A patient limb positioning apparatus comprises a movement assembly operating on a coupling bracket which can be engaged with the patient's limb, to move the limb according to a plurality of axes of movement. The movement assembly comprises, for at least one of said axes of movement, a drive unit which can be activated to move the coupling bracket according to a predetermined direction of movement. A load transducer detects a load transmitted between the coupling bracket and the drive unit in the respective direction of movement, to emit a signal representative of a detected load value. An electronic control unit is selectively switchable to a load control command mode and is suitable to cyclically compare the measured load value with a pre-set load value, to control activation of the drive unit when the detected load value differs from the pre-set load value.