Atypical Femoral Fractures: Predicting Post-surgical Healing Problems

Orthopaedic journals and OrthoBuzz have devoted ample space to the apparent association between long-term bisphosphonate use and atypical femoral fractures. The latest insight into this relationship comes from Lim et al. in the December 7, 2016 edition of The Journal of Bone & Joint Surgery. The authors analyzed factors associated with delayed union or nonunion after surgical treatment of 109 atypical femoral fractures in patients who had an average 7.4-year history of bisphosphonate use.

Here’s what Lim et al. found among the 30% of patients studied who had delayed union or nonunion, relative to the 70% who had successful healing:

• Patient Factors: Patients who had problematic fracture healing had a higher BMI, longer duration of bisphosphonate exposure, and higher rate of prodromal symptoms.
• Radiographic/Fracture Factors: Supra-isthmic/subtrochanteric fracture location, femoral bowing of ≥10° in the coronal plane, and a lateral/medial cortical thickness ratio of ≥1.4 were predictive of problematic healing.
• Operative Factors: Iatrogenic cortical breakage around the fracture site and a ratio of ≥0.2 between the remaining gap and the cortical thickness on the anterior and lateral sides of the fracture site were associated with problematic fracture healing.

In an accompanying commentary on the study, Edward J. Harvey, MD notes that most trauma surgeons use cephalomedullary nails to treat atypical femoral fractures, but that “it is impossible from this manuscript to determine what effect the fixation technique had on the outcomes.” He therefore recommends a larger multicenter study using standardized therapy and bone biopsies to further improve understanding in this area.