Abstract:Objective To study the topological structure of a new type of 3D printed height incresing insole insole for leg length discrepancy and its effect on lower limbs biomechanics. Methods The topological structure of the middle and rear part of the insole was optimized by Solid Isotropic Microstructures with Penalization, the force was loaded and the boundary conditions were set according to the force area of the insole, and the height incresing insole with TPU(Thermoplastic polyurethanes) material was printed by Selected Laser Sintering. The insole was used in 9 patients with leg length discrepancy, VAS and Maryland foot function score were used to compare the pain and foot function changes of patients before and after using insole, at the same time, the three-dimensional gait analysis system was used to compare the spatiotemporal parameters and vertical ground reaction force of both lower limbs. Results After wearing the 3D printed insole, VAS score decreased, Maryland foot function score increased, vertical ground reaction force of both lower limbs decreased, and the difference of cadence, stance phase and swing phase between the two lower limbs decreased. Conclusions The 3D printed height incresing insole insole after topology optimization can improve the coordination of lower limb movement, reduce the ground reaction force, relieve pain and improve foot function. It can provide an effective personalized orthopedic plan for the treatment of leg length discrepancy in clinic.