1. In a vertebroplasty assembly of the type including a cannula, an insert sized to be received in a lumen of the cannula, the insert having a needle tip for penetrating a vertebral body and forming a injection hole therein, and an injection device for injecting cement through said injection hole into the vertebral body via said cannula lumen, the improvement comprising:
a sleeve having a main body portion and a shield portion disposed at a distal end of said main body portion, said main body portion sized to be fitted over at least a portion of the cannula, said shield portion being penetrable by a distal end of said cannula and being sized to substantially cover said injection hole and prevent leakage therethrough when cement is injected into the vertebral body.
2. The vertebroplasty assembly of claim 1, wherein said main body portion comprises a generally cylindrical body, and said shield portion comprises a plunger.
3. The vertebroplasty assembly of claim 2, wherein said plunger comprises a smaller diameter proximal portion and a larger diameter distal portion, said smaller diameter proximal portion configured for sealing a distal end of said generally cylindrical body.
4. The vertebroplasty assembly of claim 3, wherein said plunger comprises a generally elastomeric composition.
5. The vertebroplasty assembly of claim 4, wherein said plunger smaller diameter proximal portion includes a pre-scored portion.
6. The vertebroplasty assembly of claim 2, wherein said main body portion comprises a biocompatible metal or metal alloy.
7. The vertebroplasty assembly of claim 6, wherein said main body portion comprises stainless steel.
8. In a method for performing vertebroplasty of the type wherein cement is injected via a cannula into a vertebral body through an injection hole formed in said vertebral body, the improvement comprising:
fitting a sleeve over at least a distal portion of the cannula, the sleeve having a main body portion and a shield disposed at a distal end of the main body portion, the shield being penetrable by the distal end of the cannula and being sized to substantially cover the injection hole; and
positioning the sleeve such that the shield abuts the injection hole, thereby preventing leakage of cement from the vertebral body through the hole.
9. The method of claim 8, wherein the main body portion comprises a generally cylindrical body, and the shield comprises a plunger.
10. The method of claim 9, wherein the plunger comprises a smaller diameter proximal portion and a larger diameter distal portion, the smaller diameter proximal portion configured for sealing a distal end of the main body portion.
11. The method of claim 10, wherein the plunger comprises a generally elastomeric composition.
12. The method of claim 10, wherein the smaller diameter proximal portion includes a pre-scored portion for passage of the cannula therethrough.
13. The method of claim 10, wherein the main body portion comprises a member selected from the group consisting of metals, metal alloys, semi-rigid polymers and rigid polymers.
14. The method of claim 13, wherein the main body portion comprises stainless steel.
15. A sleeve for use with a vertebroplasty assembly for preventing cement leakage during a vertebroplasty procedure, the vertebroplasty assembly of the type including a cannula and an injection device for injecting cement through the cannula into a vertebral body, the sleeve comprising:
a hollow main body portion; and
a plunger disposed at a distal end of the main body portion, the main body portion sized to be fitted over at least a portion of the cannula, the plunger being penetrable by a distal end of the cannula and sized to substantially cover an injection hole in said vertebral body when cement is injected therein.
16. The sleeve of claim 15, wherein said plunger comprises a smaller diameter proximal portion and a larger diameter distal portion, said smaller diameter proximal portion configured for sealing a distal end of said main body portion.
17. The sleeve of claim 16, wherein said plunger comprises a generally elastomeric composition
18. The sleeve of claim 16, wherein said plunger smaller diameter proximal portion includes a pre-scored portion.
19. The sleeve of claim 15, wherein said main body portion comprises a biocompatible metal or metal alloy.
20. The sleeve of claim 19, wherein said main body portion comprises stainless steel.
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 developer roller which is spaced apart by a developing gap from a photosensitive medium and supplies one-component toner to an electrostatic latent image formed on the photosensitive medium to develop the electrostatic latent image, the developer roller comprising:
a core; and
at least one material layer formed on an outer circumference of the core,
wherein an outermost layer of the material layer is a coating layer that includes beads having a diameter of about 5-15% of a width of the developing gap such that a ten-point average roughness of the outermost layer in the material layer is about 5-15% of the width of the developing gap.
2. The developer roller of claim 1, wherein an elastic layer is provided between the coating layer and the core.
3. The developer roller of claim 1, wherein the beads are at least one selected from the group consisting of an acrylic resin particle containing a PMMA particle, a silica particle, a urethane resin particle, and a fluorine resin particle.
4. The developer roller of claim 3, wherein a base resin of the coating layer comprises a urethane resin.
5. An image forming apparatus using a non-magnetic, one-component toner, comprising:
a photosensitive medium on which an electrostatic latent image is formed; and
a developer roller spaced apart from the photosensitive medium by a developing gap, the developer roller supplying toner to the electrostatic latent image to develop the electrostatic latent image, the developer roller comprising:
a core; and
at least one material layer formed on an outer circumference of the core,
wherein an outermost layer of the developer roller is a coating layer and the coating layer comprises beads having a diameter of about 5-15% of a width of the developing gap such that a ten-point average roughness of the outermost layer in the material layer is about 5-15% of the width of the developing gap.
6. The image forming apparatus of claim 5, wherein an elastic layer is positioned between the coating layer and the core.
7. The image forming apparatus of claim 5, wherein the beads are at least one selected from the group consisting of an acrylic resin particle containing a PMMA particle, a silica particle, a urethane resin particle, a polyamide resin particle, and a fluorine resin particle.
8. The image forming apparatus of claim 7, wherein a base resin of the coating layer comprises a urethane resin.
9. The image forming apparatus of claim 8, further comprising:
a gap maintaining member to maintain the width of the developing gap between the photosensitive medium and the developer roller at a constant value.
10. The image forming apparatus of claim 5, further comprising:
a layer regulation member to maintain the thickness of toner attached to the developer roller at a constant value.