Ultrasonic surgical instrument blades

A method of balancing an ultrasonic instrument having an ultrasonically actuated blade, wherein the blade comprises a body portion and a step portion extending from the body portion, wherein the body portion comprises a first side, a second side, and a width defined between the first and second sides, wherein the step portion includes a first surface, a second surface, and a cutting edge situated intermediate the first and second surfaces, wherein the second surface extends between a first plane including the cutting edge and a second plane which is parallel to the first plane, wherein the first and second surfaces are not parallel and are oriented such that there is an angle defined therebetween, the method comprising the steps of:

• configuring at least a portion of the blade such that the relationship of:
• x
• 2
• 2
• ⋆
• (
• tan
• 
• 
• α
• )
• -
• 1
• +
• (
• w
• -
• x
• )
• 2
• 
• (
• x
• ⋆
• (
• tan
• 
• 
• α
• )
• -
• 1
• -
• s
• )
• -
• (
• w
• 2
• )
• 2
• 
• (
• tan
• 
• 
• α
• )
• -
• 1
• is substantially equal to zero;
• wherein w is said width of the body portion;
• wherein s is the distance between the first plane and the second plane;
• wherein α is said angle defined between the first and second surfaces of the step portion;
• and
• wherein x is the distance between the second side of the body portion and the cutting edge.