By Emma Wilkinson
Health reporter, BBC News
Osteoporosis is a common condition which causes bones to break easily
Women who have had a fracture are not getting treatment to prevent them having future bone breaks, a Cambridge University study suggests.
An audit covering 1,600 women presenting to a specialist clinic with a fracture showed that 31% had suffered a previous break.
Yet only 28% had been put on recommended bone-protective drugs.
A GPs' leader said more could be done to find women at risk, but side-effects stopped some patients taking the drugs.
Normal ageing can lead to osteoporosis, a condition in which bones become fragile and break easily. The fractures are most common in bones of the spine, wrists and hips.
Women are more at risk after the menopause because they lose oestrogen which protects bones from damage.
Current guidelines from the National Institute of Health and Clinical Excellence say that women over the age of 75 who have had a fracture should automatically be offered preventive treatment with drugs such as bisphosphonates.
Because of the high risk of future fracture after a break, postmenopausal women under the age of 75 are supposed to have a bone density scan before being offered treatment if necessary.
Some experts argue that the guidelines do not go far enough, and more women with signs of bone-weakening should be offered protective therapy.
In the latest analysis, 526 of 1641 postmenopausal women attending a fracture clinic had previously had a bone break, the QJM journal reported.
Overall, 27% of those were taking a bisphosphonate or other treatment such as calcium or vitamin D supplements.
Among the over-75s, only 45% were receiving bone protective therapy.
The study leader, Professor Julia Compston, said some areas of England may be better than others but the low levels of treatment found in the study were "broadly applicable" to the rest of the country.
She said reasons for lack of treatment included poor recording of fractures in patient notes; absence of incentives for GPs to treat osteoporosis, unlike many other chronic conditions; and the fact that patients "get lost" between hospitals and GPs because of poor communication.
"Someone needs to take responsibility for deciding whether a patient should be treated and there are a lot of processes that can fall down.
"Patients also need to be better informed that they might need treatment."
In some areas of the country access to scans to measure bone density is problematic, she added.
Professor Steve Field, chairman of the Royal College of GPs, said the study highlighted the fact that more could be done to make sure treatment was available.
"But these drugs can have very unpleasant side-effects - so some patients are offered them but stop taking them," he said.
"Exercise and diet are also important."