US20100121380A1 - Expandable Spinal Rods and Methods of Use - Google Patents

Abstract

A spinal rod includes an elongated tubular member that is inflatable from a first insertion profile to a second enlarged profile. An expandable tubular reinforcement sleeve is concentrically positioned adjacent to the balloon. The balloon may be bonded to the sleeve. The spinal rod may also have longitudinal reinforcement members. A joining member may join two or more of the longitudinal reinforcing members at a discrete point along each. The spinal rod may further include end portions on either side of an inflatable portion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. patent application Ser. No. 11/343,595 filed on Jan. 31, 2006, the contents of which are hereby incorporated by reference in their entirety.
BACKGROUND
• Spinal rods are often used in the surgical treatment of spinal disorders such as degenerative disc disease, disc herniations, scoliosis or other curvature abnormalities, and fractures. Different types of surgical treatments are used. In some cases, spinal fusion is indicated to inhibit relative motion between vertebral bodies. In other cases, dynamic implants are used to preserve motion between attached to the exterior of two or more vertebrae, whether it is at a posterior, anterior, or lateral side of the vertebrae. In other embodiments, spinal rods are attached to the vertebrae without the use of dynamic implants or spinal fusion.
• Spinal rods may provide a stable, rigid column that encourages bones to fuse after spinal-fusion surgery. Further, the rods may redirect stresses over a wider area away from a damaged or defective region. Also, a rigid rod may restore the spine to its proper alignment. In some cases, a flexible rod may be appropriate. Flexible rods may provide some advantages over rigid rods, such as increasing loading on interbody constructs, decreasing stress transfer to adjacent vertebral elements while bone-graft healing takes place, and generally balancing strength with flexibility. One disadvantage with conventional rods is that their rigidity and length, which may span several vertebrae, may require large surgical incisions to implant the rod. Therefore, surgical procedures requiring the installation of an elongated rod have often required invasive open procedures that are more costly to perform, and potentially more dangerous and more painful for the patient.
SUMMARY
• Illustrative embodiments disclosed herein are directed to a spinal rod having an elongated tubular member that is inflatable with a substance from a first insertion profile to a second enlarged profile. In one embodiment, an expandable tubular reinforcement sleeve may be concentrically positioned relative to a balloon. The reinforcement sleeve may be inside of or outside of the balloon. The reinforcement sleeve may be bonded to the balloon. The substance and an adhesive used to bond the sleeve to the balloon may comprise a preactivated adhesive. The spinal rod may have two or more longitudinal reinforcing members and a joining member joining two or more of the longitudinal reinforcing members at a discrete point along each. The spinal rod may also include end members with the balloon secured at both end members. The balloon may be less wide than the end members when deflated and wider than the end members when inflated.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of first and second assemblies comprising spinal rods attached to vertebral members according to one embodiment;
• FIG. 2 is perspective view of a spinal rod according to one embodiment;
• FIG. 3 is a lateral view of a spinal rod according to one embodiment;
• FIG. 4 is a side cross section view of a spinal rod according to one embodiment;
• FIG. 5 is an axial cross section view of a spinal rod according to one embodiment;
• FIGS. 6-10 illustrate one exemplary percutaneous installation technique for installing a spinal rod according to one embodiment;
• FIG. 11 illustrates one exemplary percutaneous installation technique for installing a spinal rod according to one embodiment;
• FIG. 12 is perspective view of a spinal rod according to one embodiment; and
• FIG. 13 is an end view of a spinal rod according to one embodiment.
DETAILED DESCRIPTION
• The various embodiments disclosed herein are directed to spinal rods that are characterized by at least one expandable portion. The expandable portion may be compressed or left unfilled during installation of the rod and may be filled with an injectable substance once the rod is positioned within the body. Similar devices and methods are disclosed in U.S. Pat. No. 6,899,713 to Shaolian et al., the relevant portions of which are incorporated by reference herein. Various embodiments of a spinal rod may be implemented in a spinal rod assembly of the type indicated generally by thenumeral20 inFIG. 1.FIG. 1 shows a perspective view of first and secondspinal rod assemblies20 in whichspinal rods10 are attached to vertebral members V1 and V2. In theexample assembly20 shown, the rod's10 are positioned at a posterior side of the spine, on opposite sides of the spinous processes SP.Spinal rods10 may be attached to a spine at other locations, including lateral and anterior locations.Spinal rods10 may also be attached at various sections of the spine, including the base of the skull and to vertebrae in the cervical, thoracic, lumbar, and sacral regions. In one embodiment, asingle rod10 is attached to the spine. Thus, the illustration inFIG. 1 is provided merely as a representative example of one application of aspinal rod10.
• In one embodiment as illustrated inFIG. 1, thespinal rods10 are secured to vertebral members V1, V2 bypedicle assemblies12 comprising apedicle screw14 and asetscrew16. In other embodiments, thespinal rod assemblies20 may be secured to more than two vertebral members, including for example vertebral member V3. The outer surface ofspinal rod10 is grasped, clamped, or otherwise secured between thepedicle screw14 and setscrew16. Other mechanisms for securingspinal rods10 to vertebral members V1, V2 include other types of pedicle screws, hooks, cables, and other such devices. Examples of other types of retaining hardware include threaded caps, screws, and pins.Spinal rods10 are also attached to plates in other configurations. Thus, theexemplary pedicle assemblies12 shown inFIG. 1 are merely representative of one type of attachment mechanism.
• Thespinal rod assemblies20 comprise an inflatablespinal rod10 such as the embodiment illustrated inFIG. 2.FIG. 2 shows an elevated perspective view of an inflatablespinal rod10 in an uninflated state. Thespinal rod10 comprises afirst end22, asecond end24 and a compliant,inflatable balloon26 between thefirst end22 and thesecond end24. Theballoon26 may be constructed in a variety of ways, including techniques utilized for balloon angioplasty applications. Thefirst end22 comprises a self-sealingvalve28, which allows an injectable substance to flow into, but not out of, theballoon26. The injectable substance that is inserted into thespinal rod10 may include certain hardenable media, such as epoxy, PMMA, polyurethane, and silicone. Further, the substance may have a lesser or greater viscosity in a cured form as compared to its precured form.
• Thesecond end24 of thespinal rod10 comprises atip30 that is constructed of a biocompatible material. Theballoon26 comprises a suitable complaint biocompatible material, such as a polymer that may include nylon, polyethylene, polyurethane, silicone, polyethylene, polypropylene, polyimide, polyamide, and polyehteretherketone (PEEK). Theballoon26 may be formed from materials that are used in other conventionally known biomedical applications, such as balloon angioplasty. Thespinal rod10 may be reinforced with concentric layers of similar or dissimilar materials and/or fabrics.
• Generally, theballoon26 is an impermeable structure that can be collapsed diametrically for delivery and expanded in situ during implantation. Further, theexemplary balloon26 comprises thin, reinforcingrails32 running longitudinally along theballoon26. Generally, therails32 are flexible, but maintain their substantially elongated shape to help theuninflated balloon26 maintain an elongated shape during insertion (as will be described below). Therails32 may be constructed of metals such as titanium or nitinol or non-metals such as PEEK, UHMWPE, and carbon-fiber reinforced polymers and resins. Therails32 may be constructed of other suitable materials as will be understood by those with skill in the art with reference to this disclosure. In one embodiment, therails32 extend over substantially the entire proximal to distal length of theballoon26. In one embodiment, therails32 extend over less than the entire proximal length of theballoon26. Therails32 may comprise such elements as rods, wires, and cables.
• The exemplaryspinal rod10 further comprises a plurality ofstraps34 that are secured to therails32 atdiscrete points36. In one embodiment, thestraps34 are substantially rigid and maintain a substantially circular shape. In one embodiment, thestraps34 maintain a shape of theballoon26. In one embodiment, thestraps34 are flexible members that allow therails32 to expand and contract relative to one another depending on whether theballoon26 is in a compressed or inflated state. In either case, thestraps34 may maintain a desired spacing between therails32. Thestraps34 may also prevent therails32 from grouping together towards one side of therod10 as the injectable substance is inserted into theballoon26. Also, as shown inFIG. 2, thestraps34 may be disposed at various points along therails32, including at or towards thefirst end22, at or towards thesecond end24, and at intermediate points therebetween. Further, thestraps34 may be used to secure substantially allrails32 that are disposed in thespinal rod10. In this case, thestraps34 may be circumferentially disposed within theballoon26. Alternatively, thestraps34amay be used to secure fewer than all rails32. In this case, thestraps34 may be radially disposed within theballoon26. Also, thestraps34,34amay be oriented normal to, transverse to, or oblique to a longitudinal axis A of therod10.
• In one embodiment illustrated inFIG. 3, thespinal rod10acomprises two layers. A detailed cross section of this embodiment ofspinal rod10ais shown inFIG. 4.FIG. 4 also illustrates a self-sealingvalve28 in the form of a duck-bill valve. Other types of one-way valves, including check valves and reed valves, may be used. The self-sealingvalve28 may permit aninjectable substance35 to enter and remain in theballoon26. The exemplaryspinal rod10aincludes a reinforcingstructure38 such as a woven or braided mesh contained within theballoon26. The reinforcingstructure38 may be constructed of a wide variety of woven or nonwoven fibers, fabrics, metal mesh such as woven or braided wires, polymeric fibers, ceramic fibers, and carbon fibers. Biocompatible fabrics or sheet material such as ePTFE and Dacron®, Spectra®, and Kevlar® may also be used. The use of a braided sleeve may produce higher structural resistance to sheer stress as a result of torsional loads. Thebraided reinforcing structure38 may also help distribute therails32 in a homogenous manner. The reinforcingstructure38 may have radiographic markers, such as metallic wires, including materials such as gold, platinum or tantalum, disposed therein for visibility of thespinal rod10 via radiographs or fluoroscopy. Alternatively, a radiopaque material, such as barium sulfate or tantalum powder, may be dispersed among the materials forming the reinforcingstructure38. The expandability and constraining effects provided by the reinforcingstructure38 may also be controlled with the weaving or braiding pattern of the sleeve.
• The reinforcingstructure38 may resist kinking of theballoon26 as theballoon26 is advanced around corners such as during advancement through an aperture (e.g., portal or eyelet) on abone anchor14. As shown, the reinforcingstructure38 may be positioned within theballoon26. The reinforcingstructure38 may alternatively be embedded within the wall of theballoon26, or carried on the outside of theballoon26 much like a conventional stent.
• The reinforcingstructure38 may comprise braided fibers that are disposed within the range of from about 15 to about 45 degrees relative to a longitudinal axis A. The braids may be in the form of a plain weave. This braided reinforcingstructure38 may conform dimensionally to the inside diameter of the balloon. In one embodiment, the reinforcingstructure38 has a diameter of about 6 mm.
• In the illustrated embodiment, the plurality of longitudinally extendingrails32 is disposed between theballoon26 and the reinforcingstructure38. In one embodiment, therails32 are bonded to the reinforcingstructure38. In one embodiment, therails32 are bonded to theballoon26. In other embodiments, theballoon26 is disposed interior to the reinforcingstructure38, with therails32 disposed therebetween. Some examples of suitable adhesives that may be used to bond therails32,balloon26, straps34, and reinforcingstructure38 include light curing acrylics and cyanoacrylates, silicones, polyurethanes, and epoxies available from Loctite® of Rocky Hill, Conn., USA. Certain varieties of these materials may also be used as theinjectable substance35. These include light curing adhesives and preactivated epoxies. Preactivated epoxies are one example of an adhesive that will begin to cure once exposed to a certain wavelength of light (e.g., UV, IR), but will not set for some number of minutes thereafter. Thus, in one embodiment, a preactivated epoxy may be used as aninjectable substance35 in therod10. The curing process for the preactivated epoxy may be initiated before therod10 is inserted into a subject, with a full set occurring after therod10 is implanted. That is, the injectable substance may remain fluid or pliable during the installation procedure. For example, the injectable substance (or adhesive) may have a first stiffness at the time when the surgeon begins to insert therod10 into the subject. Then, as the substance cures further, the substance may have a second stiffness at the time when the surgeon secures therod10 to vertebrae within the subject.
• Although a cylindrical configuration forballoon26 is illustrated herein, any of a variety of alternative cross sectional configurations may be utilized. The overall length, diameter and wall thickness of thespinal rod10 may be varied, depending on the particular treatment and access site. In one embodiment, thespinal rod10 has an inflated length between about 20 and 120 mm, and often between about 50 mm and about 80 mm for adjacent vertebrae V1, V2 fixation. Longer lengths may be appropriate where more than two vertebrae V1, V2, V3 are joined to thespinal rod10. Further, thespinal rod10 may have an inflated diameter of generally between about 5 mm and 20 mm. Thespinal rod10 may have a deflated diameter of between about 4 mm and 7 mm, which permits installation into conventional rod securing anchors such as pedicle screws14. Generally, the expandability and constraint of the device may be partially controlled with theballoon26 diameter and thickness.
• The construction of an alternative embodiment of a compositespinal rod10bis illustrated in the cross section view shown inFIG. 5. In this embodiment, aninflatable balloon26 is provided, as has been discussed. A first reinforcingstructure40 such as a stent, or a braided or woven structure as discussed above is concentrically positioned exterior to theballoon26. A second reinforcingstructure42 is concentrically disposed within theballoon26 in the embodiment. In one embodiment the first reinforcingstructure42 comprises a diameter of about 5 mm.
• The second reinforcingstructure42 is spaced radially inwardly from the first reinforcingstructure40 and theballoon26. For example, in one embodiment, the second reinforcingstructure42 comprises a diameter of about 4 mm. A plurality ofrails32 is axially oriented within the annular space between theballoon26 and second reinforcingstructure42. A plurality ofrails32 may also be disposed between theballoon26 and the first reinforcingstructure40.FIG. 5 also shows astrap34 joining therails32. A variety of alternate constructions can be readily utilized in accordance with the teachings herein. For example, three or more reinforcing structures may be utilized. The layering sequence of the various components may be changed, and other features added or deleted depending upon the desired performance of the finishedspinal rod10. In addition, although theballoon26 in one embodiment comprises a single layer balloon, other materials may be utilized. In addition, multiple layer balloons may be utilized, with or without reinforcingstructures40,42 such as stents, wires, or woven tubular support structures disposed therebetween. Further, two or more of thecomponents26,32,40,42 shown inFIG. 5 may be bonded to one another prior to insertion into a subject patient. The bonds may be formed using biocompatible adhesives, such as those described above.
• The embodiments of aspinal rod10 disclosed herein may be inserted into a patient using a variety of surgical implantation techniques. Certainly, open and mini-open surgical procedures are possible. Percutaneous procedures are also possible. For instance,FIGS. 6-10 illustrate one exemplary percutaneous installation technique. InFIG. 6, ahollow needle44, such as a 16 gauge or 18 gauge needle, is inserted percutaneously into the subject S at location P1 and advanced to the one of the bone screws14. While thehollow needle44 is shown engaging thesuperior bone screw14 in vertebrae V2, thehollow needle44 can initially engage thebone screw14 in the inferior vertebrae V1.
• A needle-tipped,semi-rigid guidewire46 is introduced through the lumen of thehollow needle44 and through the rod seat in thebone screw14 in vertebrae V2. Theguidewire46 is directed and advanced towards thesecond bone screw14 in vertebrae V1. Certain known techniques for advancing theguidewire46 may be used. For instance, U.S. Pat. No. 6,899,713 disclosed above presents several techniques. Theguidewire46 is then extracted at a second percutaneous incision P2 as shown inFIG. 7. Then, aflexible introducer sheath48 is passed over theguidewire46 along the entire guidewire tract entering incision P1 and exiting incision P2. Theguidewire46 is removed after theintroducer sheath48 is placed.
• Next, as shown inFIG. 8, an uninflated, inflatablespinal rod10 is attached to a proximal pushingcatheter50 and advanced through theintroducer sheath48 until the inflatablespinal rod10 advances between and beyond the twobone screws14 in vertebrae V1, V2. Once thespinal rod10 is positioned in or on the bone screws14, thesheath48 is removed. At various points in the procedure, the placement of the components, including thespinal rod10, may be confirmed by fluoroscopy or other radiographic or imaging technique.
• Then, as shown inFIG. 9, theballoon26 of the inflatablespinal rod10 is inflated with an injectable substance as disclosed above. The substance may comprise a rapid setting, liquid polymer, or its equivalent, and the polymer is allowed to set. A setscrew16 (as shown inFIG. 1) or other retaining hardware may be used to secure thespinal rod10 to eachbone screw14. In one embodiment, the liquid polymer is or includes polymethylmethacrylate or other hardenable media such as those discussed elsewhere herein. In one application, theinflated balloon26 of the inflatablespinal rod10 expands longitudinally and radially beyond the head of eachbone screw14, which helps fix the bone screws14 in relation to each other.
• Finally, as shown inFIG. 10, the delivery or pushingcatheter50 is detached from the inflatablespinal rod10 by pulling on thecatheter50. The method can be repeated on the opposite side of the spinous processes of the subject's S spinal column, thereby repositioning or fixing the one or more unstable, seperated or displaced vertebrae or the one or more portions of one or more vertebrae bilaterally. The percutaneous incisions P1, P2 are closed or sealed as necessary and routine postoperative care administered.
• An alternative installation approach contemplates a minimally invasive percutaneous procedure as shown inFIG. 11. The procedure shown inFIG. 11 incorporates aninstallation instrument80. One example of an instrument suitable for this type of installation is the Sextant Rod Insertion System available from Medtronic Sofamor Danek in Memphis, Tenn., USA. The installation instrument includessupport arms78 that are coupled topedicle screw extensions76. Thesupport arms78 are pivotally connected to arod holder82 about pivot P. The first and second pedicle screws14 andpedicle screw extensions76 are engaged to the first and second vertebrae V1, V2, respectively, through first and second percutaneous punctures in the subject S. If desired, a surgeon can manipulate thepedicle screw extensions76 to apply a load to compress or distract the vertebrae V1, V2 prior to installing rod10c. As disclosed above, the uninflated spinal rod10cmay have various structural components, includingrails32 and reinforcingstructure38. In one embodiment, thesecomponents32,38 may provide sufficient structure for insertion using this illustrated technique. Specifically, the rod10cis installed through a third percutaneous puncture in the subject S using theinstallation instrument20. The rod10cis brought into engagement with the pedicle screws14 by rotating therod holder82 about pivot P.
• In one embodiment, therod holder82 is cannulated to allow a surgeon to introduce an injectable substance through therod holder82 and into the rod10c. A needle or other injection instrument is used to inject the injectable substance into the port J in therod holder82. Alternatively, a catheter may be inserted through the cannulatedrod holder82. Once the rod10cis positioned as desired (possibly verified by fluoroscopy), the rod10cmay be inflated as described above. Alternatively, the rod10cmay be wholly or partially inflated with an injectable substance prior to insertion. In one embodiment, the injectable
• FIGS. 12 and 13 illustrate an alternative embodiment of aninflatable rod10 comprisingdissimilar end members52,54 on opposite sides of aninflatable portion110. The first and second rod ends52,54 include a clampingportion56. The clampingportions56 may have similar widths and may further have a substantially similar cross section. Further,first rod end52 includes a taperedportion58 that decreases in width from the clampingportion56 towards adistal end60. The taperedportion58 may improve the ease with which therod10dis inserted, such as when inserted longitudinally using the percutaneous techniques disclosed herein. The clampingportion56 may be sized to fit within conventional rod securing devices such as the bone screws14 shown inFIG. 1 and described above. For example, the clampingportion56 may have a diameter within a range between about 4 and 7 mm. The rod ends52,54 may be constructed from a variety of surgical grade materials. These include metals such as stainless steels, cobalt-chrome, titanium, and shape memory alloys. Non-metallic rods, including polymer rods made from materials such as PEEK and UHMWPE, are also contemplated. Thespinal rod10 may have rigid or flexible rod ends52,54.
• Theinflatable portion110 may have a structure similar to one or more of the embodiments disclosed above. That is, theinflatable portion110 may have a substantiallyimpermeable balloon structure126 that can be collapsed diametrically for delivery and expanded in situ during implantation. Theinflatable portion110 may have one or more layers of reinforcingstructure138 that may be embodied as a braided, mesh, or woven structure as described above. Further, the exemplaryinflatable portion110 may comprise thin, reinforcingrails32 running longitudinally along theinflatable portion126, though none are specifically shown inFIG. 12.
• FIG. 12 depicts an embodiment of thespinal rod10dwith theinflatable portion110 in an inflated state. An injectable substance may be inserted into theinflatable portion110 through a self-sealingvalve62 that is disposed within the visible, which suggests that theinflatable portion110 may collapse to a size that is thinner than the overall width of the first andsecond end portions52,54. In the expanded state, theinflatable portion110 extends wider than the first andsecond end portions52,54, which may provide some off-axis stability in compression. In one embodiment, the injectable substance contained within theinflatable portion110 retains some flexibility after curing, which assists in a dampening effect of therod10d. With this configuration, thespinal rod10dmay replicate some of the stability that is provided by a facet joint in a healthy subject.
• FIG. 13 shows an end view of thespinal rod10d, looking into the proximal end of thesecond end member54. In the illustrated embodiment, theexpandable members126,138 of theinflatable portion110 are disposed betweenconcentric columns64,66,68. Threecolumns64,66,68 are shown, though more or fewer columns may be used. In the embodiment depicted, theballoon126 is disposed between aninner column64 and anintermediate column66. The reinforcingstructure138 is disposed between theintermediate column66 and anouter column68. In other embodiments, the reinforcingstructure138 and theballoon126 may be disposed between the same twocolumn members64,66 or66,68. In one embodiment, theinflatable portion110 does not include reinforcingstructure138. As suggested above, other embodiments may include aballoon126 that has a reinforcingstructure138 embedded therein.
• Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc and are also not intended to be limiting. Like terms refer to like elements throughout the description.
• As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
• The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. For instance, embodiments disclosed herein have contemplated oneballoon structure26,126, perhaps with one ormore rails32 or reinforcingstructures38,138. In other embodiments, multiple concentric layers ofballoons26,126 may be used. Also, the illustrated embodiment provided inFIGS. 12 and 13 include a single intermediate section betweenend portions52,54. In an alternative embodiment, the rod may comprise multiple intermediate sections disposed between additional clampingportions56. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims (20)

1. A spinal rod comprising:

a non-inflatable first member;

a non-inflatable second member; and

an inflatable member positioned between the first and second members and having an interior cavity to contain a substance, the inflatable member attached to the first member and extending into an interior of the second member away from the interior cavity;

the inflatable member and first and second members each having an elongated shape and being aligned along a longitudinal axis with the second member separate from and spaced away from the first member.

2. The spinal rod ofclaim 1, further comprising a passage that extends through the interior of the second member and to the interior cavity to insert a substance through the second member and into the interior cavity.

3. The spinal rod ofclaim 1, wherein each of the first and second members include a width greater than the inflatable member when the inflatable member is in a deflated state, and less than the inflatable member when the inflatable member is in an inflated state.

4. The spinal rod ofclaim 1, wherein the inflatable member includes a balloon and a reinforcing structure.

5. The spinal rod ofclaim 1, wherein the inflatable member comprises a plurality of elongated rails oriented along the longitudinal axis and a plurality of joining members that extend between and connect at least two of the plurality of elongated rails.

6. The spinal rod ofclaim 1, wherein the second member includes a plurality of concentric columns with the inflatable member extending into the second member between two of the plurality of concentric columns.

7. The spinal rod ofclaim 1, wherein each of the first and second members terminate at inner faces that face towards each other and are spaced apart by the inflatable member.

8. A spinal rod comprising:

a non-expandable distal section;

a non-expandable proximal section; and

an inflatable intermediate section positioned between the distal and proximal sections and isolating the distal section from the proximal section, the intermediate section including a balloon and a reinforcing structure, a portion of the intermediate section including the balloon and the reinforcing structure extending into an interior of the proximal section.

9. The spinal rod ofclaim 8, further comprising a conduit that extends through the interior of the proximal section and into the intermediate section, the intermediate section being inflatable upon introduction of a substance through the conduit and into the intermediate section.

10. The spinal rod ofclaim 8, wherein the intermediate section includes a deflated state with a width at a point between the distal and proximal sections that is smaller than the proximal section, and an inflated state with the width being greater than the proximal section.

11. The spinal rod ofclaim 10, wherein the portion of the intermediate section that extends into the interior of the proximal section includes the same width in both the inflated and deflated orientations.

12. The spinal rod ofclaim 8, wherein the balloon includes an inner expandable section positioned within an interior of an outer expandable section.

13. The spinal rod ofclaim 8, wherein the reinforcing structure extends around an exterior of the balloon.

14. The spinal rod ofclaim 10, wherein the distal and proximal sections include discrete lengths each with an inner surface that face towards the intermediate section with the inner surfaces being spaced apart from each other.

15. The spinal rod ofclaim 10, wherein the proximal section includes a plurality of concentric columns and the intermediate section extends between two of the plurality of columns and into the interior of the proximal section.

16. A spinal rod comprising:

elongated first and second sections that are spaced apart by a gap;

an intermediate section positioned in the gap and attached to each of the first and second sections, the intermediate section including a balloon and reinforcing structure that each extend into an interior of the second section and include an interior cavity;

a passage that extends through the interior of the second section and to the interior cavity to insert a substance through the second section and into the interior cavity;

the intermediate section being inflatable from a deflated state to an inflated state upon introduction of the substance through the conduit and into the interior cavity of the intermediate section.

17. The spinal rod ofclaim 16, wherein the reinforcing structure includes a plurality of rails that run longitudinally along the balloon.

18. The spinal rod ofclaim 16, wherein the first section is positioned on a distal side of the intermediate section and the second section is positioned on a proximal side of the intermediate section.

19. The spinal rod ofclaim 16, wherein the second section includes a plurality of concentric columns and the intermediate section extends between two of the plurality of columns and into the interior of the second section.

20. The spinal rod ofclaim 16, wherein each of the first and second sections include a width greater than the intermediate section when the intermediate section is in the deflated state, and less than the intermediate section when the intermediate section is in the inflated state.

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