Urso

By I. Julio. Rowan University. 2017.

Because spinal struc- tures are inherently complex generic 300 mg urso otc, the FE model utilized required considerable refinement. In a follow-up study,54,55 similar trends were observed in a more detailed model of the spine. An insignificant change in external geometry was not surprising because the models were derived directly from CT scans. The opposite held true for internal remodeling, however. The internal remodeling algorithm converged for all governing loads, excluding torsion. The total strain energy density (TSED) for cancellous bone decreased as a function of iteration (or time), reaching a minimum at iteration 30 during compression. TSED is defined in the “Strain Energy Density (SED) Theory of Adaptive Bone Remodeling” subsection of the “Empirical Models” section of this chapter. The elastic modulus distribution in the mid-transverse plane of the L4 vertebral body was higher in the postero- and central regions of the cross-section (Fig. In the coronal view, elevated values were predicted centrally and adjacent to the endplates. An approximately uniform distribution of 15 MPa was © 2001 by CRC Press LLC FIGURE 2. For example, during extension, increased elastic moduli were predicted in the anterior and posterior regions of the transverse plane, the central region of the coronal plane, and the posterocentral and anterior inferior- most elements of the midsagittal plane. The distribution for flexion and lateral bending closely resembled that of extension, deviating slightly. The predicted inhomogeneous distribution following the remodeling procedures was in agreement with the experimental data.

These cements revealed extensive bone formation immediately after implantation without any inflammatory tissue response [161] order urso 300 mg mastercard. Bone colonization occurred much earlier and faster in CPC than calcium phosphate ceramics [165]. Polymers [166], gelatin [167], and collagen [168] can be added to improve the biocompatibility of calcium phosphate cements. Chitosan and citric acid were added to improve their biocompatibility and decrease the initial inflammatory response of these self-curing cements [169]. Addition of 20% citric acid decreased the initial inflammatory response, and good bone bonding was observed in that study. Preosteoblastic cells can also be stimulated in vitro by adding TGF- into calcium phosphate cement [170]. Thus, one study found that CPC particles could adversely affect osteoblast function related with particle size [171]. The concern on the biomechanical effectiveness and slow degradation due to the nonporous structure of CPC still remains. POLYMERS Polymers are mainly used in fracture fixation, bone replacement, cartilage repair, fixation of ligaments, and drug delivery. Polylactides (PLA), polyglycolides (PGA), and polyhydroxybutyr- ates (PHBV) are the most common types of polymers used in hard tissue engineering [172]. Material properties including type, composition, surface geometry, chemistry, porosity, and degradation rate of polymers define their interaction with bone tissue. A larger surface area and the addition of quinone dye are documented to increase the risk of adverse reaction. Hydrophilic polymers need surface modification for cell adhesion and growth [173].