الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 81 |  |  |
| | | from | 81 | | |
Abstract
Rickets is a systemic disease of infancy and childhood
in which the calcification of growing skeletal elements is
deficient. It is equivalent of osteomalacia in mature
skeleton. Prematurity is a predisposing factor.
Clinically there are several classifications of different
types of rickets according to the aetiology and the age of
occurance but vito D deficiency rickets is a main clinical
problem in Egypt rather than any other types of rickets.
Infantile vito D. deficiency rickets usually develops
between 6th month and one year of age and resulting from
deficiency of vito D in the diet or from lack of exposure
to ultra-violet rays. The human skin contains pro-vitamin
D3 (7-dehydrocholecalciferoll which is activated by ultraviolet
rays. This vitamin is not active. but is transported
to the liver where it is hydroxylated and from there to the
kidney where it is hydroxlated again and becomes dihydroxyvito
D. which is the most active form of the vitamin. It acts
as a hormone. Liver and kidney disease may cause rickets ~f
hydroxylation cannot take place.
Rickets is characterised by defect of bone growth due
to lack of normal mineralisation. Cartilage cells of the
epiphyseal plate grow and reproduce normally, but fails to
-56-
calcify and degenerate as normal. These cells continue
to proliferate but with disturbance of the columnar
configuration causing patchy widening of the epiphyseal
plate seen roentgengraphically as a radiolucent area, so
that the end of bones are frayed and the epiphyseal line
is irregular.
Mineralisation of the osseus tissue and cartilage.
matrix fails, the zone of preparatory calcification does
not form and malleable non rigid tissue is produced instead.
It become compressed, cupped and flared.
Changes in bone shafts are caused by failure of osteoid
mineralisation and a shell of sub-periosteal osteoid tissue
surrounds the shaft. The osteoid continues to heap, the
underlying cortical bone is resorbed and replaced by unmineralised
osteoid, thus the shaft loss rigidity and molding
and fractures occures.
By administeration of vito D. healing occurs and the
zone of preparatory calcification becomes identifiable.
Cartilage cells then degenerate normally and invasion of
blood vessels and osteoblasts allows normal epiphyseal
growth. The skeleton is rapidly mineralised and the subperiosteal
osteoid collections are mineralised and resorbed
and bone outline returns.
-57-
The serum calcium level in vito D. deficiency rickets
ranges from normal to slightly lowered and the serum
phosphate concentration is slightly lowered. The serun,
alkaline phosphatase level is elevated but not specific.
Clinically, softening of skull bones or craniotabes
may be presented initially followed by frontal and parietal
bossing in later stages of the disease. The wrists and
ankles swell. Also the ribs show enlargement of the co:stochondral
junction ”Rachitic rosary”. Increased irritability
and sweating also occurs.
In advanced rickets, calvarial sutures are open and
soft with box-like appearance skull, denition is delayE,d,
the sides of the thorax are flattend and develops pigeon
breat deformity and curvature of the long bones also occurs.
Roentgenographically, the characteristic changes occur
in the ends of the long bones. These changes are similar
for rickets of all aetiologies (Greenfield, 1975). Epiphyseal
widening and ill definition of zone of provisional calcification
followed by metaphyseal cupping and widening owing to
the pull of muscular and ligamentous attachment. In the
shafts of long bones uncalcified sub-periosteal osteoid
is present, causing loss of sharp cortical outline and allowing
development of bowing deformities particularly in tibia.
-58-
Bone texture is also coarsened. Green-stick fractures
are also common Pseudofractures are rarely present. The
appearance of ossification centers in the epiphysis of
small bones are delayed because of the lack calcification.
With healing, mineralisation of the zone of provisional
calcification appears as a dense line in the epiphyseal
cartilage, separated from the metaphysis. The cupping increases.
Remineralization of the sub-periosteal osteoid appears as
periosteal new bone formation which may be solid and laminated.
Calcification of the ossification centers occurs ~~ith
a marginal ring shadow that gradually fuses with the center.
Although complete healing usually occurs, residual deformities
may persist.
The rachitic skull in active phase of the disease
characterised by bossings at frontal and parietal emineences
that are devoid of mineral contents and so, are not well
visualised roentgenographically with the onset of healing
the calcium contents of bosses increases and the healed
hyperostosis become more evident radiologically (Caffey,
1972) .
-------- ---- -
-59-
This rachitic bossing persist in adult life and
giving the head a ”Caput quadratum” deformity.
Due to bone softening in rachitic skull especially
skull base, basilar invagination occurs, which can be
demonstrated radiologically in postero - anterior view
by cephalic angulation of a line drawn along the superior
margins of petrous ridges (normally this line directed
caudally). And in lateral view by increase in the basal
angle more than 150° (normally between 125-142°), and by
protrusion of the odontoid process ~ em. or more abov.a
the Mc-Gregor’s line.
The rachitic vertebrae are characterised by rarefaction
either diffuse or in the form of globul~r areas
of rarefaction. The heights of the vertebral bodies are
reduced with consequent widening of the intervertebral
spaces.
The spinal deformity in the form of dorso-lumbar
Kyphosis occurs in several cases of rachitic children
who sit-up.
The radiological changes in rachitic chest appear
early in the anterior ends of the ribs in the form of
splaying and irregularity and impaired endochondral ossification.
-60-
Gross demineralization of the thoracic cage associated with
formation of Harrison sulcus at the site of costal origin
of the diaphragm.
The rachitic deformities in the thoracic cage usually
associated with chest infection as bronchitis and bronchopneumonia.
These roentgenographic findings of rickets si.muLat;e
other many skeletal disorders and the radiological differentiating
signs should be considered.
Hypophosphatasia is similar radiologically to rickets
but with more pronounced demineralisation and marked liability
to fractures.
In scurvey the deficiency is mainly in bone matrix not
in its mineralisation. So, the zone of provisional calcifications
more dense with sharp definition and marked periosteal
reaction is noticed due to sub-peri-osteal haematoma. Scurvey
is also characterised by Pencil-thin epiphyseal cortex.
The widened metaphysis which is seen in rickets should
be differentiated from other causes of metaphyseal widening
as cretinism, leukaemia, hypervitaminosis 0, osteopetrosis
and congenital syphilis.
-61-
Basilar invagination in rachitic skull due to softening
of bones of skull base. This radiological sign is also
seen in other conditions leading to bone softening as
Paget’s disease, fibrous dysplasia, osteogensisimperfec~
AchonDROPlasia and cleidocranial dysplasia.
The double contour of the long bones seen in rickets
is not fairly due to periosteal elevation and periosteal
reaction but mainly due to non-mineralised sub-cortical
osteoid tissue formation and falsly termed periosteal
reaction and so must be differentiated from other causes
of periosteal elevation as congenital syphilis, scurvey,
prematurity and Caffey’s disease.
It is to be noted that the radiation risks for a
paediatric patients include genetic, leukogenic carcinogenic
factors and cataret production. And although, theoretically
there is really no safe dose but the risk will be
greater if a large portion of the body irradiated or if
a higher dosage is used and also, the sensitivity of the
irradiated area should be considered.
A proper communication between the radiologist and
paediatrician is essential for delivery of a good radiologic
care.
-62-
Also, a good communication between the radiologist
and technologist is essen~ial for the maintenance of
a good quality films.
The rooms for paediatric radiology should have the
biggest x-ray generators possible. High milliamperage
is essential so that short times can be used.
Accurate callimators with light localization is
essential.
Pleasant and safe surroundings in the radiologic
room is essential to gain a sympathetic attitude toward
the child to ensure a good examination.