Current Insights On The Benefits Of Custom Orthoses And AFOs
Can ankle foot orthoses (AFO) prevent falls in older adults?
Dr. Mirkin believes AFOs can prevent falls in older adults. Although AFOs should not be standard wear once a person reaches a certain age, he believes the devices are indicated for certain conditions. In cases of neuropathy (diabetic, unknown origin), arthritis, nerve damage (post-cerebrovascular accident, spinal nerve injury from osteoporosis with collapsing vertebrae against a nerve) or general muscle weakness, he feels AFOs can provide a stronger base that people need to reduce the risk of falling.
When tendons are unable to support joints and patients have an inability to feel where limbs are located without looking, these factors can lead to a greater risk of falling in Dr. Mirkin’s experience. He says a brace that limits motion when there is too much or helps compensate for a weakness can only help.
In those 65 years of age and over and particularly in those over 75 years of age, Dr. Najafi says plantar sensation will be diminished. When this is combined with lower extremity muscle weakness, it can cause a higher risk for falling, according to Dr. Najafi. He cites recent studies suggesting that custom ankle foot orthoses may enhance proprioception via interfacing with sensate skin around the shank segment.7,8 He says the studies also note that custom AFOs provide stability in the ankle joint, particularly in medial-lateral direction, without limiting the motion in anterior-posterior direction (which is required for a healthy gait).9 This in turn may help older adults to have better balance with stable walking, says Dr. Najafi, who notes that further research is required to validate this hypothesis in older adults.
Dr. Landorf notes that the question of fall prevention in regard to AFOs remains unanswered as no randomized controlled trials of AFOs have been conducted with documented falls as the main outcome measure. Although there is a possibility that AFOs could enhance balance by providing additional sensory feedback, he says one needs to balance this against the possibility of restricting motion in the ankle/rearfoot complex, which could be detrimental to balance and potentially increase the risk of falling.
“We are in the early days of research in this area so it may still be some time before we know the answer with certainty,” says Dr. Landorf.
Biomechanically, what are the benefits of custom foot orthoses?
Dr. Najafi cites the major benefits of custom devices.
Reduction of plantar pressure and enhancement of dynamic plantar loading. As Dr. Najafi notes, custom devices can reduce plantar pressure via redistribution of plantar pressure. They also help to enhance normal probability distribution of plantar loading, which he says is of key importance to reduce lower extremity pain during walking.
Dr. Landorf says custom orthoses have a substantial effect on plantar pressures as orthoses redistribute plantar pressure from the forefoot and heel to the midfoot or arch area. He notes orthoses do so by increasing the surface area over which the weightbearing surface is distributed.
“From our research, the effect on plantar pressure is by far the clearest to evaluate and is the most outstanding out of all the biomechanical measures we have at our disposal,” says Dr. Landorf.
Stabilization of the foot during walking. Dr. Najafi says an appropriate design of custom foot orthoses helps maintain the center of pressure line of progression in neutral position (middle of base of support). He notes this helps stabilize the foot, which in turn reduces the risk of injury and enhances gait stability and balance.
Enhancing proprioception feedback. Dr. Najafi notes a custom orthosis can also enhance proprioception feedback by forcing the ankle joint to navigate the foot to stabilize the center of pressure. As he notes, this in turn helps stabilization of gait and enhancement of balance during walking.