Osteoporosis Flashcards
Define the term osteoporosis
Generalised progressive diminution in bone tissue mass permit volume of bone, ratio of mineral to organic elements is unchanged with remaining bone being ‘morphologically normal’
Bone is considered osteoporotic when it is is >2.5 standard deviations below peak bone mass (20-year-old sex-matched healthy person average) as measured by DEXA scan
Briefly outline the classification of osteoporosis
Primary
type 1 - Post menopausal
type 2 - Senile
Secondary due to other cause i.e. - endocrine conditions - drugs - miscellaneous (RA)
OR
Generalised (diffuse)
- Genetic (congenital) – eg Turner (XO) or Klinefelter (XXY) syndrome, anaemias (sickle cell, thalassemia, haemophilia)
- Deficiency states – Malnutrition, scurvy, protein deficiency, alcoholism and liver disease
- Neoplastic – Myeloma, leukaemia, lymphoma, metastatic disease
- Iatrogenic – Heparin, Dilantin, steroid-induced
- Miscellaneous – Involutional, post-menopausal, amyloidosis paraplegia, weightlessness, idiopathic
Localised (regional)
- Secondary to specific, identifiable aetiologies
- Less common than generalized
- Causes:
- Immobilisation/disuse
- Pain
- Infection
- Paget’s disease (hot phase)
- Transient regional OP
- Regional migratory OP
- Idiopathic juvenile OP
Compare Type I with Type II osteoporosis
Type 1
Age/gender
50-75
Aetiology:
Hormones (change in oestrogen levels with menopause)
Type of fractures:
vertebral crush, colle’s
Onset:
rapid onset with sharp decline in bone density
Type of bone affected
spongy and trabecular
Type 2
Age/gender
>70
Aetiology:
- Chronic, mild –ve calcium balance
- Increased sensitivity to PTH
- Decreased stimulation of osteoblasts (sedentary lifestyle)
Type of fractures:
- Femoral neck
- Vertebral crush
- Proximal humerus
- Proximal tibia
- Pelvis
Onset:
Insidious onset with slow decline of bone density
Type of bone affected:
cortical and trabecular
Which endocrine conditions are known to play a role in the development of osteoporosis
- Glucocorticoid excess – Excessive glucocorticoids decreases osteoblastic activity and increases osteoclastic activity, as well as decreasing GI Ca2+ absorption and increasing urinary excretion. This leads to decreased bone formation and increased bone resorption.
- Hyperparathyroidism - PTH inhibits osteoblastic activity, decreases bone mineralization and decreases transport of Ca2+ ions in cell membranes
- Hyperthryroidism - Thyroid hormones increase bone remodeling and resorption via stimulation of osteoclast activity.
- Diabetes type 2 - metabolism is impaired
What are the main symptoms of uncomplicated osteoporosis?
Uncomplicated
o Usually asymptomatic – often delayed diagnosis. Look for in history and physical observation (endomorph, sedentary etc)
o May have aching pain (especially back pain)
What is the main complication of osteoporosis? Discuss.
Complications (fracture)
o Typically vertebral crush fractures (minimal/no trauma, typically T8 or below) – Ssx include:
• Acute pain (non-radiating), subsides within days/weeks
• +/- local tenderness
• Agg: Weight bearing
• Multiple crush fractures: Kyphosis, dull aching pain (stress on spinal muscles and ligaments)
o Non-vertebral fractures – Usually secondary to falls
Can laboratory investigations be used to diagnose osteoporosis? Discuss.
Biochemical markers would only indicate secondary OP (i.e. due to another underlying cause)
Best for Dx:
Radiographic and US measurement of bone density
• Gold standard = Dual Energy X-Ray Absorptiometry (DEXA)
• Osteopenia (-1.0 to -2.5 SD from peak bone density)
• Osteoporosis (
Discuss the radiological manifestations of osteoporosis
- Radiolucent – due to decreased bone density
- Prominent cortical endplate – Most stress on endplates, therefore increased density relative to rest of VB
- Loss of horizontal trabeculae
- Wedge/crush fractures – May be evident due to stress on weakened vertebrae –> dowager’s hump
