The design and manufacture of a personalized liner for lower limb amputees

The objective of personalization is to create a product that matches the exacting requirements of the individual consumer. Where these products must interface with the changing dynamics of the human form, traditional manufacturing techniques, coupled with traditional manufacturing paradigms do not enable efficient generation of personalized products. Particularly when they must encapsulate body-parts susceptible to variations in dimension through daily activity. Emerging 3D printing methods are limited to non-conforming rigid materials, with wide tolerance bands. This can make it difficult to generate soft material conforming products that precisely match a consumer’s needs. One such application is the creation of a personalized prosthetic liner for lower limb amputees. A residuum liner is the interface that amputees wear between their residual limb and prosthesis. The comfort of a prosthetic liner/socket can determine the daily duration for which patients use their artificial limbs and can also prevent further pathological issues. The purpose of this liner is to enable correct fitting. Current methods use a range of silicon ‘socks’ that encapsulate and cushion the residuum before placement inside the prosthesis socket. The silicon sock can cause skin irritation and damage and are not designed specifically for the individual. Our novel method enables the precise and rapid generation of soft material conforming products and is termed cryogenic CNC machining. This process involves the rapid, physical alteration of soft polymers to enable efficient and direct CNC machining. This paper presents a new data driven design and manufacture methodology that enables the creation of fully personalized residuum liners for a transtibial amputees.