Articulated rod adjustable in flexion-extension

An articulated rod (10) adjustable in flexion-extension comprising a pair of arms (20), a pair of outer and inner cover plates (31, 32) and two rotation pins (24), engaged in through holes (23) of the pair of arms (20) and in through holes (33, 34) of the pair of cover plates (31, 32) to form a polycentric joint (11) articulating the pair of arms (20) in mutual rotation, wherein the rotation comprises a flexion rotation direction and an extension rotation direction, as well as two adjusting pins (27) integral with the arms (20), wherein the articulated rod (10) comprises a pair of discs (40), provided on at least a perimeter portion with a plurality of interlocking teeth (42) and a position indicating cursor (43), and comprises a locking element (50) adapted to engage with the plurality of interlocking teeth (42) of the pair of discs (40) and with at least the outer cover plate (31), wherein the discs (40) are axially hinged with the rotation pins (24) and are arranged partially overlapping on parallel rotation planes, wherein each disc bears a slot (44) shaped as an arc of a circle, which limits the movement of the adjusting pin (27) integral with each arm (20).