I've never come across any explanation as to the cause. But in my own discussions with several dozen families over the years, I have noticed that an unusual number of us also have scoliosis in our families. I don't believe, however, there's been anything proven about any kind of link between the two...but it did strike me as odd that there would be so many.
As a fetus develops the location of each cell and its surroundings determine how
the cells and tissues develop. The process is called morphogenesis. If something goes wrong in morphogenesis, the time at which it occurs influences the occurance and type of effect. If something occurs at a primary stage it is called a "malformation." (As opposed to a "deformation" which is usually at a later stage and arises from mechanical factors. )
Limb buds on the fetus develop at about 28-32 days into pregnancy and at 33-36 days the foot plate is visible. If something affects the growth of the fetus around this critical limb-formation time (2 - 5 weeks) it can lead to PFFD. A "teratogen" is the term given to the agent that causes a malformation in an embryo or fetus.
The teratogen for PFFD is unknown. PFFD is not genetic. Some have proposed that it is caused by anoxia (oxygen deficiency), ischemia (temporary blood supply deficiency), chemicals, hypothermia, radiation, bacterial toxins, viral infections, enzyme
and hormone changes. The only definite cause
is the drug Thalidomide which was used as a sedative and sleeping pill in
Europe before being discontinued in the early 1960's.2
Embryology (How does it happen?)
PFFD occurs during the first 2-7 weeks of fetal life. The limb buds start
to develop at about 32 days. The most proximal (toward center) parts of the
limbs develop first, followed by the hands and feet, which are fully formed
by the seventh week.3 The acetabulum (hip socket) and the femoral
head and neck develop from a common block of cartilage, with subsequent cleft
(opening) to create a hip joint cavity.2 The cleft gradually separates
until a definite joint cavity is formed. This point is critical for proper
diagnosis. Dr. King pointed out that the development of the acetabulum and
femoral head are mutually dependent (can't have one without the other). The
presence of an adequate acetabulum on early (1st year) X-rays always
means that the femoral head is also present - even though it's development
may be delayed and it may not be visible on the X-ray. Similarly, if no
acetabulum can be seen, no femoral head will develop.1
Whatever affects the developing limb bud during the first 2-7 weeks, it also
affects muscle development in the thigh, knee joint, and sometimes in the
lower leg.1
Comments
I've never come across any
I've never come across any explanation as to the cause. But in my own discussions with several dozen families over the years, I have noticed that an unusual number of us also have scoliosis in our families. I don't believe, however, there's been anything proven about any kind of link between the two...but it did strike me as odd that there would be so many.
I took this from "A Parent's Guide. . ." on this site
[Editors Note: Added a link to the chapter Etiology (What causes PFFD) ]
Etiology (What causes it?)
As a fetus develops the location of each cell and its surroundings determine how
the cells and tissues develop. The process is called morphogenesis. If something goes wrong in morphogenesis, the time at which it occurs influences the occurance and type of effect. If something occurs at a primary stage it is called a "malformation." (As opposed to a "deformation" which is usually at a later stage and arises from mechanical factors. )
Limb buds on the fetus develop at about 28-32 days into pregnancy and at 33-36 days the foot plate is visible. If something affects the growth of the fetus around this critical limb-formation time (2 - 5 weeks) it can lead to PFFD. A "teratogen" is the term given to the agent that causes a malformation in an embryo or fetus.
The teratogen for PFFD is unknown. PFFD is not genetic. Some have proposed that it is caused by anoxia (oxygen deficiency), ischemia (temporary blood supply deficiency), chemicals, hypothermia, radiation, bacterial toxins, viral infections, enzyme
and hormone changes. The only definite cause
is the drug Thalidomide which was used as a sedative and sleeping pill in
Europe before being discontinued in the early 1960's.2
Embryology (How does it happen?)
PFFD occurs during the first 2-7 weeks of fetal life. The limb buds start
to develop at about 32 days. The most proximal (toward center) parts of the
limbs develop first, followed by the hands and feet, which are fully formed
by the seventh week.3 The acetabulum (hip socket) and the femoral
head and neck develop from a common block of cartilage, with subsequent cleft
(opening) to create a hip joint cavity.2 The cleft gradually separates
until a definite joint cavity is formed. This point is critical for proper
diagnosis. Dr. King pointed out that the development of the acetabulum and
femoral head are mutually dependent (can't have one without the other). The
presence of an adequate acetabulum on early (1st year) X-rays always
means that the femoral head is also present - even though it's development
may be delayed and it may not be visible on the X-ray. Similarly, if no
acetabulum can be seen, no femoral head will develop.1
Whatever affects the developing limb bud during the first 2-7 weeks, it also
affects muscle development in the thigh, knee joint, and sometimes in the
lower leg.1