The Challenge

Alendronate has been a long-established treatment for osteoporosis and perceived as very effective by many in the medical field. Therapy reduces fracture risk by about 50%. Doctors, however, had more recently started to notice rare stress fractures in elderly patients who had been taking the drugs for a long time, raising questions around its long-term efficacy. A team led by Dr Richard Abel at Imperial College London was keen to understand how and why therapy might cause stress fractures. Initial studies demonstrated that bone from some bisphosphonate patients was actually weaker than untreated control samples. They were keen to find out why this was happening and study the effects of long term alendronate usage.

The Solution

Samples from the ball of the thigh bone were examined in both patients that had been prescribed alendronate before suffering a hip fracture, and hip fracture patients that had not received any treatment for metabolic bone disease. These were then compared with samples from healthy ageing people who had no history of hip disease or bone metabolic medication. The research instruments at Diamond were used to scan bone tissue and look at the bone volume and structure, including microcracks at a very tiny microscopic level; tomographic images were then reconstructed to calculate microcrack density. After scanning, cores were tested to investigate the effects of alendronate on bone strength.

The Benefits

It seems as though short-term treatment with alendronates (<4-5 years) may improve the structure and density of bone, increasing the strength. However, we have found that in the longer term, the drug caused tiny micro-cracks to form and accumulate in bone. The cracks can grow and merge, causing bones to become weak and even break. The effect probably varies from person to person; hence the study shows we urgently need more research to determine how long to prescribe alendronate to individual patients.

"Bisphosphonates are widely used to treat people affected by osteoporosis, so it is of paramount importance that we know as much about them as possible. Research in this area is crucial and more is needed to help us." 

Fizz Thomson, Clinical Director, National Osteoporosis Society