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Title: Women and men with hip fractures have a longer femoral neck moment arm and greater impact load in a sideways fall.
Authors: Wang, Q;Teo, J W;Ghasem-Zadeh, Ali;Seeman, Ego
Endocrine Centre, Department of Medicine/Austin Health, The University of Melbourne, Victoria, Australia
Issue Date: 18-Oct-2008
Citation: Osteoporosis International : A Journal Established As Result of Cooperation Between the European Foundation For Osteoporosis and the National Osteoporosis Foundation of The Usa 2008; 20(7): 1151-6
Abstract: In a case control study, we report that women and men with hip fractures have a longer moment arm of the force applied on the proximal femur during a sideways fall, a structural feature that may contribute to fracture risk. The impact load and its direction during a sideways fall onto the greater trochanter are partly determined by the geometry of the proximal femur. We hypothesized that the hip geometry in elderly with hip fractures produces a greater impact on the hip during a sideways fall.We studied 41 female (77.2 +/- 9.9 years) and 22 male (76.2 +/- 12.1 years) patients with hip fractures and 40 female (85.7 +/- 6.0 years) and 17 male (84.3 +/- 10.1 years) controls. Hip geometry was analyzed on the nonfracture hip in patients and left hip in controls using dual-energy X-ray absorptiometry.There was no difference in areal bone mineral density (aBMD), hip axis length, femoral neck axis length, or neck-shaft angle between cases and controls. However, the moment arm of the force on the hip during a sideways fall was 7.3% and 9.5% longer resulting in 5.6% and 9.1% greater moment in such a fall in female and male cases relative to their respective controls independent of height and weight (all p < 0.056). In multivariate logistic regression analysis, only the moment arm length in a sideways fall was associated with increased risk of hip fracture in females (odds ratio = 1.91, 95%CI: 1.14-3.20 for each SD increase in moment arm length of sideways fall, p = 0.02) and males (odds ratio = 2.69, 95% CI, 1.19-6.09, p = 0.01).A longer moment arm in the sideways fall increases the resultant force applied to the hip predisposing to hip fracture.
Internal ID Number: 18931818
DOI: 10.1007/s00198-008-0768-y
Type: Journal Article
Subjects: Absorptiometry, Photon.methods
Accidental Falls
Aged, 80 and over
Biomechanical Phenomena
Bone Density
Bone Diseases, Metabolic.epidemiology
Case-Control Studies
Femur.anatomy & histology.radiography
Femur Neck.anatomy & histology.radiography
Hip Fractures.etiology.pathology
Hip Joint.anatomy & histology.radiography
Middle Aged
Pelvic Bones.anatomy & histology.radiography
Pressure.adverse effects
Risk Factors
Stress, Mechanical
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