Bone disease in infants with prolonged obstructive jaundice

Investigating the "scapula sign" as an indicator of rickets

OBJECTIVE

In 1971, Weiss identified a "scapula sign" comprising a defect at the inferior angle of the scapula in juveniles with vitamin D deficiency rickets, but this has been little studied since. This study aimed to explore pathological variation of this defect in juveniles with other skeletal manifestations of vitamin D deficiency rickets.

MATERIALS AND METHODS

527 juveniles, aged from birth to 12 years, from two post-medieval British assemblages were macroscopically evaluated to document the range of pathological changes at the inferior angle. Scapula maximum lengths were recorded and supplementary radiographs were assessed.

RESULTS

Blunting, flattening or squaring of the inferior angle occurred in 34 of 155 (22%) juveniles with other indicators of rickets and occurred frequently in cases of severe active rickets. Coarsening of the border and cupping deformities were identified radiographically, as well as residual defects in healed cases. Scapula lengths in juveniles with active rickets did not consistently deviate from those expected in any age group.

CONCLUSIONS

The scapula sign is identifiable in some children with rickets. Differential diagnoses of scapula defects are important but the socio-cultural and environmental context of this sample suggests a link to vitamin D deficiency.

SIGNIFICANCE

This finding expands the range of pathological changes known to occur in rickets, helping to improve recognition of this condition in past groups.

LIMITATIONS

Small sample sizes prevented observation of the defect in adolescents with rickets. Defects can affect the positioning of standardised scapula length measures, complicating assessments of growth impacts.

SUGGESTIONS FOR FUTURE RESEARCH

Continued research into the range of skeletal changes that can develop in vitamin D deficiency to improve the identification of this deficiency in past groups.

Effect of high-dose vitamin D supplementation on radiographically detectable bone disease of very low birth weight infants

To test the hypothesis that high-dose vitamin D2 supplementation would result in a lower incidence of radiographically detectable bone disease, we randomly assigned 40 very low birth weight infants to a control group who received vitamin D2 in a dosage of 400 IU/day and 41 to an experimental group who received a dosage of 2000 IU/day. After 6 weeks, radiographs from all infants were scored blindly for degree of radiographic bone disease, and serum osteocalcin and 25-hydroxyvitamin D levels were measured. Mean vitamin D intake was 360 +/- 141 (SD) IU/day in the control group and 2170 +/- 144 (SD) IU/day in the experimental group. Median 6-week serum 25-hydroxyvitamin D levels were 24 ng/ml (range 3 to 60 ng/ml) in the control group and 68 ng/ml (range 9 to 150 ng/ml) in the experimental group (p less than 0.001). Overall, 20% of the infants had evidence of moderate radiographic bone disease and only 2% were severely affected. The radiographic bone score (median = 2.5) and serum osteocalcin concentration (mean = 21.7 +/- 8.7 ng/ml) in the control subjects did not differ significantly from those in the experimental group (median bone score = 2.0; mean osteocalcin level = 24.1 +/- 7.9 ng/ml). Although there may be a subset of very low birth weight infants who would benefit from high doses of vitamin D, we conclude that no generalized clinical improvement can be attributed to this regimen alone.

Plasma alkaline phosphatase activity in rickets of prematurity

Plasma alkaline phosphatase activity was measured in 349 infants aged between 5 and 10 days to establish a normal range for different gestational ages. Significant differences were observed between term and preterm infants, the highest values being associated with the shortest lengths of gestation. Plasma calcium, phosphate, and alkaline phosphatase activity were measured sequentially in 51 preterm infants less than 1500 g at birth. A significant correlation was found between raised plasma alkaline phosphatase activity and radiological changes of osteoporosis, metaphyseal change, and periosteal reaction. Plasma alkaline phosphatase appears to be of value in screening for and monitoring rickets of prematurity.

The "mandibular mantle"--a sign of rickets in very low birth weight infants

Mandibular periosteal new bone formation (the "mandibular mantle") is described in very low birth weight infants with other signs of severe metabolic bone disease. In infants with onset of dyspnoea and apnoea, between two and three months of age, this mandibular change suggests that the lung disorder is of skeletal, rather than pulmonary origin and aids in differentiation therefore, from the Mikity-Wilson Syndrome (pulmonary dystmaturity).

Rachitic respiratory distress in small preterm infants

A syndrome of subacute respiratory distress, severe metabolic bone disease affecting the thoracic cage, and mild cholestasis occurred in 4 small preterm infants during the first three months of life and was associated with considerable morbidity. The early radiological features in the chest resembled thos of the Mikity-Wilson syndrome, with which the disorder may be confused. After spontaneous improvement in hepatic function 3 of the infants fully recovered. The fourth died of paralytic ileus. Various nutritional and absorptive abnormalities probably contribute to the pathogenesis of the bone disorder in this syndrome. The best prophylaxis might be to supplement the diet with 25-hydroxyvitamin D rather than native vitamin D.

The osteodystrophy of prolonged obstructive liver disease in childhood

Mild rickets was present in 7, and 3 others with severe bone disease developed widespread skeletal demineralization and multiple fractures. The intake of vitamin D was apparently loosely related to the severity of the osteodystrophy. The latter however, was closely linked to both the serum inorganic phosphate and the calciumXphosphate product. The serum calcium was directly related to the infant's gestational maturity, hypocalcaemia being present in those born before 35 weeks. Pathogenetic factors have probably included reactive hyperparathyroidism and nutritional deprivation associated with preterm delivery. Five of the infants who had biliary atresia developed radiological evidence of osteoporosis from about twelve months of age. This may be related to protracted calcium malabsorption, but its true nature remains to be elucidated.