| 摘要 |
An ultrasonic surgical tool has an elongate waveguide operatively connected or connectable to a source of ultrasonic vibrations. An operative element at a distal end of the waveguide has a diameter less than that of the waveguide. A connecting portion of intermediate diameter may connect the operative element and the waveguide. A proximal end of the operative element forms a first step junction, located at a nodal plane of ultrasonic vibrations in the waveguide and operative element, producing a velocity amplitude gain across the step junction. A second zero-gain step junction between the connecting portion and the waveguide is located at an anti-nodal plane. The operative element may include a curved distal cutting and welding element having a pair of elongate welding grooves defining a cutting edge. Alternatively, the operative element may include a welding element having a flat or slightly ridged operative face. |
