1. An apparatus for severing an anatomical structure, comprising:
a single elongate body having a longitudinal axis, including:
a proximal end,
a distal end,
two parallel tubular members, each tubular member extending a length of the body parallel to the longitudinal axis and each having a distal opening disposed at the distal end of the body and a proximal opening disposed at or near the proximal end of the body, wherein the distal openings are opposed perpendicularly to the longitudinal axis, and
a flexible cutting member adapted to be threaded into one tubular member through its proximal opening, out its distal opening, into the other tubular member through its distal opening, and out its proximal opening, such that the flexible cutting member is parallel to the longitudinal axis in the tubular members and is perpendicular to the longitudinal axis between the distal openings,
wherein the distal end is adapted to receive an anatomical structure, and wherein the distal end is adapted sever the anatomical structure using the cutting member.
2. The apparatus of claim 1, further comprising an arcuate base adapted to receive the anatomical structure.
3. The apparatus of claim 1, wherein the distal openings are angled so that a top of the distal openings is more distal than a bottom of the distal openings to increase cutting efficiency.
4. The apparatus of claim 1, wherein a surface of the body is curved to aid the body in following the anatomical structure to the point where the structure is to be cut.
5. The apparatus of claim 1, wherein the proximal end of the body comprises a handle.
6. The apparatus of claim 1, wherein the anatomical structure is a tendon, a slender muscle, a long nerve filament or bundle, a vessel, or a laterally extended anatomical structure.
7. The apparatus of claim 1, further comprising:
a fiber optic system for viewing the positioning of the distal end of the apparatus,
an X-ray opaque element for X-ray monitoring of distal end positioning,
an ultrasound reflective element for ultrasound monitoring of distal end position, or
a monitor for monitoring an environment in the distal end.
8. A harvesting apparatus comprising:
an elongate flexible body including:
first, second, and third tubular members extending a length of the body, each member having a proximal opening,
a distal end comprising:
a suturing station comprising:
two opposing suturing heads,
a suture guide channel extending from the suturing heads, and
a cutting station comprising two opposing distal cutting guide heads,
a flexible cutting member adapted to be threaded into the second tubular member through its proximal opening, out its guide head, into the third tubular member through its guide head, and out its proximal opening, wherein the distal end is adapted to receive an anatomical structure and a back and forth motion of the cutting member results in severing of the anatomical structure, and
a flexible, bio-erodible or bio-degradable suturing member adapted to be threaded into the first tubular member leading to the suturing station and fitted into the suture guide channel and forming a loop at the suturing station and tied off at one of the suturing heads with a slip knot so that when the suturing member is pulled at its proximal end extending out of its proximal opening, the loop will tighten on the anatomical structure suturing the structure at the suturing station.
9. The apparatus of claim 8, wherein the cutting station further comprises opposing cutting channels.
10. The apparatus of claim 8, wherein the cutting station further comprises an arcuate base between the two guide heads adapted to receive the anatomical structure.
11. The apparatus of claim 9, wherein the cutting channels are angled so that a top of the cutting channel is more distal than a bottom of the cutting channel to increase cutting efficiency.
12. The apparatus of claim 8, wherein a top surface of the body is curved to aid the body in following the anatomical structure to the point where the structure is to be cut.
13. The apparatus of claim 8, wherein the proximal end of the body comprises a handle.
14. The apparatus of claim 8, wherein the anatomical structure is a tendon, a slender muscle, a long nerve filament or bundle, a vessel, or a laterally extended anatomical structure.
15. The apparatus of claim 8, further comprising:
A fiber optic system for viewing the positioning of the distal end of the apparatus,
an X-ray opaque element for X-ray monitoring of distal end positioning,
an ultrasound reflective element for ultrasound monitoring of distal end position, or
a monitor for monitoring an environment in the distal end.
16. The apparatus of claim 1, wherein the two tubular members are adjacent in the body.
17. The apparatus of claim 8, wherein the first, second, and third tubular members are adjacent in the body.
18. The apparatus of claim 8, wherein the first, second, and third tubular members are parallel.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A high-strength, fracture-resistant silicon nitride ceramic material comprising
about 5 to about 75 wt-% of elongated reinforcing grains of beta-silicon nitride, wherein the elongated reinforcing grains have a major axis measuring about 1 micron or greater and an aspect ratio of 2:1 or greater;
about 20 to about 95 wt-% of fine grains of beta-silicon nitride, wherein the fine grains have a major axis less than about 1 micron; and
about 1 to about 15 wt-% of an amorphous intergranular phase comprising Si, N, O, a Lanthanide series element, and a secondary densification additive comprising a secondary densification element;
wherein said elongated reinforcing grains are essentially isotropically oriented within a microstructure of the ceramic.
2. The ceramic of claim 1, wherein at room temperature said ceramic exhibits a peak flexure strength of 1,000 MPa or greater and a peak fracture toughness of 9 MPa-m(12) or greater.
3. The ceramic of claim 1, wherein the elongated reinforcing grains have a major axis measuring about 2 microns or greater.
4. The ceramic of claim 1, wherein the aspect ratio of said elongated reinforcing grains is between 2:1 and 10:1, inclusive.
5. The ceramic of claim 1, comprising about 10 to about 75 wt-% of said elongated reinforcing grains.
6. The ceramic of claim 1, further comprising about 0.5 to about 15 wt-% of a secondary crystalline phase comprising oxides and oxynitrides of Si, the lanthanide series element, the secondary densification element, and combinations thereof.
7. The ceramic of claim 1, wherein the secondary densification element is not a rare earth element.
8. The ceramic of claim 1, wherein the secondary densification additive is selected from the group consisting of oxides of aluminum, oxides of silicon, oxides of magnesium, and combinations thereof.
9. The ceramic of claim 1, wherein at 1200 degrees C. said ceramic exhibits a peak strength of 800 MPa or greater.
10. The ceramic of claim 9, wherein the secondary densification additive is selected from the group consisting of oxides of aluminum, oxides of silicon, oxides of magnesium, and combinations thereof.
11. A method of producing a high-strength, fracture-resistant silicon nitride ceramic composition according to claim 1 comprising the steps of:
providing a ceramic precursor mixture comprising:
(a) about 60 to about 99.5 wt-% of an alpha-silicon nitride powder,
(b) about 0.01 to about 15 wt-% of beta-silicon nitride seeds, having a major axis measuring less than 10 microns and a minor axis measuring less than 2 microns,
(c) about 1 to about 10 wt-% of an oxide of a lanthanide series element, and
(d) about 0.01 to about 10 wt-% of a secondary densification additive; and
sintering said ceramic precursor mixture at a temperature of at least about 1700\xb0 C. in order to form said silicon nitride ceramic, wherein components of the ceramic precursor mixture are oriented essentially isotropically prior to the sintering step, and
wherein at room temperature said ceramic exhibits a peak strength of 1,000 MPa or greater and a peak fracture toughness of 9 MPa-m(12) or greater.
12. The method of claim 11, wherein the ceramic precursor mixture comprises between about 0.01 and about 10 wt-% elongated beta-silicon nitride particles.
13. The method of claim 11, wherein the beta-silicon nitride seeds have an aspect ratio of 5:1 or less.
14. The method of claim 11, wherein the secondary densification additive does not comprise a rare earth element.
15. The method of claim 11, wherein the secondary densification additive is selected from the group consisting of oxides of aluminum, oxides of silicon, oxides of magnesium and combinations thereof.
16. A method of producing a high-strength, fracture-resistant silicon nitride ceramic composition according to claim 1 comprising the steps of:
providing a ceramic precursor mixture comprising:
(a) about 60 to about 99.5 wt-% of a silicon powder,
(b) about 1 to about 10 wt-% of an oxide of a the lanthanide series element,
(c) about 0.01 to about 5 wt-% of a densification additive, and
(d) about 0.01 to about 15% beta-silicon nitride seeds, having a major axis measuring about 10 microns or less and a minor axis measuring about 2 microns or less;
nitriding said silicon powder by exposing said ceramic precursor mixture to a nitrogen atmosphere and heating said ceramic precursor mixture at a temperature below the melting point of the silicon powder, for a period sufficient to nitride the silicon powder; and
sintering said ceramic precursor mixture at a temperature of at least about 1700\xb0 C. in order to form a sintered silicon nitride ceramic, wherein components of the ceramic precursor mixture are oriented essentially isotropically prior to the sintering step, and wherein at room temperature said sintered silicon nitride ceramic exhibiting a peak strength of 1,000 MPa or greater and a peak fracture toughness of 9 MPa-m(12) or greater.
17. The method of claim 16, wherein the ceramic precursor mixture comprises between about 0.01 and about 10 wt-% elongated beta-silicon nitride particles.
18. The method of claim 16, wherein the beta-silicon nitride seeds have an aspect ratio of about 5:1 or less.
19. The ceramic of claim 1, wherein the secondary densification additive comprises MgO, SiO2, Al2O3, MgAl spinels, AlN, and combinations thereof.