Structural integrity of 3D-printed prosthetic sockets: an experimental study for paediatric above-knee applications

Introduction of 3D printing into manufacturing of prosthetic sockets raised a question of structural integrity of such products. Prosthetic sockets, as customized products, cannot be directly included in a standardized testing protocol like other major parts of the prosthesis; this makes their mechanical assessment challenging. In this study, a prototype testing rig was developed according to BS EN ISO 10328, able to recreate the loading conditions of the early stance of the amputee gait on a paediatric transfemoral socket. A variety of above-knee prosthetic socket designs were 3D printed in PLA and carbon-fiber-reinforced nylon. The sockets were tested under static compressive load using the developed rig together with a silicone-rubber phantom limb with mechanical properties similar to those of the human tissue. New load requirements were calculated for the case of a 14-year-old male weighting in the 98th percentile. After initial design improvements, the 3D printed sockets were able to sustain loads up to five times the weight of the user without failing.