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Rickets
Osteomalacia
during enchondral bone growth
Histology
- Zone
of preparatory calcification does not form resulting in build-up of
maturing cartilage cells
- Also
occurs in shafts so that osteoid production elevates periosteum
Clinical
findings
- Irritability
- Bone
pain
- Tenderness
- Craniotabes
- Rachitic
rosary
- Bowed
legs
- Delayed
dentition
- Swelling
of wrists and ankles
Location
- Metaphyses
of long bones subjected to stress are particularly involved
Imaging
findings
- Cupping
and fraying of metaphysis
- Poorly
mineralized epiphyseal centers with delayed appearance
- Irregular
widened epiphyseal plates (increased osteoid)
- Increase
in distance between end of shaft and epiphyseal center
- Cortical
spurs projecting at right angles to metaphysis
- Coarse
trabeculation (not the ground-glass pattern found in scurvy)
- Periosteal
reaction may be present
- Deformities
common
- Bowing
of long bones
- Molding
of epiphysis
- Fractures
- Frontal
bossing
Causes
Of Rickets
- Abnormality
In Vitamin D Metabolism
- Associated
with hyperparathyroidism
- Vitamin
D deficiency
- Dietary
lack of vitamin D
- Famine
osteomalacia
- Lack
of sunshine exposure
- Malabsorption
of vitamin D
- Pancreatitis
and biliary tract disease
- Steatorrhea,
celiac disease, postgastrectomy
- Inflammatory
bowel disease
- Defective
conversion of vitamin D to 25-OH-cholecalciferol in liver
- Liver
disease
- Anticonvulsant
drug therapy (= induction of hepatic enzymes that accelerate degradation
of biologically active vitamin D metabolites)
- Defective
conversion of 25-OH-D3 to 1,25-OH-D3 in kidney
- Chronic
renal failure = renal osteodystrophy
- Vitamin
D-dependent rickets = autosomal recessive enzyme defect of 1-OHase
Abnormality
In Phosphate Metabolism
- Not
associated with hyperparathyroidism secondary to normal serum calcium
- Phosphate
deficiency
- Intestinal
malabsorption of phosphates
- Ingestion
of aluminum salts [Al(OH)2] forming insoluble complexes with phosphate
- Low
phosphate feeding in prematurely born infants
- Severe
malabsorption state
- Parenteral
hyperalimentation
- Disorders
of renal tubular reabsorption of phosphate
- Renal
tubular acidosis (renal loss of alkali)
- deToni-Debré-Fanconi
syndrome = hypophosphatemia, glucosuria, aminoaciduria
- Vitamin
D-resistant rickets
- Cystinosis
- Tyrosinosis
- Lowe
syndrome
- Hypophosphatemia
with nonendocrine tumors
- Oncogenic
rickets - elaboration of humeral substance which inhibits tubular
reabsorption of phosphates
- Sclerosing
hemangioma
- Hemangiopericytoma
- Ossifying
mesenchymal tumor
- Nonossifying
fibroma
- Hypophosphatasia
Calcium
Deficiency
- Dietary
rickets = milk-free diet (extremely rare)
- Malabsorption
- Consumption
of substances forming chelates with calcium
Classification
Of Rickets
- Primary
vitamin D-deficiency rickets
- Gastrointestinal
malabsorption
- Partial
gastrectomy
- Small
intestinal disease: gluten-sensitive enteropathy / regional enteritis
- Hepatobiliary
disease: chronic biliary obstruction / biliary cirrhosis
- Pancreatic
disease: chronic pancreatitis
- Primary
hypophosphatemia; vitamin D-deficiency rickets
- Renal
disease
- Chronic
renal failure
- Renal
tubular disorders: renal tubular acidosis
- Multiple
renal defects
Hypophosphatasia
and pseudohypophosphatasia
- Fibrogenesis
imperfecta osseum
- Axial
osteomalacia
Miscellaneous
- Hypoparathyroidism,
hyperparathyroidism, thyrotoxicosis, osteoporosis, Paget disease,
fluoride ingestion,
- ureterosigmoidostomy,
neurofibromatosis, osteopetrosis, macroglobulinemia, malignancy
Rickets of the knees demonstrates
bowing of the
femurs,
metaphyseal
cupping and
fraying,
coarsening of
the trabecular
pattern,
increase in
distance
between end of
shaft and
epiphyseal
center,
poorly
ossified
epiphyseal
centers.
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