Fri., 10/9/09 Hip & Geriatric, Paper #39, 10:25 am OTA-2009
Low-Energy Femoral Diaphyseal Fractures and Long-term Bisphosphonate Use
Brett A. Lenart, MD1 (n); Andrew S. Neviaser, MD2 (n); Stephen Lyman, PhD2 (n);
Charles C. Chang, MD, DDS2 (n); Folorunsho Edobor-Osula, MD, MPH3 (n);
Barbara Steele, MD4(n); Marjolein C.H. van der Meulen, PhD2,5 (n); Dean G. Lorich, MD6 (n); Joseph M. Lane, MD6 (n);
1Rush University Medical Center, Chicago, Illinois;
2Hospital for Special Surgery, New York, New York, USA;
3Long Island Jewish Medical Center, New Hyde Park, New York, USA;
4New York Medical College at Westchester Medical Center, Valhalla, New York, USA;
5Cornell University, Ithaca, New York, USA;
6Hospital for Special Surgery, New York-Presbyterian Hospital-Weill Cornell Medical Center, Weill Medical College of Cornell University, New York, New York, USA
Purpose: Low-energy femoral factures in patients on long-term bisphosphonate treatment have been reported. Bisphosphonates may predispose to low-energy femoral fractures via alteration of tissue mineral properties, suppression of bone turnover, and increased microdamage accumulation, each of which have the potential to compromise bone strength. Although clinical trials confirm the antifracture efficacy of bisphosphonates over 3 to 5 years, the long-term effects of bisphosphonate use on bone metabolism are unknown.
Methods: We performed a retrospective case-control study of postmenopausal women who presented with low-energy femoral fractures from 2000 to 2007. 41 subtrochanteric and femoral shaft fracture cases were identified, and matched by age, race, and body mass index to 1 intertrochanteric and femoral neck fracture each. We compared rates of bisphosphonate use in cases and controls. Patients with comorbidities or taking medications known to affect bone metabolism were excluded.
Results: Bisphosphonate use was observed in 15 of the 41 subtrochanteric/shaft cases, while seen in only 9 of the 82 intertrochanteric/femoral neck controls (Mantel-Haenszel odds ratio [OR], 4.44; 95% CI, 1.77-11.35; P = 0.002). Alendronate was significantly associated only with subtrochanteric/shaft cases, logistic regression (P =.003). A common radiographic pattern was identified in 10 of the 15 subtrochanteric/shaft cases on alendronate, defined as a simple oblique fracture with cortical thickening and beaking of the cortex on one side. This radiographic pattern was highly associated with bisphosphonate use (OR, 15.33; 95% CI, 3.06-76.90; P <0.001). The 10 subtrochanteric/shaft cases on alendronate with the radiographic pattern had an average duration of alendronate use of 7.3 years, compared to 2.8 years for those subtrochanteric/shaft cases on alendronate without the pattern (P <0.001).
Conclusions: We found a significantly greater proportion of patients with subtrochanteric/shaft fractures than intertrochanteric/femoral neck fractures to be on long-term bisphosphonates. Bisphosphonate use was highly associated with a unique radiographic pattern. Further studies are needed to determine if bisphosphonate use increases the risk of these atypical fractures and to characterize the subgroup that may be more susceptible to the effects of long-term use.
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant