A Guide To Conservative Stabilization Of The Neuromuscular Foot
- Volume 21 - Issue 11 - November 2008
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Using hinges that allow the full range of ankle motion but actively assist with dorsiflexion allows the patient without increased tone to walk normally as well as drive a car. Driving a car is certainly possible but more difficult when the patient is wearing an AFO that allows no plantarflexion.
A full foot plate, molded thermoplastic solid ankle AFO will prevent foot drop and increase propulsion power at toe-off. The same can be said for a custom AFO molded from a pre-impregnated carbon composite. One can fabricate a
single or double upright metal brace to accomplish the same goals. However, it will be bulkier and much more difficult to transfer from shoe-to-shoe.
When patients have dropfoot and mild lateral ankle instability, as one may sometimes see in patients with Charcot-Marie-Tooth disease, providers can mold a full-length custom foot orthosis — as opposed to a simple liner — into the posterior leaf spring AFO. The foot orthosis should have aggressive lateral posting.
What Are The Benefits Of Tone Reducing And Dynamic AFOs?
Can an orthotic device reduce tone? The proponents of dynamic or tone reducing AFOs maintain that the devices can indeed reduce tone in the foot and ankle. While there is data to support these claims, there are also a number of studies opposing the concept that an AFO can improve function by reducing tone. 4-9
This debate has been ongoing for years and there is, as of yet, no consensus opinion on the matter. In
general, though, just about all types of AFOs do improve gait function in a spastic foot in comparison with not using an AFO.
A dynamic AFO is constructed with a very thin, form-fitting, flexible plastic. It permits some ankle motion while maintaining the subtalar joint in a neutral position. This is important as medial-lateral ankle-foot instability is such a common component of spastic equinus. The footplate is uniquely constructed by molded protuberances that apply pressure to specific spots on the sole of the foot. Other features can include a spastic inhibitor bar (an orthotic modification akin to a toe crest), a toe extension plate, toe loops or toe separators, all of which help to keep the toes extended. 10 Specific shapes and placement of metatarsal pads also aid in reducing tone and keeping the toes extended.
Providers can build these tone-reducing features into a foot orthosis, a solid ankle AFO, a hinged AFO or a supramalleolar orthosis (SMO). The SMO is not as effective as an AFO in preventing plantarflexion as its superior trimlines typically lie just above the medial and lateral malleoli. 11
As with many other braces, the tone reducing AFO will require the application of an in-depth shoe to accommodate the extra bulk associated with the type of AFO. An in-depth shoe offers extra room in the toe box, typically ¼ inch to 3/8 inch of extra height. It will also have a removable factory insole that one will most likely need to remove to make room for the AFO.
Depth shoes do not have to be “orthopedic” looking. Many popular commercial athletic shoes are available in multiple wide widths and have removable insoles. 12
Several shoe manufacturers also make dress-type shoes that can be classified as in-depth shoes while still meeting social and cosmetic expectations.
Another consideration when dealing with the spastic foot is the type of opening on the shoe. The wider and further down the top of the shoe that the opening is, the easier it will be to don and doff.