An instrument (2) for use in manipulating an implant component, which has a face with two spaced apart edges, comprises a housing (4) and first and second arms (72,74) each having a finger (76,78) which can engage the implant component at respective edges of the face, the arms being mounted for sliding movement relative to the housing in which the fingers on the arms move along a common axis. A gear mechanism (70,124), by which the first and second arms are linked to one another, ensures that sliding movement of the first arm in a first direction relative to the housing is accompanied by equal sliding movement of the second arm in a second direction which is opposite to the first direction. A shaft (122) is mounted in the housing so that it can slide along a shaft axis which is perpendicular to the axis along which the fingers slide, the shaft has a bed (46) at its end for engaging the face of the implant component. The instrument includes a ramp surface (32,34,36,38) and a follower (125) which can move along the ramp surface with one of the ramp surface and the follower being fixed relative to the shaft so that the sliding position of the shaft relative to the housing along the shaft axis is determined by the position of the follower on the ramp surface. The position of the follower on the ramp surface varies according to the positions of the first and second arms relative to the housing.
