Atypical femoral fractures: a complication of prolonged bisphosphonate therapy?

To the Editor: Girgis and Seibel1 are to be congratulated as endocrinologists for raising the important issue of bisphosphonate therapy and femoral fractures. This is a relatively new phenomenon that even a couple of years ago, although already documented, did not seem to be on many endocrinologists’ radar.

However, I question the authors’ statement that such fractures are rare. In my small outpost of the orthopaedic world (Northeast Health Wangaratta), three cases have been seen in 12 months. All patients characteristically had a spontaneous non-traumatic fracture, a short oblique or transverse fracture in the subtrochanteric area, and had been on alendronate for more than 5 years. If a journeyman orthopaedic surgeon is seeing a cluster of cases, I suggest that these fractures are not rare.

On the other hand, a review of our audit figures in Wangaratta in north-eastern Victoria (where we have a stable rural population of about 17 000) provides an interesting statistic. Over 15 years (1993–2008), Northeast Health Wangaratta admissions for fractured neck of femur fell steadily from 74 to 35 a year. This trend continues. We should not throw out the baby with the bathwater — osteoporosis treatment is likely partly responsible. Also, a deeper level of community aged care support and much better comorbidity management may have helped to reduce falls.

The real question is whether all patients who have been on alendronate (or any bisphosphonate) for 5 years need to have a mandatory holiday from the drug. In line with Wolff’s law (bone will adapt to loads under which it is placed), the precursor femoral stress lesions will heal by remodelling, as long as bisphosphonate therapy is suspended. I suggest that the suspension should be for 2 years, which is the time required for full fracture remodelling. I agree with Girgis and Seibel that these drugs have been effective in reducing fracture incidence; however, their long-term use needs further study.