Bone disorders Flashcards
What are common fractures?
neck of femur; vertebral body; distal radius; humeral neck
What is the name for the discrete foci where bone undergoes a cycle of remodelling?
bone remodelling units
What happens during a normal bone cycle?
osteoclasts appear on a previously inactive surface and begin to resorb the bone; osteoclasts are then replaced by osteoblasts that fill the cavity by putting down osteoid that is mineralised to form new bone and then after a full cycle the resoption cavity is completely refilled with new bone
What happens in osteoporosis in compared to a normal cycle?
thre is a relative or absolute increase in resrption over formation that leads to increased bone loss
What is the major determinant of bone loss for women after menopause?
oestrogen deficiency
What are the modifiable risk factors for fragility fracture?
BMD; alcohol; weight; smoking; physical inactivity
What are non-modifiable risk factors for fragility fractures?
age; gender; ethnicitiy; previous fractures; family history; early menopause < 45 yo
Who should have theirr OP risk factors asses?
anyone over age 50 with risk factors; anyone under 50 with very strong risk factors eg early menpause or glucocorticoids
Who sohuld be referred for a DXA?
anyone with a 10 year risk assessment for any OP fracture of at last 10%
What is osteopaenia defined as?
BMD >1SD below the young adult mean but <2.5 SD below this value
What is osteoporosis?
BMD greater than or equal to 2.5 SD below the young adult mean
What is severe osteoporosis defined as?
osteoporosis with a fragility fracture
What are the secondary cuases of osteoporosis?
endocrine- hyperthyroidism; hyperparathyroidism; Cushings; GI- coeliac; IBD; chronic liver disease; chronic pancreatitis; resp- CF; COPD; chronic kidney disease
What is the lifestyle advice for management of osteoporosis?
high intensity stergth training; low impact weight bearing exerccise; avoidance of excess alcohol; avoidance of amoking; fall prevention
Who should calcium and vitamin D supplements be considered in?
pts who are at risk of deficieny due to insufficent dietary or limited sunlight exposure
When should calcium supplements be taken in relation to bisphosphonates?
should not be taken within 2 hours
Name 2 bisphosphonates
alendronate; risedronate
What is the action of bisphosphonates?
anti-resorptive agents- analogues of pyrophosphate that adsorb onto bone within the matrix and are ingested by osteoclasts leading to cell death thereby inhibiting bone resorption
What ar ethe benefits of bisphosphonates
which prevent bone loss at all sites vulnerable to osteoporosis and reduce risk of hip and spine fracture
What ar ethe long term risks of bisphosphonates?
osteonecrosis of the jaw; oseophhageal Ca; atypicla fractures
How is zoledronic acid administered?
once yearly IV infusion for 3 years
What is the action of denosumab?
fully human monoclonal Ab that targets and binds with high affinity and specificity to RANKL which prevents activation of its receptor RANK, inhibiting development and activity of osteoclasts, decreasing bone resoprtion and increasing bone density
How is denusomab give?
aubcut injection every 6 months
What are the adverse effects of denusomab?
hypocalcaemia; eczema; cellulitis
Who is strontium ranelate CI in?
if Hx of thromboembolic disease; IHD; periphera; arterial disease; uncontrolled HT
What is teriparatide?
recombinant parathyroid hormone that stimulates bone growth rather than reducing bone loss-anabolic agent
What are the effects of steroids on bone?
reduction of osteoblast activity and lifespan; suppression of replication of osteobalst precursors; reduction in calcium absorption; increase PTH
How much BMD is lost in 1st 6 months of steroid use?
30%
What happens during Paget’s disease?
abnormal osteoclastic activity followed by increased osteoblastic activity; abnormal bone structure with reduced strength and increased fracture risk
What bones does Paget’s affect?
long bones; pelvis; lumbar spine and skull
How does Paget’s present?
in older populations; with bone pain; deformity, deafness or compression neuropathies
How is Paget’s treated?
bisphosphonates if pain not responding to analgesi
What is the mutation foudn in osteogenesis imperfecta?
in type 1 collagen genes
What is osteogenesis imperfecta associated with?
blue sclera and dentiogensis imperfecta
