Over the last two decades, new materials (such as thermoplastics and fiber-reinforced composites) have improved the comfort and durability of sockets. However, the basic components and need for customization are largely unchanged. In this project, UC San Diego researchers have adopted a human-centered approach to designing a distributed infrastructure and workflow to overcome the challenge of offering more amputees access to prosthetic limbs, with a primary focus on lower limbs.

They are developing two user interfaces – a “virtual clinic” for the amputee, and a “virtual workshop” for the prosthetist – while integrating these interfaces into a workflow that results in the manufacturing of a 3D custom-printed socket:

• Virtual Clinic: Project engineers are designing a mobile-phone interface and functionality to be used by the amputee to scan the residual limb using photogrammetry via the cell phone camera to create a 3D model of the limb. The amputee effectively replaces the prosthetist in this part of the workflow, and the DIY process allows this critical work to be done from anywhere.  An outstanding question for developers of the photogrammetry system is to determine an optimal number of photos to be acquired via cell phone camera for creating a reliable 3D model of the residual limb. Researchers will also explore whether the photographic data should be processed directly on the smartphone (depending on available processing power and bandwidth), or uploaded to the cloud for processing.
• Virtual Workshop: Once the 3D computer model has been created by the amputee, it can be sent digitally to a prosthetist (anywhere), who would use the Virtual Workshop software and digital workflow that uses artificial intelligence and machine learning to manipulate and augment 3D limb scans to customize each model by applying compression zones where weight loading can be distributed on the residual limb (based on a database of compression zones based on the needs of earlier amputees, with the accuracy increasing as more data on compression zones is added to the database).
• Production Workflow:  The revised computer model from the Virtual Workshop would be sent to a next-generation 3D printer to generate a physical socket (which can be ‘printed’ anywhere). By focusing on 3D printing instead of the current labor-intensive hand-manufacturing process, the cost of building a prosthetic socket goes down substantially. As part of this process, project engineers will test various materials and printer resolutions to optimize usability versus cost.  Researchers at UC San Diego will collaborate with industry partner Hewlett-Packard, which is providing access to its HP Multi-Jet Fusion 3D Printer technology. The ultimate goal is to encourage the development of a Prosthetic Printer that could be located anywhere in the world to print the custom sockets designed in partnership between amputees and prosthetists.