Keys To Prescribing AFOs For Senior Patients

Author(s): 
Jonathan Moore, DPM, MS

   Here are some key considerations to bear in mind when prescribing AFOs for drop foot in senior patients.
• Deciding on a solid posterior leaf design versus a dorsiflexion assist AFO for the severe drop foot deformity can be challenging. Proper AFO selection must be preceded by a thorough gait assessment.
• If there is any degree of contracture or spasticity present, a solid style AFO should be of primary consideration. If there is no contracture and the foot and ankle are flaccid, clinicians should consider a dorsiflexion assist device.
• If the trim lines of the AFO fit anterior to the malleoli, one can achieve more rigid immobilization. This style of AFO is beneficial when ankle instability or spasticity is of chief concern.
• AFO trim lines posterior to the malleoli (posterior leaf spring type of AFO) will facilitate plantarflexion at heel strike, and push-off returns the foot to neutral for the swing phase. This provides dorsiflexion assistance in instances of flaccid or mild spastic equinovarus deformity, and furthermore is preferable over a more rigid device.

• Keep in mind that solid style AFOs (depending on the plastic thickness and trim lines) can often be easier to fit into a shoe than a hinged device. However, stretchable shoe styles with some extra depth can easily accommodate the extra space required.
• In some circumstances, one can order an extrinsic post (to be added to the AFO) to better accommodate a varus or valgus contracture. As I noted above, an extrinsic post will most certainly take up shoe space and often will require a larger or Lycra style shoe.
• Consider that a high percentage of patients with drop foot have profound neuropathy on their affected side and can accordingly be at risk for ulceration. It is for this reason that a full-length multi-density insert can be helpful and even necessary in some cases.
• While a simple plastic posterior leaf style AFO with no top covering or posting is the easiest style to don and doff without significant shoe size changes, some patients need padding or top covering (Plastazote) on the orthosis to reduce pressure and friction while increasing comfort.
• While podiatric physicians should make every effort to try to provide the senior patient with the lightest and easiest device to fit into a shoe, do not compromise on what the patient needs to be active and stable. Over-bracing is bad but under-bracing can be worse.
• The Tamarack joint system used in many dorsiflexion assist devices is a lightweight joint that one can easily incorporate into most AFO styles, including gauntlet and open ankle (Sporty style) designs. Incorporating the Tamarack system into an AFO with a synthetic covering and a custom Plastazote orthosis can be an excellent combination of accommodations to reduce pressure and provide more foot support.
• Velcro attachments around the ankle and at the upper leg should always be preferred over laces.
• Adding a Plastazote lining to a plastic AFO can be a great tool to reduce the risk of skin irritation.
• Clinicians should take care to address edema in these patients as this can significantly impact AFO fit around the ankle and especially in the upper leg.
• Advocating compression garments with use of the AFO is recommended.

When Patients Have Posterior Tibial Tendon Dysfunction (PTTD) And Talonavicular Joint Collapse

While much has been written and discussed regarding the use of AFOs for the common pathology of posterior tibial tendon dysfunction, less has been written on how to address the painful collapsed talonavicular joint.

   While some advocate the traditional double upright hinged AFO with an accommodated functional foot orthosis, it has been my experience that these devices most often fail in the setting of a collapsed talonavicular joint or prominent navicular.

Comments

In his zeal to promote his "Falls Prevention Brace," Dr. Moore cites literature which has no relevance to the patient population targeted in his article. The only studies that demonstrate improved balance with AFO devices were performed on patients with cerebral palsy and hemiplegia after stroke. This was clearly stipulated in the review article published by Ramstrand et al, which Dr. Moore cites.1

Furthermore, this excellent systematic review by Ramstrand et al also concluded that there is no evidence that any design of AFO can improve proprioception. The only devices thus far that have demonstrated improved proprioception are Air Cast(R) stirrup ankle braces, and these studies were performed on younger athletes with and without chronic ankle instability.

This begs the question: Can Dr. Moore provide any evidence that his device or any AFO device has demonstrated improved proprioception, balance and reduced falls in elderly patients who do not have hemiplegia or cerebral palsy?

Ramstrand N, Ramstrand S. AAOP state-of-the-science evidence report: the effect of ankle-foot orthoses on balance — a systematic review. J Prosthet Orthot. 2010;22:P4–P23.

It is important for the readers of this article to be aware of the misrepresentation of the facts of the scientific articles quoted by Dr. Moore. For example, Dr. Moore states, "In a 2006 article, Huang and colleagues reported that a solid gauntlet style AFO is the best option (over an articulated style) for those with ankle osteoarthritis arising from ankle motion.13" Yet Huang et al., did not study any type of gauntlet braces and the device which was recommended was only a simple shell brace, not a rigid gauntlet style AFO. This simple shell brace recommended by Huang et al., barely covered any portion of the foot — only the calcaneus — and was secured on the leg by a simple velcro strap.

Moore cites the study by Rao et al., to substantiate his claim that flexible AFOs improve balance and proprioception yet scrutiny of this study reveals that the single patient wore bilateral SOLID AFO devices, which are the very devices that Moore condemns for use in patients at risk for falls.

Authors should strive to present published research in an accurate and unbiased manner. Since Dr. Moore did not disclose the nature of his relationship with Arizona AFO and Langer, readers may actually believe that leather gauntlet braces are superior to all other types of AFOs as suggested in this article. I would invite any reader to review the scientific articles cited in this piece and make their own conclusions about the presentation of facts versus promotion of specific products.

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