A common medicine used to combat osteoporosis can cause fractures.
Bisphosphonates are a medication that has been administered since the 1990s, which reduces the overall risk of bone fragility. Bisphosphonates deactivate those cells that break down bone and therefore prevent fractures caused by fragility of the bone.
Although, for some time, there have suggestions that bisphosphonates can be the cause of other forms of fractures such as fatigue fractures, by virtue of the fact that they also inhibit natural degradation of bone. Bone is unable to be degraded and replaced and therefore certain types of bone fissures do not heal naturally.
The connection between the medicine and the fractures was confirmed during a study led by Per Aspenberg, professor of Orthopaedics and researcher at Linköping University. They conducted a national study on 12,777 women 55 years or older who had fractures of the femur. 59 of the subjects were diagnosed as having fatigue fractures (commonly called atypical femoral fractures). Of these 59 patients, 78 % had been administered with bisphosphonates whereas only 5% of the general population had received the same treatment.
The relative risk of an “atypical” fracture is increased 50 times with bisphosphonate treatment, but the absolute increase in risk is only 5/ 10,000-treatment years.
Presently, there is an on-going international debate, deliberating the side effects of bisphosphonates. The results from this study will probably conclude the debate. The connection between the bisphosphonates and the fractures is so strong they we propose that a causal connection can be confirmed.
However, this study also indicates that the risk of fatigue fractures diminishes once a patient ceases to be administered bisphosphonates. Following a one-year cessation from the medication, the risk of a fracture occurring is reduced by 70 %.
“This may indicate that one should use the types of bisphosphonates that are administered seldom, and that the medication should be concluded after some years’ treatment.”
However he emphasises the fact that the benefits from bisphosphonate medication greatly exceed the negatives.
“The principal effects of bisphosphonates remain: They significantly reduce the risk of fractures in patients with osteoporosis. So even if a negative connection has been established, this relates to a very small group and minimal overall risk.
Bisphosphonates prevent many more fractures than they cause. All forms of medication retain side effects and one needs to be aware of that. It is important to only use medication when needed and it should not be prescribed for healthy people.”
“We conducted a similar study in 2008 but on a smaller scale; where we delivered similar results. That study was published in Acta Ortopaedica, which is a lesser-known journal and it did not get attention from the research community.”
The pharmaceutical industry has, so far, denied that bisphosphonates could retain these side effects. Several claims for damages are currently being decided upon in the US. The results of these revised findings could influence those cases.
The research behind these findings will be published in the New England Journal of Medicine.
Text: Anika Agebjörn
Last updated: 2012-12-10