Susie Yi Huang PhD, MD, Presenter: Nothing to Disclose

Christopher D. Grimsrud MD, PhD, Abstract Co-Author: Nothing to Disclose

Malini Chandra, Abstract Co-Author: Nothing to Disclose

Bruce Ettinger MD, Abstract Co-Author: Nothing to Disclose

Joan C. Lo MD, Abstract Co-Author: Spouse, Research funded, Johnson & Johnson Spouse, Research funded, GlaxoSmithKline plc

Secular trends indicate a decline in overall hip fracture rates. However, there are recent concerns about atypical femur fracture (AFF) in patients receiving bisphosphonate drugs. This retrospective study classifies hip and femur fractures in a contemporary cohort of older women and examines clinical characteristics in those with femoral diaphyseal fracture.

We identified women 60 years and older with nontraumatic femur fracture during 2007-2008. Anatomic site was determined from operative and radiology reports with review of radiographs to classify both subtrochanteric (ST) and femoral shaft (FS) fractures and to distinguish AFF from non-AFF (NFF). AFF was defined by transverse or short oblique fracture pattern, non-comminution and localized hypertrophy of the lateral cortex. The contralateral femur was also examined. Clinical characteristics between subgroups were compared using Chi-squared or Fisher exact tests.

Among 2865 hip and femur fractures (age 82.9±8 yrs, 84.7% White), 1484 (51.8%) were femoral neck (FN), 1302 (45.4%) pertrochanteric (PT), 38 (1.3%) ST and 41 (1.4%) FS fractures. Over 95% of ICD-9 coded FN and PT fractures but only 26% of ICD-9 coded ST fractures were accurate for hip fracture site assignment. The incidence of FN and PT fractures increased exponentially with age while ST fractures increased at a lesser rate. Among 79 women with femoral diaphyseal fracture (ST+FS), 48% had AFF. Women with AFF were younger (74.0 vs 81.0 yrs), more likely to be Asian (50 vs 2.4%) and more likely to have received bisphosphonate drugs (97.4 vs 41.5%). Among AFF, the contralateral femur was more likely to have a prior or subsequent stress or complete fracture (34.2 vs 2.4%, AFF vs NFF). An additional 21.2% of AFF had localized hypertrophy of the lateral cortex in the other femur.

Systematic review of radiographs is necessary for classifying femoral diaphyseal fractures and identifying AFF. Women suffering AFF are markedly different from NFF. They are younger, disproportionately Asian, have greater bisphosphonate exposure and many demonstrate findings in the contralateral femur suggesting a generalized process.

Focal cortical hypertrophy and transverse fracture pattern suggest AFF and should prompt examination of the other femur. The role of Asian race and bisphosphonate therapy needs to be further defined.

Huang, S, Grimsrud, C, Chandra, M, Ettinger, B, Lo, J, Classification of Hip, Femur, and Atypical Femur Fractures in a Contemporary Population of Older Women.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002343.html