Understanding Medicare K-Levels and how they relate to prosthetic mobility. A K-level describes your current or expected mobility with lower-limb prosthesis. Medicare uses this classification to help determine coverage for certain prosthetic components. Understanding your level can help you discuss your needs, goals, and options with your care team. Matching Your Leg to Your Life K-levels, also called functional levels, run from K0 to K4. K-levels apply to lower limb prosthe