Osteoporosis – Bone Density Across the Lifespan

Due to many modern advances in healthcare the past century has seen significant increases in life expectancy. This fact, in combination with the ageing population we have in Australia, has therefore also seen increases in the incidence of health conditions that primarily affect the older generations. One such condition is osteoporosis, and it’s precursor osteopenia. Osteoporosis is a disease in which the density and quality of bone are reduced, leading to weakness of the skeleton and increased risk of fracture, particularly of the spine, wrist, hip, pelvis and upper arm. Osteoporosis, while a relatively common condition, can be a silent disease, and can thus remain undetected until a fracture or fall occurs (1,2). 

Osteoporosis Introduction

Incidence

In an opening statement in the most recent osteoporosis burden of disease analysis, Chairman of Osteoporosis Australia John Hewson stresses the importance of awareness and appropriate management of osteoporosis when he states “Millions of Australians are affected by poor bone health. Poor bone health costs the community and governments, and comes at a great personal cost to those diagnosed with osteoporosis or osteopenia and potentially dealing with debilitating fractures” (1). According to the statistics revealed in this report in the year 2012 4.74 million Australians over the age of 50 years have osteoporosis or poor bone health. This equates to 66% of all Australians over the age of 50. At this time it was predicted that by 2022 6.2 million Australians over 50 years of age, would have osteoporosis or osteopenia, being a 31% increase from 2012.

Diagnosis

The World Health Organisation (WHO) defines osteoporosis and osteopenia in terms of bone mineral density via imaging techniques such as dual-energy X-ray absorptiometry (DEXA). The T-score refers to the standard deviation between a patient’s bone mineral density (BMD) and that of a young adult in the reference population, and is used to classify bone densities into normal, osteopenia or osteoporotic as per below.

Osteopenia and Osteoporosis are the graded classifications of a net state of ‘low bone density’. For the purpose of ease of reading / writing, the rest of this blog will use the term ‘osteoporosis’, however please note that the following information also applies to its precursor ‘osteopenia’. 

Risk factors for osteoporosis include; 

• Advancing age
• Female sex
• Low body weight / body mass index
• Family history 
• Early menopause 
• Sedentary lifestyle 
• Excessive alcohol intake 
• Smoking 
• Low calcium and/or vitamin D intake
• Inadequate sun exposure 
• Anglo-saxon or Asian race 

Secondary osteoporosis may be the consequence of certain endocrine, metabolic or gastrointestinal disorders (such as hyperthyroidism, hypogonadism, hypercortisolism, intentional malabsorption conditions, rheumatoid arthritis, renal failure), or long term use of certain medications (including corticosteroids, selective serotonin reuptake inhibitors, anticoagulants, antidiabetic medications).  (5,6). 

Implications

Osteoporosis is a systemic condition, meaning its effects are evident globally within the body. Almost all fractures, regardless of location or type, are increased in those with low BMD. Adults who sustain an initial fracture (regardless of area or type) are subsequently at a heightened risk (2-4 fold) of sustaining another fracture, in a different area. Vertebral deformity is particularly associated with increased fracture risk, in the vertebrae or otherwise. Osteoporotic fractures can result in high morbidity, due to associated pain, reduced mobility, loss of function and reduced quality of life (7). 

Bone Density Across the Lifespan

Amy Harding featured in Episode #278 of The Physical Performance Show made the following statement; “Osteoporosis is a geriatric condition, but it’s really got paediatric origins”. As Amy eloquently put, while osteoporosis manifests in the later years, bone growth and maturity occurs in the younger years. Osteoporosis is a major public health concern worldwide, therefore preventative measures should be addressed lifelong in order to prevent the disease. 

Bone is composed of two major compartments, in which bone remodelling occurs; the periosteal (outer) surface and endocortical (inner) surface. Bone remodelling is a complex process, in which old bone is replaced with new bone.  Bone is composed of 4 different cell types; osteoblast cells, which are responsible for bone formation, osteoclasts, which resorb bone, osteocytes which are mechanosensors and control the bone remodelling process and bone lining cells. Periosteal osteocytes detect and respond to mechanical strain, with formation of new bone via various molecular pathways. Wollf’s Law of bone remodelling states that healthy bone tissue will adapt to the degree of mechanical loading it is placed under, where an increase in loading will result in an increase in bone strength, and vice versa. Sex hormones (oestrogen, testosterone) have a significant influence on the function of the bone cells responsible for remodelling, and thus as hormone levels change throughout the life-span, we see marked age-related changes in bone densities across the lifespan (11, 13). 

The following graph demonstrates the changes in bone density throughout the life-span:

Puberty – Young Adult 

Bone mass increases steadily through childhood, and more rapidly during adolescence, whereby >95% of the adult skeleton is formed by the end of adolescence. Studies suggest that from the end of adolescence into the twenties, slight changes are made to bones, with peak bone mass being reached between the mid-late twenties. Females tend to reach a lower peak bone mass, and at an earlier age than males (12). 

The balance of sex hormones in puberty are major factors in the development of bone shape, size and geometry. Bone surfaces, while under the influence of sex hormones during the prepubertal to young-adult years, are highly responsive to the mechanical loads generated by physical activity. Therefore, during these crucial years, it is imperative that bones are exposed to a wide variety of stimulating loads, with the goal of achieving as high a peak bone mass as possible (12). 

30’s – 50’s 

From the third decade onwards with each remodelling cycle we see a net reduction in bone formation, resulting in age-related bone loss, which continues at varying rates for the rest of the life-span. 

Menopause 

Oestrogen plays a major role in bone remodelling, and thus the decrease in oestrogen levels as women reach menopause, triggers a period of marked bone loss. 

Treatment of Osteoporosis

Pharmacological Interventions

Low BMD on a DXA scan does not directly constitute the need to commence anti-osteoporosis pharmacological treatment. A comprehensive assessment is required to determine the long-term fracture risk. This assessment will also take into account a variety of risk factors as well as DXA scores. Pharmacological agents are aimed for individuals who are already osteoporotic and at a high risk of fracture, rather than used as a preventative measure. Pharmacological agents in the treatment of osteoporosis aim to either decrease bone resorption (antiresorptives), therefore resulting in bone mass gains, or directly stimulate increases in bone mass (anabolics) (5).

Below is a brief overview of the major medications used in osteoporosis treatment. 

Bisphosphonates 

Bisphosphonates are compounds with anti-resorptive activity, whereby they act to inhibit osteoclast activation. Several formulations of bisphosphonates are available for management of osteoporosis (.e.g. oral or IV formulations), with various dosing schedules. Common bisphosphonates listed on the PBS in Australia are Alendronate (brand name Fosamax), Risedronate (Actonel) and Zoledondrate (Zometa / Aclasta). Studies have shown that bisphosphonates are effective at increasing bone density and reducing vertebral fracture risk, however only some of them are effective at reducing hip or other non-vertebral fracture risk. Gastrointestinal symptoms are quite a common side effect, and about 30% of patients experience a transient flu-like syndrome after the first IV dose. Atypical femoral stress fractures have been reported, associated with long term bisphosphonate use, with an increased risk of five fractures per 10 000 patient years. Osteonecrosis of the jaw is another rare complication in patients treated long term with oral bisphosphonates, with an approximate risk of one per 10 000 – 250 000 patients (13). 

RANK Ligand Inhibitor

Denosumab is an antibody that inhibits a particular bone receptor, which results in decreased bone resorption and therefore increased bone density. Denosumab is listed on the PBS for postmenopausal women who meet the criteria for primary or secondary prevention. Denosumab (Australian brand names Prolia and Xgeva) is delivered subcutaneously (i.e. via injection). As with bisphosphonate usage, denosumab usage is associated with an increased risk of atypical femoral fractures and osteonecrosis of the jaw. Rare cases of anaphylaxis and more mild allergic reactions have also been recorded. Studies show that denosumab has a withdrawal effect, whereby in the 12 months following cessation of treatment bone resorption markers are increased up to 40-60% above pre-treatment levels (15). Once commenced on denosumab treatment compliance should be encouraged to avoid the bone loss that will occur if treatment is ceased. 

Hormone Replacement Therapy 

Estrogen replacement therapy has been shown to increase bone mass, however studies would suggest that long-term adverse side effects can include; development of breast cancer, risk of cardiovascular events and thromboembolism. The Healthy Bones Australia position statement (2023) states “benefits outweigh risks when MHT is started <60 years of age or within 10 years of menopause and in women with a hysterectomy…” (8). The literature would suggest that HRT remain an option for short-term use only. 

Selective estrogen receptor modulators (SERMs) are a synthetic compound that binds to estrogen receptors to inhibit bone resorption. Raloxifene is one of the SERM compounds, and has been shown to improve bone density at the lumbar spine and femoral neck, and reduce the incidence of vertebral fractures. While SERMs have a lesser influence on improving bone density and reducing risk of fracture than estrogen replacement therapy, they do not carry the same risk of estrogen induced breast cancer. However, they do have a comparable risk of cardiovascular events and thromboembolism as a side effect as the estrogen replacement therapy (11). 

Parathyroid Hormone 

Teriparatide (Forteo or Terrosa) and Abaloparatide (Tymlos) are parathyroid hormone proteins, which act as anabolic agents to stimulate and improve bone formation. Studies show that both compounds are effective at stimulating bone formation, with similar effect sizes between the two compounds. Overall both compounds tend to be well tolerated, with only mild adverse effects such as nausea, dizziness, headache or palpitations. Hypercalcemia can also be associated with both compounds, however to a lesser degree with Abaloparatide (17). 

Medication Efficacy

Despite adherence to medication schedules, there are a percentage of patients who are non-responders to the medications, whereby they do not see a decrease in fracture risk at follow up points. A study published in 2016 title ‘Proportion of Osteoporotic Women Remaining at Risk for Fracture Despite Adherence to Oral Bisphosphonates’ found that 35% of the cohort responded sub-optimally to oral bisphosphonates despite adherence and did not see any improvements in bone density (2). The non-response rate varies between different categories and types of medications. 

For further information on osteoporosis medications speak to your GP or Endocrinologist.

The Physical Performance Show – Professor Peter Ebeling Episode #312

Non-Pharmacological Interventions

The Royal Australian College of General Practitioners (RACGP) suggests that routine treatment of osteoporosis must include addressing modifiable risk factors. As opposed to the pharmacological interventions, the below lifestyle recommendations and interventions can and should be undertaken by all, to slow the age-related decline in bone density and ideally prevent the risk of osteoporosis onset. Treatment should therefore include advice to increase weight-bearing exercise and strength training, maintaining a healthy diet (including adequate vitamin intake), ensuring safe levels of sun exposure, and avoiding smoking and excessive alcohol intake (7). 

Diet

Calcium is one of the minerals that forms a part of the bone mineral matrix, and is thus required for strong and healthy bones, however many Australians do not achieve adequate calcium intake. The Australian dietary calcium recommendations are as below;

(8) 

The best way to achieve adequate calcium intake is through dietary sources, such as dairy products, fish, legumes, and some vegetables and fruits. The below table outlines the calcium content of certain foods; 

While it is ideal to achieve adequate calcium intake from dietary sources, some of these food groups (e.g. dairy products) may be poorly tolerated by some individuals and in these cases calcium supplements may be of use. Healthy Bones Australia recommends 500-600mg of calcium supplementation dose per day when required. For more information on ensuring adequate calcium intake from dietary sources speak to your dietitian, or for information on calcium supplementation, speak to your GP or pharmacist. 

Vitamin D is a major regulator for calcium absorption, making it therefore another important component of Osteoporosis prevention. Vitamin D is produced when skin is exposed to ultraviolet B light from the sun, however it is important to balance the need for sun exposure with avoiding excessive exposure resulting in skin damage. Cancer Council Australia recommends sun protection when outdoors in the sun in the UV Index is higher than 3. Sun exposure times vary depending on season, location and skin type. Healthy Bones Australia has a sunshine map CLICK HERE and you can check the UV Index on the SunSmart app or Australian Bureau of Meteorology website. 

Vitamin D levels vary throughout the course of the year; a Vitamin D level of 50 nmol/L is recommended at the end of winter, with a higher level of 60-70 nmol/L during summer. Around 30% of Australians have some level of Vitamin D deficiency and in these cases Vitamin D supplementation may be used to increase levels. Your doctor may test your Vitamin D levels if you are at risk of a Vitamin D deficiency. 

Those at risk of Vitamin D deficiency include;

• Adults that are mainly indoors (e.g. due to health or work)
• Those who avoid the sun or cover their body, due to skin protection, medical advice, cultural or religious reasons 
• Some medical conditions can impact ability to absorb Vitamin D
• Housebound individuals 
• Naturally dark skinned (darker skin reduces UV light penetration)
• Pregnant or breastfeeding women

(8) 

Around 80-90% of Vitamin D intake is obtained via adequate sunlight exposure and the remaining 10-20% from a limited number of foods, such as oily fish, mushrooms and some fortified dairy products (9).

There are other dietary considerations, such as ensuring adequate protein intake, as well as adequate intake of other Vitamins and minerals (such as Vitamin C and K, potassium and magnesium), that have implications for bone health. 

For further information regarding the dietary considerations of bone health speak to your GP or Dietitian. 

CLICK HERE for POGO Physio Dietitian services:

Exercise

Although exercise has many known benefits, including improving and maintaining bone density, there is an alarmingly low amount of osteoporosis diagnosed Australian’s exercising. Most recent statistics in the RACGP Osteoporosis clinical guidelines (7) report that only 20% of Australians with osteoporosis report exercising most days and only 6% do strength training.

While exercise as a whole exhibits a wide variety of benefits systemically, research has shown that when it comes to bone health, not all exercise is created equal. Bones benefit from an exercise, when a certain amount of strain is placed on them, meaning that there are particular exercises that are most beneficial, depending on the specific way that is applies stress to the bone. The specific types of exercise that are most beneficial include; weight bearing impact loading exercise and resistance training. The other consideration is balance and falls prevention exercises. Current data suggests that 30% of adults over 65 years of age will experience at least one fall per year (8), and this number is predicted to rise as Australia’s population continues to age. 

ONERO ™ 

Onero ™ is a supervised, evidence-based exercise program run by ONERO Accredited health professionals around Australia. The Onero ™ program is a high intensity resistance and impact exercise program especially designed for individuals with low bone mass to strengthen bone and muscle.  

While many forms of exercise may have subtle benefits to bone, the higher intensity exercise performed during the Onero ™ program have been proven to be more effective. Onero ™ is an evidence-based program, developed from the findings of the LIFTMOR Randomised Controlled Trial, published in the Journal of Bone Mineral Research in 2018 (10). The purpose of the LIFTMOR trial was to determine the efficacy of high intensity resistance and impact training (HiRIT) on bone mineral density and physical function is postmenopausal women with low bone mass. Participants were allocated to 2 treatment groups; 1) HiRIT which consisted of 8 months of twice-weekly, 30 minute, supervised HiRIT, or 2) a control group which performed a home-based, lower intensity exercise program. Results showed that compared to the control group, the HiRIT program was superior for bone mass, femoral neck geometry and physical function measures. Notably, there were no adverse events recorded, proving that HiRIT training is safe for postmenopausal women with low bone density (10). 

The Onero ™ program is offered at POGO Physio by Onero ™ Accredited Practitioner Eliana Lonsdale. Prior to commencing the Onero ™ program an initial assessment must be completed to facilitate the adaptation of the program to your current bone and health status.

For more information on the Onero ™ program at POGO Physio CLICK HERE to book your initial assessment with Eliana CLICK HERE. 

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Eliana Lonsdale (APAM)
POGO Physiotherapist

Book an appointment with Eliana today

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 References

1. Osteoporosis Australia: Osteoporosis costing all Australians – A new burden of disease analysis – 2012 to 2022. 2012
2. Imel, E., Eckert, G., Modi, A., Li, Z., Martin, J., Papp, A., . . . Liu, Z. (2015). Proportion of osteoporotic women remaining at risk for fracture despite adherence to oral bisphosphonates. Bone, 83. doi:10.1016/j.bone.2015.11.021
3. Lorentzon, M., & Cummings, S. R. (2015). Osteoporosis: the evolution of a diagnosis. Journal of Internal Medicine, 277(6), 650-661. doi:https://doi.org/10.1111/joim.12369
4. Sleeman, A., & Clements, J. N. (2019). Abaloparatide: A new pharmacological option for osteoporosis. American Journal of Health-System Pharmacy, 76(3), 130-135. doi:10.1093/ajhp/zxy022
5. Bernabei, R., Martone, A. M., Ortolani, E., Landi, F., & Marzetti, E. (2014). Screening, diagnosis and treatment of osteoporosis: a brief review. Clinical cases in mineral and bone metabolism : the official journal of the Italian Society of Osteoporosis, Mineral Metabolism, and Skeletal Diseases, 11(3), 201–207.
6. Michael P Jeremiah et al. Am Fam Physician. (2015). Diagnosis and Management of Osteoporosis. American Academy of Family Physicians. 15;92(4):261-8.
7. The Royal Australian College of General Practitioners and Osteoporosis Australia. Osteoporosis prevention, diagnosis and management in postmenopausal women and men over 50 years of age. 2nd edn. East Melbourne, Vic: RACGP, 2017.
8. Ebeling, PR., et. al., (2023). Position Statement on the Management of Osteoporosis. Healthy Bones Australia. Retrieved from https://healthybonesaustralia.org.au/
9. Muñoz-Garach, A., García-Fontana, B., & Muñoz-Torres, M. (2020). Nutrients and Dietary Patterns Related to Osteoporosis. Nutrients, 12(7). doi:10.3390/nu12071986
10. Watson, S., Weeks, B., Weis, L., Harding, A., Horan, S., & Beck, B. (2017). High‐Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmenopausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial. Journal of Bone and Mineral Research, 33. doi:10.1002/jbmr.3284
11. Bernabei, R., Martone, A. M., Ortolani, E., Landi, F., & Marzetti, E. (2014). Screening, diagnosis and treatment of osteoporosis: a brief review. Clinical cases in mineral and bone metabolism : the official journal of the Italian Society of Osteoporosis, Mineral Metabolism, and Skeletal Diseases, 11(3), 201–207.
12. Lu, J., Shin, Y., Yen, M. S., & Sun, S. S. (2016). Peak Bone Mass and Patterns of Change in Total Bone Mineral Density and Bone Mineral Contents From Childhood Into Young Adulthood. Journal of clinical densitometry : the official journal of the International Society for Clinical Densitometry, 19(2), 180–191. https://doi.org/10.1016/j.jocd.2014.08.001
13. Florencio-Silva, R., Sasso, G. R., Sasso-Cerri, E., Simões, M. J., & Cerri, P. S. (2015). Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells. BioMed research international, 2015, 421746. https://doi.org/10.1155/2015/421746
14. Bell, S.J., Blacker, N., Edwards, S., Frank, O., Alderman, C. P., Karan, L., Husband, A., Rowett, D. (2012). Osteoporosis Pharmacological Prevention and Management in Older People. Australian Family Physician, Vol. 41, no. 3 
15. Zaheer, S., LeBoff, M., & Lewiecki, E. M. (2015). Denosumab for the treatment of osteoporosis. Expert opinion on drug metabolism & toxicology, 11(3), 461–470. https://doi.org/10.1517/17425255.2015.1000860