Understanding The Impact Of Diabetic Neuropathy On Gait
- Volume 21 - Issue 6 - June 2008
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During gait, the force of the heel at heel strike exceeds that of the body’s weight. The direction or vector of that force passes behind the ankle and knee. If the patient controls that force, the foot gently but firmly begins the process of planting itself to support the body throughout the weightbearing part of the gait cycle. However, if the force exerted at heel strike is uncontrolled due to sensorimotor neuropathy, the foot gives the floor a big, heavy slap with each step. It will also cause an excessive pronation moment during the mid-stance segment of the gait cycle. The result is a compromised gait pattern and load-related pressures that are greatly abnormal.
Conversely, at the end of the weightbearing segment of stance phase (toe off), sensorimotor neuropathy short circuits the ability of the foot to clear the floor fully in preparation for the next step. Accordingly, these patients may subsequently be prone to toe scuffing and stumbling.
Can AFOs Be Beneficial?
One may utilize an ankle-foot orthosis (AFO) to alleviate the problem. In regard to using AFOs for diabetic sensorimotor neuropathy and footdrop, they can control plantarflexion of the foot during the swing and stance phases of the gait cycle.
Some AFOs will also assist the dorsiflexors to lift the foot. These devices are effective when the foot is able to achieve a plantigrade attitude when no ankle contracture is present and when the range of motion (ROM) of the ankle and foot are within normal limits. Some AFOs are made to fit within a shoe. These AFOs are generally prefabricated or custom fabricated from lightweight polypropylene or carbon fiber composite material. The footpiece of this plastic appliance provides minimal medial lateral support of the foot and extends to the posterior aspect of the calf, encompassing half of its circumference. Its length extends 7 cm distal to the fibular head.
When one utilizes these AFOs for diabetic sensorimotor footdrop, they provide a posterior leaf spring (PLS) effect by narrowing to approximately 4 cm on each side of the lower leg midline, posterior to the malleoli. The amount of leafspring or dorsiflexion assistance depends on the rigidity, thickness and diameter of that critical area as well as the height, weight, strength and activity level of the patient. By default, it prohibits plantarflexion footdrop. A proximal anterior Velcro strap keeps it in place.
Weighing The Pros And Cons Of Custom And Prefabricated AFOs