Interface joint for an electrosurgical apparatus

An interface joint with one or both of a needle actuation mechanism or an integrated shaft rotation mechanism. The interface joint comprises a flexible shaft between a housing and an electrosurgical instrument, e.g. for conveying power and/or fluid there between. The needle actuation mechanism comprises an actuation rod extending out of the housing and an actuator movably mounted on the housing. The shaft rotation mechanism comprises a rotation actuator rotatably mounted on the housing and operably coupled to the flexible shaft. Providing an integrated shaft rotation mechanism may obviate the need for a separate torque transmission unit. The improved needle actuation mechanism may use a pivoting connection to enable longer needle extension distances to be achieved for a given actuation distance.