Nicolae Florin Cofaru

Opening wedge high tibial osteotomy (OWHTO) is a surgical procedure often used to eliminate the effects of knee osteoarthritis, a disease that is becoming more widespread worldwide. Optimizing the geometric planning of this operation is a very important preparatory step for the success of the intervention and rapid postoperative recovery. This optimization is performed in two main directions. The first direction evaluates the intraoperative behavior of the tibia during the osteotomy by optimizing four geometric parameters that characterize geometric planning. The second direction aims at a postoperative evaluation of the flat tibia-osteosynthesis assembly taking into account the optimal position on the medial–lateral articular line through which the corrected mechanical axis of the tongue passes and implicitly offloads the transfer from the medial area to the side of the knee. The research methods used are exclusively computer-assisted such as: computer-aided design (hereinafter CAD) for geometric modeling of the tibia taking into account the real bone structure, the finite element method (hereinafter FEM) for performing numerical analyses and design of the experiment (hereinafter DOE) for the design of the research. The results obtained are eloquent and clearly presented and can be important elements for orthopedic doctors at the geometric planning stage of the OWHTO.

This article presents an experimental approach to the geometrical planning of the medial opening wedge high tibial osteotomy surgery which, as it is known, is an efficient surgical strategy quite widely used in treating knee osteoarthritis. While most of the published papers focus on analyzing this surgery from a medical point of view, we suggest a postoperative experimental evaluation of the intervention from a biomechanical point of view. The geometrical planning and, more specifically, the determination of the point of intersection between the corrected mechanical axis and the medial-lateral articular line of the knee, is a problem quite often debated in literature. This paper aims to experimentally investigate the behavior of the tibia with an open wedge osteotomy fixed with a locking plate, TomoFix (DE Puy Synthes), taking into account two positions of the mechanical axis of the leg on the width of the tibial plateau, measured from medial to lateral at 50% and 62.5% (Fujisawa point), respectively. The variations of the force relative to the deformation, strains, and displacements resulting from the progressive loading of the tibial plateau are studied. The research results reveal that using the Fujisawa point is better for conducting the correction not only for medical reasons, but also from a mechanical point of view.

Background and objectives: Osteoporotic spine fractures represent a significant factor for decreasing quality of life in the elderly female population. Understanding the mechanisms involved in producing these fractures can improve their prevention and treatment. This study presents a biomechanical method to produce a vertebral fracture, conducted on a human spine segment, observing the displacements and strains in the intervertebral disc, endplate, and vertebral body. Materials and Methods: We performed two tests, one corresponding to an extension loading, and the second to an axial loading. Results: The maximum displacement in the target vertebral body presented higher values in the case of the extension as compared to the axial strain where it mainly occurred after the fracture was produced. The strains occurred simultaneously on both discs. In the case of the axial strain, due to the occurrence of the fracture, the maximum value was recorded in the spine body, while in the case of the extensions, it occurred in the neural part of the upper disc. The advantage of this method was that the entire study was an experiment, using optical methods, increasing the precision of the material data input. Conclusions: The research method allowed recording in real time of a larger amount of data from the different components of the spine segment. If there was an extension component of the compression force at the moment of the initial loading, part of this load was absorbed by the posterior column with higher mechanical resistance. After the maximum capacity of the absorption was reached, in both situations the behavior was similar.

This paper provides an analysis from a biomechanical perspective of the medial opening wedge high tibial osteotomy surgery, a medical procedure commonly used in treating knee osteoarthritis. The aim of this research is to improve the analysed surgical strategy by establishing optimal values for several very important parameters for the geometric planning of this type of surgical intervention. The research methods used are numerical and experimental. We used finite element, a numerical method used to study the intraoperative behavior of the CORA area for different positions of the initiation point of the cut of the osteotomy plane and for different correction angles. We also used an experimental method in order to determine the maximum force which causes the occurrence of cracks or microcracks in the CORA area. This helped us to determine the stresses, the maximum forces, and the force-displacement variations in the hinge area, elements that allowed us to identify the optimal geometric parameters for planning the surgery.

In this paper we present a design method for a modular device used in different types of HIGH TIBIAL OSTEOTOMY surgical procedures. The requirements, necessities and functions of this modular device are presented in the first part of the article. An important aspect is the fact that the device must be designed in a manner which permit to use it for all types of HIGH TIBIAL OSTEOTOMY: opening wedge osteotomies, closing wedge osteotomies, medial osteotomies, lateral osteotomies, uniplanar osteotomies or biplanar osteotomies. This fact is possible using modular elements for the main parts of the devices. The researches could be the starting point for others researches regarding the appropriate materials and the possibility to execution customized several parts of the modular device using Additive Manufacturing facilities.

The paper is an interdisciplinary medical and engineering approach that aims to optimize the accuracy of the High Tibial Osteotomy surgical intervention. The axial deviations of the human inferior limb are presented in the first part of the paper. Without altering the shape of the bones, these deviations cause the wear of the knee’s articular cartilage by gonarthrosis. One of the most common and effective treatment modalities for eliminating axial deviations is High Tibial Osteotomy. Because the surgical procedure involves 3D spatial bone cutting, the accuracy of the procedure and thus the success of the operation and the recovery of the patient is dependent on the execution of these cuts. Within this paper, a specialized device is proposed that makes it possible to guide the surgical saw and to accurately perform the correction angles. In the last part of the paper, customization possibilities and fabrication of the main elements of the cutting device using Additive Manufacturing processes are presented.

The article proposes a generalised CAD modeling for a surgical strategy applied to the axial deviations of the human leg. These deviations appear most of the cases from a most common disease nowadays, ghonartrosys characterised by usage of the knee’s articular cartilage. The surgical strategy is HIGH TIBIAL OSTEOTOMY and it is very appropriate in order to correct the axial deviation due several reasons such as: repair with good results the axial deviations, good rate price/quality, strongly recommended method for young patients, not needed a maintenance activity as in case of the prosthesis. In the article it starts with the presentation of the mechanical axis of the lower limb and of the axial deviations that might appear and then using the CAD type modeling tools it is simulated and modelled the surgical procedure: Closing High tibial osteotomy. The approach is very important both from didactically consideration and possible evaluations presurgical, intrasurgical and postsurgical.

The study shown in this paper presents the behavior of geomembranes used at the ecological landfills. The influences of the solar radiations has a great importance regarding the correct mounting of the geomembranes. The mathematical model developed for the determination anytime and anywhere in the world for the next values and parameters: apparent solar time, solar declination, solar altitude, solar azimuth and incidence angle, zone angle, angle of sun elevation, solar declination, solar constant, solar flux density, diffuse solar radiation, global radiation, soil albedo, total radiant flux density and relational links of these values. The results of this model was used for creations an AutoCAD subroutines useful for choosing the correct time for correct mounting anywhere of the geomembranes