A knife having a blade tip configuration that reduces incisional force by providing a more efficient distribution of tissue piercing and cutting forces over the cutting edges. The distal tip of the blade has a profile in plan view in the region of approximately 150 microns from the distal most point of the tip that may be described by the equation w=ad n , where w is the distance from the blade's longitudinal axis to the blade's cutting edge, a is a constant of proportionality not greater than 0.5 and d is the distance along the blade's longitudinal axis from the extreme distal point of the blade tip. The extreme distal point of the tip has a slightly rounded, rather than pointy, profile, with a tip radius of approximately 40 microns or less.
1. A surgical knife, comprising:
a) a handle;
b) a blade having opposing cutting edges and a longitudinal axis, the blade being attached to the handle; and
c) a distal tip on the blade, the distal tip having an extreme distal point,
wherein the distal tip has a shape generally described by the equation
w=ad n
where
w is the distance from the blade's longitudinal axis to the blade's cutting edges
a is a constant of proportionality not greater than 0.5
n is an exponent approximately between 0.9 and 1.4
d is the distance along the blade's longitudinal axis from the extreme distal point of the blade tip.
2. The surgical knife of claim 1 wherein the distal tip has a thickness of approximately between 0.003 inches and 0.007 inches.
3. The surgical knife of claim 1 wherein an angle between the cutting edges is between approximately 12° and 20°.
4. The surgical knife of claim 1 wherein the distal point is slightly rounded, with a radius of less than approximately 40 microns.
5. The surgical knife of claim 4 wherein the radius is between approximately 10 microns and 40 microns.
6. The surgical knife of claim 1 wherein the blade contains a lubricious or friction reducing coating.
7. A surgical knife, comprising:
a) a handle;
b) a blade having opposing cutting edges and a longitudinal axis, the blade being attached to the handle and containing a lubricious or friction reducing coating; and
c) a distal tip on the blade, the distal tip having a slightly rounded end having an extreme distal point,
wherein the distal tip has a shape generally described by the equation
w=ad n
where
w is the distance from the blade's longitudinal axis to the blade's cutting edges
a is a constant of proportionality not greater than 0.5
n is an exponent approximately between 0.9 and 1.4
d is the distance along the blade's longitudinal axis from the extreme distal point of the blade tip.
8. The surgical knife of claim 7 wherein the distal tip has a thickness of approximately between 0.003 inches and 0.007 inches.
9. The surgical knife of claim 7 wherein an angle between the cutting edges is between approximately 12° and 20°.
10. The surgical knife of claim 7 wherein the rounded end has a radius of less than approximately 40 microns.
11. The surgical knife of claim 10 wherein the radius is between approximately 10 microns and 40 microns.