Abstract
Purpose To determine the effect of biometrical parameters of the radial bone and due to edge defect formed on the radius strength properties using calculation methods. Materials and methods The study of bone strength affecting factors was conducted with the aid of experimental and calculation methods. Biometrical parameters were studied in 10 pairs of the human cadaveric radius as an intact bone initially and after the formation of rectangular or triangle-shaped edge cuts. To determine the stress-strain behaviour, mathematical calculations were performed based on the beam flexural theory for isotropic materials. Computation study were conducted using the finite element method with the NX Siemens software package. Based on assumed mathematical models, the actual areas of safe loads in the presence of cuts and values of destructive loads depending on the depth and shape of a cut taking into account the initial curvature of the bone as well as the criteria of a required residual strength in variation of influencing parameters were identified by means of calculations. Results It was established that an increase in bone curvature results in the reduction of longitudinal destructive loads and in increasing values of the normal strength. The 0.05 bone curvature combined with the 0.5 cut causes a decrease in the ultimate load by 20 times (up to 4.8 % for a rectangular cut and to 5.4 % for a triangular cut). A 0.5-deep cut in the bone which curvature is 0.05 enhances the normal stress by 6.9 times for a triangular cut and by 7.8 times for a rectangular one as compared to a bone without curvature. The critical values for the curvature and depth of the cut were established which permit to avoid additional bone reinforcement. Conclusion The strength of the radius with a maginal defect depends not only on the depth of a cut but on its location, shape and on the radius curvature.
Highlights
An important achievement of current reconstructive and restorative surgery is the development of precision technologies for the use of free grafts and non-free vascularized osteocutaneous grafts [1, 2]
(from the distal end of the radius), the bending moment in which is equal to М1 = 0.43 Nm; the dangerous section of the rectangular cutout is located at the distance z/l0 = 0.51, the bending moment in which is equal to М2 = 2.25 Nm
The dangerous section of the triangular cutout is in the zone of small moments under the action of physiological loads in contrast to the dangerous section of the rectangular cutout which is in the zone of medium loads
Summary
An important achievement of current reconstructive and restorative surgery is the development of precision technologies for the use of free grafts and non-free vascularized osteocutaneous grafts [1, 2] The use of such tissue complexes enables to achieve qualitatively new treatment results in many areas of reconstructive surgery, since adequate blood supply, primary union of bone fragments, their resistance to resorption as well as soft tissues recovery are provided, what is especially important in the elimination of tissue defects in various anatomical areas [1–7]. Such interventions inevitably lead to the formation of a marginal bone defect and are associated with donorsite morbidity, the management of which is a difficult problem and often worsens treatment results [8, 9]. It may cause significant cosmetic and functional disorders of the limb and prolonged treatment period [16–21]
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