A surgical instrument insert 2 is provided for connection to a handle 4. It includes an outer shaft (6, fig 3) with a through bore； an inner rod (8, fig 3) mounted in the bore； and an operative portion 10 at a distal end of the outer shaft, actuated by relative movement of the rod and shaft. A retaining member, such as a nut 12, is mounted around the shaft wherein the retaining member includes an integral resilient member (36, fig 5) to reduce the risk of it accidentally sliding along the shaft of the insert, when not secured. In another aspect, the insert includes an enlarged element (18, fig 7) attached to the proximal end of the outer shaft, wherein the enlarged element has first and second portions (42, 44, fig 7) of different diameter and acts as an electrical insulator. The instrument may be used in keyhole surgery.
