Overuse of osteoporosis drugs could make limbs weaker

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 diminished.

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.