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- Bahaloo, Hassan, 1983-, et al.
(författare)
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On the failure initiation in the proximal human femur under simulated sideways fall
- 2018
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Ingår i: Annals of Biomedical Engineering. - : Springer. - 0090-6964 .- 1573-9686. ; 46, s. 270-283
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Tidskriftsartikel (refereegranskat)abstract
- The limitations of areal bone mineral density measurements for identifying at-risk individuals have led to the development of alternative screening methods for hip fracture risk including the use of geometrical measurements from the proximal femur and subject specific finite element analysis (FEA) for predicting femoral strength, based on quantitative CT data (qCT). However, these methods need more development to gain widespread clinical applications. This study had three aims: To investigate whether proximal femur geometrical parameters correlate with obtained femur peak force during the impact testing; to examine whether or not failure of the proximal femur initiates in the cancellous (trabecular) bone; and finally, to examine whether or not surface fracture initiates in the places where holes perforate the cortex of the proximal femur. We found that cortical thickness around the trochanteric-fossa is significantly correlated to the peak force obtained from simulated sideways falling (R 2 = 0.69) more so than femoral neck cortical thickness (R 2 = 0.15). Dynamic macro level FE simulations predicted that fracture generally initiates in the cancellous bone compartments. Moreover, our micro level FEA results indicated that surface holes may be involved in primary failure events.
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| 4. |
- Fice, Jason, 1985, et al.
(författare)
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Neck Muscle and Head/Neck Kinematic Responses While Bracing Against the Steering Wheel During Front and Rear Impacts
- 2021
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Ingår i: Annals of Biomedical Engineering. - : Springer Science and Business Media LLC. - 1573-9686 .- 0090-6964. ; 49:3, s. 1069-1082
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Tidskriftsartikel (refereegranskat)abstract
- Drivers often react to an impending collision by bracing against the steering wheel. The goal of the present study was to quantify the effect of bracing on neck muscle activity and head/torso kinematics during low-speed front and rear impacts. Eleven seated subjects (3F, 8 M) experienced multiple sled impacts (Delta v = 0.77 m/s; a(peak) = 19.9 m/s(2), Delta t = 65.5 ms) with their hands on the steering wheel in two conditions: relaxed and braced against the steering wheel. Electromyographic activity in eight neck muscles (sternohyoid, sternocleidomastoid, splenius capitis, semispinalis capitis, semispinalis cervicis, multifidus, levator scapulae, and trapezius) was recorded unilaterally with indwelling electrodes and normalized by maximum voluntary contraction (MVC) levels. Head and torso kinematics (linear acceleration, angular velocity, angular rotation, and retraction) were measured with sensors and motion tracking. Muscle and kinematic variables were compared between the relaxed and braced conditions using linear mixed models. We found that pre-impact bracing generated only small increases in the pre-impact muscle activity (< 5% MVC) when compared to the relaxed condition. Pre-impact bracing did not increase peak neck muscle responses during the impacts; instead it reduced peak trapezius and multifidus muscle activity by about half during front impacts. Bracing led to widespread changes in the peak amplitude and timing of the torso and head kinematics that were not consistent with a simple stiffening of the head/neck/torso system. Instead pre-impact bracing served to couple the torso more rigidly to the seat while not necessarily coupling the head more rigidly to the torso.
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| 5. |
- Forman, Jason, et al.
(författare)
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Variability in Body Shape, Superficial Soft Tissue Geometry, and Seatbelt Fit Relative to the Pelvis in Automotive Postures—Methods for Volunteer Data Collection With Open Magnetic Resonance Imaging
- 2024
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Ingår i: Journal of Biomechanical Engineering. - 0148-0731 .- 1528-8951. ; 146:3
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Tidskriftsartikel (refereegranskat)abstract
- Variability in body shape and soft tissue geometry have the potential to affect the body’s interaction with automotive safety systems. In this study, we developed a methodology to capture information on body shape, superficial soft tissue geometry, skeletal geometry, and seatbelt fit relative to the skeleton—in automotive postures—using Open Magnetic Resonance Imaging (MRI). Volunteer posture and belt fit were first measured in a vehicle and then reproduced in a custom MRI-safe seat (with an MR-visible seatbelt) placed in an Open MR scanner. Overlapping scans were performed to create registered three-dimensional reconstructions spanning from the thigh to the clavicles. Data were collected with ten volunteers (5 female, 5 male), each in their self-selected driving posture and in a reclined posture. Examination of the MRIs showed that in the males with substantial anterior abdominal adipose tissue, the abdominal adipose tissue tended to overhang the pelvis, narrowing in the region of the Anterior Superior Iliac Spine (ASIS). For the females, the adipose tissue depth around the lower abdomen and pelvis was more uniform, with a more continuous layer superficial to the ASIS. Across the volunteers, the pelvis rotated rearward by an average of 62% of the change in seatback angle during recline. In some cases, the lap belt drew nearer to the pelvis as the volunteer reclined (as the overhanging folds of adipose tissue stretched). In others, the belt-to-pelvis distance increased as the volunteer reclined. These observations highlight the importance of considering both interdemographic and intrademographic variability when developing tools to assess safety system robustness.
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| 7. |
- Soltan, Nikoo, et al.
(författare)
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Validating a Device for Whiplash Motion Simulation in a Porcine Model
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Whiplash injury is a common outcome following minor automobile collisions. One theorized mechanism for whiplash injury is that the rapid head and neck motions induced by a collision can injure nerve cells in the dorsal root ganglia through pressure gradients developed in the spinal canal and surrounding tissues. This injury mechanism has previously been studied in human cadaver and porcine models. However, the whiplash motion simulation methods in the latter studies lacked the control necessary to explore the independent effects of head rotation and retraction on the measured spinal pressures. This project aimed to address the limitations of previous porcine whiplash studies by developing and validating a new whiplash motion simulation device to enable further study of this injury mechanism. The new proposed device consists of two servomotors which can be programmed to precisely actuate a headplate through mechanical linkages. For the current study, an inert surrogate model was used for preliminary testing of the device using a whiplash motion profile from previous porcine studies. The time scale of the motion profile was adjusted to incrementally increase severity. The positional accuracy and repeatability of the device was assessed through marker tracking of the headplate and logging of the motor encoder positions. Angular rates and linear accelerations of the plate were also measured. Testing demonstrated the strengths of the proposed device in accurately and repeatably replicating programmed motion profiles. Some design modifications can potentially enable simulating whiplash motion severities commensurate with previous porcine whiplash studies. With future testing using this device, our understanding of the pressure-induced whiplash injury mechanism can be improved, which can inform effective treatments and preventative measures for whiplash injury.
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