Touching Lives - March 2006
Quality, not quantity
Osteoporosis causes weak bones that are prone to fracture. Figures show that in the UK 230,000 fractures every year are a direct result of the condition — usually affecting the wrist, spine and hip. Although sometimes thought of as a ‘woman’s condition’, new evidence shows that 1 in 5 men over the age of 50 is affected.
Now a team of researchers funded by Action Medical Research is making real progress towards a better understanding of the condition and what makes some people more prone to fractures than others.
The team, led by Dr Jean Aaron based at the School of Biomedical Sciences, University of Leeds, has shown that quality, as well as quantity, is what matters when it comes to bone fragility.
A three year study funded with a £49,600 grant from Action Medical Research has just come to an end, and the results are exciting.The team has managed to pinpoint areas of weakness within the honeycomb structure of bone and has concluded that these do not occur randomly. Some people can develop these ‘hot spot’ points of weakness, creating vulnerable places even if their overall bone density is good.
Dr Aaron says, ^”It was puzzling why some people with apparently good bone density had a fracture, while someone with a tiny, bird-like skeleton may not.^ Of course other factors, like simply being more prone to falling, play a part; but it was a mystery why some people seemed more likely to break a bone than others with the same bone mass. Most previous research had concentrated on the quantity of bone a patient had, rather than what was actually happening inside the bone itself.
“Our research, in which we looked at the microscopic structure of the bone, showed up areas of micro-damage in the sites prone to fracture. These are tiny disconnections in the bone which seem to weaken it considerably. Think of the bone’s structure as a crane, designed for bearing loads — if in one or two small places you removed every other strut you would compromise its strength dramatically, even though only a little bit of steel had gone.”
Osteoporosis is reaching epidemic proportions and costs the NHS an estimated £1.7billion a year. Each year in the UK there are at least 40,000 cases of spinal fracture caused by osteoporosis and in severe cases the spine can eventually collapse, leading to height loss and deformity. Some fractures can be slight and go undiagnosed, leaving the patient prone to more serious problems without even knowing it. Other breaks can be devastating causing extreme pain, leading to prolonged hospital stays and permanent mobility problems.
The team studied pieces of bone under the microscope with their new method for identifying disconnections, and also used a state of the art micro CT scanner to give extremely detailed images of the bone’s internal structure. Advances in scanning technology may eventually mean that a patient could be scanned for bone health in far greater detail than is currently possible.
Dr Aaron said: “That would be the Holy Grail for us. At the moment we rely heavily on looking at slices of donated bone in the laboratory, and our methods are destructive to the bone sample and invasive for the patient — a small bone specimen has to be removed from the skeleton and that is not pleasant. A non-destructive, and better still, non-invasive technique would be a radical advance and would ultimately help diagnosis.”
The research just completed follows on from earlier Action Medical Research funding, and a third grant has now been awarded which will enable the team — Dr Aaron, Dr Roger Shore and Dr Lesley Hordon, together with bone histologist Pat Shore, to take their findings even further.
They are about to embark on a study to find out why these ‘hot spots’ occur. They suspect that the gaps may be caused by changes in the strength of special fibres hidden beneath the bone surface that help fasten the bones to each other and fix them to our muscles. These little threads, called Sharpey’s fibres, have been known about for a century, but have not been connected with osteoporosis before and may provide new insight into why some patients are more prone to fractures.
Dr Aaron said: “The fact is that osteoporosis is on the increase in developed countries, where people live longer but do less exercise. ^It’s vital to build up bone structure while you are young, then help keep bones strong by doing load bearing exercise and eating a well balanced diet as you get older.^
“Living longer is no fun if you are crippled by a condition like osteoporosis, and hip fractures in particular can have a devastating effect on people’squality of life. Although ultimately bone strength is down to genes, lifestyle also plays a part. If we are not careful, we will soon have a whole generation that is prone to osteoporosis because it is less physically active.
“It is essential that we continue to make progress in understanding the condition so that we can help early detection. Osteoporosis is the major cause of disability in the elderly and places considerable demands on the NHS. If we can find out why fractures happen, and identify more precisely who is vulnerable, we can pave the way for earlier recognition of those at risk, and develop better methods of prevention and treatment.”
**We thank The HSA Charitable Trust who have generously supported this important area of work, funding both the current and recently completed research projects.
- Adults have 206 bones in their body, but children have a lot more. This is because bones fuse together as we grow.
- The smallest bone in the human body is the stirrup-shaped ‘stapes’ which is found in the middle ear and transmits vibrations from the eardrum.
- Our bones are alive and constantly renewing and changing — a process called ‘turnover’.
- Although the strength of your skeleton is determined by your genes, lifestyle factors can have a major influence on how well your bones develop.
- Eating a well-balanced diet, rich in calcium, doing regular weight-bearing exercise, being a non-smoker and moderating alcohol intake all contribute to strong, healthy bones.