The design and manufacturing of a Patient-Specific wrist splint for rehabilitation of rheumatoid arthritis

• Published in: Materials & design 2024-02, Vol.238, p.112704, Article 112704
• Main Authors: Zhou, Mo, Sun, Changning, Naghavi, Seyed Ataollah, Wang, Ling, Tamaddon, Maryam, Wang, Jinwu, Liu, Chaozong
• Format: Article
• Language: English
• Subjects: Finite element analysis; Rheumatoid arthritis; Topology optimisation; Wrist splint
• ISSN: 0264-1275
• DOI: 10.1016/j.matdes.2024.112704

[Display omitted] •A splint design strategy based on topology optimization was developed to achieve lightness and ventilation while maintaining functionality.•Fused filament fabrication (FFF) vertical printing is the most cost-effective option among different 3D printing processes.•The designed splint can maintain the wrist at 15.3–10.5° extension and 4.6–11.7° ulnar deviation with 18.7% grip limitation. Wrist splint is a device for immobilising the wrist to facilitate the healing of wrist injury. However, conventional splint designing strategies lack consideration of biomechanical interaction with wrist joints, resulting in mechanical failure of splints or causing patient injuries. A novel design and optimisation method of customised functional wrist splints is needed clinically. In this study, we proposed a splint design method combining topology optimisation and additive manufacturing, based on the biomechanical analysis, to enable advanced customisation regarding functionality, comfort and ventilation. Three prototypes were fabricated via fused filament fabrication (FFF) horizontal printing, FFF vertical printing, and powder bed fusion (PBF). Finite element analysis was used to simulate the displacements of splints under the maximum loading provided by patients, with the results validated by physical tests. The stiffness and functionality of splints fabricated by different techniques were evaluated and compared. The results demonstrate that the developed splint is compatible with patients' functional and biomechanical needs, limiting 95.7% sagittal movement, 89.8% coronal movement, and 18.7% maximum grip strength. Moreover, among the three manufacturing methods, FFF vertical printing is recommended for general clinical use considering the safety, functionality, surface quality and cost.