Erosion fuse to reduce risk of RF tip detachment

An electrosurgical instrument end effector 40 comprising a treatment electrode 42 mounted in an insulative instrument tip 46 and an electrical connection 48 to supply radiofrequency (RF) energy to the electrode, the connection arranged to fail before the electrode. The components of the electrode are welded together in a configuration that prevents removal of the electrode from the tip. The electrode may be mechanically retained by one or more undercut protrusions 422,444 that may be at either end of the electrode, tessellating with recesses 462a,462b in the tip. The electrode connection may fail before the electrode by being made of a more quickly eroding material, by having a greater area exposed to RF plasma, a window in the insulative material, thin geometry of the connection, or a saline suction passageway that draws hot saline over the connection. The connection may fail in a time beyond normal use of the instrument.