A above knee prosthesis (P) applied to femoral connection (100) of an amputee that comprises a upper hinge (1) connected to femoral connection of the patient, an articulation axis (2) with the function of reproducing the knee movements, a tibia-calf muscle unit (3) pivotally connected to the femoral&bull；segment and a damper (5) that reproduces some functions of the calf muscle and ensures to the prosthesis to brake and to allow the sequential swing and stance phases typical of the gait. The damper comprises a cylinder (5c) wherein a piston (10) and a stem (9) act connected to each other and adapted to carry out a damping reaction of said damper responsive to the forces loaded on the prosthesis. In particular, a force transducer is provided in the damper arranged, in particular, in the stem with a microprocessor that receives a force signal from the transducer and operates means for adjusting the reaction of the damper responsive to the detected force signal.
