Evaluation of a Powered Ankle Prosthesis Capable of Bidirectional Control Via Neural Recording and Cutaneous Stimulation in Free-Space and Walking Tasks

Inclusion Criteria: * Male or Female age 18-70. The patient must have a unilateral transtibial amputation . The patient must have the ability to ambulate at variable cadence (an expected lower extremity prosthesis functional level of K3 or above). The patient must have adequate socket to support the device. Exclusion Criteria: * Women who are pregnant. Severe co morbidity, atypical skeletal anatomy, or poor general physical/mental health that, in the opinion of the Investigator, will not allow the subject to be a good study candidate (i.e. other disease processes, mental capacity, substance abuse, shortened life expectancy, vulnerable patient population, BMI \>40, etc.).