A drug that boosts the body's production of stem cells can also "jump-start" the bone-healing process for older patients who have suffered a fracture, research suggests.

A study found that teriparatide, a hormone normally used to treat osteoporosis, increases the ability of older bones to heal themselves and could even "turn back the clock", making older bones heal as quickly as those of a younger person.

The American researchers described the effects of a daily injection as "miraculous" as, in some cases, patients who had been confined to wheelchairs were able to walk or leave full-time care when their broken bones finally healed.

Researchers at the University of Rochester Medical Center, New York, gave teriparatide, also known as Forteo, to 145 people who had bone fractures that had not healed, many for six months or more.

They found that 93 per cent of them showed significant healing and pain control after eight to 12 weeks of daily injections. In some cases the skeletons of the elderly healed at the same rate as "young children", halving recuperation.

Edward Puza, who led the research, explained that a daily injection of teriparatide appeared to boost the amount of stem cells - the body's master cells, which can develop into various types of tissue - in the bones.

"In many people, as they get older, their skeleton loses the ability to heal fractures and repair itself," he said. "With careful application of teriparatide, we believe we've found a way to turn back the clock on fracture healing through a simple, in-body stem cell therapy."

The preliminary results of the trial were presented to a conference of the US Orthopaedic Research Society in February. But the researchers announced today that they were beginning full-time research, funded by the US National Institutes of Health, to see if the findings can be confirmed for men and women over 50 who have suffered a fractured pelvis.

Teriparatide was approved for the treatment of osteoporosis in 2002, but at present is most commonly prescribed if other drugs have not worked to women over 70 who have multiple fragility fractures and a high risk of further breakages. About half of women and one in five men in Britain will suffer a fracture after the age of 50.

Susan Bukata, a co-researcher and medical director of Rochester's Center for Bone Health, said that if clinical trials prove that the drug speeds bone healing, then this patient group could derive "significant" medical benefit in recovery times and quality of life.

"Typically, a pelvic fracture will take months to heal, and people are in extreme pain for the first eight to 12 weeks," she said. "This time was more than cut in half. We saw complete pain relief, callus formation and stability of the fracture in people who had fractures that up to that point had not healed."

Speeding the healing time for pelvic fractures could also reduce the risk of further illness, death and medical costs, she added.

It is estimated that hip fractures cause more than 1,500 premature deaths every month and that pelvic fractures carry a similar risks. About "one quarter of all older women with pelvic fractures will die from complications," Dr Bukata added.

Claire Bowring, Medical Policy Officer for the UK National Osteoporosis Society, welcomed the results of the trial, noting that fractures had a serious impact on quality of life for older patients. "During the first 12 months after a hip fracture, over 50 per cent of people who were previously able to walk will require assistance and a third will have trouble sleeping due to pain," she said. "A larger clinical trial will determine if this new application of an osteoporosis drug could have benefits for fracture patients that have not yet been realised."