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Osteoporotic long bone fractures
Published in Peter V. Giannoudis, Thomas A. Einhorn, Surgical and Medical Treatment of Osteoporosis, 2020
Sascha Halvachizadeh, Hans-Christoph Pape
One of the difficult tasks in treating long bone fractures with intramedullary nailing is finding the correct entry point. This depends on the still controversial discussed aspect of bending. In femoral nails, a substantial variety of different curvature diameters can be found on the market that usually are adjusted to the antecurvature of the femur. Yet, this curvature changes during life and with the degree of osteoporosis: the osteoporotic femur shows more antecurvation compared to the young healthy femur (28). Since osteoporotic changes include widening of the medullary cavity, these mismatches of curvature of the nail and the femoral bone are better accepted in osteoporotic patients compared to young adults. However, ventral cortical abutment, perforation, and even fracture have been described in geriatric patients treated with less bended nails (29). When inserting the femoral nail through the piriformis fossa, special care should be taken not to damage the circumflexa artery around the femoral neck; this may lead to femoral head necrosis (30). An additional risk of this insertion is the iatrogenic femoral head fracture. To reduce this risk, a more lateral insertion point on the greater trochanter can be chosen for a nail with an additional proximal lateral bending. Such a nail must be turned around its longitudinal axis by 90° during the process of insertion (lateral femoral nail, LFN) (Table 25.4).
The locomotor system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
This is a common developmental abnormality with a distinctive radiological appearance. There is a scalloped radiolucent area with a sclerotic margin in the metaphyseal cortex of long bones of children. These lesions may disappear spontaneously or enlarge to involve the medullary cavity, when they are known as non-ossifying fibromas. There may be pathological fracture. The lesion has a bright orange colour due to the presence of many lipid-laden macrophages, which lie in whorled fibrous tissue containing small osteoclasts.
Biomechanical Analysis of Long Bones Provides the Crucial Break in Decedent Identification
Published in Heather M. Garvin, Natalie R. Langley, Case Studies in Forensic Anthropology, 2019
According to the Mechanostat model, increased strain will result in the deposition of bone on the periosteal surface through modeling, retarded bone loss on the endosteal surface during modeling and remodeling, and decreased porosity of the cortical bone during remodeling (Robling et al., 2014). Decreased strain, on the other hand, will inhibit deposition of bone on the periosteal surface, accelerate loss of bone on the endosteal envelope, and increase cortical bone porosity due to remodeling. In other words, when deformation necessitates increasing the strength of the bone, the external size of a long bone cross-section increases, the medullary cavity remains relatively constant and the cortical bone remains dense. When bone strength isn’t necessary (e.g., due to disuse), the body removes bone from the endosteal surface, expanding the medullary cavity, and the cortical bone becomes more porous, but the periosteal surface (external bone diameter) generally remains unchanged. This is also true with pathological conditions such as osteoporosis. Bone is removed primarily from the endosteal surface as it affects overall bone strength less than removing bone from the periosteal surface.
Stress-dependent design and optimization methodology of gradient porous implant and application in femoral stem
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Changning Sun, Jianfeng Kang, Ling Wang, Zhongmin Jin, Chaozong Liu, Dichen Li
The von Mises stress at the surrounding femur of the two femoral stems are presented in Figure 9(a). The stress on the internal surface of the medullary cavity were counted and the frequency chart were shown in Figure 9(b), the overall stress of the medullary cavity of stem bVwere larger than those of bT. The level of the bone loss was assessed by S/Sref, where S was the strain tensor of the element in the femoral model with implant and Sref was the strain tensor of a completely healthy femur. The smaller the S/Sref becomes, the more bone loss was expected at a certain location. The bone loss of the femur with femoral stem bVwas 2.4%, less than half of the femur with stem bT (Figure 9(c)). The major difference was the bone loss near the proximal femur was relieved by stem bV comparing to those of stem bT.
The role of nutrition in pediatric oncology
Published in Expert Review of Anticancer Therapy, 2020
Approximately 40% of bone mineral mass is accumulated in childhood and adolescence and it is affected adversely by cancer and its treatment in this age group [56]. Osteopenia and osteoporosis have been defined in children as bone mineral density (BMD) Z scores of −1.0 to −2.0 and less than −2.0, respectively, [57]. Most studies in children with cancer have been in those with ALL. Osteopenia is often evident at diagnosis [58] and worsens with the onset of treatment [59]. Vertebral fractures are common and often unrecognized clinically [60]. Orgel and colleagues have examined this loss of bone mineral [61] using both quantitative computed tomography (QCT) and DXA. QCT has the advantages of distinguishing compact/cortical bone from the trabecular/cancellous counterpart, which is much more active metabolically, and determining volumetric (v) BMD instead of areal BMD available from DXA. Loss of vBMD occurred during remission induction. Compact/cortical bone mass was affected much less but revealed thinning associated with the expansion of the medullary cavity. Surrogate measures of bone modeling in children with ALL have shown bone resorption exceeding bone formation [62]. This imbalance, which results in loss of bone mineral, is due mainly to corticosteroids and methotrexate [56].
The effects of pulsed electromagnetic fields combined with a static magnetic intramedullary implant on the repair of bone defects: A preliminary study
Published in Electromagnetic Biology and Medicine, 2019
Zheheng Bao, Meng Fan, Le Ma, Qucheng Duan, Wenxue Jiang
At 5 weeks post-operation, the bone defect was not fully filled in the medullary cavity in the control group. New capillaries and proliferated fibroblasts were found in the medullary cavity, and inflammatory cells such as lymphocyte infiltrated locally. At the margin of the medullary cavity, a small amount of new bone tissue grew toward the center of the medullary cavity and the new bone structure was less. In the PEMFs group, the medullary cavity was basically filled with fibroblasts and capillaries. Mature lamellar bone tissue was formed at the edge of bone defect, and the osteoblasts were arranged at the edge of bone trabecula, but the formation of new bone tissue in the medullary cavity was less. In the combined magnetic field group, more new bone tissue was formed in the medullary cavity. There were more hypertrophic chondrocytes and new woven bone formation. The matrix of new bone trabeculae was unevenly stained, and a large number of osteoblasts were arranged at the edge of new bone trabeculae. Osteogenesis and bone tissue remodeling are active (Figure 5).