1. A surgical instrument including an articulation mechanism comprising: an endoscopic arm with proximal and distal portions pivotally connected by a pivot mechanism having a pivot axis, said distal arm portion containing an actuation mechanism; a flexible drive cable located within said pivot mechanism and passing through said pivot axis; a rigid backstop element secured in the pivot mechanism, wherein said backstop supports the drive cable on said pivot axis and includes a pivot connection to one of said arm portions at one end of said backstop and a slidable connection to the other said arm portion at the other end of said backstop; an articulation rod located within said proximal arm portion and longitudinally moveable therein, said articulation rod being pivotally connected to said distal arm portion such that longitudinal movement of said articulation rod causes said distal arm portion to angularly move relative to said proximal arm portion.