- The index leg will be the leg with the greater severity of CLI disease. Entry requirements apply to the index leg. The index leg may also be referred to as the treated leg or affected leg in the text of this protocol or other study documents. If the subject has two legs that have the same Rutherford classification (severe Rutherford 4 or Rutherford 5) and are both eligible for treatment, the leg with greater disease severity (based on more extensive necrosis or more extensive/deeper ulceration(s), difference in ABI or TBI ≥ 0.1, and/or more extensive vascular disease based on the angiogram) will be chosen as the index leg. If there is no clinical, hemodynamic or angiographic or other evidence to determine which leg has greater disease severity, the subject will be excluded from the study.