Intoeing, Tall, Slim, and Unusually Loose Joints May Indicate Marfan Syndrome
11 November 2003
Q. I am a concerned aunt. My nephew just started grade
4. He is extremely tall and slim for his age. Since he first
started to walk, his toes on both feet have been pointing
inwards very noticeably. His family doctor suggested that he
will outgrow it and the problem is in his hips. As he grows
older, it is not getting any better; instead it seems to be
getting worse as his feet grow longer. I am concerned that
he will have problem with his legs and feet for the rest of
his life, and he may not be able to run or play sports, or
get teased in school. I wonder whether he may need intervention
now when he is still growing instead of waiting longer.
A.
I believe your concern is well placed. You have
mentioned two aspects of his problem that I feel we should
discuss here. Many parents are worried that their children's
feet are pointing in (or pointing out), but this is usually
something that they will outgrow. The more important concern
should be his height, and this might be related to his feet
also.
Intoeing is a term commonly used to describe someone whose
feet or toes point inwards. Another name for it is 'pigeon
toes.' Most of us have feet that point straight forward or
slightly outwards. However, a small percentage of individuals,
especially children, have intoeing, and this can be completely
normal. There are three reasons that cause intoeing in
children.
The first reason is curvature of one or both feet (it is called
metatarsus adductus). This is found in newborn babies, and
it is most likely caused by pressure on their feet inside the
mother's womb. It is fairly common, happening in one out of
1000 newborn babies. Once the baby is born, the pressure is
off and the feet can gradually correct themselves with time
and growth. Most physicians would recommend stretching exercise
that can be performed by parents pushing the feet in the
opposite direction during the first few months of life. If
the problem does not correct adequately, then placing a cast
on each foot can help to correct this problem.
The second cause of intoeing is inward twisting of the leg
bones (this is called internal tibial torsion). The leg bones,
or tibia, are the two big bones between the knees and ankles.
Many children are born with some inward twisting of the leg
bones, but it is not obvious and most parents don't even notice
it. When a child grows, the leg bones gradually straighten
up so that most children have very little inward twisting left
when they start to walk. For those who still have some twisting
remaining, their parents would notice intoeing when these
children begin to stand and walk. Fortunately the leg bones
continue to straighten over the next few years so that the
problem corrects itself without medical intervention. Many
children with this condition like to 'sit on their feet,'
therefore it is advisable to discourage this type of sitting
habit.
The third reason for intoeing is femoral anteversion, or inward
twisting of the thigh bones. All children are born with some
inward twisting of the thigh bones, or femurs, but they also
gradually straighten up during the first few years of life.
The muscles and ligaments around the hip joints are tighter
early in life, so that this inward twisting of the femurs is
not obvious. However, around 2-4 years of age, these ligaments
and muscles start to loosen so that those children with
significant twisting will present with intoeing. When these
children lay down, their knee-caps (or patellae) point inward
towards each other. Their gait can be a little clumsy, and
they can trip as a result of crossing their feet when they
run. These children also tend to sit in a 'W' position which
can promote the inward twisting. Therefore it makes sense to
discourage them from sitting in such position. Again, luckily
most of these inward twisting correct themselves as children
grow older.
It is important to know that braces and special shoes are not
helpful for internal tibial torsion and femoral anteversion.
The intoeing does not cause pain in the legs or feet. These
children, like most others, can develop pain in their lower
extremities after a lot of physical activities. Only very
rarely will these children require surgery because of misalignment
of their leg or thigh bones.
What concerns me more about your nephew is your description
that he is extremely tall and slim for his age. Of course,
this can be totally normal if he has parents or close relatives
who have the same body shape. However, there are several
medical conditions which can cause people to be unusually tall
and slim, and some of these require medical intervention.
One of these conditions is Marfan Syndrome.
Marfan Syndrome is a hereditary condition caused by a defective
fibrillin-1 gene (this is called mutation of the gene) on
chromosome number 15 (humans have 46 chromosomes in each cell).
This fibrillin-1 gene ensures that a glycoprotein called
fibrillin is formed properly in the body. Fibrillin is an
essential component of all elastic connective tissue found in
most parts of the body. If a person is not able to produce
normal fibrillin, the connective tissue in ligaments and joint
capsules is weaker so that they can be stretched more than
normal. One of the hallmark of Marfan Syndrome is unusually
loose joints.
These children are not just tall, they are unusually tall and
slim, and they have long extremities and long fingers. Their
arm span (measuring from finger tip to finger tip when the
arms are stretched out) is greater than their height. Because
of weak ligaments in their feet, they usually have flat feet
and often compensate by turning their feet inwards. They also
have short-sightedness (or myopia) and dislocation of the lens
in their eyes.
One of the greatest concern for children with Marfan Syndrome
is weakening of the wall of great blood vessels in their body
and leaking of heart valves, both as a result of abnormal
fibrillin production in connective tissues. As a result, the
blood vessels can rupture and lead to catastrophic result.
Every year there are athletes that die in North America because
of undiagnosed Marfan Syndrome. Because they are much taller
than average students, children with Marfan Syndrome are often
involved in sports like basketball where height is a premium.
With their unrecognized problem, they can die suddenly when
their blood pressure goes up during competition. A class of
medicine called beta-blockers had successfully reduced the
risk of sudden death in these children when combined with
sports restriction.
I should caution here that I am not suggesting that your nephew
has Marfan Syndrome. There are many other medical conditions
that can make a child unusually tall and slim, and this can
be totally normal because of their family trait. However,
because Marfan Syndrome and other medical conditions that fit
your nephew's description requires early diagnosis and treatment,
I think it is very important for your nephew to be referred
to a paediatrician for further assessment. If his intoeing
is due to one of the benign bone alignment conditions that I
discussed earlier, then you can relax and wait, but if he does
have a more serious medical problem, early diagnosis can be
extremely helpful.
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