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Designing for Lower Torso and Leg Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The SI joint is a synovial joint with cartilage on both sides of the joint, but thinner cartilage on the articular surface of the ilium. SI joint surface area is approximately 17.5 cm2 (2.7 in.2) (Sizer & James, 2008). The articular surface of each ilium fits into/against the lateral aspect of the sacrum and the ilium transmits force from the spine to the legs. SI joint configuration influences how, and if, an individual can carry loads without back pain. Summarizing decades of research, Lee (2011, pp. 10–14) notes the mobility (and stability) of the SI joints depend on the specific shape of the sacrum: (a) the shape of the lateral aspects of the sacrum can be asymmetrical (R to L), (b) the body of the sacrum can be more or less triangular in a coronal plane—changing the angles of the SI joints to more or less vertical, and (c) the lateral aspects of the sacrum can be more or less rotated in a transverse plane, to position the SI joint surface in a more or less sagittal plane. Franke (2003) illustrates in a useful drawing (p. 23) secondary interconnected postural patterns associated with unstable SI joints—demonstrating the importance of healthy SI joint function within the musculoskeletal system. These structural and functional variations create uncertainty for designers of devices to help bear loads through the pelvis to the legs, and of products to maintain stability or to reinforce unstable SI joints.
Anatomy, Biomechanics, Work Physiology, and Anthropometry
Published in Stephan Konz, Steven Johnson, Work Design, 2018
Figure 2.1 shows the spine. The spine is divided into the cervical, thoracic, lumbar, and sacrum regions. The sacrum is linked to the ilium (top part of the pelvis) with a joint on each side—the sacroiliac joints. The low back, Lumbar 4 and Lumbar 5 (abbreviated L4 and L5) is the problem area. Note how these discs angle downward instead of being horizontal. The weight of the torso therefore tends to push these discs forward. The disc pressure is 50–100% higher when sitting than standing, especially when sitting with a slumped back. Reduce that pressure by using chairs with armrests (the armrests support some of the torso weight).
Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
The ilium is the largest and heaviest bone in the pelvic region. The hip girdle assures stability and mobility for the vertebral column. The hip has a limited degree of freedom of movement. The movements are flexion and extension in the sagittal plane and abduction and adduction in the frontal plane. Medial and lateral rotation, around the longitudinal axis of the body and lateral flexion/inclination is to the right and to the left. These movements are related to the coxofemoral articulation.
An influence study of active muscle and sitting postures on lower limb injuries during frontal impact
Published in International Journal of Crashworthiness, 2022
Sen Xiao, Wu Chen, Xinran Liu, Zhidong Qu
In all the 18 simulations, different hip joint postures would lead to different injury results. Most of the fracture happened at acetabulum and ilium areas of the pelvis. In the investigation of acetabulum simulations, injury areas of acetabulum vary. With the increase of deflections, the contact between caput femoris and acetabulum would move from acetabulum back to acetabulum bottom. When the thigh is turned inward and upward, pelvis fracture position would change from the greater sciatic notch to crista iliac. Combined with pelvis structure analysis, it can be concluded that the distance between acetabulum force point in axial would enlarge due to the change of pelvis’ restraint when hip joint deflexion angle decrease. Thus, the bending moment in the greater sciatic notch will increase relative to curvature. As a result, the material failure occurred in ilium. When the flexion angle α is small, the arm will decrease and acetabulum in caput femoris would fracture under depression.
Reliable and effective novel home-based training set-up for application of an evidence-based high-loading stimulus to improve triceps surae function
Published in Journal of Sports Sciences, 2021
Goran Radovanović, Jona Kunz, Sebastian Bohm, Adamantios Arampatzis, Kirsten Legerlotz
Participants were advised to sit with extended knees. The forefoot (with shoes) was placed in the foot plate with the widest part of the shoe (i.e. ball of the foot) positioned in the sagittal centre of the foot plate pad to ensure a standardised contact point. The participants were advised to always use the same shoes with a rigid sole. The ratchet was individually set and fixed as tightly as possible, to allow for maximal isometric plantar flexor contractions at a standardised ankle angle position (90°) (Figure 2). The straps on both sides of the pelvis were placed as close as possible to the hip bone (i.e. os ilium) to reduce spinal load. It was recommended to place one hand on the ground behind the body providing a hip (i.e. femur-to-spine) angle of >90°. For standardised alignment during the contractions, both legs had to be parallel in the frontal plane and in neutral rotational position in the hip joints in the transverse plane.
New load transfer structure to reduce body deformation in side collisions
Published in Traffic Injury Prevention, 2023
Atsushi Hasegawa, Yasuhisa Egawa, Takuro Nisida, Kengo Kishida, Yoshihiro Fujimura, Ryotaro Takeuchi, Hitomi Yamada, Takayuki Fujii, Yumi Saito
The maximum values of Aspine are shown in Figure 8. Compared to BASE, ASpine-LWR of NEW-PET and NEW EV was reduced by 56% and 58%, respectively. The average deflection values of ribs are shown in Figure 9. Compared to BASE, average rib deflection of NEW-PET and NEW EV was reduced by 73% and 76%, respectively. The average rib deflection value of NEW-PET is 15 mm below the upper limit of the IIHS Good rating. The maximum values of combined acetabulum and ilium force are shown in Figure 10. Compared to BASE, combined acetabulum and ilium force of NEW-PET and NEW EV was reduced by 43% and 51%, respectively. The combined acetabulum and ilium force value of NEW-PET is 1.59 kN below the upper limit of the IIHS Good rating.