Research

The non-infectious disease, osteoporosis, is a condition of porous bones (Tortora and Grabowski, 1999) as it is characterised by increased porosity of the skeleton and alterations in bone strength (The American Journal of Nursing, 2006), resulting from the reduced bone mass. The associated structural changes and disruptions of the microarchitecture of the bone (Poole & Compston, 2006) result in a predisposition to increased risk of bone fractures, (Robbins & Cotran, 2005) particularly of the spine, hip, wrist, humerus and pelvis (Poole & Compston, 2006). The risk of fractures increases steeply with age (examined in the graph below) where most of those affected are elderly, over 65 years of age for females and 70 years of age for males (Johns Hopkins Medicine, 2013).

Figure 1: Age-specific and sex-specific incidence of radiographic vertebral, hip and distal forearm fractures (International Osteoporosis Foundation, 2006)

As there is no known cure for osteoporosis, management has to be undertaken if individuals are diagnosed with it, or individuals can take steps to prevent its onset. (Osteoporosis and Related Bone Diseases National Resource Center, 2019)

In order to manage osteoporosis, dietary and lifestyle changes are huge factors (Dr Lavings, 2022). Making lifestyle changes such as consistently participating in weight-bearing exercise instead of endurance exercise or having a sedentary lifestyle, smoking cessation and reducing alcohol consumption, can significantly increase bone density, reducing the debilitating ramifications of osteoporosis. According to Healthy Bones Australia link: https://healthybonesaustralia.org.au/, which is an initiative of Osteoporosis Australia (OA), the three main elements contributing to developing healthy bones in an individual’s lifetime are calcium, exercise and sunshine (vitamin D) (The American Journal of Nursing, 2006).

When the depletion of calcium from the body, such as loss from urine, faeces and sweat is greater than what is absorbed from the diet, it can result in low levels of calcium, which is a major risk factor contributing to the development of osteoporosis (Tortora & Grabowski, 1999). Adults require 1,000 mg per day of calcium intake. This requirement increases to 1,300 mg per day for women over 50 and men over 70 years (Healthy Bones Australia, 2021).

• By increasing calcium intake, individuals are less susceptible to the development of osteoporosis. Some good sources of calcium through altering diet include:
• Low-fat dairy products
• Dark green leafy vegetables
• Canned salmon or sardines with bones
• Soy products, such as tofu
• Calcium-fortified cereals and orange juice
  (Mayo Clinic, 2021)

Vitamin D is essential to bone health, where low levels of vitamin D are associated with rickets, osteoporosis, and osteomalacia (Poole & Compston, 2006). Vitamin D insufficiency causes muscle weakness, contributing to muscle density loss and consequently, bone density loss as the mechanism of muscles are not being utilised to stimulate osteoblast function. (van der Mei, et al, 2007)

In addition to this, vitamin D is necessary to absorb calcium, therefore a lack of sun exposure can lead to low vitamin D levels, making individuals susceptible to developing osteoporosis (Healthy Bones Australia, 2021). Increasing consumption of mushrooms, egg yolks, tofu, orange juice or taking a vitamin D supplement can increase vitamin D levels. (Hill, 2019)

Reduced physical activity increases the rate of bone loss because mechanical forces involved with exercise are important stimuli for normal bone remodelling. Muscle contraction is the dominant source of skeletal loading, therefore exercise such as weight training or weight-bearing exercise that promote balance and good posture are more effective stimuli for increasing and retaining (Tortora and Grabowski, 1999) bone mass than repetitive endurance activities (Robbins & Cotran, 2005). Therefore, individuals who regularly sit down or have an overall sedentary lifestyle have a higher risk of osteoporosis than those who are more active (Mayo Clinic, 2021).

There is a hereditary link to poor bone health, meaning individuals whose family members, particularly parents or siblings, have osteoporosis or health conditions associated with poor bone health have an increased susceptibility to developing osteoporosis (Healthy Bones Australia, 2021).

Some medical conditions may predispose individuals to osteoporosis, even if the condition is treatable or manageable. These include other endocrine and hormonal diseases, gastrointestinal diseases, rheumatoid arthritis, certain types of cancer, HIV/AIDS, and anorexia nervosa (Osteoporosis and Related Bone Diseases National Resource Center, 2019). According to Healthy Bones Australia, (Healthy Bones Australia, 2021) which is an initiative of Osteoporosis Australia (OA), other conditions such as the following also predispose individuals to osteoporosis;

• Breaking a bone from a minor bump or fall should be investigated in anyone 50 years +
• Low hormone levels: early menopause in women or low testosterone in men
• Coeliac disease, inflammatory bowel disease and other malabsorption disorders
• Diabetes
• Certain breast cancer treatment or prostate cancer
• Corticosteroids which are commonly used for asthma, rheumatoid arthritis or other inflammatory conditions
• Thyroid conditions: overactive thyroid or parathyroid
• Chronic liver or kidney disease
• Certain epilepsy or antidepressant treatment

Osteopenia

Osteopenia is the first stage of bone loss, which affects nearly 6.3 million Australians. It is a sign that an individual’s bones are at risk of further bone loss and developing osteoporosis. (The Big Osteoporosis, 2012)

Lifestyle factors refer to factors of a particular person as a result of their direct lifestyle choices, such as living conditions, behaviour and other habits that impact their quality of life or health. There are many modifiable lifestyle factors that contribute to the development of osteoporosis, including;

• Low levels of physical activity that involve muscle contraction (Healthy Bones Australia, 2021).
• Regular smoking. (Healthy Bones Australia, 2021). Link: https://healthybonesaustralia.org.au/your-bone-health/risk-factors/. Studies indicate that smoking is a risk factor for osteoporosis and fracture. Researchers are still studying if the impact of smoking on bone health is from tobacco use alone or if people who smoke have more risk factors for osteoporosis. (Osteoporosis and Related Bone Diseases National Resource Center, 2019)
• Excessive and/ or chronic alcohol intake (Healthy Bones Australia, 2021).
• Body build, where an extremely thin body build can increase your risk (Healthy Bones Australia, 2021).
• Weight, particularly individuals with obesity. Studies suggest hormone changes associated with obesity can impact bones. (Healthy Bones Australia, 2021).

Females are at a greater risk of developing osteoporosis, as they tend to start losing bone density at an earlier age and at a faster rate than men, a contributing factor being menopause and hormonal changes associated as well as the different body builds to males (Alswat, 2017). Additionally, females are at an increased risk if they have:

• chronic kidney disease
• early menopause
• an eating disorder resulting in low body weight
• rheumatoid arthritis (Morrison, 2018)

Steroids, also called corticosteroids, are anti-inflammatory medicines used to treat a range of conditions, (NHS, 2020). They are a man-made version of hormones normally produced by 2 small glands found above the kidneys (NHS, 2020). Steroids have major effects on how the body uses and stores calcium and vitamin D to build bones. As a consequence, steroids can lead to bone loss, osteoporosis and fracturing. This is heightened when steroids are used in high doses, as fracture risk increases as the daily doses of steroids increase.

Glucocorticoid-induced osteoporosis (GIO):

Glucocorticoids are a type of steroid, typically used to treat autoimmune and inflammatory diseases. They diminish bone mass by increasing bone resorption and reducing bone formation, (Robbins & Cotran, 2005), meaning these osteoclastic and osteoblastic cells are unable to function in equilibrium. Therefore, the prevalence of glucocorticoid-induced osteoporosis (GIO) is high globally, where, of the individuals who take glucocorticoids for an extended period of time,  30-40% of them may have a history of fragile fractures. (Liu, et al, 2020).

In addition to steroid use, certain medications individuals take can also be a contributing factor to the development of osteoporosis. These medications include;

• Antiepileptic medicines, which treat seizures and other neurological disorders.
• Cancer medications, which use hormones to treat breast and prostate cancer.
• Proton pump inhibitors, which lower stomach acid.
• Selective serotonin reuptake inhibitors, which treat depression and anxiety.
• Thiazolidinediones, which treat type 2 diabetes.
  (Osteoporosis and Related Bone Diseases National Resource Center, 2019)

1 Menopause, Estrogen (or oestrogen)

The decrease in oestrogen level at menopause is the main cause of bone loss and osteoporosis. Hormones such as oestrogen suppresses the osteoclast formation activity, therefore slowing resorption by inducing osteoclast apoptosis (apoptosis is the process of programmed cell death) (National Human Genome Research Institute, 2022). Low estrogen levels in women generally occur after menopause or in premenopausal women, which occurs from the abnormal absence of menstrual periods due to hormone disorders or extreme levels of physical activity (Osteoporosis and Related Bone Diseases National Resource Center, 2019). Hormones such as parathyroid hormone and vitamin D govern remodelling and also influence blood calcium levels (Tortora and Grabowski, 1999).

According to Robbins & Cotran’s Pathologic Basis of Disease, 7th Edition, women may lose as much as 35% of their cortical bone and 50% of their trabecular bone within the 30-40 years after menopause. Postmenopausal osteoporosis is characterised by a hormone-dependent acceleration of bone loss that occurs during the decades after menopause. Decreased levels of oestrogen result in increased secretion of certain proteins which are stimulators of osteoclasts. In attempts to counteract the increased activity of osteoclasts, compensatory osteoblastic activity occurs but it cannot keep pace, leading to what is termed a ‘high turnover form’ of osteoporosis (Robbins & Cotran, 2005).

2 Low levels of testosterone in men.

Men with conditions that cause low testosterone levels, (these can include metabolic disorders such as hemochromatosis, dysfunctions or tumours of the pituitary gland, infection of the testes/ orchitis and chemotherapy treatment (Cleveland Clinic, 2018) are at a heightened risk for developing osteoporosis (Osteoporosis and Related Bone Diseases National Resource Center, 2019).

Bone mass becomes so depleted that bones fracture, often spontaneously. A fracture is any break in a bone. Common fractures include;

• Open fracture: broken ends of the bone protrude through the skin
• Comminuted fracture: bone splinters at the site of impact and smaller fragments lie between
• Greenstick fracture: partial fracture where one side of the bone is broken and the other side bends
• Impacted fracture: the end of the fractured bone is forcefully driven into the interior of the other
• Colles fracture: a fracture of the distal end of the lateral forearm bone
• Stress fracture: a series of microscopic fissures in the bone that forms without any evidence of injury to other tissues. Stress fractures can result from diseases that disrupt normal bone mineralisation such as osteoporosis.
  (Tortora and Grabowski, 1999).

Vertebral fractures that frequently occur in the thoracic and lumbar regions are painful. Multilevel fractures can cause significant loss of height and various deformities such as lumbar lordosis and kyphoscoliosis  (Robbins & Cotran, 2005).

In addition to increased susceptibility to fractures, osteoporosis causes shrinkage of vertebrae, height loss, hunches backs and bone pain (Tortora and Grabowski, 1999). Osteoporosis can also lead to various other health ramifications including limited mobility, development of depression and/ or anxiety, pain, increased hospital admissions or potential for nursing home care. The condition can be debilitating, meaning it can limit an individual’s physical activity, consequently resulting in weight gain. This increases stress on an individual’s bones, such as knees and hips, and increases the risk of developing heart disease or type 2 diabetes. Lack of physical activity and loss of independence can increase the risk of developing depression or increase anxiety surrounding activities (Morrison, 2019)

Actions to help avoid broken bones:

Undiagnosed osteoporosis means an individual is at a much greater risk of fracture meaning early investigation of any risk factors will help to diagnose osteoporosis (Healthy Bones, 2021). Bones fracture as a result of osteoporosis or undiagnosed osteoporosis is considered a serious medical emergency, typically requiring a hospital visit, possibly surgery, hospital stay, rehabilitation and home care.

Consequently, it is recommended that adults 50 years or older who have broken a bone from a minor bump or fall should take the necessary steps (such as seeing their GP or getting a DEXA Scan) to check for osteoporosis. Although broken bones can still occur in patients with diagnosed osteoporosis or osteopenia, ongoing treatment through medication and lifestyle changes as well as developing management plans with the individual’s GP will significantly decrease this debilitating risk (Healthy Bones, 2021)

Bones play an essential role of locomotion, support and protection of soft tissues, calcium and phosphate storage, and storage of bone marrow. It is continuously reabsorbed by osteoclasts and reformed by osteoblasts (Florencio-Silva, et al, 2015). The matrix of the bone contains inorganic mineral salts that, as they are deposited in the framework formed by the collagen fibres (which determine a bone’s flexibility) of the matrix, crystallise and the tissue hardens. This process of calcification or mineralisation is initiated by osteoblasts. This process only occurs in the presence of collagen fibres, as mineral salts begin to crystallise in the microscopic spaces between collagen fibres. The combination of crystallised salts and collagen fibre is responsible for the hardness that is characteristic of bone, (Tortora & Grabowski, 1999) therefore its structure is directly essential to bone fulfilling its function.

Bone mineral density (BMD) or bone mass, is a measurement of the amount of inorganic mineral content in bone tissue. (Kranioti, et al, 2018)

Factors affecting Bone Mass: Factors affecting bone mass include nutrition (such as calcium and vitamin D intake), hormonal status and physical activity all influence peak bone mass (Poole & Compston, 2006). There are two principal effects of ageing on bone tissue: loss of bone mass and brittleness.

• The first effect results from the loss of calcium and other minerals from bone matrix (demineralisation). This loss usually begins after age 30 in females, accelerates greatly around age 45 as levels of estrogens decrease and continues until as much as 30% if the calcium in bones is lost by age 70. Once bone loss begins in females, about 8% of bone mass is lost every ten years. This loss of calcium from bones is one of the problems in osteoporosis.
• The second principal effect of ageing, brittleness, results from a lowered rate of protein synthesis, which diminishes the organic portion of bone matrix, mainly collagen fibres, that gives bone its tensile strength. The loss of tensile strength causes the bones to become very brittle and susceptible to fracture (Tortora & Grabowski, 1999).

Bone remodelling

Bone is in a constant and continuous state or process of remodelling, which is important for the maintenance of normal skeletal structure and function, therefore, when an imbalance in the process of bone resorption and formation (which is called osteogenesis or ossification) (Tortora & Grabowski, 1999) arises, it can result in disease such as osteoporosis (Chen, et al, 2018). Excessive resorption by osteoclasts without the corresponding amount of reformed bone by osteoblasts contributes to bone loss and osteoporosis. This balance (or equilibrium) of bone formation and resorption is necessary and depends on the action of several local and systemic factors including hormones, cytokines, chemokines and biochemical stimulation (Florencio-Silva, et al, 2015).

Bone remodelling is a highly complex process by which old bone is replaced by new bone, in a cycle comprised of three phases;

1. Initiation of bone resorption by osteoclasts
2. The transition (or reversal period) from resorption to new bone formation
3. The bone formation by osteoblasts (Florencio-Silva, et al, 2015)

Many types of cells and factors are involved in the process of bone remodelling (Chen, et al, 2018)

Figure 8: Homeostasis maintenance (LibreTexts, 2020)

Hip fractures result in loss of independence for at least a third of people with osteoporosis, and vertebral fractures cause height loss, chronic pain, and difficulty with normal daily activities (Poole & Compston, 2006).

According to Poole & Compston, writing for the British Medical Journal link: ‘Fractures caused by osteoporosis affect one in two women and one in five men over the age of 50.’

According to Healthy Bones Australia, 2021:

• over 173,000 broken bones occur each year from poor bone health
• Hip fracture remains the most serious and costly type of fracture. Studies have shown up to half of all hip fracture patients had a prior fracture and many of these were related to undiagnosed osteoporosis.
• 30% of all fractures related to poor bone health are in men

In 2010, there were an estimated 158 million individuals at high fracture risk, by 2040 it was estimated that this figure will double because of demographic shifts (International Osteoporosis Foundation, 2019).

According to the Australian Governments Institute of Health and Welfare:

• The hip was the most common site for minimal trauma fractures (32% of fractures)
• An estimated 924,000 Australians have osteoporosis, representing 3.8% of the population
• Osteoporosis is most common in older women, affecting over 1 in 4 women aged over 75
• In 2017–18 there were 93,321 hospitalisations for minimal trauma fractures in people aged 50 and over

Two in three Australians aged over 50 years are affected by osteoporosis or have ‘thin bones’ that can lead to osteoporosis (The Big Osteoporosis, 2012).