Keys To Prescribing AFOs For Senior Patients
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.