Design, manufacture and evaluation of an offloading 3D printed wheelchair cushion

Recent developments in additive manufacturing have made possible the fabrication of custom clinical devices like wheelchair cushions that are tuneable, comfortable, and capable of achieving pressure offloading to reduce the risk of pressure injuries developing. However, no published research has demonstrated that 3D printed cushions have equivalent performance to their traditionally manufactured counterparts, which is a requisite first step towards this vision. To address this gap, this paper compares a variable stiffness 3D printed thermoplastic polyurethane gyroid wheelchair cushion with a conventional multilayered foam cushion.

The cushion was designed and printed in four sections, enabling the use of consumer grade 3D printers. The 3D printed cushion was designed with varying stiffness regions to offload pressure. Twenty-one healthy adult subjects (11 men, 10 women, age range 19-48 years, mean weight 76 kg) sat on both cushions in a blind study. Participants completed a comfort survey and cushion temperature was measured using infrared thermography. Pressure mapping data was collected for three additional subjects to compare peak contact pressure and pressure distribution across cushions.

The 3D printed and foam cushions performed equally in terms of comfort, pressure, and temperature. Notably, participants were unable to identify a difference in them when seated. Contact pressure measurements were similar across both cushion types. The 3D printed cushion was significantly cheaper and able to be customised to a specific patient at little additional cost.

It was concluded that 3D printed cushion can match the performance of an existing standard of care cushion. This provides the foundation for future development of personalised 3D printed cushions offering significant advances in affordability, comfort, and pressure reduction, for wheelchair users.