Inclusion Criteria:  unilateral lower extremity amputation; age > 18 years; amputation-adjusted Body Mass Index between 18 and 25; ability to understand the instructions; ability to wittingly sign the informed consent form.  Exclusion Criteria:  other previous knee injuries or major surgical interventions at the lower limbs; comorbidities, such as neurological conditions, vascular diseases, or diseases of orthopedic, cardiac, or pulmonary origin; cancer disease in the site under examination; other neurological pathologies with impact on balance and gait.