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.