Prosthetics involves the use of artificial limbs (prostheses) to enhance the function and lifestyle of persons with limb loss. The prosthesis must be a unique combination of appropriate materials, alignment, design, and construction to match the functional needs of the individual. These needs are complex and vary for upper and lower extremities. Lower limb prostheses might address stability in standing and walking, shock absorption, energy storage and return, cosmetic appearance, and even extraordinary functional needs associated with running, jumping, and other athletic activities. Upper limb prostheses might address reaching and grasping, specific occupational challenges such as hammering, painting, or weight lifting, and activities of daily living such as eating, writing, and dressing.