To improve the quality and efficiency of the mesh in the finite element model of the knee joint by using the cell-based smoothed finite element method（CS-FEM）.

The gradient smoothing technique is introduced on the basis of the traditional finite element method, and CS-FEM is used to mesh the finite element model of the knee joint, and to compare which of the two methods（traditional finite element method and CS-FEM）is more accurate for the experimental data of the previous study.

CS-FEM is more accurate and reduces the complexity of meshing than the traditional finite element method, and reduces the number of cells, making the solution process more efficient.

The conventional FEM methods offer high computational accuracy and stability when dealing with relatively simple geometries and linear materials due to their wide application and maturity. However, in biomechanical simulation of complex structures and nonlinear materials, CS-FEM provides higher computational efficiency and accuracy by optimizing meshing and reducing stress concentration. Therefore, CS-FEM is expected to be more widely used in the modelling of knee joints and other complex bio-logical structures in the future.

To explore the plantar pressure characteristics of flat-footed amateur runners when running on different sports surfaces.

We selected 15 individuals using the foot print method and Novel emed ^® Amateur runners with flat feet diagnosed by 3D foot scanning（arch index≥0.6）and 15 normal foot controls. Using the Pedar-X 1.0 plantar pressure testing system, the maximum plantar pressure, contact area, peak pressure, pressure time integral, and total force impulse were synchronously collected while the subjects completed multiple straight-line running tests on three surfaces at a self-paced speed（4-6 m/s）. The differences between the groups were compared through repeated measurement variance analysis.

The pressure in the heel area（M3）and midfoot area（M2）of the flat-foot group was significantly higher than that of normal feet（P<0.05）, and the pressure in the anterior lateral area（T3）was significantly lower than that of normal feet（P<0.05）. The contact area of the entire sole of flat feet was larger than that of normal feet（P<0.05）, with the most significant difference in the midfoot area（M2）（P<0.01）. The difference in elastic surface was slightly reduced but still significant. The normal foot in the forefoot area（T1-T3）was significantly higher than that in the flat foot area（P<0.05）, and the pressure on the flat foot in the middle area（M2）of the plastic track was nearly 4 times higher than that of the normal foot（P<0.01）. The pressure time integral and total impulse of flat foot M2 were significantly higher than those of normal foot（P<0.01）, while the anterior lateral area（T3）was significantly lower than that of normal foot（P<0.05）.

When running with flat feet, the plantar pressure shows the characteristics of“overload in the midfoot area and insufficient force on the anterior lateral side”. The hard ground intensifies the instantaneous impact, and the elastic surface amplifies the accumulated load. It is suggested that flat-footed runners prioritize choosing a moderately elastic surface and pairing it with arch support equipment to reduce the risk of injury.