Bone Disease Flashcards
what is the definition of osteoporosis
a decrease in bone mineral density and microarchitecture deterioration of bone tissue, leading to increased bone fragility and increased chance of fracture
how does the bone density of someone with osteoporosis differ to the normal bone density, in terms of standard deviation
bone density >2.5 SD below what is normal for that of a young adult male
how does the bone density of someone with osteopenia differ to the normal bone density, in terms of standard deviation
1-2.5 SD below what is normal for a young adult male is defined as osteopenia
what are risk factors for osteoporosis
Age
Female
Genetics
Low peak bone mass
Limited early exercise
Limited early calcium intake
Limited body habitus
Disuse
Smoking
what are secondary causes of osteoporosis
Primary hyperparathyroidism
Thyrotoxicosis
Long term glucocorticoid use
Cushings disease
Anorexia nervosa
Malabsorptive conditions (Ca2+ deficiency and secondary hyperparathyroidism)
chronic inflammatory disease/neoplastic disease
what are the most common osteoporitic fractures
colles
wedge spinal fractures
neck of femur
if osteoporosis is suspected what investigations should be done (usually done when someone presents with a pathological fracture)
DEXA of lumbar spine and iliac crest - gold standard
if osteoporosis confirmed, bloods for causes should be done: calcium phosphate, TFTs and ESR, sec hormones if <50, Vit D, PTH
what screening is available for patients at risk of decreased bone density and what is done with the results
any patient >50 should be assessed with a FRAX tool
low risk = reassurance
intermediate = DEXA scan
high = treatment started
what lifestyle advice is given to patients with osteopenia
Stop smoking
Limit alcohol to <20 units a week
Increase exercise and dietary calcium intake
Repeat DEXA scans should be offered to the group
what is the medical management for osteoporosis
weekly bisphosponates (alendronic acid)
Vit D + calcium - if found to be deficient
HRT - only for premature menopausal women
testosterone replacement - only hypogonadism males
repeat DEXA scans and FRAX scores every 2 years
what are some side effects of bisphosphonates
GI disturbance
rare - osteonecrosis of the jaw
what does NICE recommend switching to if the GI effects of alendronic acid are too much for the patient
risdronate
what is osteomalacia
inadequate bone mineralisation commonly caused by vitamin D deficiency
what are symptoms of osteomalacia
Bone pain
Bone fragility
Fractures
Malaise
Weakness
Proximal muscle weakness
whats the difference between osteomalacia, osteopenia and osteoporosis
osteopenia is a less severe form of osteoporosis which is reduced bone mineral density - usually has few symptoms. XR often abnormal, biochemistry usually normal
osteomalacia is impaired bone mineralisation, usually caused by a vitamin D deficiency - usually more symptomatic. XR often normal, biochemistry always derranged.
what is rickets
osteomalacia in children
whats the difference between a T score and a Z score from DEXA scans
T Score = standard deviation of bone density from a healthy adult male
Z score = standard deviation of bone density from a member of the same age/gender population
what are good sources of dietary vitamin D
oily fish, fortified cereals, red meat, egg yolks
whats the pathophysiology of osteomalacia
absence of vitamin D leads to impaired calcium uptake in gut and increased renal calcium secretion
low serum calcium leads to increased parathyroid hormone which increases resorption of calcium from the bone, decreases calcium excretion/increases phosphate excretion leading to impaired mineralisation
what are common causes for inadequate vitamin D levels
diet - vegans most at risk in developed world
inadequate sunlight
liver disease
drugs - bisphosphonates, fluoride/aluminium toxicity
CKD
what investigations should be done if osteomalacia is suspected
Bloods U+E for renal screen LFTs for ALP (raised = increased osteoblasts) plasma calcium - normal to low serum phosphate - low serum PTH - raised serum vit D - low
XR - often normal, widened epiphyseal plates in kids
iliac crest biopsy required if tests do not confirm
whats the treatment for osteomalacia
Vitamin D replacement
high dose for 4 weeks then maintenance
IV if issue is malabsorption
activated Vit D if the issue is renal disease
what is pagets bone disease
increased destruction and formation of bone leading to disordered architecture
what is the characteristic pattern of abnormal bone for pagets bone disease
woven, non-lamellar pattern with fibrosis of the marrow spaces
what are the clinical features of pagets bone disease
Up to 80% are asymptomatic, despite radiological evidence
Waxing/waning bone pain
Bone deformities
Cranial nerve palsy due to compression
Classically CN8
Cardiac failure due to increased bone blood flow
The ‘textbook’ presentation is
Bone pain
Pathological fractures
Deafness
how is Pagets bone disease investigated
XR - lytic and sclerotic lesions
LFT - raised ALP
Ca, Phosphatee - normal - normal high
raised urinary hydroxyproline due to increased bone turnover
bone scans show extent of disease but arent specific for pagets
what cancer is 30x more likely in pagets bone disease
osteogenic sarcoma
what is the treatment for pagets bone disease
Simple analgesics for pain
Bisphosphonates for disease modification (IV or oral) (Monitor serum ALP as a disease marker)
Surgery may be required to deal with secondary joint disease or neurological complications
what is osteonecrosis
bone necrosis of all types
what is osteonecrosis of the epiphyses of long bones called
avascular necrosis
what is osteonecrosis of the shaft of a long bone called and what parts of bone are affected
bone infarction - trabecular bone and bone marrow
what are common causes of osteonecrosis
Interrupted arterial supply (fractures)
Interrupted venous drainage and retrograde arterial stoppage
what are risk factors for osteonecrosis
Fractures
Perthes disease - AVN of femoral head
Bone marrow infiltration – malignancy
Alcohol abuse
Cushings/exogenous corticosteroids/chemo
Infection – septic arthritis
which bones are more at risk for osteonecrosis
head of femur - #NOF
proximal scaphoid - distal wrist fracture
the lunate - following dislocation
body of talus - talar neck fracture
what are symptoms of osteonecrosis
pain
stiffness
swelling
when do radiological changes occur in osteonecrosis and what do they look like
6 months of disease
increased bone density
what is the treatment for osteonecrosis
Eliminate cause
Prevent complications
Fractures
Via weight relief/splinting
Potential surgical intervention if debilitating
