Clinical Reports: Paradoxical Bone Therapy?

The FDA is warning that drugs for osteoporosis may lead to atypical fractures of the femur such as subtrochanteric femoral fractures or femoral diaphyseal fractures in patients who have been on bisphosphonates for long periods of time. 

Atypical subtrochanteric femur fractures are fractures in the bone just below the hip joint. Diaphyseal femur fractures occur in the long part of the thigh bone. These fractures are very uncommon and appear to account for less than 1% of all hip and femur fractures overall.

These are very rare fractures, and have only recently been associated with bisphosphonate usage, as noted in AAFP news:

That review included data from a report recently published in the Journal of Bone and Mineral Research that reviewed more than 300 cases of atypical femoral fractures. More than 90 percent of those patients had taken bisphosphonates for five years or more, and 25 percent of the patients had fractures in both legs.

Most patients who suffered these atypical fractures had groin or thigh pain for several weeks or months before the fracture occurred.  Therefore, if any patients on resorptive therapy present with groin or thigh pain, they should be evaluated for these atypical fractures.

The FDA cautions physicians to reassess the bone density of patients on bisphosphonates to determine if therapy can be terminated, especially if the patients have been taking the medication for more than five years. This warning includes all bisphosphonates used to treat osteoporosis.