Design of a new prosthetic alignment adaptor with quantitative alignment and height adjustment

Current alignment of transtibial prostheses is based on the prosthetist´s subjective opinion and on trial and error fittings. The adaptors used to align prostheses are inexact, time-consuming to operate, and do not allow height adjustment. The primary objectives of this design project were to 1) develop an alignment adaptor that allows a prosthetist to quickly and effectively align the device based on a patient´s gait and stance, and 2) provide the ability to quantify the patient´s specific alignment. Using computer aided design (CAD), finite element analysis (FEA), and computer aided manufacturing (CAM), a new alignment adaptor was designed and manufactured using a novel pin configuration that allows for independent height adjustment. The prototype will be tested in a prosthetist´s office using two AMTI AccuSway force platforms to measure the forces, moments, and center of pressure distributions during stance and gait. Results will be used to compare three situations on each patient: no alignment, alignment with gold standard device, and alignment with new prototype. Additionally, surveys will be conducted of the prosthetist and patient to obtain qualitative feedback. The design is innovative in its quantization and height adjustment, and results of the testing are expected to show improvement over current adaptors.