Section 2: Introduction to osteoporosis and fragility fractures

The conceptual definition of osteoporosis was made by the World Health Organization (WHO) in 1994 as a “progressive systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture” ⁶. Since microarchitectural deterioration could not be measured clinically, the operational description was based on a bone mineral density (BMD) T-Score of ≤-2.5. Over the years this was adopted as a clinical definition; however, the limitations of focusing on a BMD-based definition alone have since become clear. BMD is now viewed as one, albeit very important, risk factor to be considered when assessing fracture risk which is now viewed as the principal necessity.

The clinical significance of osteoporosis lies in the fractures that arise. Approximately one in two adult women and one in five men will sustain one or more fragility fractures (a low trauma fracture sustained from a fall from standing height or less) in their lifetime ⁷. In the UK, the prevalence of femoral neck BMD T-Score ≤-2.5, in those aged 50 years and older, is 6.8% in men and 21.8% in women ⁸. However, the majority of people who sustain a fragility fracture will have a femoral neck BMD T-Score above -2.5, reflecting the contribution of many other factors, besides BMD, to fracture risk ^9-11. Fall-related risk factors add significantly to fracture risk and often overlap with risk factors for osteoporosis, hence the need for integrated fall and fracture services.

Currently in the UK, approximately 549,000 new fragility fractures occur each year, including 105,000 hip fractures, 86,000 vertebral fractures, and 358,000 other fractures (i.e., fractures of the pelvis, ribs, humerus, forearm, tibia, fibula, clavicle, scapula, sternum, and other femoral fractures); 33% are sustained by men ^{8,
12,
13}. Such fractures cause severe pain, disability, and reduction in quality of life ^14,15. In the UK, fragility fractures are estimated to account for 579,722 DALYs (Disability Adjusted Life Years) lost, largely driven by years lived with disability. This equates to 24 DALYs per 1000 people aged over 50 years, which is comparable to the DALYs lost from dementia ⁸.

Costs of fragility fractures to the National Health Service (NHS) exceed £4.7 billion per annum, of which £2.6 billion is directly incurred after an incident fracture (£1.1 billion for hip fractures alone ¹⁶), with more than £1.7 billion attributable to institutional care costs post-fracture (estimated for 2017) ⁸. Total direct costs for 2019 were £5.4 billion accounting for 2.4% of healthcare spending ¹⁷.

Common sites of fragility fracture include the vertebral bodies, hip, distal radius, proximal humerus and pelvis. Hip fracture is the most common reason for emergency anaesthesia and surgery in older people. It is also the most common cause of death following a fall. After hip fracture the mean hospital length of stay is 20 days, accounting for half a million hospital bed days used each year, with 3,600 hospital beds (3,159 in England, 325 in Wales and 133 in Northern Ireland) occupied at any one time by patients recovering from hip fracture ^18,19. Loss of independence is common following a hip fracture with only 52% living in their own home after 120 days ¹² and 26% will die within 12 months of their fracture ²⁰. Most major osteoporotic fractures are associated with reduced relative survival, part causally related and part due to associated co-morbidity^21-23.

In the UK, fracture rates vary by geographic location, race and levels of socioeconomic deprivation ^24-26. As in many higher income countries, age- and sex-adjusted fracture rates appear relatively stable, although increases in hip fractures amongst men in the UK have been reported ^{24,
27}. Changes in vertebral fracture rates potentially reflect secular alterations to reporting of cases. Importantly, ageing of the UK population is predicted to give rise to a 19.6% increase in the number of fragility fractures by 2030 if changes are not made to current practice ⁸.