Presented in part at the 28th Annual Meeting of the American Society for Bone and Mineral Research, Philadelphia, PA, September 15–19, 2006.
Article first published online: 12 MAR 2007
Copyright © 2007 ASBMR
Journal of Bone and Mineral Research
Volume 22, Issue 6, pages 825–831, June 2007
How to Cite
Bouxsein, M. L., Szulc, P., Munoz, F., Thrall, E., Sornay-Rendu, E. and Delmas, P. D. (2007), Contribution of Trochanteric Soft Tissues to Fall Force Estimates, the Factor of Risk, and Prediction of Hip Fracture Risk*. J Bone Miner Res, 22: 825–831. doi: 10.1359/jbmr.070309
Published online on March 12, 2007;
The authors state that they have no conflicts of interest.
- Issue published online: 4 DEC 2009
- Article first published online: 12 MAR 2007
- Manuscript Accepted: 5 MAR 2007
- Manuscript Revised: 1 MAR 2007
- Manuscript Received: 25 SEP 2006
- hip fracture;
- trochanteric soft tissue;
- factor of risk;
- femoral strength;
We compared trochanteric soft tissue thickness, femoral aBMD, and the ratio of fall force to femoral strength (i.e., factor of risk) in 21 postmenopausal women with incident hip fracture and 42 age-matched controls. Reduced trochanteric soft tissue thickness, low femoral aBMD, and increased ratio of fall force to femoral strength (i.e., factor of risk) were associated with increased risk of hip fracture.
Introduction: The contribution of trochanteric soft tissue thickness to hip fracture risk is incompletely understood. A biomechanical approach to assessing hip fracture risk that compares forces applied to the hip during a sideways fall to femoral strength may by improved by incorporating the force-attenuating effects of trochanteric soft tissues.
Materials and Methods: We determined the relationship between femoral areal BMD (aBMD) and femoral failure load in 49 human cadaveric specimens, 53–99 yr of age. We compared femoral aBMD, trochanteric soft tissue thickness, and the ratio of fall forces to bone strength (i.e., the factor of risk for hip fracture, Φ), before and after accounting for the force-attenuating properties of trochanteric soft tissue in 21 postmenopausal women with incident hip fracture and 42 age-matched controls.
Results: Femoral aBMD correlated strongly with femoral failure load (r2 = 0.73–0.83). Age, height, and weight did not differ; however, women with hip fracture had lower total femur aBMD (OR = 2.06; 95% CI, 1.19–3.56) and trochanteric soft tissue thickness (OR = 1.82; 95% CI, 1.01, 3.31). Incorporation of trochanteric soft tissue thickness measurements reduced the estimates of fall forces by ∼50%. After accounting for force-attenuating properties of trochanteric soft tissue, the ratio of fall forces to femoral strength was 50% higher in cases than controls (0.92 ± 0.44 versus 0.65 ± 0.50, respectively; p = 0.04).
Conclusions: It is possible to compute a biomechanically based estimate of hip fracture risk by combining estimates of femoral strength based on an empirical relationship between femoral aBMD and bone strength in cadaveric femora, along with estimates of loads applied to the hip during a sideways fall that account for thickness of trochanteric soft tissues. Our findings suggest that trochanteric soft tissue thickness may influence hip fracture risk by attenuating forces applied to the femur during a sideways fall and provide rationale for developing improved measurements of trochanteric soft tissue and for studying a larger cohort to determine whether trochanteric soft tissue thickness contributes to hip fracture risk independently of aBMD.