An Affordable 3D-Printable Suction Suspension Valvefor Transfemoral Prosthesis Users in LLMICs : Developing a locally manufacturable prosthetic suction-suspension valve to reduce dependence on costly commercial components

Sammanfattning

While access to assistive technology is a recognized human right, many transfemoral prosthesis users in low- and lower-middle-income countries (LLMICs) lack effective suspension because commercial suction valves are expensive, difficult to import, and not designed for the local context. In the first place, the aim of this project was to identify context-specific needs for a suction suspension valve in LLMICs. Secondly, the aim is to translate these needs into an affordable, 3D-printable valve design that can be manufactured locally, using Nepal as a practical reference context. A laboratory proof of concept was used to verify the main mechanical functions of the prototype. The method combined a literature review with two semi-structured interviews with Certified Prosthetists and Orthotists (CPOs) experienced in LLMICs. Findings were structured using the Human Activity Assistive Technology (HAAT) model and analyzed through inductive content analysis. The identified needs were translated into a MoSCoW-prioritised list of requirements, which served as the foundation for an iterative design process structured by the Double Diamond model. Nineteen physical prototypes were developed in Autodesk Fusion 360 and produced by 3D-printing. The final prototype was evaluated against the requirements and tested in a gait analysis laboratory. The findings show that affordability, local manufacturing, supply chain independence, environmental durability, modularity, and ease of use are the key context-specific needs. These needs were addressed in a nine- component valve, consisting of three 3D-printed parts and six locally available standard components, organised into a Socket Housing Assembly and a removable Valve Insert Assembly. Laboratory testing showed that the prototype maintained sub- atmospheric pressure under forces up to 102 N, more than 2.5 times the gravitational load of a reference transfemoral prosthesis, and that the automatic air expulsion and manual release functions worked as intended. The implications of this work are that 3D-printing combined with locally available standard components offers a realistic route to more accessible suction suspension in LLMICs. The design is grounded in needs that are shared across LLMICs, so it can serve as a starting point that can be adapted to other countries beyond Nepal. The project also shows the value of involving clinical professionals from the target context early in the design process. Limitations of this work are that only two interviews were conducted, end-users were not directly involved, all data collection was online, prototype testing took place in Sweden rather than in the intended context, and clinical testing with prosthesis users was outside the scope. The prototype should therefore be understood as an early-stage proof of concept rather than a market-ready product.