Abstract: The invention provides an impactor for transmitting an assembly force to a component of an orthopaedic implant. The impactor has first and second telescoping parts which are biased apart by means of a main spring. The main spring is compressed when an assembly force is applied to the parts. An indicator is latched against movement until it is released when the extent of the compression of the main spring by the application of an assembly force exceeds a threshold. The indicator then moves to provide the user with an indication that a minimum assembly force has been applied.

Abstract: An instrument for removing tissue from a bone to create a cavity consists of an approximately spherical body having cutting formations in its external surface for cutting a bone. The body has a connector by which it can be connected to a drive by which it can be rotated about an axis, and a recess at the pole, opposite the connector. When the instrument is applied to the surface of a bone and is rotated about its axis, bone is cut as a result of the action of the formations against the bone, and a circular region of bone adjacent to the polar recess in the body remains generally intact.