A comparative study of polyethylene and silicone insoles for patient-specific conditions using computational and experimental methods

Flatfoot is a very common condition that alters gait mechanics and is usually accompanied by pain. In this current study, two types of custom-made insoles using polyethylene and silicon, respectively, were designed to help alleviate this condition. Such insoles are tested for their functionality using advanced 3D printing and finite element analysis. Tests were conducted at body weights of 60, 80, 100, and 120 kg. Results indicated that silicone insoles outperformed the others by effecting a better redistribution of pressure with higher magnitudes of strain and stress. Specifically, silicon had strain values between 1.44 × 10⁻⁷ and 2.88 × 10⁻⁷, much lower than polyethylene’s 5.92 × 10⁻⁵–1.18 × 10⁻⁴. Whereby, silicon would withstand stress levels to about 47,058 Pa, while polyethylene would do so at 31,932 Pa, making it more resilient under higher loads. Further validation through kinematic analysis proved that silicon insoles enhance the symmetry of walk and disperses the concentration of pressures of the feet, therefore providing more comfort and support during locomotion. These results suggest that silicon insoles offer significant benefits for managing flatfoot, paving the way for future innovations in personalized orthopedic footwear.