Bone Disease Flashcards
What is the epidemiology of paed fracture?
M>F
M peaks at age 14-15yrs
F peaks at age 13-14yrs (CHECK)
Bones get longer before they get wider so we have an increased fracture risk during the growing periods (as reflected in incidence peaks)
Boys also have a greater incidence anyway, possibly due to general greater levels of vigorous activity - jumping out of trees, play fighting etc
Majority of fractures are traumatic, a small portion are due to metabolic disease
What is the definition of osteoporosis in children?
(Is still a degradation of the microarchitecture and demineralisation of bone but)
1 or more vertebral crush fractures (not secondary to trauma) OR
Size adjusted bone ‘density’ less than -2SD below mean AND 2+ fractures by age 10/3+ fractures by age 15 (CHECK)
Bone density measured on dexa scan - 2d image of bone mass (which doesn’t necessarily overlap with density in this age group due to differing growing rates/stages)
What is the epidemiology, aetiology and pathophysiology of osteogenesis imperfecta?
Commonest form of inherited bone disease - 650-750/year/UK - Sheffield is a hub of it
Autosomal dominant inheritance - COL1A1 and COL1A2 - genes that are responsible for the production of type one collagen (though 18 other genes also identified); though also de novo mutations
Chains of collagen aren’t produced straight - kinks lead to space between chains when they are grouped together - when mineralised with hydroxyapatite crystals this solidifies the space and subsequently increases fragility/brittleness
How does OI present?
Bone fragility manifesting as fracture and subsequent deformity (because of impaired healing or natural bowing over time)
Born pain - due to high bone substrate turnover
Impaired mobility - breaks + subsequent muscle weakness, contractures
Stunted growth - more severe disease = shorter
Deafness, hernias, heart valve prolapse, blue sclera
What is the Sillence classification for OI?
Type 1 = mild, 1+ break a year, may fatigue easily, generally normally QoL, may still get bowing of bones
Type 4 = intermediate (THOUGH UNSURE BETWEEN WHAT AND WHAT..)
Type 3 = severely deforming e.g. Wormian bones in skull = feels like bubble wrap
Type 2 = lethal, really short long bones
How do you manage OI?
Drugs: bisphosphonates e.g. Pamidronate - given IV long term throughout childhood (AND ONWARDS?) - works to increase bone mass by feeding the substrate into the growth plate - leads to reduced fracture risk/increased vertebral height/generally feeling well and stronger - no longer term adverse effects
Surgery - may need various castings etc; telescopic bone rods that grow as patient grows; spinal rods; skull base support - as odontoid peg can progress up through skull base ad into brainstem…
Pain team - can give morphine for bone fractures in children
Teeth checking
Management of concomitant health problems
PT/OT/MH support
What is the aetiology of rickets?
Lack of sunlight (vitamin D) and poor nutrition
What counts as vitamin D deficiency?
Measured on a blood test - 25(OD)D
<25nmol = deficient
Ideally you want >50nmol with a good diet - most of UK sit around 40nmol
75nmol = max Ca absorption
How do you ensure you’re getting enough vitamin D?
10 mins of sunlight exposure/day - even on the hands and face only - will be enough
England in autumn/winter/early spring - the latitude means we don’t get the right wavelengths to make vit D
People it’s darker skin make less; women who wear burka’s also might be at a particular risk of deficiency, as will refugees (as often compounded by poor quality diets)
Supplementation and fortification - Vit D2 (ergocalciferol) or D3 (cholecalciferol) doesn’t matter a end up at same end product - D2 from mushrooms fortified foods; D3 (mostly animal sources) from yellow spreads, cereals, meats, fish, eggs
What is the relationship between maternal vitamin D and baby vitamin D?
If baby is exclusively breastfed - at more of a risk of deficiency (one of the few things breast milk doesn’t contain much of) - mum would have to be taking 10x the required vit D to pass enough in her milk
Important that mother gets enough as her levels whilst pregnant are related to bone size and strength in childhood
How does rickets present?
Rare in this country now
Limb deformity - bowed legs, metaphyseal swellings, short stature
Gross motor delay
Hypotonia
Fractures
Weakness
Misery…
How do you investigate low vit D/rickets?
Bloods:
Low fasting phosphate is a key identifier -
Raised alk phos -
High PTH
Variable serum Ca - need to maintain some level or will get convulsions..
Low 25(OH)D - from Bristol labs which take 3wks..
XR - cupping, splaying and fraying at the ends of the long bones
How do you manage rickets (?) ?
Give IV Ca
Give slow else will wreck vein and will put patients into a prothrombotic state so don’t wanna kill them..
SLIDES FOR DOSES
How to you manage vitamin D deficiency?
Vit D + Ca - PO or IV depending on need
DOSES
if compliance issues - can give 150,000 units stat IV with no adverse affects
What’s the most likely cause of death in someone with vit D deficiency?
Cardiomyopathy
Or hypocalcaemic convulsions (when exercising really hard, the fuzziness that you feel is the prodrome to this)
