Key Pearls For Prescribing AFOs

Author(s): 
Clinical Editor: Howard Dananberg, DPM

You may find that even the best of custom foot orthotics are insufficient to manage a particular patient’s problem. Either too much force is applied to the foot or perhaps the foot orthotic cannot provide the necessary support. In some of these cases, one may consider using an ankle foot orthotic (AFO). In a follow-up to last month’s cover story, a panel of experts address how and when they employ these devices in treatment. Q: In what type of situation do you consider using an AFO or similar brace? A: Alan Banks, DPM, uses an AFO in various situations, saying the device can be helpful in treating a variety of conditions. Sometimes he uses a prefabricated AFO for patients who have some type of dorsal or anterior nerve injury. Dr. Banks says plantarflexion of the foot during sleep serves as a source of traction to such nerves. He notes that this plantarflexion can aggravate or reduce the rate of healing if there is a nerve injury or neuritis. Since the AFO is typically only used at night, a custom fitted device is not required. “The prefabricated AFOs are economical and effective in this setting,” explains Dr. Banks. In some instances, they can also be employed by the patient during the day if necessary. Both Dr. Banks and Doug Richie, Jr., DPM, have found AFOs useful in treating Charcot conditions. Dr. Banks notes that he may use them to treat patients who have an early or mild Charcot deformity once the condition is quiescent. “If the device is rigid, it will alleviate much of the bending stress at the ankle,” maintains Dr. Banks. “It is this force which is the most destructive in patients with neuropathy.” In Dr. Richie’s experience, an AFO can reduce plantar pressures and resist contracture of the heel cord in the Charcot foot. More advanced Charcot conditions are a different story, according to Dr. Banks. When treating these patients, particularly those with transverse plane dominance, Dr. Banks has found the AFO “simply does not provide enough accommodation for the foot deformity.” Instead of an AFO, he typically uses a double upright brace in combination with a molded shoe or perhaps a depth oxford with an orthotic or molded plastazote liner. “This generally tends to provide better protection for the foot itself,” notes Dr. Banks. How Should You Use AFOs For Dropfoot? Howard Dananberg, DPM, most commonly uses AFOs to treat dropfoot. Dr. Dananberg notes that following conditions like CVA, problem back surgery or spinal injury, the anterior musculature of the patient’s lower leg may fail to function normally. When this specifically involves the anterior tibial muscle, the foot does not have effective dorsiflexion capacity. During swing phase, this lack of dorsiflexion causes the toes to touch the floor and patients frequently are subject to tripping, according to Dr. Dananberg. “The most usual patient accommodation for this is a steppage-type gait,” says Dr. Dananberg. “In these cases, AFOs can be quite effective.” Dr. Richie notes that when you employ the device to treat conditions such as dropfoot and lateral ankle instability, the AFO can control sagittal plane ankle rotation and also resist unwanted subtalar and midtarsal joint inversion instability if the orthotic footplate is properly contoured and balanced. Historically, bracing has been used to treat patients with dropfoot and is still “a reasonable conservative alternative for this condition,” according to Dr. Banks. However, Dr. Banks also points out that “the need for bracing of the foot and ankle has, in many circumstances, been obviated with the advancement of surgical techniques that allow patients to undergo repair of their deformities and/or with tendon transfers to provide dorsiflexion.” There are also clinical situations in which prescribing an AFO may not be the best course of action. Dr. Banks says a common problem is physicians prescribing an AFO for a patient who has a spastic equinus following a stroke. In this circumstance, the foot is often fixed in equinus and therefore the AFO is “of little benefit, except to possibly counteract some additional degree of contracture.” That said, Dr. Banks says using an AFO may be an acceptable means of controlling patients with tibialis posterior tendon dysfunction who are not surgical candidates or are waiting for a more convenient time to undergo surgery.

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