Key Insights On Managing Pediatric Equinus With Orthoses
Dr. Harris considers any child who cannot achieve neutral ankle position to be functionally unbraceable if walking is the goal. He adds that children who can come to neutral are “marginal candidates” for AFOs. Under these circumstances, the AFO may be the only treatment option short of tendon lengthening and capsulotomy. If this is the case, one can use a solid AFO to maintain position and prevent worsening. Dr. Harris says progressing equinus is undesirable in children with Duchenne muscular dystrophy. He says a nighttime AFO prevents but does not reverse the progression of equinus.
To achieve adequate control for walking, Dr. Harris says there must be at least 10 degrees of ankle dorsiflexion when the knee is extended and adds that 15 degrees is an ideal angle for dorsiflexion.
Q: What is the role of botulinum toxin type A (Botox, Allergan) in managing equinus deformity? What are the indications for solid ankle versus articulated AFOs?
A: The physiology behind Botox is “very simple,” says Dr. Harris, noting that the toxin paralyzes the neuromuscular junction, which weakens the muscle.
Dr. Bielski has found that Botox seems to work best in those patients who have developed equinus due to spasticity. “I have been less impressed with Botox in patients who have contractures from other causes (arthrogryposis, post-traumatic, etc.),” he asserts.
“Serial casting definitely can work without Botox. I generally will use Botox when therapy and casting have reached a plateau and the equinus persists.”
Dr. Keen uses Botox in patients with significant hypertonia. She recommends using a prearticulated AFO with articulations in place but not opened up when a clinician wonders if the child will have adequate tone reduction to make use of articulations. If the child has severe hypertonia to the point where he or she will not have functional use of any ankle ROM, Dr. Keen recommends a solid AFO. If there is no hypertonia and one suspects simple habitual toe walking, Dr. Keen suggests using articulated AFOs. She says patients should wear the AFO day and night initially with a weaning schedule in place as patients “break the habit.”
Dr. Harris contends the best use of Botox is in equinus deformity that results from “dynamic contracture,” a form of contracture that occurs when the tone in the muscle is so high that attempts at dorsiflexion fail. If this form of limited ROM exists, he says the combination of Botox and serial casting will often result in an acceptable range of motion. Some contractures are myostatic in nature, points out Dr. Harris. Essentially, the muscle itself is permanently shortened and the only way to achieve joint motion is by lengthening the tendon. He says the use of Botox in this circumstance is not physiologic.
Dr. Harris cautions DPMs about Botox, saying it has a very narrow indication and its effects are not permanent. He says using Botox as a monotherapy in this patient population is less likely to be successful as Botox requires intramuscular injection and is “still very expensive.”
Q: Are there any contraindications to orthotic therapy in managing equinus?
A: If the equinus is due to a myopathy such as Duchenne muscular dystrophy (DMD), Dr. Keen says the toe walking is compensatory early on and is necessary to maintain an upright posture.
“Daytime orthotics may be counterproductive in this circumstance but a night time stretch splint to prevent worsening contracture formation that would interfere with shoe use may be reasonable,” she says.
If the foot is not near a neutral position, Dr. Bielski says forcing it into an AFO can cause overpronation and a midfoot break.
The most important contraindication, advises Dr. Harris, is using an orthosis to control equinus before the child has an acceptable range of ankle motion. He says a child with an ankle ROM restricted below neutral cannot possibly achieve a plantigrade foot in an orthosis.
Another contraindication is using a neutral orthosis in a child who compensates equinus by pronating excessively, according to Dr. Harris. Although it is possible to get the ankle to neutral, he says the additional problems generated by excessive pronation overcome the good accomplished by getting the ankle to neutral.