Biomechanical evaluation of insole subjected to single-leg landing

Abstract

Badminton games are based on footwork techniques. Among badminton players, 92% of leg injuries have been recorded. In preventing the injuries, insoles are widely used in sports where insole’s wall height, heel cup, arch-support height, thickness, and material properties will influence the stress, displacement, and rotation angle value of foot. Furthermore, the insoles are used to treat misalignment of foot and diabetes ulcers. However, there are still lacking in the analysis on insole during single-leg landing. This study was conducted with the main aims to establish a static analysis on three different insoles of badminton athletes during single-leg landing and to modify the material of pre-fabricated insoles for better performance in terms of shock absorption during single-leg landing. Three-dimensional (3D) finite element models of ankle-foot complex consisted of skin, talus, calcaneus, navicular, three cuneiform, cuboid, five metatarsals, and five phalanges were segmented from computed tomography (CT) data. The midsole and outsole were designed using 3-Matic software and three pre-fabricated insoles; insole 1 (Yonex Active Pro Truactive), insole 2 (Li-Ning L6200LA) and insole 3 (Victor VT-XD 8) were 3D scanned. In completing the ankle joint, a total of 21 ligaments were modelled. The single-leg landing was simulated with 2.95° of ankle plantar-flexion. On the superior surface of the skin, the load of 2.57 times bodyweight was applied, and the inferior surface of the outsole was fixed. The results showed the insole 3 is the most optimum in portraying the lowest peak stress on the metatarsals (3.807 MPa). Besides, the insole 3 recorded the least displacement value (10.81 mm) and acceptable bone rotation angle (3.29°). The insole 3 with ethylene-vinyl acetate medium density (EVA MD) material perform better compared to polyvinyl chloride (PVC) and ethylene-vinyl acetate low density (EVA LD) the lowest metatarsals’ peak stress (3.554 MPa), displacement (13.08 mm), and bones rotation angle (2.93°) were recorded. Further design of the custom insole based on insole 3 and EVA MD material produced the lowest peak metatarsal stress (3.210 MPa) and displacement (8.99 mm), and bones rotation angle of 1.80°. This study contributes to the better understanding on biomechanics during single-leg landing hence lead to better insole development.