Analysis 1.1. Comparison 1 Gene therapy versus no gene therapy control, Outcome 1 Amputation-free survival.. . Analysis 1.2. Comparison 1 Gene therapy versus no gene therapy control, Outcome 2 Complete ulcer healing.. . Analysis 1.3. Comparison 1 Gene therapy versus no gene therapy control, Outcome 3 Amputation (above-ankle amputation of the index limb