Atypical Femoral Fractures (AFF)

This talk was presented by Dr. Heather McDonald-Blumer at the ORA 2015 meeting. We felt that this information was important to disseminate and we have included it in the EULAR report.

The treatment of osteoporosis should be confined to those at high risk defined by prior fragility fractures or by risk stratification based largely on age and bone mineral density. Treatments generally reduce vertebral fractures by 50% and reduce non-vertebral fractures by 20-40%. There has been a real world decrease in the incidence of hip fractures of 31% between 1997 to 2006!

Should osteoprotective medications even be discontinued? Generally we stop treatment because our practice patterns have changed or the patient has co-morbidities (e.g. renal dysfunction with bisphosphonates). We also stop because of side effects including GI issues, MSK pain, osteonecrosis of the jaw, and atypical femoral fractures (AFF).

Femoral neck and inter-trochanteric fractures are typical femoral fractures seen in osteoporosis. An AFF is found distal to the lesser trochanter and proximal the supracondylar flare. Patients with AFF present with thigh pain and the typical patient profile includes those who start bisphosphonates at earlier ages and those of Asian ethnicity. These patients are often using concomitant medications including corticosteroids and proton pump inhibitors.

The risk of AFFs does increase with anti-resorptive use in osteoporosis, but AFFs can also occur in the absence of anti-resorptive treatment. There have been no case reports of these fractures in association with estrogen therapy or SERMs. The absolute risk of an AFF is somewhere between 0.13 and 0.22%.

The incidence of typical hip fractures is about 5300 per 100,000 including low, intermediate, and high-risk individuals. The incidence of AFF is about 80 per 100,000 for those on long-term (>8 years) bisphosphonates.

AFFs are detected by typical symptoms of thigh pain along with plain x-rays, bone scans, CT, and MRI.

Once a patient has an AFF what should we do? Stopping anti-resorptive therapy is considered to be important . The risk of AFF is reduced by 70% for each year following discontinuation of anti-resorptive therapy. Patients should continue taking calcium and vitamin D. An incomplete fracture can be treated by an intramedullary nail but a completed fracture needs to be further stabilized surgically. There is some data to suggest that teriparatide may be helpful.

More reports from EULAR 2015