By Jane Elliott
BBC News, Health reporter
When Maureen Dickinson was asked to help with a study into osteoarthritis and osteoporosis she was keen to help.
Maureen has never broken a bone
She was pleased to think that the information researchers collected could help others with the condition.
But within weeks of starting the study, Maureen found she was also going to benefit.
A full body scan - offered as a routine part of the study - revealed that Maureen, from Chingford, had already got severe osteoporosis at the age of 48.
"I had no idea. There are no symptoms, and the first I would have known was when I broke a bone.
"They said it was so severe that I could have ended up in a wheelchair."
But because Maureen was part of the research, she immediately got expert advice, X-rays and regular bone scans.
She was put on HRT for a decade and now takes the bone strengthening drug, Fosamax (alendronate).
Maureen, now 63, said: "They say my bones are now back to normal, but that I must remain on Fosamax for life," she said.
"I wanted to do what I could do to help, but they have ended up helping me more than I have helped them."
Maureen was one of 1,000 women originally recruited to take part in the "Chingford study" which launched 15 years ago to look at risk factors for osteoarthritis and osteoporosis.
Osteoporosis - literally "porous bones" - causes a loss of mineral density in the bones, which makes them more likely to break.
Osteoarthritis is the most common form of arthritis, affecting over 5% of adults which causes the progressive loss of protective cartilage in the joints.
Although Maureen had no signs of either osteoarthritis or osteoporosis when she was recruited, she knew her early menopause, following a hysterectomy at 40, put her at greater risk.
Women aged between 45 and 64 were approached through their GPs to take part in the long-term population study because there is known to be an increase in the prevalence of osteoarthritis and osteoporosis during the menopause.
Fifteen years later, 750 of the original women are still actively involved and having the annual checks - others dropped out or died.
Another of those still taking part is Brenda Dowsett, aged 78, from Theydon Bois, Essex.
When she signed up for she had arthritis in her wrists, but she has since developed it in her knees and she has needed to have both knee-joints replaced.
She said it is the support and advice of the researchers that has kept her fit and active.
Brenda feels the study has kept her active
"I have always felt that if I had aches and pains in my joints and didn't want to bother my doctor, I could talk to the doctors on the study.
"I feel I owe it to them to keep going now, because of the way they have helped me."
Brenda, a social worker who worked with the elderly, said: "I know how easy it is to become immobile, but I think the advice from the Chingford study about what exercise I could and could not do has kept me active - I was playing table tennis until recently."
Dr Deborah Hart, who still works on the project, said it is a fantastic resource.
"We have used it for research and share our data with other clinicians helping them with their work.
"I think one of the secrets of its success has been the continuity of people.
A spokeswoman for the Arthritis Research Campaign, which recently awarded a further £400,000 to keep the study going for the next five years, said: "The Chingford Study is all about ordinary women contributing to important research, which has led to major advances in our knowledge of osteoarthritis and osteoporosis."
The Medicines and Healthcare products Regulatory Agency (MHRA) said taking part in studies and trials is an excellent way to help advance science.
A spokesman said: "Public participation like this is necessary for innovative treatments and medicines to treat disease."