A Step Change in LMIC Prosthetics Provision through Computer Aided Design, Actimetry and Database Technologies Approximately 100M people worldwide need prosthetic and orthotic (P&O) devices [1]. Low-cost, robust devices are only half the story; an estimated 80-90% do not have access to P&O services "due to a shortage of personnel, service units and health rehabilitation infrastructures" [2]. All three barriers could be addressed by data, so we propose research into novel tools to enhance P&O data.  Access is particularly poor for people in Lower and Middle Income Countries (LMICs) such as Cambodia with its landmine legacy, who are typically young and live longer lives of more physical work than in the developed world, for whom most prosthetics technology has been developed. LMICs have higher levels traumatic amputation from accidents, conflict and landmine injuries, and humanitarian crises present particular access challenges [3]. Services are set up primarily for trauma injuries but by 2035 it is estimate diabetes may affect over 500M people, and is growing fastest in LMICs [4].  Through the International Society for Prosthetics and Orthotics (ISPO), substantial improvements have been made in P&O design and training for LMICs [2,5]. An overwhelming patient:clinician ratio remains and "the development of the sector is too slow ... to meet existing needs or keep pace with the growing populations of people with disabilities" [2]. Even with ISPO accredited training, in South East Asian LMICs it is estimated that three times the current number of clinician is required for the current amputee population [6].  We will conduct two data-technology research studies, to develop tools to improve P&O service access, train clinicians and improve efficiency of service funding use. With a team of expert clinicians, academics and policy makers in Cambodia, we will investigate: 1) digital measurement tools to assess a user's residual limb anatomy, biomechanics of gait, typical daily prosthetic limb use, and health status; and 2) the architecture for a portable digital patient casenote system: a robust and secure IT network for travelling prosthetists to visit provincial areas to provide evidence-based treatment for those in remote communities who cannot afford to travel.  Beside these scientific challenges, the context makes this work highly ambitious. Experience shows that care must be taken in applying P&O from Western countries directly in LMICs. As well as users' different needs, their relationship with clinicians and prosthetics are different for complex cultural, social and environmental reasons. We frame our scientific research using a first-of-kind ethnographic study of P&O service providers and users to ensure the developed technologies are practical. We will also conduct business modelling research, producing tools to ensure the technologies are cost effective and can be implemented sustainably.  These technologies have the potential to transform the quality of life of prosthetic limb users worldwide and are required today. A more portable P&O service would enable people to access provision, fitting, adjustment and repair of their prosthetics with reduced time off work - essential where an agricultural worker spends their day's earnings on the same day's food. Prosthetists would access and update casenotes for their patients, provide a repository for clinician training, and enable users to access information regarding their progress and report problems to obtain critical treatment.  Longer term the project results will enable a valuable database to become established. The data will enable selection of technology that delivers greatest quality of life benefit, making best use of limited budgets [7]. It will support academics and trainee healthcare providers in research and education. We have a network of Asia's most influential clinicians, educators and policymakers to help achieve these ambitious benefits. Finally, the research will return benefits to the UK - we do not yet have a unified P&O digital record system and database. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.