 In the prosthetics industry a trans-femoral prosthetic leg is often referred to as an "AK" or above the knee prosthesis.A transtibial prosthesis is an artificial limb that replaces a leg missing below the knee.A transtibial amputee is usually able to regain normal movement more readily than someone with a transfemoral amputation, due in large part to retaining the knee, which allows for easier movement.