OI is caused by a Type 1 collagen defect (can be qualitative, quantitative or breakdown). Typically there are rib / vertebral fractures or just periosteal thickening (tram line on XR). Characterised by high bone turnover.
Ix: 25OHD, PTH, Urine Ca/phos (for differential). Gene test v. expensive, not usually necessary.
Rx: no medical rx works except bisposphonates (normalize bone density, improve growth and activity, decrease fracture rate. Binds permanently to bone, inhibits osteoclasts. ?long term teratogen, microfractures, petrosis... Rods can be inserted for frequent fracture sites, or deformity.
Associated with family history, breech lie, talipes. Also seen more commonly in cultures where babies are swaddled with the legs together eg Inuit, whereas cultures where babies are carried in a frog leg posture on the back or hip have a lower incidence.
Screened for at birth and in neonatal period. Asymmetrical groin creases, Ortolani-Barlow manoeuvre will reveal instability.
Hip ultrasound will confirm the immature development of the acetabulum and femoral head. This is usually correctable by splinting in the first instance (using double nappies, else a Pavlik harness, to maintain flexion and abduction) else by surgery.
Or Metabolic bone disease of prematurity. Asymptomatic fractures and radiological ricketts frequently seen in the first 6 months of life of preterm babies. Calcium accretion by fetal bones takes place mainly in the third trimester; further bone demineralization occurs due to prolonged TPN, low mineral levels in EBM, inactivity and use of frusemide or steroids.
Vitamin D is usually supplemented in preterm babies, so normal or high levels are seen; but demineralization may continue due to low plasma phosphate.
Liver disease and conjugated bilirubinaemia may impair vitamin D metabolism. Vitamin D deficient mothers, esp Asian Muslims, also pass on the deficiency to their babies, putting them at risk of hypocalcaemia as well as osteopathy.
Low phosphate and high alkaline phosphatase are the usual indicators, although the latter is not sensitive or specific on its own. Negative urinary phosphate excretion index is better. X-rays are not helpful in the absence of frank fractures or rickets; DEXA and quantitative ultrasound are research techniques.
Treatment is with mineral supplementation. TPN and unfortified EBM to not match the natural levels of third trimester accretion.
Fractures in premature babies complicate the diagnosis of NAI, which appears to be more common in this group. Whether or not osteopathy in prematurity predisposes to adult osteoporosis is not known.
Copper is another bone mineral implicated in pathological fractures.
Also known as wry neck. Describes a twisted head position. Not a diagnosis. Different aetiologies in infants compared with older children/adults. In babies usually due to Congenital muscular torticollis - previously called "sternomastoid tumour", a term best now avoided. But beware spinal abnormalities.
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