Microprocessor (MP) controlled knees have evolved into fantastic tools that offer prosthetic wearers unmatched stance phase stability and ease of swing. These characteristics make them a great choice for many prosthetic wearers. MP knees differ from conventional knees because they can distinguish between heel load and toe load. Stance release is safe-guarded and only triggered when 3 specific criteria are met. These stance characteristics make MP knee units the safest option for all types of ambulation. The Rheo Knee developed by Hugh Herr and Ossur as well as the C-leg developed by Otto Bock are exceptional choices for above knee amputees to tackle the challenge of ambulating with a transfemoral prosthesis.