Effect of pelvis impact angle on stresses at the femoral neck during falls

被引:18
作者
Choi, W. J. [1 ]
Robinovitch, S. N. [2 ]
机构
[1] Yonsei Univ, Dept Phys Therapy, Injury Prevent & Biomech Lab, Wonju, Gangwon Do, South Korea
[2] Simon Fraser Univ, Dept Biomed Physiol & Kinesiol, Burnaby, BC, Canada
关键词
Falls; Hip fracture; Hip protector; Muscle force; Stress analysis; HIP FRACTURE RISK; PROXIMAL FEMUR; MECHANICAL-PROPERTIES; TRABECULAR BONE; CANCELLOUS BONE; CORTICAL BONE; MUSCLE FORCES; FAILURE LOAD; STRENGTH; DIRECTION;
D O I
10.1016/j.jbiomech.2018.04.015
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
Improved understanding is required of how the mechanics of the fall affect hip fracture risk. We used a hip impact simulator to determine how peak stresses at the femoral neck were affected by pelvis impact angle, hip abductor muscle force, and use of a wearable hip protector. We simulated falls from standing (2 m/s impact velocity) involving initial hip abductor muscle forces of 700 or 300 N. Trials were acquired for impact to the lateral aspect of the greater trochanter, and impact to the pelvis rotated 5 degrees, 10 degrees and 15 degrees anteriorly (positive) or posteriorly (negative). Measures were acquired with and without a commercially available hip protector. During trials, we measured three-dimensional forces with a load cell at the femoral neck, and derived peak compressive and tensile stresses. Peak compressive stress increased 37% (5.91 versus 4.31 MPa; p < 0.0005) and peak tensile stress increased 209% (2.31 versus 0.75 MPa; p < 0.0005) when the pelvis impact angle changed from 15 degrees anterior to -15 degrees posterior. For lateral impacts, the peak tensile and compressive stresses averaged 73% and 8% lower, respectively, in the 700 N than 300 N muscle force condition, but the effect was reversed for anteriolateral or posteriolateral impacts. The attenuation in peak compressive stress from the hip protector was greatest for posteriolateral impacts (-15 to -5 degrees; 36-41%), and least for anteriolateral (+15 degrees; 10%). These results clarify the effects on hip fracture risk during a fall of pelvis impact angle and muscle forces, and should inform the design of improved hip protectors. (C) 2018 Elsevier Ltd. All rights reserved.
引用
收藏
页码:41 / 49
页数:9
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