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Quarterly Consult January 2006: Recognizing Normal Development of the Lower Extremities

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The Quarterly Consult is a quarterly supplement to the Bulletin highlighting pediatric clinical expertise. If you have an item of interest to include in the Quarterly Consult, contact Dr. Steve Dassel at (206) 625-7373, mailbox 8588.

By Steve Dassel, MD

It has been a number of years since Consult discussed angular and torsional deformities of the lower extremities and positional foot deformities in children. I discussed these topics with Vince Mosca, MD, associate professor of Orthopedics, University of Washington, and past director of the Department of Orthopedics at Seattle Children's Hospital.

Q: Vince, let's start with intoeing. What should we do about it?

A: It can be caused by femoral anteversion, internal tibial torsion and metatarsus varus or adductus. Femoral anteversion is measured by the number of degrees of internal and external rotation at the hip.

Anteversion is defined as greater internal than external hip rotation. It peaks between 5 and 6 years of age and improves spontaneously thereafter in most children. It almost never requires intervention.

Q: And why might it come to intervention?

A: About 0.1 percent of the time, the anteversion is severe enough to cause functional impairment. If this does not self-correct by age 10, we may recommend derotational osteotomies. We perform the surgery about once per year here at Seattle Children's.

Q: Any association with developmental delay?

A: If hypotonia is present, as it is in many developmentally delayed children, then there is a greater likelihood of femoral anteversion and flexible flat feet.

Q: Many children, when sitting on the floor, press their medial malleoli downward against the floor, out to the side, rather than placing their lateral malleoli in front of them. You refer to this as the "W" position. What is the association between the "W" position and femoral anteversion?

A: Kids with femoral anteversion assume that position because that is the shape of their bones and the comfortable rotational alignment of their hips. The position neither causes the anteversion nor does it make the anteversion worse. There is absolutely no reason to try to prevent the child from sitting in the "W" position.

Q: Comment, please, on asymmetrical femoral anteversion vs. bilateral symmetrical femoral anteversion.

A: Physiologic femoral anteversion is always symmetrical. If you note asymmetry, check for a dislocated hip. As a matter of fact, if you should note femoral anteversion in your chart, make sure you also note if it is bilateral and symmetrical.

Q: Let's go on to intoeing caused by internal tibial torsion.

A: It is seen normally up until the toddler years. The tibia then externally rotates to an adult position during the first decade. Internal tibial torsion is always greater on the left than on the right, so here asymmetry is the norm. There is no functional impairment to internal tibial torsion. It is measured by the thigh-foot angle.

Q: I once had an Israeli soccer star in my practice and when I started to discuss his child's internal tibial torsion, he quickly interrupted me, pointed at his own tibial torsion, and said, "I know and you leave him alone."

A: Yes, a disproportionate number of professional athletes have internal tibial torsion. It certainly does not impair their function and may even be a bit helpful. Surgery is almost never necessary. On the other hand, external tibial torsion never corrects by itself and occasionally, about one per year here at Children's, comes to surgery.

Q: Finally, what about metatarsus varus (adductus)?

A: This is measured by the angle of the forefoot to the hindfoot. It is almost always flexible enough that you are able to straighten out the foot with gentle manipulation. No treatment is needed for these. If it is rigid at 6 months, i.e., you are unable to straighten the lateral border of the foot, serial casting should be considered.

Q: Let's turn to the angular deformities: bowlegs and knock-knees. What about referral of those conditions?

A: Bowlegs are normal from birth to 18 months of age. Differential diagnosis is Blount disease and rickets and, as you know, those are extremely rare. Those diagnoses should not even be considered until after 18 months unless there are other obvious signs of rickets or the bowing is extreme.

Both Blount and rickets cause a bowing that is centered at the knees. However, the vast majority of bowlegs you see are physiologic, and the bowing is all along the lower extremity or at the level of the distal tibia.

A good way to bring this out in physical examination is to mask the foot and lower leg. Look at the knee with the patella facing forward and it will often not appear bowed. Then unmask the lower leg and it reveals the bowing at the level of the distal tibia.

Q: What about knock-knees?

A: Knock-knees are normal between 18 months and 6 years of age. So, first we bow and then we knock, and that's physiologic for humans.

Q: Tell us about flat feet.

A: Flat feet are normal (about 90 percent occurrence) in babies before they begin to walk. The overwhelming number of babies and children with flat feet never have a problem.

The arch elevates spontaneously in most children during the first decade of life, yet flatfoot persists in about 20 percent of adults. Pain is a problem in only about 25% of those adults with flat feet: no pain, no problem.

Q: What about the parent who wants flatfoot treated because their child may be the one in 16 who will have painful flat feet?

A: There is no evidence you can build an arch with orthotics, shoes or physical therapy. We certainly are not going to do surgery when the chance is so overwhelming that there will never be a problem.

Q: What about the admittedly rare vertical talus as a cause of flatfoot?

A: Vertical talus or ridged rocker bottomed flatfoot can be distinguished from the physiologic flatfoot by the lack of flexibility of the arch, determined by manipulation of the foot.

Q: And a tarsal coalition?

A: This also is rare and causes a progressive, rigid flatfoot deformity starting after 8 years of age. Flexible flat feet, by contrast, are improving at this age. Only about 25% of feet with tarsal coalitions will develop pain. Again, it is very unusual for babies with rigid or flexible flat feet to have a problem. We humans can live very well in almost all instances with flat feet.

Q: So, 90% of our toddlers will have flat feet and 90% will have internal tibial torsion. One hundred percent of our patients younger than 18 months will have bowlegs and 100% of our patients younger than 6 years will have knock-knees. Many will have femoral anteversion at 6 years. All of this is normal, right?

A: Yes.

Q: Not much business there for the pediatric orthopedist. What about toe walking?

A: That is unusual in primates, whereas most other land mammals walk on their toes. There are four causes of toe walking. The first is habitual toe walking. It is noticed in the first year of walking, i.e., generally in the 1- to 2-year-old. It is intermittent and there are no cerebral palsy risk factors. The passive physical examination is normal.

Q: What is the natural course or outcome of habitual toe walking?

A: It spontaneously resolves.

Q: And the other three causes?

A: Toe walking caused by cerebral palsy is the second. Cerebral palsy risk factors are obtainable by history (low birth weight, neonatal anoxia, etc.) and confirmed by physical examination.

In toe walking caused by cerebral palsy associated with prematurity, the Achilles tendons are not contracted at birth but become tight gradually in the first few years of life. This is almost always bilateral.

A subcategory of this is seen in the child who had a normal birth history, walks on the toes of only one foot and has spasticity of only that lower limb and the ipsilateral upper extremity. This asymmetry can be brought out by having the child stand on one foot at a time or run down a hall.

The etiology is a hemiplegia due to a stroke, TORCH virus, etc. Duchenne muscular dystrophy is the third cause for toe walking. Here, the child has a normal gait until 4 years of age. The patient is always male and weakness is demonstrated by a positive Gowers sign. Finally, there are congenitally short heel cords. This may be due to contracture of either the gastrocnemius muscle alone or the entire Achilles tendon.

There is a limitation of ankle dorsiflexion, a normal neurologic examination and a negative Gowers. This is a diagnosis made by excluding the other three possible etiologies for toe walking. The patient is too old to fall into the first category. The negative Gowers sign and normal neurologic examination rule out the second two categories.

Q: I'd like to close this interview by asking the question: "What mistakes do you see us making in our prior handling of the patients we refer to you?"

A: Probably the only significant mistake I see is unnecessary radiographs for torsional problems, unless there is a concern about congenitally dislocated hips. Radiographs are also rarely necessary in bowlegs and flat feet. A pediatric orthopedic surgeon can frequently make the appropriate diagnosis without radiographs.

Q: Finally, one of the most useful books on my shelf over the years has been Lynn Staheli's Fundamentals of Pediatric Orthopedics. Any updates?

A: Yes, the third edition was published in 2003. There are some changes in the charts and algorithms, but the basics have stayed the same.

Q: Thanks Vince.

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