Paeds Ortho Flashcards
A 2wk old neonate is brought to A&E crying inconsolably. Right leg is not moving. No Hx of trauma.
FHx - mum had six fractures as child, most from trivial trauma. Grandad also had ‘a lot’ of fractures.
Differentials?
osteogenesis imperfecta osteomyelitis / septic arthritis NAI rickets birth injury
What is included in a ‘bone profile’ blood test?
Ca, phos, alk phos, albumin
What investigations would you do to distinguish between osteogenesis imperfecta and NAI?
bone profile, serum Vit D, PTH
genetic testing
NAI: skeletal survey top to toe Ex. CT head (to look for shaken baby) clotting profile (if signs of bruising) opthalm (for retinal haemorrhages)
involvement of social services / police?
What is the mode of inheritance for osteogenesis imperfecta?
Autosomal Dominant
A 2wk old neonate has had a fracture. What is appropriate analgesia at this age?
oramorph !
regular paraz + ibuprofen
What is vitamin D2 called and which food?
ergocalciferol
mushrooms
What is vitamin D3 called and which food?
cholecalficerol
egg yolk, oily fish
What is the precursor to vit D3 called, from sunlight?
7-dehydrocholesterol
Which form of vit D is stored in the liver?
25-hydroxy vit D
Which form of vit D is stored in the kidneys?
1,25-dihydroxy vit D
a.k.a. calcitriol , “activated vit D”
What is calcitriol?
1,25-dihydroxy vit D
What are the 3 ways that vitamin D makes calcium available?
- increase bone resorption (releases Ca)
- increase Ca absorption from gut
- increase Ca reabsorption from kidney (get rid of phos)
Vit D def can present as rickets, or more acutely as what?
hypocalcaemia
convulsions, tetany and cardiomyopathy
Define osteoporosis!
low bone density + microarchitectural destruction
… leading to …
increased fragility and risk of fracture
What is the diagnostic criteria for osteoporosis in kids?
one or more vertebral crush fractures
OR
low bone density PLUS long bone fractures
(2# by age 10 or 3# by age 15)
Give me two INHERITED causes of osteoporosis in children?
- osteogenesis imperfecta
- inborn errors e.g. galactosemia
Give me three ACQUIRED causes of osteoporosis in children?
- drugs (steroids)
- malabsorption (vit D, Ca)
- low weight bearing (cerebral palsy, JIA)
Osteogenesis imperfecta is a defect in ….?
Type 1 collagen
Name three key symptoms of osteogenesis imperfecta.
fragility fractures
blue sclerae
deafness - we’re not sure why
What is the classification of osteogenesis imperfecta?
“Sillence” classification - types of O.I. (mainly type 1, type 2)
What happens in Type 2 osteogenesis imperfecta?
fractures in utero, IUGR, wormian bones. Usually die in utero.
What might you notice about a child’s face in osteogenesis imperfecta?
Triangular face
What is the treatment for osteogenesis imperfecta?
There’s no cure :(
- surgical correction of deformities (e.g. rod placement)
- physio
- mobility aids.
brittle bone disease a.k.a
osteogenesis imperfecta
What is the management of osteoporosis in children?
bisphosphonates e.g. pamidronate
physio
(correct vit D def)
Genetic disease where bones are DENSE but brittle. Need bone marrow transplant.
Osteopetrosis
Disease of high bone turnover and remodelling. Bone pain and deformity (skull, pelvis). What’s this?
Paget’s disease
What is the difference between osteoporosis and osteomalacia?
They both cause weak bones.
- In osteoporosis, there is decreased bone mass with a normal ratio of mineral to matrix.
- In osteomalacia, there is less mineralization.
osteoporosis - low bone density
osteomalacia - failure of bone mineralization
The catch-phrase of osteoporosis is “normal-enough bone, but not enough of it!”
What is rickets?
osteomalacia in kids
failure of bone mineralization
What is Fanconi syndrome?
loss of phosphate at kidney
it causes rickets rickets because cant swap phosphate for Ca reabsorption
Which drugs can speed metabolism of vit D, causing rickets?
carbamazepine
phenytoin
phenobarbital
vit D3 and vit D2 can be got from food. But 90% of ours comes from sunlight. In UVB, there is the vit D3 PRECURSOR, which is called…
7-dehydrocholesterol
Give me some RISK FACTORS for vit D deficiency (–> rickets)
not including underlying conditions that cause secondary vit D def
dark skin living in northern latitudes EBF after 6months maternal vit D def being housebound or institutionalised (no sun) poverty, vegetarianism
Vit D def can also be secondary to lots of different underlying conditions. Name some.
malabsorption - CF, coeliac
hepatic and renal disease (impaired vit D conversion)
As well as Calcium (which you get via vit D), bones also need phosphate to mineralize. If they don’t have enough phosphate, this can cause failure of bone mineralization. What’s this called and what two genetic conditions can cause it?
HYPOPHOSPHATAEMIC RICKETS
- Fanconi sydrome
- X-linked hypophosphataemia
What enzyme is defunct in X-linked hypophosphataemia causing rickets?
PHEX
Kate, what is the actual difference between parenteral nutrition and enteral nutrition?
parenteral = IV enteral = NG, PEG, JEJ
Give me 4 signs of rickets .
not the fancy ones
poor growth / short stature
frontal bossing
bowed legs
widened wrists
+ bone and joint pain.
Give me 3 fancy signs of rickets.
Rachitic rosary
Harrisons sulcus
Craniotabes
What is Rachitic rosary in rickets?
palpable costochondral junction
What is Harrisons sulcus in rickets?
indentation of soft lower ribcage where diaphragm inserts
What is craniotabes in rickets?
soft skull bones, can press finger into them
You have identified a child has low vitamin D levels. What is now required to diagnose rickets?
wrist X ray
definitive diagnosis of rickets requires X ray of a long bone
Definitive diagnosis of rickets requires X ray of a long bone. What would it show?
cupping + fraying of metaphysis
splaying of epiphyseal plate
e.g. champagne glass wrist
Describe the management of rickets.
oral cholecalciferol daily (vit D3)
dietary advice
encourage sunlight exposure
treat any underlying condition
treat pain
?ortho intervention
What would vit D (25-hydroxy) level be in rickets?
low
What would Ca level be in rickets?
low / normal
What would phosphate level be in rickets?
low (getting rid at kidneys to increase Ca reabsorption)
What would Alk Phos level be in rickets?
high - lots of bone turnover - because high resorption to increase serum Ca
What would PTH level be in rickets?
high (PTH is busy trying to increase serum Ca)
What does PTH try to do?
increase serum Ca
