Design and Preliminary Validation of Individual Customized Insole for Adults with Flexible Flatfeet Based on the Plantar Pressure Redistribution

Abstract

Flatfoot is a common musculoskeletal deformity. One of the most effective treatments is to wear individually customized plantar pressure-based insoles to help users change the abnormally distributed pressure on the pelma. However, most previous studies were divided only into several plantar areas without detailed plantar characteristic analysis. In this study, a new insole is designed which redistributes pressure following the analysis of characteristic points of plantar pressure, and practical evaluation during walking of subjects while wearing the insole. In total, 10 subjects with flexible flatfeet have participated in the performance of gait experiments by wearing flat insoles, orthotic insoles, and plantar pressure redistribution insoles (PPRI). The results showed that the stance time of PPRI was significantly lower than that of the flat insoles under slow gait. PPRI in the second to third metatarsal and medial heel area showed better unloading capabilities than orthotic insoles. In the metatarsal and heel area, the PPRI also had its advantage in percentage of contact area compared to flat insole and orthotic insole. The results prove that PPRI improves the plantar pressure distribution and gait efficiency of adults with flexible flatfeet, and can be applied into clinical application.

Keywords: 3D modeling; flatfoot; gait; insole; plantar pressure redistribution.

Figure 1

(a) Self-designed plantar pressure test plate; (b) Wireless insole.

Figure 2

Design process of PPRI. (a) Characteristic point data collection of plantar pressure; (b) 3D map of insole surface characteristic point cloud; (c) Insole software model preview; (d) PPRI 3D printing.

Figure 3

Conversion of pressure distribution to height information in each area (including T, M, MF, and H area). (a) Original pressure value. (b) Redistribution plan for the pressure value of four plantar areas.

Figure 4

Comparison of different insoles (a) PPRI; (b) Orthotic insole; (c) Flat insole.

Figure 5

The peak pressure of the T, M2, and MH area. * significant difference found between the PPRI and orthotic insole. ^† significant difference found between the PPRI and flat insole. ^‡ significant difference found between the orthotic insole and flat insole.