Extremely Tall And Slim Child With Loose Joints Can Be Due To Marfan Syndrome

Question: 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.

Answer:

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 near-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.