PubMed · 8638569
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R J Isaacson. 1996. Superimposition and structural analysis.. https://doi.org/10.1016/s0889-5406(96)70180-4
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Mechanical loading plays an important role in regulating bone remodeling, and nitric oxide may be one regulator of this process. To determine how mechanical stress modulates osteoblast function, we loaded cyclic tensile stretch on osteoblast-like cells and measured levels of nitric oxide in the medium. High frequency of stretch at any magnitude inhibited release of nitric oxide; however, low frequency of stretch enhanced its release from the static control. To examine the involvement of G protein (guanine nucleotide-binding regulatory protein) in stress-inhibited release of nitric oxide, we added pertussis toxin, a specific inhibitor of the Gi class, and found that it completely reversed the stress-inhibited release. These data support the idea that pertussis toxin-sensitive G protein is activated in the presence of cyclic tensile stretch.
For osteosynthesis and for bone transplant fixation in particular, a lag screw with a biconcave washer, the so called "Anchor Screw" (AS) has been introduced in maxillo-facial surgery. Using 2D-finite element analysis (FEA), the v. Mises and the circumferential stresses induced in underlying bone by this AS are analysed and compared to those under a conventional lag screw. The stress distributions below the biconcave washer of the AS were correlated with histomorphological bone reactions after AS osteosynthesis in two tumor patients, retrieved 12 weeks and 19 months after tumor surgery, respectively. Depending on the thickness of cortical bone, the v. Mises stress concentrations below the biconcave washer were lower than under the head of the conventional lag screw (CLS), but with a higher stress maximum concentrated around the rim of the washer. The circumferential stresses were only half as high around the AS, and thus the deformation of bone was reduced. As predicted by FEA, histology showed microcrack formation, but then after minimal resorption, remodelling of bone below the biconcave washer. Stable osteosynthesis could be demonstrated by bony union already after 12 weeks, and, while bone remodelling continued in the healed osteotomy, it had decreased around the screws after 19 months. It can be concluded from the biomechanical principles and the histomorphological findings that the AS appears superior to the CLS.
The aim of this paper is to illustrate the application of mathematical tools for the analysis of non-linear dynamical systems to the study of global stability of one kind of bone remodeling scheme applied to n unit-elements model. The particular aspects analyzed here are the stationary states related to this theory and a condition of their stability. The non-linear equations governing the remodeling process are solved by finite-difference method and the well-known results on the heterogeneous spatial organizations have been retrieved and confirm the analytical study. This kind of remodeling theory is useful for investigating the effects of physiological parameters on the development, maintenance, and adaptation of bone under mechanical loading.