Rickets is described as a disease of infancy and childhood in which there is inadequate mineralization of growing bone.
Rickets is the clinical consequence of impaired mineralization of bone matrix through the growing skeleton in children.
Bone is mineralized by the crystallization of calcium and phosphates in the presence of alkaline phosphatase enzyme.
Rickets is a failure of or delays in calcification of newly formed bone at long-bone physis.
Calcipenic rickets: Calcium deficiency or interruption in the supply, metabolism, or utilization of vitamin D.
Dietary Calcium deficiency
Nutritional vitamin D deficiency
Vitamin D deficiency secondary to malabsorption, liver disease, renal insufficiency
Vitamin D dependent rickets type I
Vitamin D dependent rickets type II
Phosphopenic rickets: Inadequate dietary phosphate intake or excess renal tubular loss.
Primary – X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets, X-linked recessive and hereditary hypophosphatemia with hypercalciuria
Secondary – Oncogenic osteomalacia (Tumour induced osteomalacia), Fibrous dysplasia [McCune Albright syndrome], Epidermal nevus syndrome, ifosfamide nephrotoxicity, Fanconi syndrome, low dietary phosphate intake
Alkaline phosphatase deficiency
The clinical manifestations of rickets include changes in growth-plate morphology, with decreased longitudinal growth and angular deformities of the long bones.
The skeletal abnormalities of severe rickets present in early childhood and often before the age of 2 years.
The child may have a history consistent with hypocalcemia in infancy, including apneic spells, convulsions, tetany, and stridor prior to the age of months.
The child is often hypotonic with delayed motor activity milestones for sitting, crawling, and walking.
There is proximal muscle weakness and sometimes profuse sweating.
Cardiomyopathy, respiratory and gastrointestinal infections may accompany the clinical presentation.
Signs of rickets in osseous tissue –
Craniotabes in the newborn and young infant
Rickets hydrocephalus – Frontal bossing in early infancy due to expansion of cranial bones relative to facial bones
Caput quadratum or Hot cross bun appearance – Delayed closure of fontanelle and sutures are thickened
Delayed primary dentition – Deciduous incisors not present by 9 months and first molar by 14 months
Enamel hypoplasia and greater susceptibility to caries in the first dentition
Rachitic rosary – Beading enlargement at the costochondral junction (Specificity 64%)
Harrison’s sulcus – Indentation of lower ribs caused by indrawing on the softened ribs
Pigeon chest – Chest cage narrowed transversely and elongated anteroposteriorly
Pot-belly – Protuberent abdomen with separation of recti muscle
Pelvis – Compressed transversely by weight bearing, narrow inlet
Spine – Kyphoscoliosis
Widened wrists – An apparent bracelet of bone around the wrist (Specificity 81%)
The string of pearls deformity – Sausages like enlargement of ends of phalanges and metacarpals
Enlarged epiphysis – Elbow, knee, and ankle
Skeletal deformities –
Anterolateral bowing of the femur
Lateral bowing with the rotation of tibia – rachitic saber shin
Genu valgum (Older children)
The earliest sign is osteopenia
Followed by a widening of the growth plate from the proliferation of uncalcified cartilage and osteoid
Followed by metaphyseal widening, splaying, cupping, and fraying
There are four stages of rickets –
Stage I – Normal rounded appearance of the epiphysis is replaced by a cloudy area containing one or more indistinct centers of ossification. The metaphysis is splayed out and deficient in calcium shadow.
Stage II – Epiphysis is mottled, irregular, and ill-defined. The metaphysis is ragged, broader than normal running out from the side.
Stage III – Shadow becomes denser and at the end of metaphysis a dense line appears. There is a marked difference in size between the end of shaft and epiphysis.
Stage IV – Increase in the breadth of metaphysis is still present. Bone is clearly defined and shows a normal content of calcium.