Osteoporosis

Epidemiology

 

1/3 caucasian women > 64

 

Risk Factors

 

Insufficient bone mass at time of skeletal maturity

- peak bone mass is achieved at age 25

 

Rapid loss of bone after menopause

 

Low body weight / weight loss / history of smoking / steroids

 

Primary

 

Type 1

- postmenopausal

- high turnover / osteoclast mediated

- F x 6

           

Type 2

- age-related / senile

- low turnover / osteoblast mediated

- F x 2

 

Can have both

 

Secondary

 

DDD NICE

 

Disuse

- prolonged bed rest

- inactivity

- paralysis

- space travel

 

Diet

- low calcium, insufficient vitamin C

- anorexia nervosa

 

Drugs

- heparin

- methotrexate

- ethanol

- steroids

 

Neoplasms

- metastatic disease

- myeloma / lymphoma / leukemia

 

Idiopathic

- adolescent (10-18 years)

- middle-age men

 

Chronic Illness

- RA / cirrhosis / sarcoidosis      

 

Endocrine Abnormalities

- DM

- pituitary hypersecretion

- adrenal cortex excess

- ovary- oestrogen deficiency

- testis - testosterone deficiency

- hyperparathyroidism

- hyperthyroidism

 

DEXA Screening

 

DEXA ScanBMD Hip 2

 

BMD Spine

 

Definition

 

Dual Energy X-ray Absorptiometry

- hip and spine

 

Method

 

Compare bone mass values

- to ideal peak bone mass in pool of peers / young people

 

False negatives

- osteophytes in hip or spine

 

Grading

 

Within 1 SD of ideal

- normal

 

1 – 2.5 SD below ideal

- osteopenic

 

>2.5

- osteporotic

 

> 2.5 + fragility fracture

- severe, established osteoporosis

 

Scores

 

T score

- SD below young adult at peak bone density

 

Z score

- SD below average person of same age

 

Investigation

 

Exclude secondary causes

 

Neoplasm

- multiple myeloma (se electrophoresis)

 

Endocrine

- hyperparathyroidism (Ca, PO4, PTH)

- hyperthyroidism (TFT, T3, T4)

- Cushing’s / CRF (U&E)

- DM (glucose)

- osteomalacia (low Ca, Vit D)

- FSH / LH / T

 

Issues

 

Wrist fractures

Hip fractures

Vertebral fractures

Sacral insufficiency fractures

 

Sacral Insufficiency Fracture

 

Management

 

Premenopausal

 

Adequate calcium and vit D

Adequate weight

Exercise

No smoking

 

Post menopausal

 

Calcium Carbonate

 

Basis

 

Quite often have inadequate calcium intake

- need 1500 mg / day

- patents develop osteomalacia with secondary hyperparathyroidism

 

Effect

 

Reduces rate of bone loss

- very cost effective

- supplement with vit D

 

Vitamin D

 

Physiology

- 25 hydroxy Vitamin D ingested

- alpha-hydroxylation in kidney to 1,25

- 1,25 dihyroxy D is active form

- enhances absorption of GIT calcium

 

Treatment

 

Calcitriol (1,25 dihyroxy Vit D)

 

Effect

 

Salovaara et al J Bone Mineral Research

- RCT of vit D3 and calcium v placebo in 3500 women > 60

- 3 year follow up

- reduced distal forearm fractures by 30%

- no effect on incidence lower limb fractures

 

Estrogen

 

Method

 

Osteoblasts have receptors for estrogen

 

Menopause

- skeletal bone loss increases 2% per year

- 8% cancellous

- 0.5% cortical

 

Results

 

PEARL trial of Lasofoxifene in postmenopausal women

- reduced risk of CAD and CVA

- reduced risk of breast cancer

- increased risk of thromboembolic events

 

Cummings et al N Eng J Med 2010

- RCT of 8550 women lasofoxifene v placebo

- significantly improved BMD

- reduced rates of vertebral and non vertebral fracture

- reduced rates breast cancer, CVA and MI

 

Calcitonin

 

Action

- binds to osteoclast

- decreases their number and activity

 

Administration

- nasal spray

 

Problems

- 22% people develop resistance

 

Effects

 

Kaskani et al Clin Rheumatol 2005

- RCT of calcitonin v vit D3

- calcitonin increased BMD at 1 year

 

Tascioglu et al Rheumatol Int 2005

- RCT of calcitonin v aledronate

- aledronate significantly better improvements in BMD

 

Bisphosphonates

 

Action

 

Pyrophosphate analogs

- bind to surface HA crystals

- inhibit osteoclast resorption

 

Indications

 

Low energy fracture

T score > 2.5 below

 

Side effects

 

Indigestion 30%

Occasional diarrhea

Bone pain (remedy by giving calcium at same time)

Very rarely jaw necrosis at high doses IV

 

Etidronate

- increases risk GI ulceration and bleeding

 

Atypical femoral fracture related to bisphosphonates

- reports of atraumatic bilateral femoral fracture

- seen in women taking bisphosphonates for more than 5 years

- insufficiency fracture

- characterised by short oblique subtrochanteric and diaphyseal fractures

- typically see lateral cortical thickening / sclerosis / beaking before the fracture

- must check contralateral femur if have a fracture

- xray any patient complaining of thigh pain

- recommend drug holidays to prevent this complication

 

Bisphosphonate Cortical ThickeningBisphosphonate Cortical Thickening 2

 

Bisphosphonates Femoral insufficiency fractureBisphosphonate Femoral Fracture

 

Doses

 

Aledronate / fosamax 70 mg weekly

- must take on empty stomach, with no food for one hour

 

IV risedronate

- take only once per year

 

Results

 

Harris et al JAMA 1999

- RCT of oral risedronate v placebo 2500 women with history vertebral fracture

- reduced risk of vertebral fracture by 40%

- reduced risk of non vertebral fracture by 40%

- increases BMD at vertebrae by 5%

- prevents loss of BMD at femoral neck

 

Exercise