Osteoporosis

Question 1

What is osteoporosis?

Answer 1

Osteoporosis is a progressive systemic skeletal disease characterised by reduced bone mass and micro-architectural deterioration of bone tissue. As a result, bone is increasingly fragile and more susceptible to fracture

Question 2

What are osteoporotic fractures?

Answer 2

Osteoporotic (fragility) fractures are fractures that result from mechanical forces that would not ordinarily result in fracture.

Osteoporotic fractures are defined as fractures associated with low bone mineral density (BMD) and include spine, forearm, hip and shoulder fractures.

Question 3

What is the T score?

Answer 3

Bone density values in individuals can be expressed in relation to a reference population in standard deviation (SD); when SDs are used in relation to the young healthy population, this measurement is referred to as the T score.

Question 4

What is a Z score?

Answer 4

A Z score compares bone density to the normal at that age, and a score of -2 indicates bone density below normal for a person of that age.

Question 5

What is value for normal bone mineral density?

Answer 5

Normal: hip BMD greater than the lower limit of normal which is taken as 1 SD below the young adult reference mean (T score ≥-1).

Question 6

What is the value for osteopenia?

Answer 6

Low bone mass (osteopenia): hip BMD between 1 and 2.5 SD below the young adult reference mean (T score less than -1 but above -2.5).

Question 7

What is the value for osteoporosis?

Answer 7

Osteoporosis: hip BMD 2.5 SD or more below the young adult reference mean (T score ≤-2.5).

Severe osteoporosis: hip BMD 2.5 SD or more below the young adult reference mean in the presence of one or more fragility fractures (T score ≤-2.5 PLUS fracture).

Question 8

Which investigative test is used to measure bone density?

Answer 8

Bone density can be measured by a number of investigative tests but the one most commonly used is dual-energy X-ray absorptiometry (abbreviated to DEXA or DXA)

Question 9

What are the major risk factors for osteoporosis?

Answer 9

Reduced BMD is a major risk factor for fragility fracture.

Advancing age and female sex are significant risk factors for osteoporosis.

There are many other risk factors and secondary causes of osteoporosis. We’ll start by looking at the most ‘important’ ones - these are risk factors that are used by major risk assessment tools such as FRAX:

• history of glucocorticoid use
• rheumatoid arthritis
• alcohol excess
• history of parental hip fracture
• low body mass index
• current smoking
• falls

Question 10

What are the minor risk factors for osteoporosis?

Answer 10

Sedentary lifestyle
Premature menopause
Caucasians and Asians
Endocrine disorders: hyperthyroidism, hypogonadism (e.g. Turner's, testosterone deficiency), growth hormone deficiency, hyperparathyroidism, diabetes mellitus
Multiple myeloma, lymphoma
Gastrointestinal disorders: inflammatory bowel disease, malabsorption (e.g. Coeliac's), gastrectomy, liver disease
Chronic kidney disease
Osteogenesis imperfecta, homocystinuria

Question 11

Which medications can worsen osteoporosis?

Answer 11

SSRIs
Antiepileptics
Proton pump inhibitors
Glitazones
Long term heparin therapy
Aromatase inhibitors e.g. anastrozole

Question 12

What is the presentation of osteoporosis?

Answer 12

Unfortunately, the process that leads to established osteoporosis is asymptomatic and the condition usually presents only after bone fracture.

It is important that clinicians be alert to recognise low-trauma ‘fragility fractures’ (fracture caused by a force equivalent to the force of a fall from the height of an ordinary chair or less).

Fragility fractures occur most commonly in the spine (vertebrae), hip (proximal femur) and wrist (distal radius). They may also occur in the arm (humerus), pelvis, ribs and other bones. Signs differ according to the fracture site.

Question 13

What are the investigations for osteoporosis?

Answer 13

DEXA scan for bone density. 
USS measurement of bone 
Consider the following screening blood tests, in patients suffering from osteoporosis, to identify treatable underlying causes and to rule out differential diagnoses (osteomalacia, myeloma):
-FBC and ESR or CRP.
-U&E, LFTs, TFTs, serum calcium.
-Testosterone/gonadotrophins in men.
-Serum immunoglobulins and paraproteins, urinary Bence-Jones' proteins.
FRAX
OFracture

Question 14

When should a risk assessment for osteoporosis be considered?

Answer 14

Broadly, consider a risk assessment in:

• Those with a history of fragility fracture. Some guidelines suggest this should trigger BMD measurement; others suggest these should be considered for treatment without the need for further assessment.
• Postmenopausal women with risk factors.
• Women or men with significant risk factors.
• Women or men on oral corticosteroid treatment. (Any dose taken continuously over three months or frequent courses. 7.5 mg prednisolone or equivalent per day over three months continuously is considered high dose by NICE and confers higher risk.)
• All women over 65 and all men over 75 (NICE only).

Question 15

What is FRAX?

Answer 15

estimates the 10-year risk of fragility fracture

valid for patients aged 40-90 years

based on international data so use not limited to UK patients

assesses the following factors: age, sex, weight, height, previous fracture, parental fracture, current smoking, glucocorticoids, rheumatoid arthritis, secondary osteoporosis, alcohol intake

bone mineral density (BMD) is optional, but clearly improves the accuracy of the results. NICE recommend arranging a DEXA scan if FRAX (without BMD) shows an intermediate result

Question 16

What is OFracture?

Answer 16

estimates the 10-year risk of fragility fracture
developed in 2009 based on UK primary care dataset
can be used for patients aged 30-99 years (this is stated on the QFracture website, but other sources give a figure of 30-85 years)
includes a larger group of risk factors e.g. cardiovascular disease, history of falls, chronic liver disease, rheumatoid arthritis, type 2 diabetes and tricyclic antidepressants

Question 17

What is the management of osteoporosis?

Answer 17

As osteoporosis is an asymptomatic condition, management is centred on preventing fragility fractures, which are associated with enormous morbidity and mortality.

Treatment for osteoporosis should include not only drug treatment but also advice on lifestyle, nutrition, exercise and measures to reduce falls. Advise on smoking cessation where indicated, and moderation of alcohol intake. Advise regular weight-bearing exercise.

Calcium and vitamin D supplements

Bisphosphonate (usually alendronate)

Denosumab (bisphosphonates CI)

Strontium ranelate (2nd line)

Question 18

When is treatment with bisphosphonates recommended?

Answer 18

Start bisphosphonates in osteoporotic women without fragility fracture once they reach age 65 if they have any independent clinical risk factor for fracture, or over the age of 70 if they just have an indicator of low BMD.

Second-line treatments (risedronate and etidronate) may be considered if the patient is aged over 65 and unable to take alendronate

Question 19

What is the mechanism of action of bisphosphonates?

Answer 19

Bisphosphonates act by inhibiting the action of osteoclasts.

They are, however, poorly absorbed and need to be taken separately from food. They may cause oesophageal irritation and should be taken by the patient sitting up with plenty of water.

Question 20

What are the adverse effects of bisphosphonates?

Answer 20

Gastrointestinal adverse effects.

Poor adherence to treatment (partly due to complex instructions about taking them - the tablet is taken first thing in the morning on an empty stomach with a large glass of water. The person should be sitting upright or standing when the tablet is taken and must not lie down, eat or take other oral medication for at least 30 minutes afterwards (60 minutes for ibandronate). Most are taken on a weekly basis).

Osteonecrosis of the jaw.

Atypical femoral fractures.

Review treatment after 5 years

Question 21

What is denosumab?

Answer 21

Denosumab is a monoclonal antibody that reduces osteoclast activity (and hence bone breakdown) which is given by six-monthly subcutaneous injections. It may be a suitable option in women who are unable to comply with instructions for alendronate and either risedronate or etidronate.

Question 22

What is strontium ranelate?

Answer 22

Strontium ranelate was also licensed for the prevention of osteoporotic fractures in postmenopausal women with osteoporosis.

The European Medicines Agency (EMA) advised that it only be used where other medications are not tolerated and there are few cardiovascular risk factors. Not used anymore as it is not produced.

Question 23

What is raloxifene?

Answer 23

Raloxifene is not recommended as a treatment option for the primary prevention of osteoporotic fragility fractures.

Raloxifene, a selective oestrogen receptor modulator (SERM), reduces postmenopausal bone loss and reduces vertebral fractures but, like HRT, may increase the risk of venous thromboembolism. Unlike HRT, however, it decreases the risk of breast cancer (oestrogen-positive tumours) but may exacerbate hot flushes.

Question 24

What is the primary prevention of osteoporosis?

Answer 24

The person should be encouraged to take adequate calcium throughout life. Where intake may be suboptimal, provide supplementation with calcium and vitamin D (particularly for patients with low BMI and patients in residential and nursing homes).

Calcium-rich foods include milk and dairy products (can be reduced-fat) and vegetables such as broccoli and cabbage.

Dietary calcium intake may be estimated by one of several online calculators.

The healthy eating diet, with ‘5 a day’ of fruit and vegetables (vitamin C), fish meals at least weekly (vitamins D and K), is a good start.

Encourage a reduced salt and phosphate intake, and the moderation of alcohol intake; give anti-smoking advice as appropriate.

Encourage exercise, both traditional weight-bearing exercise and exercise that involves pulling forces acting on entheses (tendon insertions) of long bones.

Question 25

What should be prescribed for patients using glucocorticoids long-term?

Answer 25

The risk of osteoporosis is thought to rise significantly once a patient is taking the equivalent of prednisolone 7.5mg a day for 3 or more months. It is important to note that we should manage patients in an anticipatory, i.e. if it likely that the patient will have to take steroids for at least 3 months then we should start bone protection straight away, rather than waiting until 3 months has elapsed.

Question 26

What is the main complication of osteoporosis?

Answer 26

Compression fractures

Compression fractures cause:

• Pain and morbidity associated with high doses of analgesia.
• Loss of height.
• Difficulty breathing.
• Loss of mobility.
• Gastrointestinal symptoms.
• Difficulty sleeping.
• Symptoms of depression.

Question 27

What is the management of compression fractures?

Answer 27

Management aims to reduce these problems and options include:
Analgesia.
Back braces.
Physiotherapy.
Percutaneous vertebroplasty - Injection of bone cement into the vertebral body.
Balloon kyphoplasty - inflation of a balloon-like device into the vertebral body to restore its height, followed by injection of bone cement.

NICE advises the latter surgical options only in those with severe pain despite conservative measures, and where it has been confirmed that the pain is due to the fracture