ABSTRACT
Objective To evaluate surgeons' performance in resecting CAM-type deformities using a realistic arthroscopic surgery simulator. Methods An arthroscopic simulator was created using low-cost materials with the help of a GTMax Core A1 3D printer and the programs Invesalius and Meshmixer 2017, which were used to develop femoral head parts in ABS material, with the presence of a CAM-type deformity, to mimic a femoroacetabular impact situation. After the operations were performed by 16 surgeons, the femurs were compared to a previous model with deformity and another without, using Cloudcompare, and parameters such as the volumetric difference between the operated femurs, with and without deformity, the minimum and maximum distance between them, the percentage of the deformity resected, the estimated time for total resection of the deformity, as well as a qualitative analysis based on the images and graphs provided by the program representing the areas of the parts resected, were evaluated at the end. Results The average resection speed was 34.66 mm 3 /min (SD = 46 mm 3 /min, max = 147.33; min = -2.66). The average resection rate was 26.2% (SD = 34.7%, max = 111; min = -2). Qualitative analysis showed hyporesection of deformities and sometimes hyperresection of nondeformed areas. The simulator was highly rated by the surgeons, with a tactile sensation very similar to real surgery, according to them. Conclusion Arthroscopic simulators have proved very useful in training less experienced surgeons.
ABSTRACT
The knowledge of contact forces in teeth surfaces during mastication or para-functional movements can help to understand processes related to friction and wear of human dental enamel. The development of a numerical model for analysis of the occlusal contact between two antagonistic teeth is proposed, which includes three basic steps: the characterisation of the surface roughness, its homogenisation using an assumed distribution function and the numerical determination of the resulting forces. Finite element strain results for the main different asperities are statistically combined, deriving the predicted macroscopic behaviour of the interface. Axisymmetric and 3D numerical models with an elasto-plastic constitutive law are used to simulate micro-indentations and micro-contacts, respectively. The contact is allowed to occur locally in planes not necessarily parallel to the surface's mean plane, a problem for which there is no analytical solution. The three identified parameters, homogenised surface hardness (3.68 GPa), surface yield stress (3.08 GPa) and static friction coefficient (0.23), agree with the experimental values reported in the literature.
