The assistive devices for people with disabilities are configured as a set of mechanical, electromechanical, orthotic and prosthetic parts designed to assist in the rehabilitation process of patients who suffered amputation of their lower limbs, whether the injury generates The implementation of a transtibial or transfemoral prosthesis these elements must be performed with proper analysis of pre-amputation, amputation and post amputation in order to achieve specific objectives for each patient, achieving the best possible treatment. It is important to ensure that in the treatment of lower limb disability by amputation, the best decisions are generated for the patient, with the objective of bringing the patient closer to a normal gait pattern. Considering these characteristics it will be possible to elaborate a prosthetic element that meets the physical and personal characteristics of the patient such as activity level, age, weight ... etc. Taking into account each of these variables we have decided to analyze in depth a crucial element in the implementation of lower limb prosthesis such as the foot, which we carry from a phase of analysis, design, to implementation in carbon fiber where we currently perform tests with our patients under study.