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All you need to know about ... osteoporosis

Henrietta Hardiman
IDE RN MA HEALTH Ed (Europe)
Osteoporosis Specialist Nurse
Public Health Brighton & Hove City PCT

Fragility fracture
A fracture that occurs without any force/height being involved and/or following a fall from standing height or less. A fracture resulting from a fall off a 10cm high stool is not a fragility fracture

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Osteoporosis is a systemic bone disease that affects men and women with late clinical consequences. It affects the bone architecture, its quality and its strength, thereby making it less able to tolerate loading and more prone to fracture(s).
Bones are continuously going through a lifelong remodelling process, starting at birth, accelerating during puberty to reach what is called the peak bone mass by the late 20s and early 30s; followed by a period of stabilisation until the early 40s; and finally succeeded by very slow loss of bone thereafter.  Oestrogen inhibits bone resorption, and its decrease during the perimenopausal period is responsible for an accelerated rate of bone loss. The bone loss then slows down, to increase again after 70, reaching 1-2% a year after the age of 80.
The process of bone remodelling is due largely to genetic factors, lifestyle issues such as diet and exercise, and long periods of amenorrhea, except pregnancies, that can be due to anorexia nervosa and extreme exercise such as seen in young ballet dancers and competitive athletes. It is achieved in five stages:

  1. Normal resting bone is normally quiescent at any given time.
  2. Activation: under the influence of hormones, lifestyle, etc, the osteocytes (bone lining cells) retract and are replaced by osteoclasts.
  3. Bone resorption: osteoclasts start digesting the bone, thereby digging a small hole in the bone. This lasts for two to three weeks.
  4. Bone formation: osteoclasts are replaced by osteoblasts (bone building cells) that start filling the cavity dug up by the osteoclasts.
  5. Quiescence: this is a period of consolidation. This cycle lasts for about three to four months, and it is followed by a period of consolidation of six to 12 months.

Hormones play an important role in bone metabolism, in particular calcium-regulating hormones such as parathyroid hormones, calcitriol (active vitamin D) and calcitonin; others include sex hormones (oestrogen and testosterone) and systemic hormones (growth hormone/insulin-like hormone, growth factor and cortisol). 
Osteoporosis is a silent, painless, asymptomatic disease that frequently goes undetected until a "fragility" or "low trauma" fracture occurs after a fall. Typically it is a postmenopausal woman who slips on the pavement, puts her hand forward and incurs a Colles' fracture. It could also be a 65-year-old man coughing or turning in bed who breaks a vertebrae or an 85-year-old woman tripping on her phone line who falls on her hip and breaks it. When osteoporosis is severe the patient may first sustain a spontaneous break of the femoral neck with subsequent fall.(1)

Risk factors for osteoporosis and osteoporotic fractures
A fragility fracture is often the first sign of osteoporosis and should be investigated as such. It is the most common cause of fractures in older people; these fractures are due to aging bones, diminishing eyesight, poor balance due to lower muscle mass, hearing loss and medication that may affect the patient's balance.(2) However, other risk factors should alert the practice nurse:
 
Genetic

  • Maternal family history of hip fracture before the age of 75.
  • Race (white) and gender (women) can be a determining factor. However, it does not mean that women from other ethnic backgrounds should be excluded.
  • Thin and slender women with a body mass index (BMI) lower than 19.

Medical disorders

  • Anorexia.
  • Rheumatoid arthritis.
  • Hyperparathyroidism.
  • Hyperthyroidism.
  • Severe chronic diseases such as congestive heart failure, chronic renal disease, chronic liver disease, chronic pulmonary disease.
  • Conditions that affects bone metabolism (eg, coeliac disease).
  • HIV/AIDS.

Hormonal

  • Untreated oestrogen deficiency (early menopause/ hysterectomy before the age of 45).
  • Hypogonadism in men.

Lifestyle

  • Low calcium intake.
  • Vitamin D3 deficiency.
  • Smoking.
  • Excessive alcohol intake (two to three units daily for women and three to four for men). It is worth noting that for older frail people this may be too much and that excessive drinking may lead to increased risk of fall(s) and fracture(s).
  • Sedentary lifestyle. This includes younger people with physical disabilities.
  • Falls.

Drug treatment

  • Glucocorticoids: any amount in excess of three months. People over 65 should be given bone-sparing treatment preventively and those younger should be investigated with a dual energy X-ray absorptiometry (DEXA) scan.
  • Anticonvulsants.
  • Aromatase inhibitors.

Diagnosis of osteoporosis(2)
People with osteoporosis have a risk of fragility fractures and the most common sites are the wrist, vertebrae and the hip. Wrist and hip fractures are usually quite easily diagnosed but some of my patients have had to endure two or three weeks of increasing pain before a diagnosis of hip fracture has been made, especially when no fall had occurred. Vertebral fractures are common in men and women but it is estimated that only one-third are diagnosed and fewer are treated.

Methods of assessing bone(1)
Radiological
The gold standard for the clinical diagnosis of osteoporosis is made by assessing the bone mass density (BMD) by axial (DEXA). 
It is based on the 1994 WHO classification that has been widely adopted: "Osteoporosis is present when the bone mineral density or bone mineral content is over 2.5 standard deviations (SD) below the young adult mean (T-score of -2.5)." This can be further defined as:

  • Normal: T- score of -1 SD or more.
  • Osteopenia: T-score between -1 and -2.5 SD.
  • Osteoporosis: T-score below -2.5 SD.
  • Established osteoporosis: T-score below -2.5 SD, with one or more associated fragility fracture.

Other radiological methods of assessing bone include:

  • X-ray. This detects the presence of fracture(s), but it is insensitive to bone loss and, except for vertebral osteoporosis, there is a 30% loss of bone mass before changes are detectable.
  • Quantitative ultrasound (QUS). These scanners measure the attenuation of soundwaves as they pass through the bones and are useful for the provision of five-year risk fracture. There is a paucity of data regarding interpretation of QUS for men, children, premenopausal women and women from ethnic population; therefore they should only be restricted to postmenopausal Caucasian women. They are not used for the diagnosis of osteoporosis, but with more sophisticated equipment coming on to the market this position may change. (My personal experience with QUS has been mixed - the majority of mostly young women referred to my clinic for a DEXA scan following diagnosis by QUS had been wrongly diagnosed.)

Biochemical
Bone formation markers (ALP) can be measured in serum or plasma and bone resorption markers (CTX) can be measured in both serum and urine; they do not confirm the diagnosis of osteoporosis, but they can be useful for early indicators of compliance and response to therapy. 

Socioeconomic impact(2)
The cost to the NHS of treating osteoporotic fractures in postmenopausal women was estimated at between £1.5b and £1.8b. It is predicted to rise to £2.2b by 2010.
The personal and financial cost to the patients and to their families can be devastating: increased mortality rate within the first 12 months of a hip fracture and after 12 months for vertebral fractures, disabilities, pain, loss of independence due to the fear of falling again, inability to walk on their own and admission to expensive long-term residential care.

Treatment options(3)
NICE estimates that in the UK only 10-20% of women receive drug therapy for their condition.
In England and Wales the secondary prevention of osteoporotic fragility fractures in postmenopausal women is guided by the NICE Technology Appraisal document, Osteoporosis - Secondary Prevention, published in 2005 with added guidance on the use of strontium ranelate in September 2005, to be updated.It recommends treatment for:

  • Women 75 years and older, without the need for prior DEXA scanning.
  • Women aged between 65 and 74 years if the presence of osteoporosis is confirmed by DEXA scanning.
  • Postmenopausal women younger than 65 years of age, if they have a very low BMD (T-score of approximately -3 SD or below, established by a DEXA scan), or if they have confirmed osteoporosis plus one, or more, additional age-independent risk factor:
    • Low body mass index (
    • Family history of maternal hip fracture before the age of 75.
    • Untreated premature menopause.
    • Certain disorders independently associated with bone loss (inflammatory bowel disorder, rheumatoid arthritis, hyperthyroidism, coeliac disease).
    • Conditions associated with prolonged immobility.

Medical treatments
The drugs involved in the treatment of osteoporosis and the prevention of repeat fracture are very effective; however, it must be noted that these medicines must be taken for between five and 10 years, which can be a compliance issue for the patients.
The following drugs are only licensed for postmenopausal women and they can be divided according to their mode of actions:

  1. Bisphosphonates. These prevent bone resorption. They can be administered on a daily, weekly or monthly basis. Two of them - alendronic acid and risedronate - are licensed for prevention/treatment of vertebral and nonvertebral osteoporosis. Etidronate is only licensed for the prevention/treatment of vertebral osteoporosis. In order to maximise its benefit and reduce side-effects, the drug needs to be swallowed before breakfast with a big glass of tap water and the patient must remain upright for at least 30 minutes before their breakfast. The most common side-effects can include gastrointestinal intolerance such as mild oesophagitis, gastritis and abdominal pain.
  2. Strontium ranelate (Protelos; Servier) reduces bone resorption and promotes bone formation. It is a tasteless powder to be taken every day, usually at night, two hours after the last meal/intake of dairy product/calcium supplement. It is licensed for the treatment of vertebral and nonvertebral fractures. It is well tolerated, diarrhoea being the most frequently reported side-effect, although it tends to resolve after three months. It should be used with caution in patients with increased risk of thromboembolism.
  3. Selective oestrogen-receptor modulators (raloxifene) is to be taken daily. It is only licensed for the treatment of vertebral osteoporosis. It increases slightly the risk of blood clots and postmenopausal symptoms.
  4. Parathyroid hormone (Forsteo; Lilly) is self-administered daily by subcutaneous injections for an 18-month period. It is prescribed within strict criteria, to women with severe vertebral osteoporosis who do not respond/are intolerant to bisphosphonates.
  5. Calcium and vitamin D3 supplementation. This is not a substitute for treatment for osteoporosis but it is recommended to people who have a recognised low intake of dietary calcium (lower than 400mg per day), and for older people in care/nursing homes as it may help to prevent falls. It is prescribed as an adjuvant to other bone-sparing treatments.
  6. Hormone replacement therapy. Further to the Women's Health Initiative in 2002 HRT is not prescribed for osteoporosis treatment anymore.

Please refer to NICE criteria for drug treatment according to age and DEXA T-scores. The only licensed treatment for men is alendronic acid.

Lifestyle advice(2)
Nutrition
Calcium is an essential part of a lifelong healthy, balanced diet. Its adequate intake is of paramount importance throughout childhood and young adulthood in order to reach an optimum peak bone mass (see Table 1). It is found mostly in dairy products and also in foods such as tinned sardines, kidney beans, nuts and vegetables.

[[nip33_table1_68]]

Vitamin D facilitates calcium absorption in the gut and its deficiency is linked with rickets in children and osteomalacia, osteoporosis, muscle weakness and decreased immune function in adults. It is not easily found in food and children especially may not be keen on eating liver or fatty fish. It can be found in some vitamin-fortified food such as cereals, margarine and nonorganic soya milk. A cheap source of vitamin D is daily exposure to the sun, without sunscreen, for 20 minutes early morning/late afternoon between April and October.

Exercise
More than 90% of fractures occur after a fall, but by strengthening bones and doing muscles exercise, especially load-bearing exercises, you can help prevent such events. This is especially relevant to older people who fall due to poor muscle tone and bad coordination; they seem to benefit extremely well from targeted and specific exercises. Exercise will help young people to optimise their peak bone mass.
Smoking and heavy drinking should be discouraged as they may predispose to early menopause and accelerated bone loss.

Challenges for the practice nurse

As noted earlier, a small number of patients are diagnosed and treated for osteoporosis. The challenges are therefore on three fronts:

  1. Prevention - by advocating a healthy lifestyle from pregnancy to old age.
  2. Diagnosis:
  • Suspect osteoporosis when a postmenopausal woman presents with a fragility fracture.
  • Flag-up patients on long-term steroids.
  • In the case of primary prevention, the NICE guidance should be issued in 2007.
  • Supporting patients:
      • Encourage patients to talk about any problem they may have with their treatment and explain to them why they have to be treated for so long.
      • Repeat scans are not necessary, unless they have been requested by the specialist centre or are needed to motivate women after four or five years of treatment or if a repeat fracture occurs after one year of treatment and there is known patient compliance.
      • Refer any patient with side-effects) to the GP for further investigation and/or a change of medicine. One of my patients complained to me of severe oesophageal pain after starting her treatment. Further investigation diagnosed an underlying oesophageal tumour!

    Conclusion
    Osteoporosis is a silent disease affecting mostly post-menopausal women, with a higher rate of mortality and disabling fractures in the older age groups. Men should not be ignored as the rate of osteoporosis is also increasing in this population.
    The diagnosis is simple and the treatment cheap and effective. Plus with the possibility of yearly injections we might find in a few years time that we are offering an osteo jab at the same time as the flu jab.

    References

    1. Cummins SR, Cosman F, Jamal S. Osteoporosis, an evidence-based guide to prevention and management. Philadelphia: American College of Physicians; 2002.
    2. Kassianos G, Compston J, Brown P. Osteoporosis. Singapore: Best Medicine; 2005.
    3. National Institute for Health and Clinical Excellence. Osteoporosis - secondary prevention. Technology Appraisal Guidance 87. London: NICE; 2005

    Resources
    National Osteoporosis Society
    W: www.nos.org.uk

    International Osteoporosis Foundation
    W: www.osteofound.org

    International Bone and Mineral Society
    W: www.ibmonline.org

    The Bone and Tooth Society
    W: www.batsoc.org.uk