Instruments for delivering interspinous process spacers

Description of equivalent WO 2007117882 A1

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METHODS AND INSTRUMENTS FOR DELIVERING INTERSPINOUS PROCΕSS SPACERS

BACKGROUND

Lumbar spinal stenosis ("LSS", and sometimes called sciatica) is a condition of the spine characterized by a narrowing of the lumbar spinal canal With spinal stenosis, the spinal canal narrows and pinches the spinal cord and nerves, causing pain in the back and legs One fO surgical technique for relieving LSS involves distracting adjacent vertebrae and implanting an interspinous process spacer to maintain the desired separation betw een the segments I his technique is somewhat less im ash c than alternative treatments such as decompressive laminectomy , but may actually pro\ide significant benefits to patients experiencing (.SS symptoms λs with other surgeries, one consideration when performing surgen to implant

15 an interspinous spaeei is the si/e of the incision that is required to allow introduction of the device Interspinous spacers previously known to the art were not easily implanted with minima!!} invasive surgical techniques A need exists for instrumentation and methods for implanting an interspinous process spacer using minimally im ashe surgical techniques SUMMARY

20 In one embodiment, a system for implanting an interspinous process spacer comprises a deformation instrument adapted to engage a pair of opposing arms of the interspinous process spacer and operable to move the opposing arms relative to one another to deform the interspinous process spacer from an uncollapsed state to a collapsed state I he system further comprises a cannula adapted to receive the collapsed interspinous process spacer from the

25 deformation instrument and direct the interspinous process spacer to an area between a pair of spinous processes

In another embodiment, a system for minimally in\ asi ve implantation of an interspinous process space? comprises a pair of actuators adapted for insertion between a pair of collapsible arms of the interspinous process spacer and a phot joint connecting the pair of

30 actuators and adapted to cause the actuators to mo\ e apart and to therebs move the collapsible arras from an uncollapsed state to a collapsed slate

In another embodiment, a method comprises selecting an interspinous process spacer ha\ing a first pair of opposing arms interconnected by a blocking member The method further comprises selecting a deformation instrument ha\ing a first mo\able portion and a PCOO 1 1060 !

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second movable portion, engaging the first movable portion with one of the opposing amis, and engaging the second movable portion with the other opposing arm. The method further includes moving the first movable portion relative to the second movable portion to move the interspinous process spacer into a collapsed state. The method also includes inserting a first 5 guide tube into a space between a pair of spinous processes and inserting the interspinous process spacer in the collapsed state into the first guide tube.

Additional embodiments are included in the attached drawings and the description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS 10 FIG. i is a sagittal view of a section of a vertebral column.

FIG. 2 is an interspinous process spacer engaged with a spacer deformation instrument according to one embodiment of the present disclosure.

FIG. 3 is an implantation system including the instalment and spacer of FlG 2.

FIG. 4 is an interspinous process spacer engaged with a spacer deformation ! 5 instrument according to another embodiment of the present disclosure.

FIG. 5 is an implantation system including the instrument and spacer of HG. 4

FKJ, 6 is an interspinous process spacer engaged with a spacer deformation instrument according to another embodiment of the present disclosure.

FIG. 7 is an implantation system including the instrument and spacer of FlG. 6. 20 FIG. 8 is an implantation system according to another embodiment of the present disclosure.

FIG. 9 is an implantation system and interspinous process spacer according to another embodiment of the present disclosure

FIG. 10 is an implantation system according to another embodiment of the present 25 disclosure.

FSG. i 1 is an implantation system according to another embodiment of the present disclosure.

FIG. 12 is an interspinous process spacer according to another embodiment of the present disclosure 30 FICϊ S3 is a view of the spacer of FIG S 2 after transformation Io an uπcollapsed state

FIGS 14-15 show an interspinous spacer according to another embodiment of the present disclosure. PCOO 1 1060 !

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DETA i 1 JB) DESCRi Pl K)N

The present disclosure relates generally to vertebral device implantation systems, and more particularly, to systems and procedures for minimally invasive interspmous process spacer implantation. For the purposes of promoting an understanding of the principles of the 5 invention, reference will now be made to the embodiments, or examples, illustrated in the drawings and specific language will be used to describe the same, it will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would

10 normally occur to one skilled in the art to which the invention relates

Referring first to FlG. ! , the reference numeral 10 refers to a vertebral joint section or a motion segment of a vertebra! column The joint section 10 includes adjacent vertebral bodies 12, 14 The vertebral bodies 12, 14 include spinous processes 16, 18, respectively. An interspinoυs process space 20 is located between the spinous processes 16, 18

15 Referring now to FIG 2, an interspinoυs process spacer 30 is adapted for implantation in the interspinous space 20. The interspinous spacer 30 is designed to maintain a minima! distance between the spinous processes of adjacent vertebrae 12, 14. As such, the spacer 30 has a blocking portion 32 that keeps the vertebrae from coming together. The spacer 30 may be designed to fit snugly around the spinous processes, and thus to avoid being dislodged by

20 movement of the spine In this embodiment, the spacer 30 achieves a snug fit by including

"arms" 34, 36, extending from the blocking portion 32 upward along both sides of the upper spinous process, and "arms" 38, 40 extending from the blocking portion 32 downward along both sides of the lower spinous process. The arms 34, 36, 38, 40 may keep the spacer 30 from moving laterally with respect to the spinous processes. In FlG. 2, spacer 30 is shown in an

25 uncollapsed, generally "H" shaped configuration The shape as well as the material properties of the spacer may allow it to assume a collapsed configuration which may further allow the spacer to be implanted using a minimally invasive surgical technique.

An interspinous process spacer may be formed from a wide variety of biocompatible materials including those that can undergo reversible elastic deformation. Examples of such

30 materials include elastic or rubbery polymers, bydrogeis or other hydrophilic polymers, or composites thereof. Examples of suitable polymers may include silicone, poiyurethane, silicone-polyurethane copolymers, polyesters, polyeihyienes, polyethyleneterephthaltates, polyaryletherketone (PAEK) poly ether block copolymer (PEBAX), ABS (aeryionitrile PCOO 1 1060 !

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4 butadiene styrene), ANS (aery I oni true styrene), delrin acetal; PVC (polyvinyl chloride). PHN (polyethylene napthaiate), PBT (polybυtylene lerephthalate), polycarbonate, PEΪ (poiyetherimide), PES (polyether sulfαoe), PET (polyethylene terephthalate), PEIG (polyethylene terephthalate glycol), polyamide, aromatic polyamide, polyether, polyester, 5 polymethylmethacrylate, polyurethane copolymer, ethylene vinyl acetate (BVA), ethylene vinyl alcohol, FEP (fluorinated ethylene polymer), PTFE (polytetrafluoroethyleii- e), PFA (perfiuoro-alkoxyalkaiie), polypropylene, polyolefm, polysiloxane, liquid crystal polymer. ionomer, poiytøthylene-co-methacrylic) acid, SAN {styrene acrylonitrile), nylon, polyether block amide and thermoplastic elastomer

10 The spacer material may be a solid, sheet/film, fiber, mesh and/or braided configurations The elastomeric material can be formed into a solid one-piece, monobloek unit having the configuration described above. In one alternative, the spacer may be tillable or have otherwise alterable material properties as described more fully below. Examples of suitable polyυrethaπes for use in forming a spacer may include thermoplastic

15 polyurethanes, aliphatic polyurethanes, segmented polyurethanes, hydrophilic polyurethanes, polyether-υrethane. polycarbonate-υrethane and silicone polyetherurethane. Other suitable hydrophilic polymers include polyvinyl alcohol hydrogel.. polyacrylamide hydrogel, polyacrylic hydrogel, poly(N-vinyl-2-pyττolidone hydrogel, polyhydroxyethyl methacrylate hydrogel, and naturally occurring materials such as collagen and polysaccharides, such as

20 hyaluronic acid and cross-linked carboxyl-containing polysaccharides, and combinations thereof.

In other embodiments, the spacer is made of a metal that can undergo reversible elastic deformation, such as shape memory metals or nickel titanium. Further description of interspinous process spacers, of the type shown in FIG. 2, is provided in detail in pending

25 U.S. Patent Application No. 10/851 ,889, entitled "Interspinous Spacer" which is incorporated herein by reference.

FIG. 2 also depicts an interspinous process spacer deformation instrument 42 The instalment 42 includes supports 44, 46 pivotal Iy connected by pivot mechanism 48 and arranged in an "X" shaped configuration. The pivot mechanism 48 may allow the supports

30 44, 46 to pivotally move relative Io each other in the directions shown in FΪG, 2. The movement of the pivot mechanism 48 may be controlled or biased by a mechanical spring mechanism, a ratchet mechanism, a shape memory- material, or other bias or control mechanisms known in the art. The supports 44, 46 include projections 50, 52, respectively PCOO 1 1060 !

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which, as shown in FlG 2, may be configured to extend between arms 44.. 46 of the spacer 30, The projections 50, 52 may be fitted with rollers 54, 56, respectively. The opposite side of the supports 44. 46 may also be fitted with corresponding projections and rollers to fit between arms 38, 40 of the spacer 30.

5 Referring now to FIG 3, the deformation instalment 42 may be used to deform the spacer 30 into a collapsed state suitable for implanting the spacer 30 into a patient in a minimally invasive way With the deformation instrument 42 positioned as shown in FIG. 2 with the rollers 54, 56 engaged with the arms 34, 36, respectively, the supports 44, 46 are pivoted about the pivot mechanism 48 As the supports 44, 46 are moved, the rollers 54, 56

10 are separated, moving the spacer 30 into a collapsed state with arms 34 and 38 moved toward one another and arms 36, 40 moved toward each other. As the supports 44, 46 are moved, the rollers 54, 56 may roll along the arms 34, 36. reducing friction while collapsing the spacer 30. A cannula 58 may be inserted into the vicinity of a patient^'s vertebral column and positioned adjacent to or between the spinous processes 16, 18 of a spinal joint 10 The spacer 30, now

15 in a collapsed state, may be positioned at the opening of the cannula 58 An insertion instrument 60, such as a probe, may then be used to push the spacer 30 along the rollers 54, 56. into the cannula 58, and into the interspinous process space 20. As the spacer 30 is pushed from the cannula 58, it returns from the collapsed state to the unco! lapsed state and assumes its original "X" shape with the blocking portion 32 positioned between the adjacent

20 spinous processes 16, 18 and the unfolded amis 34, 38 extending upward and downward along one side of two spinous processes, as shown in PIG. 3. The cannula 58 is then withdrawn as the spacer 30 is ejected, and the second pair of arms 36 and 40 unfolds to extend upward and downward along the second side of the spinous processes, as shown in FIG 3.

25 The surgery may be accomplished using, for example, a posterior oblique approach through a small incision in the patient's back. Prior to the implantation of the interspinous process spacer, the interspinous space may be prepared by removing soft tissue from around the spinous processes. The spinous processes may also be distracted to enlarge the space for receiving the spacer

30 Referring now to FlG 4, the spacer 30 may be reduced to a collapsed state using an alternative embodiment of a deformation instrument. The deformation instrument may include a pulling device 70 that may include wires attached to each of the arms 34, 36, 38, 40. in use, the wires may be used to collapse the spacer 30 by pulling arms 38.. 38 together and PCOO 1 1060 !

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arms 36, 40 together, As shown in FKJ. 5, the collapsed spacer 30 may then be introduced to cannula 58, with the wires 70 removed, and implanted between the spinous processes 16, 18 as described above.

Referring now to FIG. 6, a deformation instrument 80 may, alternatively, be used to 5 reduce the spacer 30 from an unco! lapsed to a collapsed state. The instrument 80 may comprise a pair of actuators or supports 82, 84 connected by a pivot mechanism 86. In use, the pivot mechanism 86 may be positioned between the arms 34, 36 of the spacer 30 with the supports 82, 84 engaged with the arms. The deformation instalment 80 may include a second pivot mechanism 88 and arms 90. 92 that are substantially similar to those described above

10 for positioning between the arms 38, 40. The movement of the pi\ ot mechanism 86 may be controlled or biased by a mechanical spring mechanism, a ratchet mechanism, a shape memory material, or other bias or control mechanisms known in the art

With the deformation instrument 80 positioned within the spacer 30, pivot mechanism 86 may be operated to move the supports 82, 84 from a "V" shaped configuration to a straight

! 5 or elongated configuration (as shown in FlG. 7) The pι\ ot mechanism 88 and supports 90,

92 located between arms 38, 40 may operate in a similar manner to reduce the spacer 30 from an unco! lapsed state to a collapsed state. The straightened supports 82, 84, 00, 92 may form a portion of a guide tube which may serve a similar function as the cannula 58 described above. Λs shown in FIG. 7, with the collapsed spacer 30 positioned within the guide tube formed by

20 the straightened supports 82, 84, 90, 92, the insertion instrument 60 may be used to push the spacer 30 through the guide tube and into the interspinous process space 20 where it is allowed to return to its unco! lapsed state.

Referring now to FIG. 8, in an alternative embodiment to cannula 58 or the guide tube created by supports 82, 84, 90, 92, a multi-part cannula 100 may include two cannula halves

25 !02, 104. The cannula half 102 may be sized and configured to fit within a flare 106 of the cannula 104 to form a single, essentially continuous cannula. The collapsed spacer 30 may be deformed using any of the deformation instruments described above and inserted through the cannula 100 using any of the techniques described above. The multi-part cannula 100 may suitable for situations in which the arms 36, 40 are collapsed prior to collapsing the arms

30 34, 38 The multi-part cannula 100 allows one half of the spacer 30 to be held in a collapsed position while the opposite half of the spacer is being collapsed

Referring now to FIG 9, a spacer 120 includes a body 122 having arms 126, 128 and a body 124 having arms 130, 132 The spacer 120 may further include a spring 134 to bias PCOO 1 1060 !

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7 the arras into an uneollapsed position Such an embodiment may work much like a pair of scissors, with the four arms 126, 128, ] 30, 132 extending from a central pivot, As with scissors, the device may be convened from a generally "X"-shaped device to a generally T'- shaped device by pivoting one pair of arms relative to the other. Such a spacer is disclosed in 5 detail in pending U S Patent Application No 10/851,889, entitled "Interspinous Spacer" which is incorporated herein fay reference.

The spacer 120 may be collapsed using any of the deformation instruments disclosed above or any other deformation technique known in the art. In a collapsed configuration, as shown in FlG. 9, arms 132, 128 are drawn together, and amis 126, 130 are drawn together

10 The spacer may then be delivered to the interspinous process space 20 using any of the cannula configurations disclosed above. When the spacer 120 is ejected from the cannula, the spring 134 may bias the spacer 120 to return to its uncollapsed state.

Referring now to FIG. 10, in this embodiment, precision alignment through a minimally invasive approach may be achieved with an installation instrument 1 10 used to

15 install a spacer 11 1 between spinous processes 16, 18. The installation instrument 1 10 includes a fixed member 1 12 which is connectable to either a fixed location on the patient^'s body or to an external location A swing member 1 14 may have a distal end pivotaliy connected to the fixed member 1 12. A proximal end of the swing member 1 14 may be connected to a curved member 1 11> The curved member 1 11> may be a curved cannula

20 capable of receiving an interspinous process spacer Alternatively, the curved member may have a holder for attaching a spacer to a distal end of the curved member. The swing member 114 may be connected to the curved cannula 1 16 with a release knob 1 17 to allow for simplified release and locking of the curved cannula 1 16 to the swing member 1 14 In use, the fixed member 1 12 may be held stable relative to the interspinous space 20. An

25 interspinous process spacer 1 1 I may be collapsed using one of the methods described above or any other known in the art With the swing member 114 detached or extended away from the interspinous process space 20, the collapsed spacer may be inserted through the curved cannula 1 16. The swing arm 1 14 may then be pivoted to move the curved cannula to the interspinous process space 20 The spacer 1 1 1 may then be ejected from the curved cannula

30 1 16. The use of the installation instrument 1 10 may reduce the invasiveness of the spacer implantation by delivering the spacer to the interspinous space with a controlled and precise technique Such a technique may improve efforts to preserve the surrounding soft tissue PCOO 1 1060 !

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S

Several features of the minimally invasive installation instrument are disclosed in pending V. S. Patent Application No. 10/769,569 which is incorporated herein by reference. In this embodiment, the spacer 1 1 1 may be similar to either spacer 30 or spacer 120 but may include additional features which permit a more minimally invasive implantation using the 5 installation instrument 110. For example, the spacer 1 1 1 may be "banana" shaped or slightly curved in the direction of insertion. The curvature of the spacer 1 1 1 may match the curvature of the curved cannula 1 16.

Referring now to FIG. 1 1 , in an alternative embodiment, a cannula 136 may have a distal end section with an opening 138 that may be enlarged to permit distraction of the

10 adjacent spinous processes, in use, the cannula 136 may be inserted through a minimally invasive opening and positioned between the spinous processes 16. 18. Once in position, the opening 138 may be enlarged to further separate the spinous processes and provide additional space to position a spacer. The enlargement of the opening may be mechanically or thermally actuated

15 The deformation instruments, installation instalments, and cannula systems described above may also be used to deliver other types of interspinous process devices. For example, as shown in FIGS 12 and 13, a filiable spacer 140 may inserted between the spinous processes 16, 18 in a collapsed and unfilled state Once in position, the tillable spacer 140 may be injected or otherwise filled with any of a variety of filling materials to transform the

20 spacer 140 from the collapsed state to an uncoil apsed state.

Examples of injectable materials for injection into the inflatable interspinous process spacers include elastomers, hydrogels, or rigid polymers. Examples of elastomers include silicone elastomers, poiyurethane elastomers, siiicone-polyurethane copolymers, poiyoiefin rubbers, butyl rubbers, or combinations thereof. Example of hydrogels include

25 polysaccharides, proteins, polyphospbazenes, po1y{oxyetbylene)~poly(oxypropyiene) biock polymers. po!y(oxyethylene)-ρoly{oxyproρylene) block polymers of ethylene diamine, poly(acry1ic acids). po1y{meth aery lie acids), copolymers of acrylic acid and nieihacrylic acid, polyvinyl acetate), sulfonated polymers, or combinations thereof. Examples of rigid polymers include polymethylmethacrylate, silicones, polyurethanes, polyvinyl alcohol,

30 polyamide. aromatic poly amide, polyether, polyesterliquid crystal polymer, ionorner. poly(ethylene-co-røethacrylic) acid. PBT (polyhutyiene terephthalate), polycarbonate, or combinations PCOO 1 1060 !

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9

Suitable materials may be natural or synthetic. The filling materials may cure or polymerize in situ The filling materials may be transformable such that when the spacer is filled and in an uncoilapsed state, the materia! may harden to create a rigid spacer

In an alternative embodiment as shown in FIG. 14, a tillable spacer ! 50 may include 5 one or more inflatable chambers 152. in this example, the arms of the spacer 150 may be formed of solid eSastomeric material and the blocking portion of the spacer may include the inflatable chamber 152 to allow the physician to create a customized distraction between the spinous processes This spacer 150 may be inserted in a collapsed state, with the arm folded into a low profile package, using any of the instruments described above. When implanted

10 the arms of the spacer 150 may unfold as shown in FIG 14 and the chamber 152 may be subsequently filled with a material, including those tilling materials described above, to distract the spinous processes to a desired level as shown in FIG 15. The in situ curable materials may cure to a compliant or rigid mass depending upon the materials selected. Biological or pharmaceutical agents may be added to the filling material.

15 The arms of the spacer may be elastic or rigid and formed of any of the materials listed above When used with rigid arms, an injectable materia! capable of setting or curing can lock the rigid arms into a desired position.

The partially inflatable spacer 150 may be incrementally adjustable to allow for better fit and customized distraction Because the chambers 152 may be filled to different levels, the need

20 to maintain large inventories of implants in a wide variety of sizes may be reduced.

The delivery of any of the spacers described above may facilitated by lubricating any of the instruments described above. Suitable lubricants may include oils, solvents, bodily fluids, fat, saline, or hydroge! coatings. For example, in FIG. 3, a lubricant may be applied to the rollers 54, 56, and to the interior shaft of the cannula 58 to reduce friction and ease the

25 passage of the spacer 30.

In still another alternative, spinous process systems may include artificial ligaments or tethers for connecting two or more spinous processes These ligaments may be connect to or extend through a spacer and wrap around one or both of the adjacent spinous processes to hold the spacer securely in place. Such ligaments may be elastic or non-elastic and may be

30 made of woven or braided textiles.

Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and PCOO 1 1060 !

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10 advantages of this disclosure. Accordingly, all such modifications and alternative are intended to be included within the scope of the invention as defined in the following claims. Those skilled in the art should also realize that such modifications and equivalent constructions or methods do not depart from the spirit and scope of the present disclosure, 5 and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure, it is understood that all spatial references, such as "horizontal," "vertical," "top," ''upper," "lower," "bottom," "left," "^■right,^" "anterior,^" "posterior,^" "superior,^" "inferior,^"" '-upper,^"" and "lower" are for illustrative purposes only and can be varied within the scope of the disclosure. In the claims, 10 raeans-ρiυs~function clauses are intended to co\ er the elements described herein as performing the recited function and not only structural equivalents, but also equivalent elements.