US Patent 7198625 Surgical instrument with retractable sheath

An electrosurgical suction/irrigation instrument includes a shaft hub, an electrically conductive member, and a sheath. The conductive member has a proximal end mounted to the shaft hub and a distal end including a conductive operating tip. The sheath covers the conductive member so that the operating tip is covered when the sheath is in an extended position and exposed when the sheath is in a retracted position. The sheath hub is coupled to the sheath and is movably engaged with the shaft hub. The surgical instrument further includes a locking mechanism to lock the sheath in the retracted position, and a bias element to bias the sheath toward the extended position.