Can the Entire Function of the Foot Be Concentrated in the Forefoot Area during the Running Stance Phase? A Finite Element Study of Different Shoe Soles

Abstract

The goal of this study was to use the finite element (FE) method to compare and study the differences between bionic shoes (BS) and normal shoes (NS) forefoot strike patterns when running. In addition, we separated the forefoot area when forefoot running as a way to create a small and independent area of instability. An adult male of Chinese descent was recruited for this investigation (age: 26 years old; body height: 185 cm; body mass: 82 kg) (forefoot strike patterns). We analyzed forefoot running under two different conditions through FE analysis, and used bone stress distribution feature classification and recognition for further analysis. The metatarsal stress values in forefoot strike patterns with BS were less than with NS. Additionally, the bone stress classification of features and the recognition accuracy rate of metatarsal (MT) 2, MT3 and MT5 were higher than other foot bones in the first 5%, 10%, 20% and 50% of nodes. BS forefoot running helped reduce the probability of occurrence of metatarsal stress fractures. In addition, the findings further revealed that BS may have important implications for the prevention of hallux valgus, which may be more effective in adolescent children. Finally, this study presents a post-processing method for FE results, which is of great significance for further understanding and exploration of FE results.

Keywords: feature classification and recognition; shoes; unstable conditions.

Figure 1

Pictorial illustration of the biomechanical steps applied to the investigation. A: Display of retroreflective markers placed on lower limb joints and segments; B: Description of the experiment setup designed to gather data on dynamics and kinematics; C: Outcomes of the muscular force; D: CT and MRI scans; E: Illustration of bones and cartilages; F: Illustration of muscles and ligaments; H: Illustration showing the two distinct types of shoes; G: Illustration of the simulation's ultimate output; I: Representation figure depicting the steps involved in creating BS.

Figure 2

A–E: Illustration of each muscle force (blue arrow: the value to take into the model); F: Illustration of EMG/activation of each muscle. The scale on the left of the image shows that 0 (no activity) ~ 1 (full activity); G: The angle between the sole and the ground; H: Illustration of the vertical GRF.

Figure 3

A: Illustration of fixed and loading condition; B: Vertical displacement validation of the model.

Figure 4

Illustration of the stress distribution of the 1^st–5^th proximal phalanx and metatarsal bones between BS and NS during forefoot running.

Figure 5

A–E: Results of the three different classification algorithm models between BS and NS during forefoot running, including the features classification and recognition accuracy rate in each contrasting scenario. F–J: Results of the total classification algorithm models between BS and NS during forefoot running, including the features classification and recognition accuracy rate in each foot bone. A and F: First 5% of nodes; B and G: First 10% of nodes; C and D: First 20% of nodes; D and I: First 50% of nodes; E and J: All nodes. K: Total classification and recognition accuracy of all features in the different nodes of MT and PP bones.