An above-
knee prosthesis that allows the user to control the resistance of 
knee flexion or extension, and to voluntary lock and release the 
knee joint, at any and all bending angles, comprising a 
thigh frame 
assembly that receives a 
thigh stump; a leg frame 
assembly with foot attached; a hinge interconnecting the 
thigh frame and leg frame assemblies to form an 
artificial knee joint; a closed hydraulic 
system further interconnecting the thigh frame and leg frame assemblies to provide resistance to the bending of said 
artificial knee joint, a means to vary the resistance provided by said closed hydraulic 
system, and a means to translate the AP movement of said thigh stump into the degree of resistance provided by said closed hydraulic 
system. In its preferred embodiments, the AP movement of the thigh stump is communicated by means of a linkage, sliding or screw 
assembly, to a flow 
rate control valve. The flow 
rate control valve varies the amount of the resistance provided by the closed hydraulic system controlling, thereby, the amount of resistance within the 
artificial knee. Pressing the thigh stump backwards within the thigh frame assembly increases the resistance within the hydraulic system and slows knee bending until the knee locks. Pressing the thigh stump forward decreases the hydraulic resistive force and allows the artificial 
knee joint to yield to outside forces, such as gravity and / or stump thrust, until the 
prosthesis rotates freely about the knee hinge. The above-knee prosthetic prevents the 
knee joint from giving way, promotes a balanced stance, and facilitates a near normal reciprocating gate while ascending and descending 
stairs and slopes.