Advanced Process Chain for Manufacturing Individual 3D-Printed Insoles for Patients with Diabetic Foot Syndrome

The use of diabetic insoles is crucial for preventing and rehabilitating foot ulcers associated with diabetic foot syndrome. However, conventional insole manufacturing is often expensive, labour-intensive, and requires specialised expertise. Therefore, an advanced, partly automated manufacturing process chain for individualised 3D-printed insoles was developed, combining techniques such as 3D-scanning and additive manufacturing for diabetic patients. After scanning both feet, a virtual insole was loaded from a data library in the software, which automatically suggested the appropriate size and adjusted the heel support based on the plantar pressure distribution of the foot. The template of the individual insole was manually adjusted and the final insole was manufactured using a 3D-printer. A feasibility study was conducted involving five patients with diabetic polyneuropathic foot syndrome to compare the conventionally manufactured and 3D-printed insoles regarding the plantar pressure distribution, spatiotemporal gait parameters, and subjective comfort. The 3D-printed insoles showed a partially improved plantar pressure distribution in the descriptive analysis and only a slightly higher peak plantar pressure (n = 4; standing 2.0%, d = 0.09; walking 14.5%, d = 1.08). Marginally reduced gait velocity (n = 5, 14.0%, d = 0.40) was observed with the 3D-printed insoles, whereas the step length (n = 5, 2.5%, d = 0.18) remained similar for both insoles. No differences in the overall wearing comfort (n = 5, d = 0.16) were observed. In conclusion, the proposed process chain was feasible and the 3D-printed insoles showed indications of functional comparability to conventionally manufactured insoles. Therefore, they may represent a promising alternative for diabetic patients. However, larger comparative studies are required to confirm our findings.