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In Vivo Testing of Biodegradable Mg Alloy Implants
Published in Yufeng Zheng, Magnesium Alloys as Degradable Biomaterials, 2015
The inflammation stage begins the moment the bone is broken and lasts for around 1-7 days. As the inflammation response subsides, the repair phase begins and gradually becomes the predominant pattern. As the first step in the reparative phase, the hematoma is organized. The hematoma serves primarily as a fibrin scaffold over which repair cells perform their function. During the first 2-3 weeks postfracture, the soft callus is formed, which corresponds roughly to the time when the fragments are no longer moving freely. This early soft callus can resist compression, but shows similar tensile properties to fibrous tissue (Johnson et al. 2006). Hence the mineralization of the soft callus proceeds from the fragment ends toward the center of the fracture site and forms a hard callus, which has regained enough strength and rigidity to allow low-impact exercise at the end of the repair phases (Ruedi and Murphy 2001; Johnson et al. 2006). The time to achieve the hard bone union varies greatly according to the fracture configuration and location and status of the adjacent soft tissues as well as patient characteristics (age, health status, concurrent injuries/diseases). According to Perkin's classification of fracture healing, a spiral fracture in the upper limb unites in 3 weeks and consolidates in 6 weeks. The fracture healing time doubles for a transverse fracture and doubles again for the lower limb. Table 14.1 lists a rough estimate of bone healing time for different fractures. Hence, the mechanical support should be sustained for 12-24 weeks, depending on the clinical conditions.
Segmentation and Analysis of CT Images for Bone Fracture Detection and Labeling
Published in K.C. Santosh, Sameer Antani, D.S. Guru, Nilanjan Dey, Medical Imaging, 2019
Darshan D. Ruikar, K.C. Santosh, Ravindra S. Hegadi
In a greenstick fracture, one side of the bone is broken, and the other only bent. The fracture line is perpendicular to the shaft in a transverse fracture, whereas the fracture line makes an angle with the bone in an oblique fracture. A spiral fracture occurs when the body is in motion,and a rotating force is applied along the axis of a bone. An avulsed fracture occurs when a tendon or ligament pulls off a piece of the bone. A segmental fracture contains at least two fracture lines with several separate pieces. If the bone is broken into multiple pieces, possibly with dislocation, then the fracture is called comminuted [3]. All of the fracture types mentioned are shown in Figure 7.4.
Fracture of geometric bone models. Multiscale simulation issues
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2022
Francisco Daniel Pérez Cano, Adrián Luque Luque, Juan José Jiménez Delgado
Although the methods mentioned before are generic to geometric models, they can be applied to bone models after they have been digitised. Therefore, it is essential to know the different types of fractures in the bones so that the generated fractures and the fracture patterns used for the generation of these fractures are more accurate to the real morphology of the fractures. Egol et al. (2010) determined that bone fractures can be classified into 7 different kinds (Figure 1): Greenstick fracture: a portion of the bone breaks but not completely.Transverse fracture: is one that occurs at a 90-degree angle, straight across the bone.Oblique fracture: occurs when the bone breaks at an angle.Spiral fracture: is the result of the forceful rotation or twisting of a limb.Avulsed fracture: is a break at the site where bone attaches to a tendon or ligament.Segmental fracture: is a fracture composed of at least two fracture lines that together isolate a segment of bone.Comminuted fracture: divides the bone into several fragments.
Humerus fractures in an infant: which causal mechanisms?
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
A. Delbreil, M. Bouriat, A. Pin, P. Rigoard, T. Vendeuvre, A. Germaneau
One main limitation of this work was the precise determination of the maximum stress limit. One solution could be to use mechanical data providing bending and torsional strength measured on young bone in growing from animal specimens to validate our FE model (Bertocci et al. 2017). The results obtained in the present study can be corroborated with the clinical case of child fracture. The spiral fracture has been certainly caused by a torsion loading or by a combination of bending and torsion. It is important now to determine if this type of mechanism can be caused by movements of dressing/undressing of the infant. In future works, we could characterize these types of movements from a kinematical analysis to obtain real values of motion amplitudes and loadings.