Bones Flashcards
Osteoclast
Break bone down
Osteoblast
Bone formation
Name some regulating factors of bone density
Genetics 70-80%
Body weight- Low BMI is bad
Sex hormones
Diet and Exercise
What causes bone density loss?
Sex hormone deficiency e.g menopause
Low BMI
Diet low in Vitamins C and D
Where are the common sites of osteoporotic bone fractures?
Neck of the femur
Vertebral body
Distal Radiu
Humeral Neck
What is DXA
A scan used to measure bone density
What sites are used in a DXA scan?
Lower Lumbar spine
Hip
What is normal in DXA?
Bone density within 1 SD of young adults
What scale is used in in deterring whether someone is osteoporotic?
Standard deviation SD from the norm of peak bone density
What is classed as Osteopenia?
BMD >1 SD below mean but <2.5SD
What is classes as osteoporosis?
BMD >2.5 SD below mean
What is classed as severe osteoporosis ?
BMD >2,5 SD below mean and a fragility fracture
What are modifiable risk factors for fractures?
Alcohol
Weight
Smoking
Physical inactivity
What are non modifiable risk factors for fractures?
Gender and menopause
What are secondary causes of fragility fractures?
Hypothyroidism
Coeliac disease
IBD
Cushings
What is the lifestyle advice given to those at risk of fractures?
High intensity strength training
Low impact weight bearing
Avoid excess alcohol and smoking
Fall prevention
What dietary supplements should be taken by those at risk of fractures?
700Mg calcium
1000Mg post menopausal
What treatment should be started on menopausal women before 45 years of age?
HRT
When is testosterone replacement used?
Hypogonadal men
How do bisphosphonates work?
Taken up by osteoclasts and cause cell death, resulting in reduced bone breakdown
Reduce risk of fractures at all sites
Name a bisphosphonate
Alendronate
Risendronate
What is the main risk with bisphosphonates?
Osteonecrosis of the Jaw
What other bisphosphanate can be used?
Zoledronic acid - IV infusion once yearly
What is Denosumab?
Monoclonal antibody for RANKL
What is the function of RANKL in osteoclasts?
Prevents activation of RANK which inhibits osteoclast activation
What is the monoclonal antibody used in osteoporosis?
Denosumab
What is the effect of Corticosteroids on bone?
Reduction of osteoblast activity and lifespan
Suppression of osteoblast precursor
Reduction of Ca2+ absorption
What is usual age of Pagets?
<40 increased incidence in age
What is the cause of Pagets?
Environmental trigger in a genetically predisposed individual
Where does pages affect?
Long Bones
Pelvis
Lumbar spine
Skull
Pagets Presentation
Bone Pain and deformity
Deafness
Compression neuropathies
Raised alkaline phosphates
What scan shows the distribution of Pagets?
Isotope scan
Treatments in Pagets?
Analgesics and Bisphosphonates
What is pathology of Pagets?
Abnormal osteoclast activity followed by abnormal osteoblast activity resulting in abnormal bone
-reduced strength and increased fracture risk
What is Osteogenesis imperfecta?
Rare group of genetic disorders of Type 1 Collagen
What genes are affected?
COLIA1 and COLIA2I
What is osteogenesis imperfecta type 1?
Mild
What is osteogenesis imperfecta type 2?
Presents in neonates
Incompatible with life
What is osteogenesis imperfecta type 3 and 4
Very severe
What is the treatment in osteogenesis imperfecta?
No cure
Fracture fixation
Consider bisphosphonates
In a young child presenting with fractures what should always be considered?
Non accidental injury
What mode of inheritance is osteogenesis imperfecta?
Autosomal dominant
