Apparatus and methods for accessing and dilating bone structures using a narrow gauge cannula

1. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: (a) a single catheter shaft having a long axis and proximal and distal catheter portions; (b) an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion bonded at a bond juncture to the distal catheter portion, wherein the distal catheter portion and the proximal neck portion of the expandable element have substantially the same outer diameters at a juncture location where they are butt-jointed and bonded to form a smooth, uninterrupted outer surface at and proximally and distally of the bond juncture such that the bond juncture and the balloon portion will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion; and (c) a fluid passageway extending from the proximal catheter portion to the balloon interior;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element, and wherein the floating mandrel element comprises a distal mandrel end bonded to the interior distal wall portion of the expandable element and a free, unbonded proximal mandrel end whereby the floating mandrel element can slide toward or away from the distal assembly end along or parallel to the long axis of the catheter shaft.

2. A system for carrying out a medical dilatation and/or a cavity creation, enlargement or treatment procedure at an internal body site comprising a catheter/expandable element assembly according to claim 1 in combination with an 11-gauge or smaller diameter cannula for delivering the expandable element from outside the body to the desired internal body site and, following a balloon inflation treatment procedure, for withdrawing a deflated expandable element from the body site.

3. A system according to claim 2 wherein the interior of the cannula is free of any lubricant and also wherein no lubricant is applied to the catheter/expandable element assembly.

4. A method for carrying out a medical treatment that includes a dilatation and/or a cavity creation, enlargement or treatment procedure using a system according to claim 2 , the method comprising the steps of: (A) positioning the cannula in a body location so that a distal end of the cannula is proximate to the intended treatment site; (B) inserting at least the expandable element portion of the assembly through the interior of the cannula to position the expandable element in the interior of a bone or body site without the use of any lubricants; (C) inflating the balloon portion of the expandable element inside the interior of the bone or body site to a size and/or inflation pressure and for a time sufficient to complete the treatment; (D) deflating the balloon portion of the expandable element; and, (E) withdrawing the expandable element including the deflated balloon portion of the assembly through the interior of the cannula without the use of any lubricants.

5. A method for carrying out a medical treatment that includes a dilatation and/or a cavity creation, enlargement or treatment procedure that is performed with an expandable conforming balloon using a catheter/expandable element assembly according to claim 1 , the method comprising the steps of:

(A) inserting at least the expandable element portion of the assembly through the interior of a previously-placed 11-gauge or smaller diameter cannula to position the expandable element including a distal tip of the expandable element in the interior of a bone or body site; (B) inflating the balloon portion of the expandable element inside the interior of the bone or body site to a size and/or inflation pressure and for a time sufficient to complete the treatment; (C) deflating the balloon portion of the expandable element; and (D) withdrawing the expandable element including the deflated balloon portion of the assembly through the interior of the 11-gauge or smaller diameter cannula.

6. A method of manufacturing the assembly of claim 1 by bonding the catheter shaft to the expandable element, the method comprising the steps of butting an end of the catheter shaft against a similarly-sized open end of the proximal neck portion of the expandable element followed by an adhesive bonding procedure, a solvent bonding procedure or a thermal bonding procedure for securing the two abutting ends to one another thereby creating a fluid passageway through the interior of the catheter shaft and into the balloon portion of the expandable element.

7. A system for carrying out a medical dilatation and/or a cavity creation, enlargement or treatment procedure at an internal body site comprising a catheter/expandable element assembly according to claim 1 in combination with an 11-gauge or smaller diameter cannula for delivering the expandable element from outside the body to the desired internal body site and, following a treatment procedure, for withdrawing a deflated expandable element from the body site.

8. A system according to claim 7 wherein the interior of the cannula is free of any lubricant and also wherein no lubricant is applied to the catheter/expandable element assembly.

9. An assembly according to claim 1 wherein the bond juncture between the distal catheter portion and the proximal neck portion is formed such that the maximum diameter of the assembly at the bond juncture is less than 0.092 inches.

10. An assembly according to claim 1 further wherein the balloon portion has a 0.010 inch or greater double wall thickness (DWT).

11. An assembly according to claim 1 wherein the catheter shaft is a single lumen catheter.

12. An assembly according to claim 1 wherein the expandable element further comprises a distal neck portion having a sealed tip, and the sealed tip contains the only radiopaque marker along the expandable element.

13. An assembly according to claim 1 wherein the expandable element comprises one or more bands of a radiopaque material in the balloon interior.

14. An assembly according to claim 1 further wherein the mandrel element is capable of only limited, constrained axial movement, and the extent of such movement is defined by a sleeve in which the proximal mandrel end can slide.

15. An assembly according to claim 1 further wherein the proximal mandrel end comprises a geometrical feature selected from a ball end, another enlarged shape, or a hooked or angled section.

16. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: a single catheter shaft having a long axis and proximal and distal catheter portions; an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion bonded at a bond juncture to the distal catheter portion; and a fluid passageway extending from the proximal catheter portion to the balloon interior, the fluid passageway having a circular cross-section with a passageway diameter defined by an inner wall of the catheter shaft such that the passageway diameter at the bond juncture is the same size as an inner diameter of the distal catheter portion;

wherein the balloon portion of the expandable element and the bond juncture between the distal catheter portion and the proximal neck portion of the expandable element will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element,

and wherein the inner diameter of the distal catheter portion, the passageway diameter, and an inner diameter of the proximal neck portion of the expandable element are substantially the same size at a juncture location where the distal catheter portion and the proximal neck portion are butt-jointed and bonded to form the bond juncture.

17. An assembly according to claim 16 wherein the distal catheter portion and the proximal neck portion are bonded at the juncture location by adhesive bonding, solvent bonding, thermal bonding and/or an equivalent bonding procedure.

18. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: a single catheter shaft having a long axis and proximal and distal catheter portions; an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion butt-jointed and bonded at a bond juncture to the distal catheter portion; and a fluid passageway extending from the proximal catheter portion to the balloon interior, the fluid passageway having a circular cross-section with a passageway diameter defined by an inner wall of the catheter shaft such that the passageway diameter at the bond juncture is the same size as an inner diameter of the distal catheter portion;

wherein the balloon portion of the expandable element and the bond juncture between the distal catheter portion and the proximal neck portion of the expandable element will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element,

and wherein the bond juncture has substantially the same outer diameter as the outer diameters of the distal catheter portion and the proximal neck portion of the expandable element to form a smooth, uninterrupted outer surface at and proximally and distally of the bond juncture.

19. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: a catheter shaft having a long axis and proximal and distal catheter portions; an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion bonded at a bond juncture to the distal catheter portion; and a fluid passageway extending from the proximal catheter portion to the balloon interior;

wherein the balloon portion of the expandable element and the bond juncture between the distal catheter portion and the proximal neck portion of the expandable element will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element, and also wherein the floating mandrel element comprises a distal mandrel end bonded to the interior distal wall portion of the expandable element and a free, unbonded proximal mandrel end whereby the floating mandrel element can slide toward or away from the distal assembly end along or parallel to the long axis of the catheter shaft;

the assembly further comprising a helically coiled mandrel bonding spring element that is attached at the distal mandrel end where it extends beyond the distal mandrel end and is encapsulated with a material that fills the spring's interior and covers the exterior of its most distal length of coils.

20. An assembly according to claim 19 wherein the mandrel bonding spring element comprises a radiopaque material.

21. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: a catheter shaft having a long axis and proximal and distal catheter portions; an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion bonded at a bond juncture to the distal catheter portion; and a fluid passageway extending from the proximal catheter portion to the balloon interior;

wherein the balloon portion of the expandable element and the bond juncture between the distal catheter portion and the proximal neck portion of the expandable element will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element, and also wherein the floating mandrel element comprises a distal mandrel end bonded to the interior distal wall portion of the expandable element and a free, unbonded proximal mandrel end whereby the floating mandrel element can slide toward or away from the distal assembly end along or parallel to the long axis of the catheter shaft;

and also wherein the distal mandrel end comprises braided wires or a hypotube with holes or slots, or otherwise comprises openings in the distal mandrel end whereby a bonding material can be applied to fill in the openings and form a strong mechanical bond between the mandrel end and the interior distal wall portion of the expandable element when the bonding material hardens.

22. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: a catheter shaft having a long axis and proximal and distal catheter portions; an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion bonded at a bond juncture to the distal catheter portion; and a fluid passageway extending from the proximal catheter portion to the balloon interior;

wherein the balloon portion of the expandable element and the bond juncture between the distal catheter portion and the proximal neck portion of the expandable element will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element, and also wherein the floating mandrel element comprises a distal mandrel end bonded to the interior distal wall portion of the expandable element and a free, unbonded proximal mandrel end whereby the floating mandrel element can slide toward or away from the distal assembly end along or parallel to the long axis of the catheter shaft;

and also wherein a distal mandrel portion comprises a reduced diameter section, or a spring section, or a flattened section to provide increased flexibility for a mandrel portion located inside the expandable element.

23. A catheter/expandable element assembly with proximal and distal assembly ends for medical applications comprising: a catheter shaft having a long axis and proximal and distal catheter portions; an expandable element comprising a conforming balloon portion with a balloon interior and also comprising a proximal neck portion bonded at a bond juncture to the distal catheter portion; and a fluid passageway extending from the proximal catheter portion to the balloon interior;

wherein the balloon portion of the expandable element and the bond juncture between the distal catheter portion and the proximal neck portion of the expandable element will fit through the interior of an 11-gauge medical cannula before and after inflation of the balloon portion;

and additionally comprising a floating mandrel element that extends through the distal catheter portion, and through the expandable element, to an interior distal wall portion of the expandable element, and also wherein the floating mandrel element comprises a distal mandrel end bonded to the interior distal wall portion of the expandable element and a free, unbonded proximal mandrel end whereby the floating mandrel element can slide toward or away from the distal assembly end along or parallel to the long axis of the catheter shaft;

the assembly further comprising a spring element located inside the expandable element and also wherein the distal mandrel end comprises a core wire with a hooked or angled end that can engage a distal portion of the spring element to provide active deflection of the distal end of the expandable element.