A surgical instrument includes a housing that supports an elongated shaft. A selectively movable drive rod extends through the elongated shaft and carries a cam pin in a longitudinal direction. An end effector for surgically treating tissue is supported by the elongated shaft and includes upper and lower jaw members pivotally coupled to one another about a pivot axis. The upper jaw member includes a first pair of laterally spaced flanges, and the lower jaw member includes a second pair of laterally spaced flanges defining a camming slot for engaging the cam pin. The flanges are arranged in an offset configuration where one flange of the upper jaw member is positioned on a laterally exterior side of a corresponding flange of the lower jaw member, and the other flange of the upper jaw member is positioned on a laterally interior side of the other flange of the lower jaw member.