Osteoporosis Flashcards
Define osteoporosis
Imbalance of bone remodelling cause a decrease in bone mass and bone density, and a deterioration of bone microarchitecture. Clinically defined as 2.5 standard deviations or greater below average youth bone density.
- Most common bone disease and major public health concern
- Affects areas of high trabecular bone the most: spine, wrist, head of femur
List osteoporosis risk factors
- Age
- Female
- Menopause
- Family history
- Low physical activity
- Smoking
- Alcohol
- Low vitamin D levels
- Low dietary calcium
- Drugs (e.g. corticosteroids)
- Diseases (e.g. hyperthyroidism)
Describe the concept and mechanism of osteo porosis
Osteoporosis occurs when the coupling of bone resorption and bone formation is disrupted. Factors include:
- Genetic
- Age
- Mechanical loading
- Mineral balance: vitamin D, PTH, sex steroids
Best way to prevent osteoporosis?
Maximize peak bone mass as youth and minimize bone loss with age. Peak bone mass affected by: - Genetics - Amount of physical activity - Dietary calcium intake - Smoking
Outline roles of vitamin D
- Ensures that enough blood calcium and phosphate is available
- Low vitamin D leads to increased PTH
Outline roles of PTH
- Increases bone resorption
- Reduces bone density
- Increased by both low vitamin D or low calcium
Outline roles of sex hormones:
- Maintains coupling between osteoblasts and osteoclasts
- Keeps bone cells alive
- Reduce bone turnover
- Mechanically strengthen bone
Explain mechanical loading’s interaction with maintenance of bone mass
- Needed to promote formation of bone
- Causes bone to remodel in areas that experience stresses
Explain interaction of low sex hormones in maintenance of bone mass
Low estrogen and testosterone: Results in impaired coupling resorption and formation -> net effect is bone loss. Deficiency from: - anorexia - Congenital deficiency - Alcoholism - Menopause - Age
List fracture risks from low sex hormones
- Low bone mass
- More dead bone cells
- Loss of connectivity
- High bone turnover
- Poor bone geometry
Explain interaction of testosterone and maintaining bone mass
Testosterone (androgens)
- Causes bone remodelling to resorb inner bone and form bone on outer surface
- Greater strengthens the bone (per mass)
Explain interaction of oestrogen and maintenance of bone mass
Estrogen
- Maintains balance between bone formation and resorption
- Keeps bone cells alive (e.g. osteoblasts and osteocytes)
- Reduces rates of bone turnover
Outline the mechanisms of bone loss due to glucocorticoid excess or sex steroid deficiency
- E.g. cortisone
- Effects -> cause decrease in bone mass:
1) Gut: decreases calcium absorption
2) Kidney: Increases calcium loss
3) Bone: decreases osteoblasts (i.e. lowers bone formation)
Explain the mechanisms of drugs used to treat osteoporosis
Pharmacological treatment for OP:
- Bone resorption inhibitors:
1) Bisphosphonates -> kill osteoclasts on bone surface; inhibit bone remodelling: e.g. risedronate, alendronate and zoledronic acid.
2) RANKL-inhibitor - Bone formation stimulators: calcium and vitamin D
Discuss issues associated with hip fractures, including risk factors for falls, disability and death after hip fracture and prevention of falls.
Hip fracture:
- 20000 per year
- Most serious fracture for elderly
- 20% die within a year
- Most survivors don’t regain full function.
Risk factors for hip fracture:
- Osteoporosis
- Impaired balance
- Muscle weakness
- Low body weight
- Tallness
- Smoking
- Low calcium intake
Describe the oral manifestations of osteoporosis and outline how oral health and dental management could be impacted. Outline possible radiographic changes
- Rapid bone resorption of mandible body and alveolar bone
- High risk of fracture due to extraction and trauma
- Likely association with periodontitis
Define medication-related osteonecrosis of the jaws (MRONJ) and explain the risks associated with biphosphonate and other medication that effects bone turnover for dental patients
Bisphosphonates prevent bone from remodelling in jaw (e.g. Risedronate, alendronate, and zoledronic acid):
- Bisphosphonates used as treatment/prevention for pathologies involving bone turnover or bone resorption: e.g. Osteoporosis, bone cancers, hypercalcaemia, etc.
- Bisphosphonates kill osteoclasts on surface of bone
Jaw bone become susceptible for infection.
Jaw bone become destroyed over time.
Risk factors of MRONJ:
- Medication-related: high potency bisphosphonate agents used, intravenous administration, long duration of therapy
- Trauma to jaw: Extraction, oral surgery, dental implants
