Pediatric equinus can be a challenging condition to diagnose and treat. With this in mind, these expert panelists discuss the differential diagnosis, the positioning of orthoses to control the condition, and the benefits that various modalities can have in managing the condition.
Q: How do you narrow down the differential diagnosis of pediatric equinus?
A: Edwin Harris, DPM, cites several possible causes for equinus deformity including: hemiplegic and diplegic cerebral palsy, muscular dystrophies, peripheral neuropathy, spinal cord pathology, acquired contractures and idiopathic toe walking syndrome. He says one can narrow the differential diagnosis by starting with the chronology of the toe walking itself.
“Children who start toe walking from the time they first walk are less worrisome than children who walk normally for a period of time and then start toe walking,” points out Dr. Harris.
In general, Dr. Harris says toe walking associated with the muscular dystrophies occurs in older children and their gait patterns suggest pelvic weakness. In these cases, Dr. Harris advises clinicians to draw creatine, phosphokinase and aldolase. If one suspects central nervous system pathology at that level, Dr. Harris advises referring the patient for magnetic resonance imaging (MRI) of the brain and spinal cord.
The major causes of equinus vary with age, according to Mary Keen, MD. One must consider if the deformity is present at birth, if it is symmetric or asymmetric, if there is arthrogryposis and if the condition is syndromic or non-syndromic.
If equinus is asymmetric in a preschool child, Dr. Keen suspects hemiplegic cerebral palsy. If a preschool child has symmetric equinus, she considers various causes of an upper motor neuron syndrome or sensory integration dysfunction. Dr. Keen notes many children with autism spectrum disorders seem to have toe walking tendencies. She also considers idiopathic toe walking (which often tends to run in families) and dystrophin deficient myopathy.
Dr. Keen, Dr. Harris and Robert Bielski, MD, note that birth history is critical. Dr. Harris adds that circumstances surrounding the mother’s pregnancy that could be contributing factors include: premature delivery, maternal bleeding, prolonged labor, nuchal cord, fetal bradycardia, postnatal seizures and respiratory difficulties. He says all of these factors point to possible central nervous system insult and inappropriate acquisition of major motor milestones also suggests some degree of nervous system malfunction.
In addition to ascertaining the birth history, Dr. Bielski encourages clinicians to narrow down the differential diagnosis by asking about the developmental history. He notes that he will ask about changes in strength, coordination, endurance and bladder control. Doing so will usually rule out most of the neuromuscular problems, according to Dr. Bielski.
In the review of systems (ROS), Dr. Keen says one should assess for any associated physical or behavioral abnormalities or concerns.
In regard to the physical examination, Dr. Keen advises clinicians to look for long track signs, range of motion loss, atrophy or hypertrophy among other factors. As part of his exam, Dr. Bielski looks for increased tone, checks tibialis anterior strength and checks the back for signs of dimples, hairy patches or scoliosis.
Dr. Harris says the physical examination, with emphasis on ranges of motion, and neurological evaluation will also help narrow the differential diagnosis. As he points out, abnormal deep tendon reflexes, a positive Babinski sign and alteration in tone implicate the central nervous system.
“Idiopathic toe walkers are preferential toe walkers,” adds Dr. Harris. “They will come down on command but revert to an equinus gait when they are distracted.”
Q: How proximal does an orthosis need to be to control equinus?
A: Dr. Keen notes that an orthosis must enclose the calf to control equinus. She recommends an orthotic wearing schedule that varies depending on the severity of tone (if present), contracture risk based on tone and gait habits, and the degree of severity of the toe walking habit.
The length of the orthosis depends on what one is treating and how severe the equinus is, according to Dr. Bielski. He typically will use a full-length (above calf) ankle-foot orthosis (AFO).
To effectively control equinus, orthoses should come just below the knee, according to Dr. Harris. “The lower the orthosis, the shorter its proximal lever arm. The shorter the lever arm, the less efficient it is in controlling the ankle joint,” he explains. Dr. Harris says stiffness in the proximal portion of the orthosis is another factor in control. The more forward the proximal medial and lateral trim lines, the stiffer the posterior portion of the orthosis becomes, according to Dr. Harris. He also notes the possibility of articulating the orthosis at the ankle to allow varying degrees of ankle motion, saying it is necessary to restrict plantarflexion to neutral in the control of equinus.
Q: What physical therapy techniques are available to help manage equinus deformity?
A: Dr. Bielski thinks mild equinus does respond to manual stretching and older kids, and pre-teens can actively participate in a stretching program. In several patients, he has found that the tibialis anterior will show improved strength if he treats some of the equinus with physical therapy.
Dr. Harris also notes the effectiveness of regular stretching. “It becomes impractical and uneconomical to schedule a large number of physical therapy sessions to do stretching,” he cautions. “The therapist’s role in stretching is to train the parents to perform home stretching correctly and then supervise their performance regularly.”
Serial stretching casting can help increase the range of ankle dorsiflexion, says Dr. Harris. Although such a technique is most effective in children who cannot dorsiflex to a neutral position, he notes there are some risks to serial stretching casting. He says pressure sores can occur even in a perfectly applied cast, particularly in children with spasticity. Children with osteopenia secondary either to their disease or to disuse may sustain fractures during serial casting, notes Dr. Harris.
Dr. Keen’s recommendations for physical therapy depend on several factors. If she encounters a contracture in equinus without apparent hypertonia, Dr. Keen says serial stretch casting, followed by a home program of stretching and night splinting as well as gait training, can be very effective. In addition, clinicians should consider casting, night splinting, an AFO for daytime use and gait training in physical therapy for these patients.
If there is some good underlying active movement in the anterior compartment muscles after casting, Dr. Keen says subsequent active strengthening of these muscles is an important part of physical therapy as well. If there is some active movement but the child has a hard time learning how to get these muscles activated and moving, she may suggest electrical stimulation as a method of helping the child learn how it feels to activate the muscle. If there is mild weakness, kinesiotaping can provide a gentle dorsiflexion assist, according to Dr. Keen.
A physical therapist’s assessment serves as another document of the ranges of motion, says Dr. Harris, and it frequently identifies subtle alterations in tone that the physician may not recognize. Once one has achieved an acceptable range of motion, the physical therapist can further assist by training and strengthening the muscles in the anterior compartment.
Q: Are there any steps one should take before prescribing ankle foot orthoses for equinus?
A: Attempting to force a contracted equinus foot into a neutral AFO can lead to a midfoot “break,” cautions Dr. Bielski. However, he notes stretching casts will often help get the ankle to neutral prior to AFO fitting. Dr. Bielski has also used nighttime splints (similar to plantar fasciitis splinting programs) that allow patients to stretch the Achilles at night.
Reduce contractures before fitting the AFO, says Dr. Keen, who looks for a passive range of motion (ROM) of at least 10 to 15 degrees at the ankle with the knee extended before recommending AFOs.
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.
Attempting to brace equinus in the presence of an inverted rearfoot “cannot possibly work and becomes an exercise in futility for the physician, the orthotist and the patient,” says Dr. Harris. He notes a relative contraindication to orthotic use is that some children with equinus deformity are insensate and may have significant cognitive impairment, conditions that predispose the child to skin breakdown and ulceration.
Dr. Bielski is an Assistant Professor of Orthopedic Surgery at the University of Chicago Comer Children’s Hospital. He is a member of the Orthopedic Society of North America.
Dr. Keen specializes in pediatric physical medicine and rehabilitation.
Dr. Harris is a Clinical Associate Professor in the Department of Orthopaedics and Rehabilitation at the Loyola Medical Center in Maywood, Ill. He is a Fellow of the American College of Foot and Ankle Surgeons.