Biomechanics of the foot and ankle
Maneesh Bhatia in Essentials of Foot and Ankle Surgery, 2021
The primary stabilisers of the longitudinal arch are interosseous ligaments and plantar fascia. The plantar fascia originates from medial aspect of calcaneum and passes distally under all the metatarsophalangeal joints to insert onto the bases of proximal phalanges of the toes. It supports the arch by forming a triangular tie-rod and truss connection with the bones. In this arrangement, the talus and calcaneus form the posterior strut, tarsals and metatarsal form the anterior strut and plantar fascia forms a cable connecting them. When the body weight is applied, the bones are under compression and the plantar fascia is subjected to tension (Figure 3.10b).21 As a result, bending moments that can cause injury to the components of the arch are minimised.
Effects of introducing gap constraints in the masticatory system: A finite element study
J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares in Biodental Engineering V, 2019
The jaw muscles present in our model are the lateral pterygoid, digastric, masseter, temporalis and medial pterygoid. Muscles are composed by two entities, one representing the fibrous part and the other the tendon. Hill’s muscle model was employed to represent the fibers and an inextensible wire to represent the tendons, because they undergo very small deformation and may, for this reason, be ignored. In total, eight truss elements represent the following muscles (on each side): Anterior and posterior temporalis, superficial and deep masseter, superior and inferior lateral pterygoid, medial pterygoid and digastric. Muscle fibers are composed by myofibrils. In the case of striated muscles, the myofibrils are arranged into contractile units called sarcomeres. Forces produced by this type of muscle are influenced by the length of their sarcomeres (force-length relationship) and their contraction velocities (force-velocity relationship). Additionally, the muscle exhibits a passive elastic force when stretched. In our model, the characteristic curves of the muscle are taken from van Ruijven & Weijs (1990).
Biomechanics and Joint Replacement of the Foot and Ankle
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
The function of the plantar fascia is complex. From its attachment to the calcaneum, the plantar fascia extends forwards to span all the tarsal and metatarsophalangeal joints and to attach to the plantar aspect of the proximal phalanges. The result is a truss-like structure whose links are the tarsal bones and ligaments of the foot, which is held at its base by a tether, the plantar fascia. The windlass mechanism is formed at the metatarsophalangeal attachment of the fascia. As the metatarsophalangeal joints are extended passively when one stands on the ball of the foot, the plantar fascia is pulled distally across them, shortening the distance from the calcaneum to the metatarsal heads. This process makes the base of the truss shorter. The tarsal joints are locked into a forced flexed position and the height of the longitudinal arch of the foot is increased. Thus, extension of the toes helps to turn the foot into a rigid lever before push-off (Figure 24.7).
Changes of adjacent segment biomechanics after anterior cervical interbody fusion with different profile design plate: single- versus double-level
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Lin-Yu Jin, Ke Wei, Da-Ming Feng, Jian-Dong Li, Xiao-Xing Song, Hong-Ling Yin, Xin-Feng Li
FE analysis is an effective simulation method for predicting the trend in biomechanics after different surgical procedures and thereby providing certain guidance for clinical management. However, there are some limitations in the current study which should be taken into account. First, caution should be taken when interpreting the results of the current study, because the intact FEM is based on a single scan of a normal man. The FE simulation aimed to provide the trend rather than the actual data. FE analysis has limitations, similar to the cadaver studies and other published FE studies. Second, Truss elements were used for ligaments modeling. The contact interaction between ligaments and vertebrae does not take into account such simplification, but this has the advantage of avoiding unrealistic shearing forces in the ligaments and thus has a reduced computation time. Third, the absence of neck muscles may affect the finite element biomechanical features, for instance, motion and stress. Because of the role of these muscles is to control the cervical range of motion. The biomechanical behavior of different fusion devices should be evaluated with future clinical studies and in vivo biomechanical works are warranted.
Biomechanical evaluation of Percutaneous endoscopic posterior lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion: a biomechanical analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Jia-Rui Li, Yang Yan, Xiao-Gang Wu, Li-Ming He, Hao-Yu Feng
The thickness of cortical bone was 1.0 mm, the thickness of cartilage endplate was 0.5 mm, and the thickness of bony endplate was 1.0 mm. The bony structure was meshed by three-dimensional tetrahedral meshes (C3D4) (Du et al. 2021). The annulus fibrosus and nucleus pulposus were set as Hyperelastic materials (Mooney-Rivlin), and the mechanical properties are 100% tension and 30% compression. Compared with adjacent structures, they were treated with common nodes (Figure. 1). The ligaments were set as ‘TRUSS’ element and could only bear tensile loads. The ligaments were tied to the attachment points of cortical bone. The facet joint surfaces are set for face-to-surface contact, whose properties were set as tangential action frictionless and normal action as the ‘penalty’ friction.
A simple and effective 1D-element discrete-based method for computational bone remodeling
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Diego Quexada-Rodríguez, Kalenia Márquez-Flórez, Miguel Cerrolaza, Carlos Duque-Daza, Olfa Trabelsi, M.A Velasco, Salah Ramtani, Marie Christine Ho-Ba-Tho, Diego Garzón-Alvarado
Figure 10 displays a comparison between frame (three degrees of freedom: horizontal, vertical, and rotational displacement) and truss elements (two degrees of freedom: horizontal and vertical displacement). In this case, the capacity to bear moments is noted in the frame topology, since the final result shows a structure with longer horizontal supports, whereas in the truss case a structure with long diagonal supports at an angle of 45° is seen along the structure. Both results are structurally consistent and serve as a conceptual basis for design. It is worth noting that although there are different results in the topologies obtained, the strain energy found in the structure stays the same but concentrated along the remaining trabeculae. With the aim in mind to address bone remodelling problems, frame elements will be used in further cases, since they can bear moments, similar to trabeculae structures.
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