Exploring the feasibility of 3D printing in the treatment of diabetic foot ulcers

Diabetes is a chronic health condition affecting approximately 10.5% of the global adult population (537 million people) (Sun et al. 2022). The progressive nature of diabetes can lead to complications such as neuropathy, Charcot foot and diabetic foot ulcers. Approximately 25% of adults with diabetes develop diabetic foot ulcers (Hicks et al. 2020). Offloading by use of total contact cast has long been considered the gold standard for treatment of diabetic foot ulcers (Armstrong et al. 2001). A total contact cast is custom made for each patient, covering the lower leg and foot, and requires application by a specialist health care professional. Despite being the gold standard for treatment, monitoring of the wound is limited to weekly check-ups at outpatient appointments. There is a high time and resource cost associated with total contact cast treatment. 3D printing has the potential to reduce these time and resource costs, thereby expanding access to more patients.

In this body of work, the design requirements for an alternative to current total contact casts were identified through clinical observation, and expert feedback within the local diabetic foot clinic in Croom Orthopaedic Hospital, Limerick. With the requirement for large format 3D printing, fused deposition modelling (FDM) was identified as an appropriate technology to explore. The effects of process parameters on part strength and print time were investigated, and a design for a 3D printed total contact cast was developed. This design was reviewed and optimised as part of the iterative design process, and initial user testing was conducted on a healthy volunteer.

Design requirements were established that focused on offloading of the plantar region and immobilisation of the ankle. Process parameters were successfully adjusted to reduce the production time of FDM parts without negatively impacting part strength. A workflow to design and 3D print total contact casts using FDM technology was developed using an iterative design process. Initial testing of prototypes on a healthy volunteer yielded positive results - offloading was improved, immobilisation was achieved and weight was more evenly distributed compared to barefoot and wearing shoes. The outcome of this research was an optimised model for a total contact cast, suitable for 3D printing using FDM technology. This model met all the design requirements as established during expert review.