Dr Ashok Bhalla, consultant rheumatologist at the Royal National Hospital for Rheumatic Diseases provides an introduction to osteoporosis. He talks about why osteoporosis occurs; who is most at risk of developing the condition; types of osteoporotic fractures; the role of calcium and vitamin D in protecting our bones and the different treatments available to date.
What is osteoporosis?
Dr Bhalla explains what osteoporosis is
Osteoporosis literally means porous bone. The medical community defines osteoporosis as a skeletal disorder in which bone strength is reduced as a result of loss of bone mass and through the deterioration of the bone architecture. The consequence of these changes is an increased fracture risk. Fractures that occur as a result of low-trauma are known as fragility fractures.
Osteoporosis is a common condition and becomes more common with increasing age. One in two women over the age of 50 is likely to experience an osteoporotic fracture in their lifetime. For men this is less common and it is estimated that one in five males over the age of 50 will experience an osteoporotic fracture (National Society for Osteoporosis. June 2017).
What is bone made of?
What is bone made of and why are women more at risk of osteoporosis?
As mentioned in the video clip above, bone consists of a tough outer shell known as the cortex and an inner honeycomb structure known as trabecular bone. Bone is not a dead tissue. It is constantly undergoing change throughout life. In this process some bits of bone are removed by bone removing cells known as osteoclasts. At the same site, or at an adjacent site, new bone is formed by bone forming cells known as osteoblasts.
The process of bone removal and bone formation is known as bone turnover. The function of bone turnover is to remove bone that’s worn out and is no longer capable of providing structural support. This process helps to maintain the structural integrity and strength of bone.
When we are very young our bone density increases with age. This is because our bodies are forming more bone than is being removed. The greatest increases in bone density occur during the teenage years. In most people bone density continues to increase with age until we are in our mid-to-late 20’s. There then follows a period of time when we are forming and removing bone at an equal rate. During this time our bone density remains relatively stable. During our 30’s and beyond the amount of bone removed begins to exceed the amount of new bone formed, leading to a small net bone loss. This slight mismatch accounts for the normal age-related bone loss.
In women, at the time of the menopause, oestrogen levels fall. This oestrogen deficiency leads to an increase in bone turnover and the amount of bone removed is greater than that which is formed resulting in reduced bone strength and higher susceptibility to fractures than men.
Types of osteoporotic fracture
Dr Bhalla talks about different types of osteoporotic fracture.
The main clinical problem with osteoporosis is the occurrence of fractures. Low bone density by itself causes no symptoms.
Osteoporotic fractures occur most commonly at the wrist, the upper arm bone (known as the humerus), the hips, and the vertebral bodies that make up the spine. Fractures of the upper arm, wrist, and hips, usually occur after a fall. Spinal fractures however, can occur spontaneously without trauma.
A hip fracture is probably the most serious of all osteoporotic fractures. It requires hospitalisation and surgery to correct the fracture.
Fractures of the spine can cause considerable pain or sometimes cause no pain, but alter the shape of the spine. The acute pain of a spinal fracture often settles over a two-month period. Multiple spinal fractures lead to loss of height and a forward stoop known as a kyphosis or Dowager’s hump. The altered shape of the spine may lead to a person developing chronic spinal pain.
How is osteoporosis diagnosed?
Diagnosing and predicting an individuals risk of fractures.
At the present time bone density measurement is the best estimate we have of bone strength. Bone density can easily be measured at the hip and spine using a DXA machine. This is a painless procedure and takes no more than twenty minutes to perform.
Bone density does not fully explain an individual’s risk of sustaining a fracture. Many other factors are important which include life style factors, such as smoking and excess alcohol intake, taking certain medications such as corticosteroids, older age, a previous fracture, female sex, a parent with a hip fracture, inflammatory joint disease such as rheumatoid arthritis, premature menopause, low body weight, type 1 diabetes mellitus, overactive thyroid gland, liver disease, and bowel disorders that impair absorption of nutrients.
Taking these risk factors into account, with or without a bone density reading, allows us to predict an individual’s ten year probability of sustaining a fracture. Using such probabilities we can then decide on whether or not an individual needs treatment to reduce their risk of fractures in the future. This analysis is now done using a programme developed by WHO (World Health Organisation) called FRAX. This model requires an individual’s age, weight, height, and answers to 8 additional questions to allow the doctor to calculate the 10 year probability of fracture.
How is osteoporosis treated?
Dr Bhalla explains the different treatments available to someone with osteoporosis and those who…
The pain arising from a fractured bone can be reduced by immobilising the bone in a plaster cast such as might occur after a wrist fracture. In some instances surgery may be required to align the bones in their correct position. Fractures of a major bone, such as a hip, often require surgery. Fractures of the spine, causing back pain can sometimes be helped by surgical procedures.
Other treatments that can help to reduce pain arising from fractures include various painkillers, non-drug based treatments, such as hydrotherapy (which is pool based exercise) , which can help to reduce muscle spasm and pain, as well as improve an individual’s mobility. An alternative treatment is to use TENS (Transcutaneous electrical nerve stimulation).
It is important to mobilise individuals as quickly as possible since bed rest increases bone loss and therefore increases the risk of future fractures. Apart from reducing pain there are a number of medications available to treat the condition of osteoporosis. These medications fall into two groups. The first group work to reduce bone loss and are known as antiresorptive drugs (including bisphosphonates, Denosumab, hormone replacement therapy and Raloxifene). The second group, fewer in number, help to stimulate new bone formation and are known as anabolic drugs (parathyroid hormone treatment such as teriparatide). The most commonly used medications are the antiresorptives.
In order for osteoporosis medications to work effectively patients should also be given supplements of calcium and Vitamin D. The absorption of calcium from the gut into the body is aided by Vitamin D and therefore it is important that there is enough Vitamin D in people’s blood to help with this process.