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The skeleton and muscles
Published in Frank J. Dye, Human Life Before Birth, 2019
Without our skeleton and muscles, we would not be able to move about or maintain our posture. Moreover, our ability to hear also depends on three small bones—the incus, malleus, and stapes—in our middle ear and the muscles attached to these bones. Like other vertebrates, we have an endoskeleton (internal skeleton), which provides protection for our soft parts. We do not have an exoskeleton (shell) like some animals, but if you have ever banged your head against something hard, you can appreciate the skull's protection of your brain! Our skeleton is divided into two general parts (Figure 14.1): the axial skeleton is composed of the skull, vertebral column (backbone), sternum, and ribs, and the appendicular skeleton is composed of limbs, pelvic girdle, and pectoral girdle.
Restoration: Nanotechnology in Tissue Replacement and Prosthetics
Published in Harry F. Tibbals, Medical Nanotechnology and Nanomedicine, 2017
Unlike the exoskeleton of sea shells, the endoskeleton of vertebrate bone contains living cells—osteoblasts—which renew deposits of mineral from within the structure. Bony skeletons must perform a varied and complex set of functions; bones have to bear complex loads of moving bodies, provide a protective cage for vital organs, anchor tendons and muscles, and act as joints, fulcrums, and levers. Because of this functional complexity, the nano- and microstructure of bone is more complex than the carbonate nano-structure of shells. Different parts of the same skeleton must have different directional, compression, and tension strengths to prevent fracture and distortion under stresses, loads, impact, and fatigue [104].
Metabolic and endocrine bone disorders
Published in Ashley W. Blom, David Warwick, Michael R. Whitehouse, Apley and Solomon’s System of Orthopaedics and Trauma, 2017
One of the primary roles of the skeleton is to provide an endoskeleton, transmitting forces applied by muscles acting as external levers for the purposes of locomotion and other activities. The skeleton is designed to withstand different types of forces such as compression, tension, shear and torsion. However, at any one site a specific type of force tends to predominate; for example, compression is the predominant force acting on lumbar vertebrae while tensile forces predominate at the superior surface of the femoral neck. The direction and thickness of trabeculae in cancellous bone are related to regional stress trajectories. This is recognized in Wolff’s law (1896), which states that the architecture and mass of the skeleton are adjusted to withstand the prevailing forces imposed by functional need or deformity (see Figure 7.10). This has led to the concept of the mechanostat, whereby bone remodelling and bone mass are regulated to ensure that bone strain (defined as deformation in response to an externally applied load per unit length) is kept within a target range (Frost, 1987).
The Altura endograft system for endovascular aneurysm repair: presentation of its unique design with clinical implications
Published in Expert Review of Medical Devices, 2022
Efstratios Georgakarakos, Konstantinos Dimitriadis, Gioultzan Memet Efenti, Georgios I Karaolanis, Christos Argyriou, George S. Georgiadis
The braided endoskeleton of the Altura endograft carries unique features, the main of which is the adjustable length of its segments according to the vessel diameter where they are deployed. Greater vessel diameters necessitate greater compression of the endoskeleton of a given diameter to achieve apposition and sealing, thus resulting in shorter covering lengths (Figure 4A-C). Figure 3 and Table 1 exemplify the aforementioned, showing the lengths that a certain main body of 24 mm can obtain; with increasing vessel diameters of 18,19,20,21 and 22 mm, the ‘D’ segment (marked with the black triangle) receives lengths of 39,36,34,31 and 28 mm accordingly, as previously explained. Likewise, the 27 mm and 30 mm main bodies can obtain lengths of 40–29 mm and 42–29 mm, accordingly, as shown in Table 1. The distal (limb) segment (marked with the black circle) of the main body accommodates the iliac diameters from 5 to 13 mm, receiving lengths from 116 to 40 mm, accordingly.
A clinical update on the mid-term clinical performance of the Ovation endograft
Published in Expert Review of Medical Devices, 2019
Andreas Koutsoumpelis, Efstratios Georgakarakos, Kalliopi-Maria Tasopoulou, Nikolaos Kontopodis, Christos Argyriou, George S. Georgiadis
The Ovation device uses a combination of active suprarenal fixation via a long nitinol stent with a pair of polymer-filled inflatable rings that achieve sealing at the infrarenal neck, regardless of its shape and length. The minimal outward radial force exerted by the fixed sealing rings at the infrarenal neck enables fixation in AAA cases with presence of thrombus and calcification infrarenally, even if this is not regularly suggested -for the time being at least- according to the instructions-for-use of the endograft [7,8]. Its main-body is deprived of Nitinol endoskeleton. Consequently, its delivery system carries the lowest profile on the market (14F), expanding the possibilities of EVAR in patients with small or tortuous iliac arteries [7,8]. This facilitates the navigation and deployment of the endograft in smaller aortas and expands the spectrum of EVAR application even in women ineligible for EVAR with conventional devices [9]. With respect to the proximal aortic neck, the device is the only FDA- approved device for use in a neck of length ≥7 mm and diameter not exceeding 30 mm at 13 mm below the lowermost renal artery [10].
Τhe AFX unibody bifurcated unibody aortic endograft for the treatment of abdominal aortic aneurysms: current evidence and future perspectives
Published in Expert Review of Medical Devices, 2020
Efstratios Georgakarakos, Georgios Ioannidis, Andreas Koutsoumpelis, Nikolaos Papatheodorou, Christos Argyriou, Konstantinos Spanos, Athanasios D. Giannoukas, George S. Georgiadis
Additionally, the AFX could be considered ideal for patients with infrainguinal disease that would possibly need endovascular intervention in the long term. In such cases, the preservation of the aortic bifurcation due to AFX anatomical fixation preserves the option for easy contralateral cannulation (Figure 6). Still, in contrast to other endograft designs, the AFX endoskeleton can prove challenging with reinterventions to avoid wireframe entrapment [24].