University of Twente Student Theses


Standardization of offloading devices for the treatment of diabetic foot ulcers by 3D printing

Moormans, L.R. (2020) Standardization of offloading devices for the treatment of diabetic foot ulcers by 3D printing.

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Abstract:Background: Diabetic foot ulceration is the most common complication in diabetes, affecting up to one-third of people with diabetes. Treatment of diabetic foot ulcers consists of reducing excessive mechanical stress by redistributing the plantar pressure with offloading devices. The choice and fabrication of these devices are commonly based on clinical experience and a trial-and-error approach. Furthermore, the current golden standard offloading devices are handmade and customized, resulting in a time-consuming and expensive fabrication process. These disadvantages may be overcome by developing a standardized method using objective measures, such as 3D scanning and printing, for the creation of offloading devices. Aims: The main objective of this proof-of-concept study was to create a method to develop offloading devices using 3D scanning and printing. Sub-objectives were: (1) to determine the inter-performer reliability of and geometric differences between different 3D foot scans and a plaster cast sole, (2) to design and 3D print shape-based and pressure-plus-shape-based insoles, (3) to measure and compare the plantar pressure distribution of the 3D printed insoles and the conventional offloading devices and (4) to present a conceptional workflow to create 3D printed offloading devices based on 3D foot scans. Methods: To measure the inter-performer reliability, three plaster cast masters obtained foot impressions of six healthy subjects independently. The foot impressions consisted of a plaster sole and three 3D foot scans in a different weight-bearing conditions. The mean difference and intra-class correlation coefficients (ICCs) were calculated for several foot parameters. Of the two 3D scans with the highest inter-performer reliabilities, insoles were designed and manufactured using 3D printing for three healthy subjects. Furthermore, insoles were developed using both a 3D scan and a barefoot plantar pressure measurement. In-shoe peak plantar pressures of the 3D printed insole designs and the conventional offloading devices were measured. In addition, a 3D printed shoe was developed based on three 3D foot scans. Results: The non-weight-bearing 3D scans showed excellent ICC values for all foot parameters. Nevertheless, poor ICC values were observed for the medial arch height of the semi-weight-bearing foot scan. Furthermore, the non-weight-bearing 3D scan most closely resembled the shape of the plaster cast sole. The insoles based on a non- and full-weight-bearing foot scan were designed and 3D printed in TPU. The full-weight-bearing insoles showed the lowest peak pressures compared to the non-weight-bearing insoles. Moreover, the pressure-plus-shape-based insoles showed a reduction of 3.2% and 4.8% in plantar peak pressures compared to the shape-based insoles. Conclusion: This study gave insight into the differences between 3D foot scans in different weight-bearing conditions and plaster casts in reproducibility, geometry, and plantar pressure distribution. Based on the designs and results of this study, the WB scan is most appropriate to use for the insole design. Furthermore, the use of barefoot plantar pressure measurements in the workflow provides objective measures to implement pressure-relieving features to the insole model. The created insole designs were not viable yet to implement in clinical practice. Further research must be conducted to create and test new prototypes on patients to ensure ulcer protection and improvements in plantar pressure relief.
Item Type:Essay (Master)
UMC Utrecht
Faculty:TNW: Science and Technology
Subject:44 medicine, 50 technical science in general, 51 materials science
Programme:Technical Medicine MSc (60033)
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