Hydraulic Prosthetic Leg A hydraulic prosthetic leg is a type of prosthetic leg that uses hydraulic fluid to control the movement of the knee joint. It is designed to simulate the natural movement and function of a real leg. The hydraulic system allows for smooth, controlled movement and stability, making it easier for the wearer to walk, run, climb stairs, and perform other daily activities. Hydraulic prosthetic legs typically consist of a socket that fits over the residual limb, a knee joint that is controlled by hydraulic fluid, and an ankle joint that provides support and stability. The hydraulic system is usually powered by a battery or a pump, and is controlled by sensors that detect the wearer's movements and adjust the fluid pressure accordingly. Both pneumatic (air) and hydraulic (fluid) systems mimic the muscles of the natural knee by responding to different walking speeds. Hydraulic knees tend to be heavier than pneumatic knees because they require fluids, but they also provide a smoother walking pattern over a wider range of speeds. Both hydraulic and pneumatic knees require frequent routine maintenance.