Overuse of osteoporosis drugs `could make limbs weaker`: Study
Last Updated: Thursday, March 11, 2010, 00:00

London: Drugs used to treat osteoporosis --
the brittle bone disease -- could make limbs easier to break
if used for too long, new studies have found.

According to two studies -- presented at the annual
meeting of the American Academy of Orthopaedic Surgeons` in
New Orleans -- overuse of the drugs upset the mineral and
crystalline structure of bone, causing weaknesses that can
lead to fractures.

A team of investigators from Columbia University Medical
Center (CUMC) studied bone structure of 111 post-menopausal
women with osteoporosis -- 61 of whom had been taking the
drugs for at least four years while remaining 50 were treated
with calcium and vitamin D supplements.

The team found that bisphosphonates improved bone
structure early on in treatment, but over time this benefit

Dr Melvin Rosenwasser, an orthopaedic surgeon at the
CUMC, said: "In the early treatment period, patients using
bisphosphonates experienced improvements in all parameters,
including decreased buckling ratio and increased
cross-sectional area.

"However, after four years of use, these trends reversed,
revealing an association between prolonged therapy and
declining cortical bone structural integrity," Rosenwasser

The second study conducted at the Hospital for Special
Surgery (HSS) evaluated the bone composition of 21
post-menopausal women treated for thigh fractures.

Of these 21 women, 12 had a history of bisphosphonate
treatment for an average of 8.5 years while nine had not been
given bisphosphonates.

Researchers collected samples of bone from each patient`s
thigh bone and analysed it. They observed less structural
uniformity in the bone tissue from bisphosphonate-treated

This could result in weakness and contribute to
out-of-the-ordinary fractures, the researchers said.

"Patients who had been treated with bisphosphonates
showed a reduction in tissue heterogeneity, specifically with
mineral content and crystal size compared with the control
group," said researcher Brian Gladnick, from HSS.

"This tells us that there may be some measurable
differences in bone quality parameters in patients on
long-term bisphosphonate therapy, which might contribute to
the development of atypical fractures," Gladnick said.

The scientists believe bisphosphonates suppress the
body`s natural ability to remodel bone, but say more research
is needed to assess the long-term effectiveness of the drugs.


First Published: Thursday, March 11, 2010, 00:00

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