A surgical instrument includes a housing, a handle, an elongated shaft, an end effector assembly, a drive assembly, a support, a roller, and an extension depending from the handle. The end effector assembly includes a first jaw member and a second jaw member. At least one of the jaw members is movable with respect to the other jaw member. The drive assembly includes a drive bar extending at least partially through the elongated shaft such that longitudinal translation of the drive bar causes movement of the jaw members. The extension includes a proximal surface and a channel defined therein. The proximal surface is configured to contact a portion of the drive assembly such that movement of the handle with respect to the housing causes longitudinal translation of the drive bar. The channel is positioned for mechanical engagement by the roller.
