Abstract: A surgical instrument is configured to reduce conductivity between an RF electrosurgical portion and a cutting portion. This reduces improves the efficiency and consistency of the generated RF field, with higher current densities nearest the target tissue, improving the performance of the RF electrosurgical instrument. The conductivity may be reduced using a layer of insulating material, a projecting insulating portion or a cutting portion constructed from an insulating material. Further, by providing a lubricous insulating layer shedding may be reduced, increasing the usable life of the cutting portion.

Abstract: A handpiece for a surgical instrument having a valve position sensing circuit arranged to detect the position of a valve arranged to control the flow of fluid through the suction lumen of the instrument. The distal end of the handpiece is arranged to couple to a cutting accessory. The handpiece comprises: a housing; a suction lumen within the housing extending from the distal end of the handpiece to a proximal end of the handpiece; a valve arranged to control the flow of fluid through the suction lumen; and a valve position sensing circuit arranged to detect a position of the valve. The valve position sensing circuit can be used to alert a surgeon if the valve is closed when it would be preferable for it to be open. For example, if the motor is overheating, the in-joint temperature is too high, or the RF component is activated.