Showing papers by "Veronika Kralj-Iglič published in 2005"
TL;DR: The contact hip stress before and after the Bernese periacetabular osteotomy was determined and the relief of stress with the long-term radiographic and clinical outcome was compared.
Abstract: Background The Bernese periacetabular osteotomy is used in dysplastic hips to increase the load-bearing area of the hip and to prevent osteoarthritis.The aim of our work was to determine the contact hip stress before and after the osteotomy and to compare the relief of stress with the long-term radiographic and clinical outcome.Patients and methods We followed 26 dysplastic hips (26 patients) for 7–15 years after the index operation. Clinical evaluation was based on the WOMAC score, osteoarthrosis was evaluated with the Tonnis classification, the angles of lateral (CE) and anterior (VCA) femoral coverage were measured, and biomechanical parameters were studied.Results Periacetabular osteotomy increased the mean CE from 15° to 37°, and the mean VCA from 22° to 38°. The mean normalized peak contact stress was reduced from 5.2 to 3.0 kPa/N. Four hips required total hip arthroplasty after an average of 4.5 years, 8 hips showed considerable arthrosis progression, and 14 hips had no or mild arthrosis at follow-...
131 citations
TL;DR: It is suggested that the characteristic horseshoe shape of the articular cartilage in the human acetabulum optimizes the contact stress distribution in the hip joint.
Abstract: The biomechanical role of the horseshoe geometry of the acetabular cartilage is described using a three-dimensional mathematical model. It is shown that the acetabular fossa contributes to a more uniform articular contact stress distribution and a consequent decrease in the peak contact stress. Based on the results it is suggested that the characteristic horseshoe shape of the articular cartilage in the human acetabulum optimizes the contact stress distribution in the hip joint.
56 citations
TL;DR: In this paper, the authors generalized the Helfrich expression for the isotropic membrane bending energy by taking into account two intrinsic (spontaneous) curvatures, i.e., the intrinsic mean curvature Hm and the intrinsic curvature deviator Dm.
Abstract: The Helfrich expression for the isotropic membrane bending energy was generalized for the case of anisotropic membranes by taking into account two intrinsic (spontaneous) curvatures, i.e., the intrinsic mean curvature Hm and the intrinsic curvature deviator Dm. Using this generalized expression for the membrane bending energy the shape equation for closed axisymmetric anisotropic membranes is solved numerically for the case of undulated tubular shapes. It is shown that the variation of one of the two intrinsic curvatures, Hm or Dm, may induce the first-order-like shape transitions between the undulated tubular membrane structures. The predicted discontinuous shape transitions were applied to explain the beading transitions without stretching, which were recently observed in nerve fibres.
51 citations
TL;DR: It appears that not only isotropic but also strongly anisotropic inclusions can significantly contribute to the budding energetics, a finding that is discussed in terms of recent experiments.
Abstract: A membrane inclusion can be defined as a complex of protein or peptide and the surrounding significantly distorted lipids. We suggest a theoretical model that allows for the estimation of the influence of membrane inclusions on the curvature elastic properties of lipid membranes. Our treatment includes anisotropic inclusions whose energetics depends on their in-plane orientation within the membrane. On the basis of continuum elasticity theory, we calculate the inclusion-membrane interaction energy that reflects the protein or peptide-induced short-ranged elastic deformation of a bent lipid layer. A numerical estimate of the corresponding interaction constants indicates the ability of inclusions to sense membrane bending and to accumulate at regions of favorable curvature, matching the effective shape of the inclusions. Strongly anisotropic inclusions interact favorably with lipid layers that adopt saddlelike curvature; such structures may be stabilized energetically. We explore this possibility for the ca...
49 citations
TL;DR: The tubular budding may be explained by in-plane ordering of anisotropic membrane inclusions in the buds where the difference between the principal membrane curvatures is very large.
Abstract: Amphiphile-induced tubular budding of the erythrocyte membrane was studied using transmission electron microscopy. No chiral patterns of the intramembraneous particles were found, either on the cylindrical buds, or on the tubular nanoexovesicles. In agreement with these observations, the tubular budding may be explained by in-plane ordering of anisotropic membrane inclusions in the buds where the difference between the principal membrane curvatures is very large. In contrast to previously reported theories, no direct external mechanical force is needed to explain tubular budding of the bilayer membrane.
47 citations
TL;DR: In this article, it was shown that minimization of the elastic energy of the strip including the deviatoric contribution may explain the stability of the observed helical and twisted shapes of inorganic nano-strips (helix A and B).
Abstract: The elastic properties of a thin anisotropic nano‐strip are characterized by its intrinsic mean curvature and intrinsic curvature deviator. It is shown that minimization of the elastic energy of the strip including the deviatoric contribution may explain the stability of the observed helical and twisted shapes of inorganic nano‐strips (helix A and B).
16 citations
TL;DR: The estimated size of the vesicle containing cardiolipin was found to be smaller than the size of pure palmitoyloleylphosphatidylcholine vesicles.
Abstract: The effect of cardiolipin content on the shape and size of giant palmitoyloleylphosphatidylcholine/cardiolipin vesicles was studied. Unilamellar vesicles were prepared in sugar solution by the method of electroformation, from mixtures containing up to 50% weight ratio of cardiolipin. At room temperature the vesicles containing cardiolipin exhibited abrupt changes in the curvature of the vesicle contour indicating regions of phase separation. The deviations from the spherical shape were larger if vesicles were made from mixtures with a higher content of cardiolipin. Numerous vesicles with soft fluctuating walls were observed. The estimated size of the vesicles containing cardiolipin was found to be smaller than the size of pure palmitoyloleylphosphatidylcholine vesicles.
15 citations
TL;DR: It is found that an increased ion size reduces the number of counterions near the charged inner surface of the nanotube, leading to an enlarged electrostatic surface potential, which affects the electrical properties of cylindrical nanotubes filled with electrolyte solution.
15 citations
TL;DR: The computer system for quantitative determination of musculoskeletal geometry from computer tomography images has been developed and has flexible modular structure and is suitable also for educational purposes.
Abstract: The computer system for quantitative determination of musculoskeletal geometry from computer tomography (CT) images has been developed. The computer system processes series of CT images to obtain three-dimensional (3D) model of bony structures where the effective muscle fibres can be interactively defined. Presented computer system has flexible modular structure and is suitable also for educational purposes.
11 citations