Ultrasonic surgical instruments

1. A surgical instrument, comprising:

a transducer configured to provide vibrations along a longitudinal axis at a predetermined frequency, the transducer comprising:

a piezoelectric stack positioned along the longitudinal axis;

a first metallic end mass positioned along the longitudinal axis adjacent a first end of the piezoelectric stack;

a second metallic end mass positioned along the longitudinal axis adjacent a second end of the piezoelectric stack, wherein the length of the transducer is greater than or equal to ¼ of one wavelength and less than ½ of one wavelength; and

an end effector extending along the longitudinal axis coupled to the transducer at a location offset from a nearest anti-node, wherein a length of the end effector is a non-integer multiple of ½ of one wavelength, and wherein a sum of the length of the transducer and the length of the end effector is an integer multiple of ½ of one wavelength.

2. The surgical instrument of claim 1 , wherein the end effector comprises a waveguide.

3. The surgical instrument of claim 1 , wherein the piezoelectric stack comprises a plurality of piezoelectric elements.

4. The surgical instrument of claim 1 , wherein the piezoelectric stack is positioned about at a node of the transducer, wherein the node is a point along the longitudinal axis about ¼ of one wavelength from an end of the transducer.

5. The surgical instrument of claim 1 , wherein the length of the instrument is about one wavelength.

6. A method for processing a surgical instrument for surgery, comprising:

obtaining the surgical instrument of claim 1 ;

sterilizing the surgical instrument; and

storing the surgical instrument in a sterile container.

7. The surgical instrument of claim 1 , wherein the sum, of the length of the transducer and the length of the end effector is about equal to ½ of one wavelength.

8. A surgical instrument, comprising:

a transducer configured to provide vibrations along a longitudinal axis at a predetermined frequency, the transducer comprising:

a piezoelectric stack positioned along the longitudinal axis;

a first metallic end mass positioned along the longitudinal axis adjacent a first end of the piezoelectric stack;

a second metallic end mass positioned along the longitudinal axis adjacent a second end of the piezoelectric stack, wherein the amplitude gain of the transducer is equal to one; and

an end effector extending along the longitudinal axis coupled to the transducer, wherein the end effector comprises:

a plurality of first sections positioned along the longitudinal axis having a first diameter;

a plurality of second sections positioned along the longitudinal axis between the plurality of first sections, wherein the plurality of second sections have a second diameter larger than the first diameter, wherein at least a portion of distally facing ends of the plurality of second sections are located at a first plurality of zero-displacement nodes, wherein at least a portion of proximally facing ends of the second sections are located at a second plurality of zero-displacement nodes, and wherein the first plurality and the second plurality of zero-displacement nodes do not include any zero-displacement nodes in common.

9. The surgical instrument of claim 8 , wherein the end effector comprises a waveguide.

10. The surgical instrument of claim 8 , wherein the amplitude gain of the ultrasonic surgical instrument is between about 10 and about 50.

11. A method for processing a surgical instrument for surgery, comprising:

obtaining the surgical instrument of claim 8 ;

sterilizing the surgical instrument; and

storing the surgical instrument in a sterile container.