Dr. Clark observed that the ASBMR task force conclusion was that a causal relationship between bisphosphonates and atypical femoral fractures has not been established, but data continue to accumulate.
What should clinicians do if AFF is suspected?
"A significant number of atypical fractures are asymptomatic prior to completion," Dr. Stone warned. He noted that he had a relatively low threshold for scanning someone if he suspected AFF, but advised using "a reasonable amount of common sense" in that one might consider it in someone who is experiencing any new groin, thigh, or hip pain, or if there is worsening pain. In such cases, he might initially perform radiography, and then, if the level of clinical suspicion remains high, proceed to magnetic resonance imaging (MRI) or an isotope bone scan.
In terms of managing a patient with osteoporosis who develops AFF while taking bisphosphonates and is at high risk for other fractures, it is very difficult to know what to do. Stopping bisphosphonates might need to be considered because these drugs can impair healing of the fracture. Use of an alternative, such as strontium or teriparatide might be considered if the risk of fracture remains high.
In fact, according to MHRA guidance, stopping bisphosphonate therapy should be considered in patients suspected of AFF while they are evaluated, and should be based on an assessment of the benefits and risks of continuing treatment. The regulatory body also suggests that the need to continue therapy should be periodically evaluated, particularly after 5 or more years of use.
Drug manufacturer information provides guidance on the use of bisphosphonates and should be consulted regarding stopping treatment, Dr. Clark advised.
In an interview, Dr. Stone noted that patients on glucocorticoids should probably stop bisphosphonate treatment much sooner than the recommended 5 years, perhaps after 2-3 years of use. Conceding that that was controversial, because that’s not what the MHRA guidelines say, he noted that "for patients on glucocorticoids, where in the longer term you are going to be suppressing bone turnover and where the evidence of bisphosphonates reducing the risk of nonvertebral fracture is pretty much nonexistent, the concern should be higher in my opinion, and one needs to be cautious committing everybody without careful consideration to bisphosphonates beyond 2 or 3 years."
Dr. Clark observed in an interview: "I would also say I think we use bisphosphonates slightly differently now. We don’t consider them a treatment for people at low risk; we don’t give them to osteopenic, perimenopausal women who have not had a fracture; and we do not say it is a treatment for life anymore. We say it is a treatment for a fixed period of time at which point we should reassess."
Dr. Clark added: "I think it is something that we should all be aware of and we shouldn’t just use these medications without considering the risks." With regard to informing patients, she noted that she tells them that these sorts of fractures are rare, and the fracture-reducing benefits of bisphosphonates in high-risk patients with osteoporosis far outweigh their potential to cause these unusual fractures.
Atypical femoral fracture register planned
"We shouldn’t throw the baby out with the bath water," commented Dr. Eugene McCloskey, professor of adult bone disease at the University of Sheffield and a consultant at the Northern General Hospital in Sheffield, England.
"Osteoporotic fractures will remain a big problem, but we can’t ignore the fact that we are seeing patients with these atypical fractures, and I think they are really a heterogeneous group of patients that we need to categorize better," Dr. McCloskey added, noting that there were plans to set up a national AFF register in the United Kingdom.
Dr. Stone, Dr. Clark, and Dr. McCloskey have received research support, honoraria, or acted as consultants for several pharmaceutical companies involved in bone research, including Eli Lilly and Co., who provided an unrestricted educational grant to fund the Osteoporosis Special Interest Group Session.