Device for converting a mechanical cutting device to an electrosurgical cutting device

An adapter unit for a mechanical tissue cutting implement such as a shaver, morcellator or the like includes a mounting block from which an electrically insulating sheath extends. The sheath fits over the cannula or shaft of the cutting implement, and is secured in alignment and attached so that the cutting tip, for example, the tool and its window in the cannula tip, are exposed through the sheath. A conductor, which may be a conductive layer, extends along the length of the sheath and is exposed to form a distal electrode at the tip in close proximity to the opening, constituting one electrode of a bipolar electrode arrangement at the exposed tool. The other electrode is provided by electrical connection to the implement itself, so that a high current density path is formed through tissue in the cutting region. Preferably both output connections of an electrosurgical generator are coupled through a matching transformer to the mounting block by a plug, socket, cable or fixed cord arrangement, and the mounting block may, for example, be formed of plastic, preferably having an alignment feature such as a notch to fasten to the implement so that the sheath opening aligns with the cutter. Electrical connection to the implement may be effected via a conductive bushing, fastening bolt or the like which contacts one of the supply leads through a wire, spring or other conductive path. The adapter may also provide a sheath opening and distal electrode about a non-apertured region of the cannula, for example on the rear surface of the cannula opposed to the cutting tool aperture, to form a hemostasis element that may be rotated into position to coagulate bleeding. In this case the bipolar electrode geometry may be configured for high energy density delivery that does not vary with tool rotation. The adapter may also convert a monopolar device to bipolar operation, providing a single additional electrode positioned by the sheath at the cutting aperture.