reasons). In fact, the strategy is to see how little covering can hold all the anatomical requirements and also to see how thin (for sensory reasons) the brace bottom can be without the brace falling apart. These orthoses work when others fail. Down side? They are beasts to make and worse to adjust. Those few brace makers who can make this brace, groan when they are asked to do so.

Combination Needs:

Some children have foot needs met by their AFOs, but that alone does not control a remaining problem, leg rotation. A twister cable (metal cable) or a side metal bar extending down from a metal or plastic pelvic piece can satisfy that. But a simple elastic strap, as shown on the right, attached by Velcro to a neoprene pelvic belt also does fine. Structurally, elastic control straps are like garters with an attitude. Parents can easily adjust the latter and use them intermittently as need requires. The elastics are soft, cheap, and easily modified. Strung as shown, they let go (pull wise) in sitting. If the straps are run deep to the underpants, then the kids can toilet without assistance.

So, for Blount’s disease, for example, we do not need to worry about control arcs, as the kids are totally normal in skills. We need to change shape, the leg angles AND twists. Twisting is easier when the joints are bent (e.g.: knee flexed). Alignment angles of the long bones are most efficiently steered when the limbs are straight (extended). Such braces allow full ranges to get at both postures (as the child moves). The same brace corrects different parts of the problem as the child moves into different positions.

There are two ways to identify the brace needy group. 1) The lazy way, let all those who will get better (physiologic bowing) get better and whoever is left must be the ones. Or, 2) actually look closely. Physiologic bow is usually minimal with actual bow shape minimal to zero, most being twist (torsion). The physiologic ones are improving with time. Blount’s disease has major high tibial angulation with a few other oddities, and twist as well. The big thing is that Blount’s kids are WORSENING (even at 18 months old, worsening is NOT physiologic). An x-ray taken with the knee pointed straight ahead (foot looks wrong when doing it correctly) will show that a line (weight bearing line) drawn on the x-ray from hip to ankle passes outside the knee – unsupported by bone. That lack of support may very well be what pinches and damages the inner growth plate at the knee to create Blount’s disease (or at least what makes it become a permanent growth defect, rather than a passing phase).

What does this have to do with AFOs? Well, the AFO may actually get in the way. These braces need special metallurgy for the reshaping and AFO components may overly stiffen the construct creating too high a focal pressure at the knee. See?

For more information about these products, please feel free to consult us at www.bracemasters.com. We would be glad to be of service to you.