1. Introduction
The principal function of the vertebral column is to support loads. These loads can challenge both bone tissues of vertebral column (Ashish et al. 2013). To achieve the strongest fusion and the best clinical outcomes, several surgical procedures and fusion devices have been developed. Interbody techniques have been reported to effectively preserve the disc height and lead to better fusions. Interbody cages allow for a bone graft to be placed within the loadbearing column of the spine and can achieve osseous integration with adjacent end plates of the vertebral bodies (McGilvray et al. Citation2017).
Spinal implant, such as cages, are widely used for different indications, ranging from indisputable indications such as reconstruction of the destabilized spine by trauma and reconstruction after surgical resection of vertebral tumours to less clear reasons such as stabilization for degenerative spinal conditions (Moojen et al. Citation2014). Cage design and material properties play a crucial role in the long-term results, since interbody fusions using intervertebral cages have become one of the basic procedures in spinal surgery (Bozkurt et al. Citation2018).
Topology optimization in conjunction with the finite element method could be used to optimize the layout of limited implant material in order to meet specific performance criteria (de Jongh et al. Citation2008). This approach could lead to the development of novel implant geometries and topologies predicted to have robust mechanical fixation under pre-determined loading conditions while limiting the amount of implant material.
In this work we, explore an advanced reconstruction method of the spine in order to create a specific anatomy of each patient in a reduced time after the first diagnosis. This reconstruction of three dimensional (3D) CAD models was based on reverse engineering techniques (Chougule et al. Citation2014) and shall constitute a database for designers. On the basis of data provided by this method and load analysis, the goal is to propose a custom cage implant.
2. Methods
2.1. Patient populations and implant used
In our study the North African people’s anatomy was used to improve the treatments by designing a custom cage implants. In this order, the activities of populations influence the life.
2.2. 3D CAD models of spine and cage
The reverse engineering approach can be considered as a methodology to reduce risk and satisfy the constraints in systems engineering. Different techniques in engineering design are used and employed at each stage in the reverse engineering. Reverse engineering calls for the acquisition of dimensions on parts of various shapes (mechanical parts, medical devices…). As shown in . The medical field is among the areas that solicits this activity. We start from an existing physical patient and collect data from various scanners. In this work, Engineers and surgeons we obtained an ordered data because a scanline is obtained for each slicing plane. The system of digitization is very important and each application or part requires the use of specific system (coordinate measuring machine, 3D scanner, MRI scanner …). In the design process of a custom cage implant, the most difficult point is how to find a good contact and stability between the components and the implant.
2.3. Topologies optimisation and MEF analysis of custom cage implant
Our study will be carried out on two types of prosthesis of the lumbar part of the spine; they play the role of the interbody cage
To ensure a better compatibility between these models and the geometries of the reconstructed bone parts (the vertebrae of the lumbar part of the spine), an adaptation is made in order to bring the outer surfaces of these two implants closer to the 3 D CAD model of the bone. To finalize and improve the initial design of these two cages, an optimization analysis was done using SolidWorks-simulation.
Our optimization analysis for the design of the first cage takes 14 scenarios, the last two are eliminated, because the cage is deformed (takes a different geometry). We have chosen mass as an objective function. The minimum mass under the conditions required for cage design is given in scenario 12 (1.0640 g), which is the optimal choice as shown in .
Table 1. Different design topologies optimisation of custom cage implant scenario.
3. Results and discussion
In order to study the activities of people in North Africa and their influences from spinal, it is necessary to design the different element of the spinal, with regard the recommendation of surgeons and in cooperation with engineers. Therefore, this study develops the CAD environment and data collecting in the upstream design stage applying reverse engineering techniques help the development of this knowledge and the results significantly contribute to a custom cage implants.
Results obtained by Reverse engineering techniques are cloud of points. Exploiting this cloud is an increasing trend in the design process structure and Computer Aided Design practice.
The finite element analysis of the complete assembly is of a great significance because it is almost a complete knowledge of its mechanical behavior. During this analysis, we came to characterize the behavior of the two models, subject to various loads. At the end of this study, we can conclude through the results obtained that the first model is more reliable than the second in terms of deformation, and at the level of the realization the 2nd cage is more complex than the first one.
The product obtained and its influence on the amelioration of patient activities is the interest contribution of the new design implant.
4. Conclusions
The results of our study indicate different parameters obtained from the 3 D models reconstruction in order to design the custom cage implants. By reconstruction techniques we can save time for manufacturing and materially accurate in the vertebrae and discs of spine for the North Africa peoples.
Figure 1. Process to reconstruction of the spine and design a custom cage implants.
References
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