| dc.description.abstract | Certain skeletal abnormalities of legs and chest are normally
regarded as sequelae of rickets, '. and due to vitamin D deficiency. In
seeking to throw light on the prevalence and characteristics of these
abnormalities in South African schoolchildren, prior to and during
adolescence, it was deemed important, firstly, to assess prevalences
of these abnormalities and secondly, to investigate their relationship
to vitamin D status. Hence, prevalences of bowing and knock knee, and
of chest abnormalities such as Harrison's sulcus, pigeon breast, etc.,
were determined, and dietary, radiological and biochemical studies
were made.
Appropriate measurements in the four ethnic groups (Bantu, Coloured,
Indian, White) revealed that bowing and knock knee were unexpectedly
common, affecting a fifth, and a third of all children, respectively.
Prevalences were not obviously affected by a higher dietary intake of
vitamin D, rural-urban location, habitual exposure to radiation, or
skin pigmentation. Prevalences of chest abnormalities, Harrison's sulcus,
0-5%; pigeon breast, 0-2%, also appeared unrelated to these factors.
An important finding was that with age, bowing frequency increased
mainly during the adolescent growth spurt. Prevalence of knock knee
was little affected by age, but increased markedly with body mass. There
was no age trend with prevalences of chest abnormalities.
Since leg abnormalities were approximately equally common in groups
accustomed to a high compared with a low dietary intake of vitamin D,
it is inferred that a primary deficiency of vitamin D is not the causal
factor. The most plausable explanation is that a secondary deficiency
of vitamin D is involved, arising from an impairment in metabolic
availability. However, the possibilities cannot be excluded that the
leg abnormalities; in large measure, are physiological variants, or that
an unknown factor or factors may bear, or share, in the responsibility.
What is urgently required is an attempt to correlate individual
vitamin D status of schoolchildren during their pubertal growth spurt;
also the carrying out of long-term studies from birth to post-adolescence ,
of the type already undertaken. | en_US |
