Bone abnormalities

Question 1

What is osteoporosis?

Answer 1

Weak or fragile bones caused by loss in density

Increases likelihood of fracture

Question 2

What is Osteopetrosis?

Answer 2

Increased density of bones

Very rare

Question 3

What can cause fractures?

Answer 3

Normal bone + Excessive force

Weak bone + Normal force

Question 4

What conditions are characterised by defective mineralisation in bones?

Answer 4

Rickets (Osteomalacia)

Hyperparathyroidism

Question 5

What conditions are characterised by changes in bone structure?

Answer 5

Osteogenesis Imperfecta (type I collagen defect causing brittle bones)
Paget’s Disease (overactive osteoclasts causing poor quality woven bone)
Tumours

Question 6

What blood tests can be used to assess bone?

Answer 6

Alkaline Phosphatase, Albumin (routine)

Calcium, Phosphate, Vitamin D, Parathyroid hormone (additional tests)

Question 7

What imaging can be used to assess bone?

Answer 7

Plain X-Ray
Radionuclide scans (radioactive material injected into body - can be aimed at osteoblasts or osteoclasts)
CT/ MRI/ Ultrasound

Question 8

When would you do a bone biopsy?

Answer 8

Query malignancy

Question 9

How is bone density assessed?

Answer 9

DEXA Scan

Question 10

What bones are commonly fractured due to osteoporosis?

Answer 10

Neck of femur
Vertebral bodies
Wrist

Question 11

What are the wider complications of osteoporosis?

Answer 11

Increased risk of fractures
Quality of life - loss of confidence, less exercise, loss of independence 
Pain 
Long term admission
High mortality (e.g. due to #NOF) 
Cost to health service

Question 12

What are some risk factors for osteoporosis?

Answer 12

Old age 
Sex (females esp. post-menopause) 
Ethnicity (Caucasian + Asian populations) 
Low BMI
Family history 
Smoking/ alcohol 
Immobility 
Vit D or Calcium deficiencies 
Long term steroids

Question 13

How does ageing influence osteoporosis?

Answer 13

Reduced physical activity
Decreased osteoprogenitor cells means decreased osteoblasts (+ decreased activity of osteoblasts) so new bone not being formed
Increased RANKL (in post-menopausal women) stimulates osteoclasts to resorb bone causes net loss and lower bone density

Question 14

How can osteoporosis be prevented?

Answer 14

Secondary prevention (e.g. mobility aids, additional care) 
FRAX tool (assesses risk factors for fractures - used by GPs to guide management) 
DEXA Scan (to assess bone density to guide management)

Question 15

How does a DEXA scan work?

Answer 15

2 X-ray beams of different energy levels aimed at patient

Soft tissue subtracted to determine bone density

Question 16

What scores are used to analyse DEXA scans?

Answer 16

T-score:
Normal <1 SD
Osteopenia -1 to -2.5 SD
Osteoporosis >-2.5 SD

Question 17

How is osteoporosis managed?

Answer 17

Diet 
Exercise 
Supplements (e.g. Vit D and calcium)
Fall prevention (e.g. mobility aids)
Medication (1st line = bisphosphonates, 2nd line = SERMs, PTH, Denosumab)

Question 18

What bisphosphonates are used to manage osteoporosis?

Answer 18

Alendronic Acid (Alendronate) - taken orally OD or OW 
Risedronate 
Zoledronic acid (not on drugs list)

Question 19

How do bisphosphonates work?

Answer 19

Slow rate of bone remodelling
Alendronic acid = binds to hydroxyapatite crystals so osteoclasts take up bisphosphonate which prevents osteoclasts making seal with bone (so osteoclasts cannot form seal and resorb bone)
Some bisphosphonates work by inducing apoptosis of osteoclasts

Question 20

What are the problems with taking alendronic acid?

Answer 20

Must be taken on empty stomach and sit upright for half hour as bisphosphonates are irritants to oesophageal mucosa

Question 21

What conditions are bisphosphonates used to treat?

Answer 21

Osteoporosis
Paget’s Disease
Hypercalcaemia of malignancy

Question 22

What are the side effects of bisphosphonates?

Answer 22

Asymptomatic hypocalcaemia
GI disturbance/ Oesophageal reactions
Osteonecrosis - need to be aware of pts dental hygiene

Question 23

What are selective estrogen receptor modulators?

Answer 23

Raloxifene
Tissue specific - mixed agonist/ antagonist
Agonist in bones to stimulate bone formation
Antagonist in breast and uterine tissue so no increased risk of cancer as with HRT

Question 24

How does parathyroid hormone work as treatment for osteoporosis?

Answer 24

Promotes bone production
Subcutaneous injection OD
SEs: hypercalcaemia, muscle cramp, nausea/ vomiting, can cause bone loss if given continuously

Question 25

What is Denosumab?

Answer 25

Monoclonal antibody used to treat osteoporosis by inhibiting osteoclast formation, function and survival (by mopping up RANKL) Administered by SC injection

Question 26

What is the difference between Rickets and Osteomalacia?

Answer 26

Both characterised by defective mineralisation (usually due to vitamin D deficiency resulting in low calcium and phosphate) Rickets = defective mineralisation at growth plates causing growth retardation and joint deformity (affects children) Osteomalacia = defective mineralisation of osteoid (affects children and adults)

Question 27

What features of Rickets can be seen in imaging?

Answer 27

Widening of the epiphyseal growth plates

Question 28

What are the symptoms of osteomalacia?

Answer 28

Can be asymptomatic Proximal muscle weakness Bone pain Fractures

Question 29

What blood tests results would you expect to see in a patient with Rickets or Osteomalacia?

Answer 29

``` Calcium Phosphates (Low) Alkaline Phosphatase (High) Vitamin D (Low) ```

Question 30

How is Rickets/ Osteomalacia typically managed?

Answer 30

Education - diet | Vitamin D supplements

Question 31

What is Paget's Disease of the bone?

Answer 31

Imbalance in bone remodelling causing increased bone turnover (overactive osteoclasts leads to overactive osteoblasts) Leads to weak woven bone due to speed at which is being remodelled Lytic and sclerotic lesions Can be focal (affecting one bone) or multifocal Results in overgrowth, bowing, pain, fracture, deformity More susceptible to malignancies

Question 32

What blood test results would you expect to see in a patient with Paget's Disease of the bone?

Answer 32

``` Alk P (high) Serum Ca (normal) PTH (normal) ```

Question 33

How can Paget's Disease of the bone be managed?

Answer 33

``` Mobility aids Analgesia Supplements Bisphosphonates (osteoclast apoptosis, decreased depth of resorption site) Surgery ```

Question 34

What is osteogenesis imperfecta?

Answer 34

Group of disorders characterised by defective production of type I collagen through genetic mutation of collagen genes (hereditary) Systemic - causes brittle bones, blue/ grey tinted sclera,, brownish teeth, growth retardation, hearing loss, fractures Type I and Type II (type II more severe and can cause scoliosis, respiratory depression etc. - high fatality at birth) **Can be confused with child abuse in ED**